Dissertations / Theses: 'Food matrices'

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Llorca-Casamayor, Marta. "Analysis of perfluoroalkyl substances in food and evironmental matrices." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/97204.

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Per- and poly- fluoroalkyl substances (PFASs) are a group of manmade substances synthesised for more than 60 years. Due to their specific properties, PFASs have been widely used for industrial applications including: electronics, textiles, food packaging, flame retardant formulae and laboratory tools, among others. However, it was during the last fifteen years ago that interest for this group of compounds as environmental pollutants was initiated. Due to their high release levels into the environment, stability and accumulation, PFASs have been found ubiquitous in the environment and in biota. In this context, the main goal of this doctoral PhD thesis was the study of the occurrence, fate and behaviour of a wide range of PFASs in the environment, in food and, finally, in some human matrices. In addition, the physicochemical properties studies and the aerobic biodegradation experiments of 3 perfluoroalkyl phosphonic acids were also evaluated. Therefore, the first specific objective was the development of different analytical methods to study a wide range of PFASs in selected matrices. The analytical methods have been based on the use of on-line chromatography and off-line extraction, followed by liquid chromatography coupled to tandem mass spectrometry. These methods have been employed to assess the presence of PFASs in different type of waters from different steps along the water cycle, and also in fish and other food commodities. And finally, the PFAS accumulation in human samples was studied in cord blood and breast milk. This work is divided into six chapters. The first chapter is the general introduction and the objectives of this PhD Thesis. In the introduction, different aspects are revised, such as synthesis and global production, environmental fate and occurrence, human accumulation, toxicology, regulations and future trends. Chapters 2, 3, 4 and 5 present the experimental work undertaken during this research. Each chapter has been divided into a specific introduction, results (presented through the corresponding publications) and discussion. Part of the results contained in Chapters 2 and 5 correspond to the experimental work carried out in the laboratory of Prof. Dr. Thomas P. Knepper (Hochschule Fresenius, Idstein, Germany) during a four month research internship, a part of the European Doctoral Programme. Chapter 6 contains the general conclusions. Finally, a small summary in Catalan is presented. The cited literature and indexes for tables and figures can be found at the end of this work, as well as the list of publications produced along the duration of the pre-doctoral studies, but which are not presented in this thesis. The distribution of the publications included in this Thesis is the following: Chapter 2: Environmental occurrence Publication 1: “Analysis of perfluoroalkyl substances in waters from Germany and Spain.” Llorca, M., Farré, M., Picó, Y., Müller, J., Knepper, T. P. and Barceló, D. (2012). Science of The Total Environment, 431(0): 139-150. Publication 2: “Analysis of perfluorinated compounds in sewage sludge by pressurized solvent extraction followed by liquid chromatography–mass spectrometry.” Llorca, M; Farré, M; Picó, Y; Barceló,D; (2011). Journal of Chromatography A, 1218 (30) 4840-4846. Publication 3: “Fate of a broad spectrum of perfluorinated compounds in soils and biota from Tierra del Fuego and Antarctica.” Llorca, M., Farré, M., Tavano, M. S., Alonso, B., Koremblit, G. and Barceló, D. (2012). Environmental Pollution 163(0): 158-166. Chapter 3: PFASs in food Publication 4: “Development and validation of a pressurized liquid extraction liquid chromatography-tandem mass spectrometry method for perfluorinated compounds determination in fish.” Llorca, M., Farré, M., Picó, Y., and Barceló, D. (2009). Journal of Chromatography A 1216(43): 7195-7204. Publication 5: “Study of the performance of three LC-MS/MS platforms for analysis of perfluorinated compounds.” Llorca, M., Farré, M., Picó, Y., and Barceló, D. (2010) Analytical and Bioanalytical Chemistry 398(3): 1145-1159. Publication 6: “Infant exposure of perfluorinated compounds: Levels in breast milk and commercial baby food.” Llorca, M., Farré, M., Picó, Y., Teijón, M. L., Álvarez, J. G. and Barceló, D. (2010). Environment International 36(6): 584-592. Chapter 4: PFASs accumulation in humans Publication 7: “Analysis of perfluoroalkyl substances in cord blood by turbulent flow chromatography coupled to tandem mass spectrometry.” Llorca, M., Pérez, F., Farré, M., Agramunt, S., Kogevinas, M. and Barceló, D. (2012). Science of The Total Environment 433(0): 151-160.
Les substàncies per- i poli- fluorades (PFASs) són d’origen antropogènic. Aquest ampli grup de compostos s’ha sintetitzat durant més de 60 anys. Degut a les seves propietats específiques s’utilitzen encara en l’actualitat en diferents aplicacions industrials tals com: electrònica, recobriments tèxtils, embolcall d’aliments, escumes ignífugues i material de laboratori entre d’altres. No obstant, no ha estat fins els últims 15 anys quan a aquests compostos se’ls ha començat a considerar contaminants ambientals. Degut als nivells que es troben en el medi ambient, l’estabilitat i l’acumulació que presenten, aquests anàlits tenen una distribució global en el medi i en biota. En aquest context, el principal objectiu d’aquesta tesi doctoral ha estat l’estudi de la presència, destí i comportament d’un ampli grup de PFASs (13 àcids prfluoroalquílics, 4 perfluorosulfats, 1 perfluorosulfonamida i 3 àcids perfluorofosfònics) en el medi ambient, aliments i, finalment, en algunes matrius humanes. En paral•lel a l’estudi dels esmentats treballs, s’han realitzat en experiments per determinar algunes de les propietats fisicoquímiques i la possible biodegradació aeròbica de 3 àcids perfluorofosfònics. Per aquest motiu, el primer objectiu específic ha esta el desenvolupament de diferents mètodes analítics per a l’estudi d’aquests anàlits en les matrius seleccionades. Els mètodes analítics desenvolupats han inclòs tant mètodes d’extracció fora de línia com de cromatografia en línia, seguit d’una separació per cromatografia líquida acoblada en tàndem a l’espectrometria de masses. Aquests mètodes han estat utilitzats per al posterior estudi de la presència de PFASs en diferents mostres d’aigua provinents de tot el cicle de l’aigua així com peix i altres aliments. Finalment, l’acumulació de PFASs en humans s’ha estudiat a partir de l’anàlisi de mostres de sang de cordó umbilical i llet materna.

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PIRAS, CRISTINA. "Metabolomic investigation of food matrices by ¹H NMR spectroscopy." Doctoral thesis, Università degli Studi di Cagliari, 2012. http://hdl.handle.net/11584/266182.

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The present Ph.D. work shows some applications on the NMR-based metabolomic approach in food science. The investigated food matrices are largely different, from a manufactured product that undergoes only physical treatments (bottarga), to a manufactured product where biochemical transformations take place (Fiore Sardo cheese), and, finally, a raw food (Argentina sphyraena). All of these food matrices were not chosen by chance, but they represent an important piece of economy of the island of Sardinia, or might be further valorized, gaining more importance in the near future. Indeed, bottarga and Fiore Sardo are typical products exported all over the world, while Argentina sphyraena is a fish a low economic interest, finding no appreciation, at the moment, on the market. The results of this PhD study have contributed with new insights and deeper understanding of the potential perspective of the combined NMR/multivariate methods approach in food science, showing the great versatility of NMR spectroscopy and the strong synergetic relation between NMR and chemometrics. NMR revealed its extraordinary potential, when applied to natural samples and products, while chemometric analytical technique proved to be an essential tool to get information on the properties of interest (e.g., geographical origin for bottarga) based on the knowledge of other properties easily obtained (i.e. NMR spectra). The investigation performed on bottarga demonstrated that a NMR-based metabolomics technique can be a powerful tool for the detection of novel biomarkers and establishing quality control parameters for bottarga. The work presented in this study evidenced the effectiveness of metabolite fingerprinting as a tool to distinguish samples according both to the geographical origin of fish and the manufacturing process. The results relative to the Fiore Sardo showed the potential of the combination of NMR spectroscopy and chemometrics as a promising partnership for detailed cheese analysis, providing knowledge that can facilitate better monitoring of the food production chain and create new opportunities for targeted strategies for processing. Such analysis may be performed in any stage of the cheese manufacturing, allowing for thorough evaluation of every step in the process. Finally, the preliminary results relative to the metabolomic investigation of Argentina sphyraena should certainly serve as a basis for implement a research tool able to provide deeper insights on the biology of this fish species with all advantages offered by the metabolomics approach.

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Bugatti, Valeria. "Dispersion of inorganic fillers in polymeric matrices for food packaging applications." Doctoral thesis, Universita degli studi di Salerno, 2012. http://hdl.handle.net/10556/274.

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2010 - 2011
The objective of this PhD project regards the formulation, preparation and characterization of polymeric materials in which lamellar inorganic solids containing potentially active molecules are dispersed. In particular the present work was aimed at the preparation and characterization of "Active Food Packaging Materials" using inorganic fillers modified with active molecules (antimicrobials, antioxidants) dispersed in polymeric matrices for the realization of: 1) Materials with improved barrier properties to gases and vapors 2) Systems for controlled release of active molecules, act to protect and extend the shelf life of food products. Two techniques of dispersion of active inorganic fillers in polymer matrices have been used, generating: 1) polymeric nanocomposites 2) coatings of polymeric surfaces. A screening of different polymers, from biodegradable and thermoplastic to natural, was done to compare the effect of the fillers and of the dispersion technique on the properties mentioned above.[edited by author]
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Andreani, Nadia Andrea. "INTO THE BLUE: Spoilage phenotypes of Pseudomonas fluorescens in food matrices." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424342.

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Spoilage induced by Pseudomonas strains is commonly found in a wide range of food products as a result of the ubiquitous presence of these strains and their ability to induce alteration through different mechanisms. Particular attention has been recently paid on those P. fluorescens strains able to induce a blue discolouration on several food matrices (e.g. dairy or meat products). Actually, poor data are available about this curious event that draw the attention of European consumer from 2010. In the present manuscript a step-by-step investigation of the spoilage potential of Pseudomonas fluorescens species complex strains is reported, focusing in particular on the ability to produce an unpleasant blue pigment in food. Firstly, some general information is given to the reader to understand the P. fluorescens group as food spoiler. Then, the application of a polyphasic approach is described with the aim to investigate 136 Pseudomonas fluorescens group strains. Additionally, the achievement and the analyses of draft genomes and transcriptomes for 4 P. fluorescens strains are described to investigate the biosynthetic pathways involved in the blue pigment production. The attempt to chemically characterise the blue molecule using MALDI-TOF mass spectrometry is also reported. Finally, the execution of a transposon-mediated mutagenesis is described to confirm previously obtained genomic data and to highlight further genes involved in the blue-pigment production. The phenotypic and genotypic characterisation, based on the combination of classical microbiological tests and a MLST scheme, allowed the reconstruction of phylogenetic relationships among the isolates and the identification of a monophyletic group (named “the blue branch”) grouping all the blue-pigmenting and few uncoloured strains. The real involvement of these strains in the blue mozzarella event was confirmed by their ability to induce a blue discolouration on mozzarella cheese during a challenge test. The genomic investigation confirmed the strict phylogenetic relationship between the strains belonging to the “blue branch”. Additionally, comparative genomic tools revealed the presence of a genetic cluster unique to the blue pigmenting strains containing a second copy of five trp genes, clearly involved in the blue pigment production. The biochemical characterisation of the pigment, hampered by strong issues of solubility, led to the conclusion that the molecule is an indigo-derivative. Transposon-induced mutants confirmed the involvement of the previously identified unique cluster and the association of several genes affecting directly or indirectly the blue molecule production. Furthermore, the phenotypic characterisation of the mutants revealed a key role of iron in the production of the pigment, such as absence of any advantage of the wild-type strain in co-culture with a non-pigmenting mutant. To conclude, the present work represents an exhaustive investigation of the spoilage potential of the blue-pigmenting P. fluorescens strains, giving to food industry reliable approaches to identify, track and prevent spoilage related to the growth of these interesting bacteria.
Le alterazioni causate da ceppi di Pseudomonas sono solitamente riscontrate in una grande varietà di alimenti a causa del loro essere ubiquitari e dalla loro capacità di indurre modificazioni organolettiche negli alimenti mediante diversi meccanismi. Particolare attenzione è stata posta su alcuni ceppi di P. fluorescens in grado di indurre una colorazione blu in diverse matrici alimentari (quali prodotti lattiero-caseari o carne). In realtà, poche informazioni sono ad oggi disponibili riguardo al curioso caso che ha attirato l’attenzione pubblica a partire dal 2010. In questo lavoro è riportata un’analisi a più livelli del potenziale alternate dei ceppi appartenenti allo Pseudomonas fluorescens species complex, ponendo particolare attenzione alla capacità di produrre un indesiderato pigmento blu negli alimenti. In primo luogo, ai lettori sono date delle informazioni generali per una migliore comprensione di P. fluorescens come alterante alimentare. In seguito, è descritta la messa a punto e applicazione di un approccio polifasico con l’obbiettivo di indagare 136 ceppi appartenenti al gruppo P. fluorescens. Inoltre, sono descritti l’ottenimento e le analisi dei genomi draft e dei trascrittomi di 4 ceppi di P. fluorescens con la finalità di comprendere il pathway biosintetico coinvolto nella produzione del pigmento blu. In aggiunta, è riportato il tentativo di caratterizzare chimicamente il pigmento mediante la metodica della spettrometria di massa MALDI-TOF. Infine, è riportata l’esecuzione della mutagenesi random con la finalità di confermare i risultati genomici precedentemente ottenuti e di individuare ulteriori geni coinvolti nella produzione del pigmento blu. La caratterizzazione fenotipica e genotipica, basata sulla combinazione di metodiche di microbiologia classica e di uno schema MLST, ha permesso la ricostruzione delle relazioni filogenetiche tra gli isolati e l’identificazione di un gruppo monofiletico (chiamato “ramo blu”) che raggruppa tutti i ceppi pigmentanti e pochi ceppi non-pigmentanti. Il reale coinvolgimento dei ceppi blu nei casi di mozzarella blu è stato confermato dalla possibilità degli stessi di indurre un’anomala colorazione blu su mozzarella durante un challenge test. Le analisi genomiche hanno confermato la stretta vicinanza filogenetica tra i ceppi del “ramo blu”. Inoltre, analisi di genomica comparativa hanno rivelato la presenza di un cluster genico unicamente presente nei ceppi blu, contenente una seconda copia di cinque dei sette geni per la biosintesi del triptofano, chiaramente coinvolto nella produzione del pigmento blu. La caratterizzazione biochimica del pigmento, resa difficoltosa da problemi di solubilità, ha portato alla conclusione che la molecola blu sia un derivato dell’indigo. I mutanti ottenuti mediante l’applicazione di trasposoni hanno confermato il coinvolgimento del cluster genico precedentemente identificato nella produzione del pigmento e l’associazione di ulteriori geni che influenzano direttamente o indirettamente la produzione della molecola blu. Inoltre, la caratterizzazione dei mutanti ha rivelato il ruolo importante del ferro nella produzione del pigmento e l’assenza di un effettivo vantaggio del ceppo wild-type posto in co-cultura con un mutante non pigmentante. In conclusione, questo studio rappresenta un’indagine esaustiva del potenziale alterante dei ceppi blu, dando inoltre all’industria alimentare sistemi efficaci per identificare, tracciare e prevenire l’alterazione indotta da questi interessanti ceppi.

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Milke, Donka Todorova. "Characterization of the growth/survival of Francisella tularensis in selected food matrices." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/32815.

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Master of Science
Food Science Institute
Randall K. Phebus
Francisella tularensis is a Gram-negative bacterium that can cause tularemia in humans. The disease can be acquired through several routes, one of which is the ingestion of contaminated food and water. The pathogen has the potential to be used as a biological weapon, and its intentional introduction in the food supply is a possible way to cause public harm. The purpose of this study was to evaluate the growth and/or survival of F. tularensis in food matrices under various storage conditions. Cystine Heart Agar enriched with 2% hemoglobin and supplemented with antibiotics was used to aid the enumeration of the target organism by suppressing the levels of indigenous microflora in foods. During the first portion of the study, the growth/survival of highly virulent F. tularensis subsp. tularensis SCHU S4 strain was investigated in prepared bagged iceberg lettuce stored at two temperatures. F. tularensis counts were significantly different (p≤0.05) among temperature levels for days 1-3, but not day 4. After the first 24 h of incubation, the mean estimates of F. tularensis counts were 1.00 log cfu g⁻¹ lower in lettuce stored at 23±1°C compared to lettuce stored at 6±1°C. Lower recovery rates at higher temperatures are likely due to the more rapid proliferation of naturally present bacteria which can inhibit the growth of F. tularensis. After 48 and 72 h, differences in F. tularensis counts between temperatures were 0.55 log cfu g⁻¹ and 0.3 log cfu g⁻¹, respectively. For the second portion of the experiment, the ability of F. tularensis to grow or survive was evaluated in nine food matrices with variable compositional content (red delicious apples, green bell pepper, shredded iceberg lettuce, strawberries, whole liquid eggs, boneless ham steak, beef hot dogs, 80-20 ground beef, and 2% UHT milk) at 4, 21, and 37°C. F. tularensis grew well in pasteurized whole liquid eggs stored at 21 and 37°C. With the exception of ham, liquid whole eggs, and bell pepper, the pathogen was detected infrequently throughout the duration of the study. Very low recovery rates were obtained for shredded lettuce, hot dogs, and ground beef.

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MARINELLI, VALERIA. "Optimization of food matrices enriched with bioactive compounds from fruits and vegetables." Doctoral thesis, Università degli Studi di Foggia, 2019. http://hdl.handle.net/11369/382620.

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Negli ultimi decenni, argomenti quali sostenibilità, impatto ambientale e smaltimento degli scarti sono ampiamente discussi in tutto il mondo. Il pianeta è severamente minacciato dalle azioni dell’uomo e se non si interviene tempestivamente con azioni correttive, la prosperità delle future generazioni sarà compromessa. In particolare, il settore alimentare sta suscitando molta attenzione in quanto è responsabile della generazione di enormi volumi di scarti. Attualmente il sistema alimentare è costretto ad aumentare la produzione per far fronte alla crescita della popolazione mondiale, ma allo stesso tempo deve affrontare il problema dei rifiuti e delle risorse naturali limitate. Ogni anno vengono generati milioni di tonnellate di sottoprodotti alimentari lungo l’intera filiera: dalla produzione industriale fino al consumo casalingo, costituendo un serio problema sia economico che ambientale. In genere, i sottoprodotti industriali sono gestiti come scarti, ovvero vengono inviati alle discariche dove vengono trasformati in gas serra mediante digestione anaerobica. Questo impatta negativamente sull’ambiente, causando cambiamenti climatici, e arreca danni economici al produttore, costretto a sostenere spese per il loro smaltimento. Quindi, nell’ottica della sostenibilità, è necessaria un’adeguata strategia di gestione degli scarti. A tal proposito, la teoria dello “zero-waste” risulta molto interessante. Si tratta di un sistema di gestione il cui scopo è di riciclare i sottoprodotti, utilizzandoli come risorse in altri sistemi di produzione. In questo modo nessuno scarto verrà mandato agli inceneritori o alle discariche. Negli ultimi anni anche i bisogni del mercato sono cambiati in quanto i consumatori sono sempre più consapevoli dei problemi di salute legati all’alimentazione. Di conseguenza, alimenti con ingredienti naturali e una migliore qualità nutrizionale sono sempre più richiesti. Pertanto, i sottoprodotti alimentari, soprattutto quelli provenienti dal settore ortofrutticolo, ampiamente riconosciuti come fonti eccellenti di composti bioattivi, possono essere usati come ingredienti naturali per fortificare i comuni alimenti che vengono consumati quotidianamente. Queste risorse possono essere usate come coloranti naturali o come ingredienti naturali ad alto valore per produrre alimenti con proprietà funzionali, che possono avere effetti positivi sulla salute umana, come riduzione del colesterolo e del rischio di varie malattie croniche, quali diabete, malattie cardiovascolari e cancro. Tuttavia, l’incorporazione delle sostanze vegetali all’interno degli alimenti influenza le proprietà tecnologiche e sensoriali, pertanto la sfida è di trovare un compromesso tra gli aspetti nutrizionali e sensoriali in quanto aumentando la concentrazione dei prodotti vegetali la qualità nutrizionale del nuovo alimento migliora mentre peggiora quella sensoriale. In questo contesto, il presente lavoro di dottorato si è focalizzato sull’arricchimento di matrici alimentari con sottoprodotti di origine vegetale e sulla loro relativa ottimizzazione. In particolare, prodotti cerealicoli, quali pane e pasta, sono stati usati come veicoli di sostanze benefiche per la salute essendo alimenti base della dieta umana in tutto il mondo. Il pane è stato arricchito con farina di scarti di carciofo, mentre gli spaghetti con farina di vinaccia rossa. Inoltre, è stato preso in considerazione lo sviluppo di una caramella a base di anguria fortificata con scarti di arancia, essendo un prodotto destinato a un vasto gruppo di consumatori (dai bambini agli anziani). Infine, gli estratti di scarti di broccolo sono stati proposti come ingredienti per fortificare burger di pesce. Ogni caso studio affrontato dimostra come i sottoprodotti vegetali possono essere usati come materia prima di alto valore permettendo di produrre alimenti con proprietà salutari, soddisfando le nuove esigenze dei consumatori e riducendo allo stesso tempo il problema dell’inquinamento ambientale
Over the last few decades, topics such as sustainability, environmental impact and waste disposal are widely discussed worldwide. The planet is severely threat by human actions and it is necessary to put in place corrective actions to keep the prosperity of future generations. In particular, the food sector is a priority area where you have to act immediately, given the enormous volumes of recorded waste. Currently, the food system is forced to increase the production to face world population growth, but at the same time it must address the waste problem and the limited natural resources. Every year millions tonnes of food by-products are generated along the whole chain: from industrial production until household consumption, becoming a serious economic and environmental problem. These are commonly managed as waste, therefore sent to landfills, where turned into greenhouse gas by anaerobic digestion. This negatively impacts on the environment, causing climate changes, and provoking economic problems to the producers, being their disposal not free. Thus, in the optic of sustainability, an appropriate strategy of waste management becomes necessary. In this regard, the “zero waste” theory is very interesting. It is a waste management system whose aim is to recycle waste, being considered a resource to be reused in other productions. Zero waste manufacturing involves designing of products and processes in which no trash is sent to landfills or incinerators. In recent years market needs have changed because of consumers’ increasing awareness of diet related health problems. As a result, foods with natural ingredients and a better nutritional quality are increasingly in demand. Therefore, the food by-products, especially fruit and vegetable ones, widely recognized as excellent sources of bioactive compounds, can be used to fortify common foods eaten daily, improving their nutritional value. These can be used as natural colorants or as high-value natural ingredients to produce foods with functional properties, that can have positive effects on human health, such as reducing cholesterol and risk of various chronic diseases, including diabetes, cardiovascular diseases and cancer. However, their incorporation into food products affects the technological and sensory properties, so the challenge is to find a compromise between the nutritional and sensory aspects of enriched foods. In this context, the present PhD research study has been focused on the enrichment of food matrices with plant by-products and their relative optimization. In particular, cereal products, as bread and pasta, were used as vehicles of beneficial substances from fruit and vegetables by-products, being staple food within human diet. The bread was enriched with artichoke leaf flour, while spaghetti with red grape marc. In addition, the development of a watermelon-based jelly candy enriched with orange by-products was taken into account, being a product intended for a large group of consumers (from children to adults). Finally, the broccoli by-products extracts were proposed as ingredients to fortify fish-burger. Each case study addressed proves that vegetable by-products from industrial processing can be used as high value food ingredients, allowing to better satisfy consumer demand for healthy food products in a more sustainable perspective.

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Caldera, L. "IDENTIFICATION AND CHARACTERIZATION OF SPECIFIC SPOILAGE ORGANISMS (SSOS) IN DIFFERENT FOOD MATRICES." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/230015.

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This PhD thesis aims to improve the actual systems of management and quality control of food, expanding the knowledge about the microorganisms responsible of food spoilage (Specific Spoilage Organisms) and their degradative activities. The analysed foods were of vegetable and animal origin: in particular they were ready-to-eat vegetables (carrots and green salads packaged in air and MAP), milk and dairy products (raw, pasteurized, UHT and micro-filtered milk and mozzarella cheese) and beef and hamburger packaged traditionally or in master bag. Firstly the microbial quality of each food was monitored from the production, during the declared shelf life and even after the expiration date. The isolates were phenotypically and genotipically characterized and identified; for each food SSOs were recognized. Some microorganisms appeared typical of each product, sometimes also depending on the packaging and storage conditions. Leuconostoc spp. was indicated as typical carrots spoiler; Enterobacteriaceae family was involved in spoilage of salads packaged under modified atmosphere; lactic acid bacteria were typical of food packaged in low oxygen concentrations (salads in MAP and meat in master bag) and Brochothrix thermosphacta was specific of beef. Pseudomonas spp. appeared common to all the analysed products and dominant among the bacterial spoilers. For this genus more detailed studies were conducted: the classification was made up to the biotype and biovar level; the characterization focused on different enzymatic activities and in particular the proteolysis was qualitatively and quantitatively evaluated; a phylogenetic study, based on the gene codifying for the most common Pseudomonas protease, was made. Subsequently each food was analysed with a different approach. For vegetables the influence of temperature on microbiota was verified, resulting that low temperature slowed down microbial growth and partially modified the composition of the microbiota. In milk proteolytic activity of Pseudomonas spp. was evaluated and the formation of Pseudo-GMPs, deriving from the cutting of K-casein (103-104 position), were recognized. In mozzarella the blue pigment formation was studied and a rapid method for the detection and the quantification of alive, dead and Viable But Non Colturable (VBNC) cells was set up. For meat, a primer specific for Brochothrix genus was built and the packaging conditions were studied to verify the evolution of microbiota and the possible effects on the growth of Listeria monocytogenes (challenge test).

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Collette, Catherine. "Détection des virus entériques dans les matrices alimentaires." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1060.

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Les principaux virus entériques à l’origine de toxi-infections alimentaires collectives (TIAC) sont les norovirus (NoV) et les virus d’hépatites (VHA et VHE) responsables respectivement de gastro-entérites et d’hépatites. Ces virus entériques sont transmis principalement par la voie féco-orale directe ou par ingestion d‘eaux ou d’aliments consommés crus ou peu cuits tels que les mollusques et les végétaux. La norme CEN/ISO 15216 propose des méthodes d’extraction et de détection par RT-qPCR pour les NoV et le VHA dans les végétaux, l'eau et les mollusques bivalves. Mais en cas de TIAC, divers aliments peuvent être suspectés et ces dernières années le VHE dont le potentiel zoonotique a été démontré est devenu un virus d’intérêt en hygiène alimentaire. Les travaux de thèse ont pour objectif le développement de méthodes de diagnostic viral dans le domaine alimentaire.Ces travaux ont permis de développer des méthodes pour la détection des NoV dans les produits laitiers et pour l’extraction du VHA à partir de tomates semi-séchées, aliments incriminés dans des épidémies d’hépatite A en Europe. De plus, le développement d’une méthode d’extraction et de détection du VHE par RT-PCR quantitative a permis d’estimer la prévalence du VHE dans les figatelli et les saucisses sèches de foie à environ 30%, confortant ainsi la possibilité d’une transmission du VHE à l’homme via ces aliments.Dans la norme CEN/ISO, la validation du diagnostic viral repose en partie sur l’ajout d’un virus contrôle de processus afin de mesurer l’efficacité de l’extraction virale. Des travaux ont montré que le choix du virus contrôle de processus était fonction de la matrice alimentaire analysée et du virus recherché.Dans le but de rechercher simultanément les NoV de génogroupe I et II et le virus contrôle de processus, une RT-qPCR multiplex a été développée pour les eaux de consommation et a montré une sensibilité similaire à la RT-qPCR en simplex. Récemment, la digital PCR (RT-dPCR) a été décrite comme une nouvelle approche de quantification absolue des génomes qui ne nécessite pas l’utilisation de gamme standard. L’évaluation des performances de quantification des génomes du VHE par RT-dPCR en microfluidique dans des matrices à base de foie naturellement contaminées a montré que la RT-dPCR permettait la quantification du VHE avec une sensibilité similaire par rapport à la RT-qPCR.En conclusion, ces travaux ont permis de contribuer à l’amélioration du diagnostic viral dans le domaine alimentaire
The main enteric viruses that cause foodborne outbreaks are noroviruses (NoV) and viruses of hepatitis (VHA and VHE) respectively responsible of gastroenteritis and hepatitis. These enteric viruses are mainly transmitted by the direct fecal-oral way or by the ingestion of water or raw or undercooked food such as shellfish and vegetables. The standard CEN/ISO 15216 proposes methods of extraction and detection by RT-qPCR for NoV and VHA in vegetable, water and shellfish. But in case of foodborne outbreaks, different foods can be suspected and these last years the VHE the zoonotic potential of which was demonstrated became a virus of interest in food hygiene. This thesis works aim to propose development of methods of viral diagnosis in the food domain.These works allowed to develop methods for the detection of the NoV in dairy products and for the extraction of the VHA from semi-dried tomatoes, food were incriminated in epidemics of hepatitis A in Europe. Furthermore, the development of a method of extraction and detection of the VHE by quantitative RT-PCR allowed to estimate prevalence of the VHE in figatelli and dried sausages of liver at approximately 30 %, so consolidating the possibility of a transmission of the VHE to the man via this food.One of the general requirements for detecting these viruses in food involves the use of a process control virus to monitor the quality of the entire viral extraction procedure as described in the standard CEN/ISO. Studies showed that the choice of virus depends on food type and the screened pathogenic virus.An one-step multiplex RT-qPCR assay was developed in bottled and tap water for the simultaneous detection of NoV GI, NoV GII and process control virus and showed a sensibility similar to the RT-qPCR simplex. Recently, digital PCR (RT-dPCR) has been described as a novel approach to genome quantification with no need for a standard curve. The performance of microfluidic RT-dPCR was compared to RT-qPCR when detecting HEV in pig liver products. The sensitivity of the RT-dPCR assay was similar to that of RT-qPCR.To summarize, this work has contributed to the improvement of the viral diagnosis in the food microbiology

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9

Li, Yue. "Analysis of acidity in oil-based matrices by infrared spectroscopy." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86906.

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The feasibility of employing a portable variable filter array (VFA) infrared spectrometer equipped with a transmission flow cell to quantitatively analyze edible oils for free fatty acids (FFA) was evaluated. The approach to FFA determination was based on a previously reported FTIR method that involves the extraction of FFAs into methanol containing the base sodium hydrogen cyanamide (NaHNCN), which converts the FFAs to their salts, followed by measurement of the carboxylate absorbance at 1571 cm-1 in the spectrum of the methanol phase. The VFA IR spectrometer, which had a relatively weak pulsed IR source, was found to provide insufficient energy for accurate measurement of the carboxylate absorption superimposed on the strong methanol absorption at 1450 cm-1. By changing the extraction solvent to ethanol, good spectra and calibrations having an overall SD of ±0.07% FFA could be obtained. This work in turn led to the investigation of an ethanol solution of NaHNCN as a signal transduction reagent for Acid Number (AN) analysis in mineral-based lubricants, whereby total acidity would be measured by monitoring the decrease of the νC≡N absorption of NaHNCN at 2109 cm-1 as a result of the acid/base reaction. The equivalent response of the νC≡N band to strong inorganic acids and oleic acid demonstrated that NaHNCN, a somewhat weaker base than KOH, fully ionizes organic acids. Calibration standards were prepared by direct addition of oleic acid to the NaHNCN/ethanol solution, and a calibration equation for the determination of AN was obtained by a quadratic fit of the concentration data to the FTIR νC≡N absorbance data. The AN values obtained for ethanolic NaHNCN extracts of used oils by the FTIR method correlated well with those produced by titration of these extracts. Comparison between FTIR and titrimetric AN values (obtained by ASTM Standard Method D664-89) for a set of used oils spanning an AN range of 0.3-5 mg KOH/g showed a reasonably good linear relati
La praticabilité d'utiliser un spectromètre infrarouge portatif comportant un filtre variable superposé à une barrette de détecteurs (dénommé un spectromètre VFA IR) et équipé d'une cellule d'écoulement de transmission pour analyser quantitativement les huiles de table pour leur teneur en acide gras libre (AGL) a été évaluée. L'approche à la détermination de la teneur en AGL a été basée sur une méthode précédemment élaborée sur un spectromètre infrarouge à transformée de Fourier (IRTF) qui implique l'extraction des AGL dans le méthanol contenant le cyanamide d'hydrogène de sodium, qui convertit les AGL en leurs sels, suivie de la mesure de l'absorbance de carboxylate à 1571 cm-1 dans le spectre de la phase de méthanol. L'Énergie fournie par la source pulsée relativement faible du spectromètre VFA IR s'est avérée insuffisante pour la mesure précise de l'absorption de carboxylate superposée à l'absorption forte de méthanol à 1450 cm-1. En changeant le dissolvant d'extraction en éthanol, de bons spectres et des courbes d'étalonnage ayant un écart-type global de ±0.07% AGL ont pu être obtenus. Ce travail a à son tour mené à la recherche sur l'utilisation d'une solution d'éthanol et de NaHNCN comme réactif de transduction de signal pour une analyse de nombre acide (NA) en huiles lubrifiantes à base minérale, par lequel l'acidité totale soit mesurée par la diminution de l'absorption νC≡N du NaHNCN à 2109 cm-1 comme résultat de la réaction acide-base. La réponse équivalente de l'absorption νC≡N aux acides inorganiques forts et à l'acide oléique a démontré que le NaHNCN, une base légèrement plus faible que le KOH, ionise entièrement les acides organiques. Des solutions étalons ont été préparées par l'addition directe de l'acide oléique à la solution de NaHNCN/éthanol, et une équation de calibrage pour la détermination de NA a été obtenue par un ajustement quadratique des données de co

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10

Park, Clifford. "Physical Properties of Oleocolloid and Hydro-Oleocolloid Matrices Made of Whey Protein and Oleogel." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618592720965005.

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11

Frederick, Jennifer Leanne. "EVALUATION OF SEPARATION METHOD ADDITIVES FOR THE RECOVERY OF BACTERIA FROM FOOD MATRICES." UKnowledge, 2012. http://uknowledge.uky.edu/bae_etds/10.

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The microbiological testing of foods is a well-established science. Due to the severity of foodborne pathogen illnesses, the widespread use and implementation of rapid detection methods in food testing labs is increasingly important. The first step for successful testing is sampling. Surfactants have been highly used in food microbiology, but there is not much, if any, published research about the use of fatty alcohols and chemical dispersants as aids in microbial separation. The microbial extraction efficiency of Escherichia coli K12 and Listeria innocua from hot dogs, spinach, and milk was measured using chemical additives (surfactants, fatty alcohols, and a chemical dispersant) in a buffer solution. Dry matter content was calculated using the oven method to determine how clean the sample was at the end of processing. Tween 80 at 0.01% was found to be the most effective additive for microbial recovery for each food matrix examined. The addition of fatty alcohols to surfactants also showed much promise in aiding separation as well as in minimizing dry matter in the final solution. However, the use of Buffered Peptone Water as the diluting agent resulted in very high recovery percentages without the need for additives.

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12

Hajjar, Ghina. "Authentication of food matrices using lipid markers obtained by isotopic and metabolomic NMR." Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4083.

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Les indications relatives aux origines (géographique, botanique ou animale) des aliments constituent des critères de vente persuasifs surtout lorsque la provenance est reliée étroitement à la qualité du produit. Les risques de fraudes étant non négligeables, la mise en place de méthodes d’authentification robuste est alors une nécessité. La Résonance Magnétique Nucléaire (RMN) est l’une des techniques analytiques utilisées à cette fin. Elle permet d’identifier des marqueurs d’origines au sein de la matrice en question. A cet égard, les lipides peuvent être considérés comme source quasi-universelle de biomarqueurs grâce à leur présence ubiquitaire dans les matrices alimentaires. Dans ce projet, la spectroscopie RMN a été utilisée pour la caractérisation des lipides et pour l’identification de biomarqueurs métabolomiques et isotopiques qui permettent de remonter à l’origine des produits analysés. L’œuf de poule a servi de matrice modèle pour mener nos investigations. Les analyses des triacylglycérols (TAG), des phospholipides (PL) et du cholestérol ont été réalisées après amélioration des protocoles d’extraction, d’acquisition et de traitement de leurs spectres RMN 1H et 13C. Les données métabisotopomiques (métabolomiques et isotopiques), obtenues de la déconvolution spectrale (utilisées comme variables d’entrée pour la construction de modèles), ont permis la classification des échantillons selon leur origine et selon la race et le système d’élevage des poules. Les variables métabolomiques ont aussi servi à la quantification individuelle des acides gras dans les TAG et les PL, y compris ceux présents en quantités minimes tels que les acides punicique, ruménique et d’Osbond
Origin of food products is an important criterion that affects the costumer’s choice since the food quality is determined, among other factors, by geographical and botanical or animal origins. The risk of fraud being considerable, implementation of robust authentication methods is then an urge. Nuclear Magnetic Resonance (NMR) is one of the analytical tools used for this purpose. It allows the identification of origin-related markers within the studied matrix. In this respect, lipids can be considered as a source of quasi-universal biomarkers due to their ubiquitous presence in food matrices. In this project, NMR spectroscopy was used for characterization of lipids and for identification of metabolomic and isotopic biomarkers tracing back origin of analyzed product. Hen egg served as a model matrix to conduct our investigations. Analyzes of triacylglycerols (TAG), phospholipids (PL), and cholesterol were carried out after improving extraction protocols and acquisition and processing conditions of their 1H and 13C NMR spectra. Metabisotopomic (metabolomic and isotopic) data resulting from spectral deconvolution were used as predictors in multivariate discriminant analysis allowing classification of samples according to their origin, to the hen breed, and to the farming system. Metabolomic variables were also used for the individual quantification of fatty acids within TAG and PL, even those present in minute amounts such as punicic, rumenic and Osbond acids

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Roberts, Beverley. "The development and critical evaluation of an immunoassay for hypoxanthine in biological matrices." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/847948/.

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A classical radioimmunoassay for hypoxanthine was developed and validated. Hypoxanthine, being a low molecular weight compound (M.W. 136.11) is not immunogenic unless first attached to a macromolecule such as a protein. Derivatives of hypoxanthine were synthesised for this purpose. In addition to the standard preparation of 6-trichloromethyl purine, a derivative of this compound with a 4-carbon spacer arm was prepared, namely purine-6-carboxypropanamide. Hypoxanthine itself showed an unusual degree of stability, having no reactivity towards reagents when considered in either the keto or the enol form. The use of 6-chloropurine, a far more reactive analogue of hypoxanthine, resulted in the synthesis of a novel carboxymethoxylamine derivative, purine-6-carboxymethyl oxime. Four conjugates were prepared using ovalbumin as carrier protein. Hypoxanthine derivatives with a free carboxyl group were conjugated using the mixed anhydride method. 6-trichloromethyl purine was reactive enough to be coupled directly. Hypoxanthine-9-B-D-arabinofuranoside was coupled using the periodate oxidation method for sugar derivatives with vicinal hydroxyl groups. As the hapten was linked via the E-amino groups of lysine residues in each case, the molar derivatisation of each conjugate was calculated by measuring the number of free amino groups in the protein before and after conjugation using 2, 4, 6-trinitrobenzene sulphonic acid. With one of the conjugates ultraviolet spectrophotometric analysis, and calculation of the amount of purine removed during dialysis were also used for comparison and confirmation of the value obtained. The antisera were affinity purified and twelve reagents were compared for their ability to elute anti-hypoxanthine antibodies, whilst retaining immunoreactivity of the eluted fractions. For the determination of hypoxanthine by radioimmunoassay two phase separation systems were investigated, namely chemical precipitation of antigen-antibody complexes using ammonium sulphate, and adsorption of free hypoxanthine using activated charcoal. The antisera were shown to be highly specific for hypoxanthine, with cross-reactivities to six analagous compounds being < 0.1%, and crossreactivity to two further compounds, adenine and allopurinol being 1.9 and 3.2% respectively. Recovery of hypoxanthine added to samples was of the order of 97.3%, and the limit of detection was > 150 nmole/g. Inter-assay coefficient of variation for the data points for the hypoxanthine standard curve was < 10% for hypoxanthine concentrations below 125 nmole/ml. Inter-assay coefficient of variation for samples of fish extract containing hypoxanthine was approximately 12%. Hypoxanthine levels increased with time in samples of trout and whitebait, so that its concentration was indicative of quality, but hypoxanthine levels in liver decreased with length of storage time. Hypoxanthine concentrations in fish samples, as determined by radioimmunoassay, were compared with the values obtained using a well established spectrophotometric method. The correlation coefficient for the two methods was 0.84507 (n = 45) using hypoxanthine solutions extracted from whitebait and 0.93298 (n = 33) for samples of trout muscle, so establishing the radioimmunoassay as a technique for measuring the quality of such foods.

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Noel, Robert. "The characterisation of alternative separation matrices for the use in the food and biopharmaceutical industries." Thesis, Teesside University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410838.

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Barbarossa, Andrea <1981&gt. "Perfluoroalkylated substances in food matrices: development of mass spectrometry based analytical methods and preliminary monitoring." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4670/1/barbarossa_andrea_tesi.pdf.

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Perfluoroalkylated substances are a group of chemicals that have been largely employed during the last 60 years in several applications, widely spreading and accumulating in the environment due to their extreme resistance to degradation. As a consequence, they have been found also in various types of food as well as in drinking water, proving that they can easily reach humans through the diet. The available information concerning their adverse effects on health has recently increased the interest towards these contaminants and highlighted the importance of investigating all the potential sources of human exposure, among which diet was proved to be the most relevant. This need has been underlined by the European Union through Recommendation 2010/161/EU: in this document, Member States were called to monitor their presence of in food, producing accurate estimations of human exposure. The purpose of the research presented in this thesis, which is the result of a partnership between an Italian and a French laboratory, was to develop reliable tools for the analysis of these pollutants in food, to be used for generating data on potentially contaminated matrices. An efficient method based on liquid chromatography-mass spectrometry for the detection of 16 different perfluorinated compounds in milk has been validated in accordance with current European regulation guidelines (2002/657/EC) and is currently under evaluation for ISO 17025 accreditation. The proposed technique was applied to cow, powder and human breast milk samples from Italy and France to produce a preliminary monitoring on the presence of these contaminants. In accordance with the above mentioned European Recommendation, this project led also to the development of a promising technique for the quantification of some precursors of these substances in fish. This method showed extremely satisfying performances in terms of linearity and limits of detection, and will be useful for future surveys.

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Barbarossa, Andrea <1981&gt. "Perfluoroalkylated substances in food matrices: development of mass spectrometry based analytical methods and preliminary monitoring." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4670/.

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Perfluoroalkylated substances are a group of chemicals that have been largely employed during the last 60 years in several applications, widely spreading and accumulating in the environment due to their extreme resistance to degradation. As a consequence, they have been found also in various types of food as well as in drinking water, proving that they can easily reach humans through the diet. The available information concerning their adverse effects on health has recently increased the interest towards these contaminants and highlighted the importance of investigating all the potential sources of human exposure, among which diet was proved to be the most relevant. This need has been underlined by the European Union through Recommendation 2010/161/EU: in this document, Member States were called to monitor their presence of in food, producing accurate estimations of human exposure. The purpose of the research presented in this thesis, which is the result of a partnership between an Italian and a French laboratory, was to develop reliable tools for the analysis of these pollutants in food, to be used for generating data on potentially contaminated matrices. An efficient method based on liquid chromatography-mass spectrometry for the detection of 16 different perfluorinated compounds in milk has been validated in accordance with current European regulation guidelines (2002/657/EC) and is currently under evaluation for ISO 17025 accreditation. The proposed technique was applied to cow, powder and human breast milk samples from Italy and France to produce a preliminary monitoring on the presence of these contaminants. In accordance with the above mentioned European Recommendation, this project led also to the development of a promising technique for the quantification of some precursors of these substances in fish. This method showed extremely satisfying performances in terms of linearity and limits of detection, and will be useful for future surveys.

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Gao, Fang. "Determination of small molecules in food matrices by molecularly imprinted polymers and surface enhanced Raman spectroscopy." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56280.

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The research work focuses on developing novel methods for determining small molecules in food matrices using molecularly imprinted polymers (MIPs) and surface enhanced Raman spectroscopy (SERS). MIPs are synthesized as artificial antibodies towards target molecules utilizing interactions between templates and functional monomers to impress complementary binding sites on polymers. MIPs selectively isolate templates from food extracts. SERS technique provides rapid and sensitive detection of MIPs-separated molecules. Statistical analysis including unsupervised principal component analysis (PCA), supervised simple linear regression and partial least square regression (PLSR) is employed to analyze SERS spectra. Chloramphenicol in milk and honey was determined using MIPs-packed solid phase extraction cartridge to isolate chloramphenicol from food matrices and dendritic silver to acquire SERS spectra of the eluted chloramphenicol. These spectra obtained from different spiked contents (0, 0.1, 0.5, 1, 5 ppm) of chloramphenicol in milk and honey were analyzed by PCA and PLSR (R > 0.9). MIPs particles were spread onto a thin layer chromatography (TLC) plate to determine Sudan I in paprika powder. Separation of Sudan I from paprika extract by an MIPs-TLC plate takes 30-40 s. SERS spectra obtained from Sudan I spot on the plate can be acquired within 1 s with gold colloid serving as SERS active substrate. A PLSR (R² = 0.978) model was constructed based on spiking levels (5, 10, 40, 70 and 100 ppm) of Sudan I in paprika powder. Histamine level in canned tuna was investigated using MIPs-polyvinyl chloride (PVC)-SERS method. MIPs-PVC films (recognition element) selectively extracted histamine from tuna extract. A gold colloid solution served as an eluting solvent to extract histamine from MIPs-PVC film and conducted a SERS detection of histamine. A PLSR model (R² = 0.947, RMSECV = 3.526) was built on SERS spectra of histamine with different spiking levels (3, 30 and 90 ppm) in canned tuna. The spectral results suggest the powerful separation of MIPs and sensitive detection of SERS. With statistical analysis, we have confirmed that SERS signals obtained by this MIPs-SERS approach rapidly and accurately quantify chloramphenicol in milk and honey, Sudan I in paprika powder and histamine in canned tuna.
Science, Faculty of
Chemistry, Department of
Graduate

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Bisha, Bledar. "Fluorescence in situ hybridization-based detection of Salmonella spp. and Listeria monocytogenes in complex food matrices." [Ames, Iowa : Iowa State University], 2009.

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Carneado, Moreno Sergio. "Determination of mercury and antimony in environmental and food matrices: development of analytical methodology and migration studies." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/401592.

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Food safety is an issue of vital importance in the world. It must be sustained so as to avoid pollution episodes in food, which subsequently could cause potential risks to health. The main approach of this thesis consist of the study of two particular food contamination cases: primary contamination of the aquatic media and the corresponding seafood with mercury, and direct contamination of beverages due to polyethylene terephthalate containers (PET) with antimony. To carry out these studies, the work was structured in three sections. The first one is the development of analytical methodology for the correct determination of mercury and antimony, in which atomic fluorescence spectrometry and inductive coupled plasma mass spectrometry were used to know the total content, whereas the coupling of the liquid chromatography to these detector was used for speciation. Additionally, online preconcentration methods for the speciation of these elements were successfully developed to determine the trace amounts present in the matrices under study, comprising tap and PET-bottled waters. The second section deals with the application of the developed methodology in real samples. Antimony was determined in PET-bottled waters, juices, spirits and PET bottles, obtaining concentrations under the limits established for the European Union, and different species depending on the matrix: Sb(V) for waters, Sb(III) for juices and both for spirits and PET extracts. Mercury was determined in seafood, obtaining concentrations beyond the limits for four predator fish, being methylmercury the predominant species. The third section consists of the study of the mechanisms of antimony migration from PET to beverages. To know the main variables which enhances migration, studies with waters, juices and spirits were performed at different times and temperatures. Results demonstrated that high temperatures (60ºC) enhanced migration, as antimony concentration rapidly increased and the limit permitted was exceeded in waters and spirits. Differences among the matrices studied and the tendencies observed throughout time demonstrated that not only temperature, but also matrix characteristics and the type of PET had influence on migration. These facts were demonstrated with the performance of crossed migration experiments, using different types of PET bottles for the storage of the aforementioned matrices.
La seguretat alimentària és un tema de vital importància en el món sencer. Aquesta s’ha de preservar per tal d’evitar episodis de contaminació en els aliments, els quals, a la vegada, poden provocar riscos a la salut humana, animal i mediambiental. La present tesi té com a principal enfoc l’estudi de dos casos particulars de contaminació dels aliments: la contaminació primària del medi aquàtic i dels peixos que hi viuen amb mercuri, i la contaminació directa de begudes deguda als envasos de polietilentereftalat (PET) amb antimoni. Per tal de realitzar aquests estudis, el treball s’ha estructurat en tres grans blocs: desenvolupament de metodologia analítica per a la correcta determinació de mercuri i antimoni, aplicació de la metodologia desenvolupada a mostres reals i la realització d’estudis per avaluar la potencial migració d’antimoni en diferents begudes embotellades en PET. El desenvolupament de mètodes per la determinació de mercuri i antimoni s’ha dut a terme mitjançant espectroscòpia de fluorescència atòmica (AFS) i plasma acoblat inductivament amb espectrometria de masses per conèixer el contingut total. Per l’especiació, s’ha acoblat la cromatografia de líquids a aquestes tècniques. Addicionalment, donat que les matrius a estudiar presenten concentracions baixes de mercuri i antimoni, s’han desenvolupat mètodes de preconcentració online per a la seva especiació utilitzant AFS com a detecció. Aquests s’han realitzat de manera sistemàtica estudiant diferents variables, com ara l’agent complexant o el volum de ruptura, entre d’altres. D’aquesta manera, s’ha aconseguit establir unes condicions òptimes d’anàlisi que proporcionen bones recuperacions, factors de preconcentració i reproductibilitat. Els mètodes s’han aplicat a mostres d’aigua d’aixeta i envasada, i s’han obtingut uns factors de 10, 70 i 30 per a Sb(V), Sb(III) i les espècies de mercuri, respectivament. Els mètodes esmentats s’han aplicat per determinar antimoni en aigües, sucs i licors envasats en PET, així com en el propi plàstic, i mercuri en peixos. En quant a l’antimoni, les concentracions trobades en les begudes no superen el límit màxim permès per la Unió Europea (5 µg L-1) en aigües. L’especiació, amb l’ajut de l’espectrometria de masses, va posar de manifest que la forma predominant en aigua és Sb(V) sense complexar, pels sucs és Sb(III) amb citrat i pels licors un complex orgànic de Sb(V). En el cas del plàstic, l’antimoni es pot extreure en qualsevol de les dues espècies inorgàniques, desconeixent la seva estructura en la superfície. En quant el mercuri, es van trobar concentracions superiors a les permeses (1 mg kg-1) en quatre mostres de peixos depredadors, sent el metilmercuri la forma predominant. Per tal de conèixer els mecanismes de migració d’antimoni del PET a la beguda i quines són les variables que més potencien el seu alliberament, s’han realitzat estudis en aigües, sucs i licors. Aquests s’han dut a terme a diferents temps i temperatures. Els resultats van demostrar per una banda que les temperatures altes (60ºC) afavoreixen la migració. Les aigües van superar els límits permesos al cap de 30 dies i els licors al cap d’una setmana, mentre que els sucs no el van superar. Les diferències entre matrius i les tendències observades al llarg del temps van demostrar que, a més de la temperatura, la migració pot dependre depèn d’altres variables, com ara la matriu o el tipus de PET de l’ampolla. Per estudiar aquest fet, es va realitzar un experiment de migració creuada a elevada temperatura amb aigües i sucs, en el qual es van envasar les matrius en ampolles diferents de les originals. Aquest experiment va demostrar que la migració d’antimoni també depèn de les característiques del PET així com de la matriu de la beguda.

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McMullen, Kevin Patrick. "Inhibitory effects of food matrices on real-time reverse transcription polymerase chain reaction detection of foodborne viruses." [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000100.

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EMIDE, DAVIDE. "MOLECULAR CHARACTERIZATION OF PROTEINS IN FOOD MATRICES: HOW THEIR STRUCTURE EVOLVE FROM RAW MATERIALS TO FINISHED PRODUCTS." Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/940416.

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Proteins have a fundamental importance for their peculiar chemical characteristic, implication in metabolism and structure for all living organisms. In food systems, proteins provide both nutritional and non-nutritional functionalities and, with other macromolecules, contribute in define the characteristics of the food systems. Technological and biotechnological treatments used in food processing are also responsible for the formation of new inter- and intra-molecular interactions, driven by changes in the structure of proteins, often in association with other food components. In the present PhD thesis, the structural evolution of proteins from raw materials to finished products was studied in different food systems, with the aim of connecting protein molecular features - and the changes they undergo upon processing - with their functional properties. This PhD thesis aims at improving the current understanding of the structure/function relationship of macromolecules in various food systems, and of how the new relationships affect their technological properties. The approaches and results presented are of practical relevance for the food industry, that require to understand how to tailor processes in order to fit the nutritional, sensorial and environmental requests from the consumers. The introduction (Chapter 2) provides a review of the current knowledge and of the approaches used to study the structure of proteins in food systems. The gluten network is used as a model system in this context, because of its high level of complexity and of its importance in defining the properties of cereal-based food systems. The first four sections (4.1, 4.2, 4.3 and 4.4) of the Results presents the structural and geometrical events leading to the formation of the gluten-network, and discusses some novel approaches set-up to investigate the three- dimensional rearrangements resulting from a transformation process (such as bread making). These approaches were also applied to clarify the impact of other macromolecules (amylose and amylopectin) in the gluten-network development, that in turn affects the properties of the derived products. Sections 4.5, 4.6 and 4.7 discusses the impact of technological treatments on proteins in gluten-free flours, using lentils as a model and analyzing protein structural changes as a function of different technological treatments. Biochemical characterization was one prong of a multidisciplinary approach (rheology and calorimetry) that showed how the technological treatments affect the protein structure, improving the transformability of lentis flour in gluten- free pasta. Pseudo cereals, such as buckwheat (Section 4.8), represent a suitable system to show how biotechnological treatments like sprouting can positively affect the nutritional properties, also thanks to modification of the protein pattern and structure. The overall features of proteins in sprouted grains made them more suitable for the formation of protein network, useful for appropriate texturing of specific foods, like couscous. The nutritional properties were assessed in couscous fortified with the sprouted flour, after a simulation of an in vivo digestion. Finally, proteins can also impact the flavor of the products acting as a source of reactive and/or bioactive components, often originated by breakdown by endogenous or added proteases. In Sections 4.9, 4.10 and 4.11, the nature and amount of peptides and amino acids released during fermentation of cocoa was related to the selected inoculum and to the flavor of the final product.

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Mcmullen, Kevin Patrick. "Inhibitory Effects of Food Matrices on Inhibition Real-Time Reverse Transcription Polymerase Chain Reaction Detection of Foodborne Viruses." Scholar Commons, 2003. https://scholarcommons.usf.edu/etd/1429.

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The Centers for Disease Control and Prevention estimated 23,000,000 cases of viral gastroenteritis caused by Norovirus in 2000, 40% of which were transmitted by food including: a variety of fresh produce, cake, deli meats, fruit salad, cheeses and ice. (CDC, 2003). An estimated 83,391 cases of Hepatitis A virus was reported in 2000, of which 5% was attributed to foodborne transmission (CDC, 2003). These figures underscore an urgent need for a method that can isolate virus from a variety of food matrices. The aim of this study was to develop an overall assessment of the inhibitory effects of a variety of food matrices on Real Time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). Additionally, to compare a sequence specific hybridization probe amplification format to a non sequence specific SYBR Green format using the Roche LightCycler. The secondary aim was to evaluate the effectiveness of a food virus concentration and isolation protocol under development at the Florida Department of Health Bureau of Laboratories, Tampa. Three food specimens consisting of prepackaged smoked ham, fresh cilantro, and Thompson's green grapes were seeded with three dilutions of poliovirus 3 (Sabin strain). A viral concentration procedure under development at the Florida Department of Health Bureau of Laboratories, Tampa was used to isolate the virus. Real Time RT-PCR was carried out on the Roche LightCycler in SYBR Green and Hybridization probe formats. Spiking the virus-negative samples of each matrix with a dilution series of poliovirus 3 created post flocculation spikes. This post-flocculation dilution series amplification allowed a standard curve to be created unique to each food matrix. The flocculation and concentrations specimens were then amplified and the standard curves from the post-flocculation seed were used to calculate the loss associated with the concentration procedure. This study reports significant differences (p<0.05) in recovery detected between the various matrices, and Real Time RT-PCR formats. The concentration protocol under development at the Florida Department of Health Bureau of Laboratories, Tampa, demonstrates a 12-78% recovery of seeded virus in a simulated “real world” virus contamination event among the various matrices.

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Muhammad, Kwestan Rafat. "Biochemistry of antioxidants : antioxidant capacity measurment methods and their application to develop useful indicators of stability and functionality in food matrices." Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1089.

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Antioxidant properties of green tea (GT) have been widely reported. The antioxidant capacity (AOC) of green tea was investigated to include the effect of infusion time over 24 hours. The AOC was measured by the FRAP, DPPH, TEAC, and CBA assays. It was proven according that after 2 hours of brewing, tea has higher AOC and Total phenolic content (TPC), these significantly decreases after 4 hours. GT has a high amount of polyphenols with potent AOC. However, interactions between polyphenols and food matrix may decrease their potential benefit. The objective of this experiment was to test the hypothesis that the addition of milk (full fat, semi-skimmed, and skimmed) may affect the phenolic content and AOC was measured. The results indicated the plain GT had highest activity; then tea with FFM had a significantly higher amount of AO than others. Plant extracts possess health promoting properties. The objective of this study was to determine the TPC and AOA of different concentrations of spice extracts (fennel, clove, cardamom, cinnamon, ginger, anise, and black pepper) with DPPH, TEAC and Rancimat methods. At low concentration, black pepper had a highest activity but at high concentration, ginger showed the highest activity among the extracts. The TPC for spice extract was greater for anise. Results provided evidence that the studied spices may be used as a natural AO. In recent decades, saliva has emerged as a new way to diagnose and investigate basic health problems. In this study, salivary TPC and AOC were measured after consumption a single cup of green tea with and without of milk. In a healthy adult crossover design. The salivary AOC and TPC were measured before and after consumption up to 3 hours. Results indicated that milk decreased AOC of GT when compared with the control water. The activity reached peak 1 hour after ingestion and then decreased returning to the baseline. Results confirmed that saliva could be used as an easier and safer alternative to blood to assess AOA in humans.

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Barnaba, Chiara. "Non-targeted, suspect and targeted High Resolution Mass Spectrometry (HRMS) approaches for the profiling of oenological matrices and different food commodities." Doctoral thesis, country:UY, 2018. http://hdl.handle.net/10449/53028.

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The increasing number of foodomics studies based on non-targeted methods shows that this approach is considered by scientists to be an efficient way of evaluating food safety and quality. In the last few years, high resolution mass spectrometry (HRMS) has indeed gained wider acceptance thanks to the high selectivity and sensitivity achievable during analysis. In contrast to the classic unit-mass-resolution MS/MS approach, HRMS provides more information on sample composition through collection of full-scan spectra and thanks to the possibility of performing retrospective data analysis. Consequently, even without defining compound-specific tuning, HRMS data can be used for identification of suspect compounds or for structural elucidation of unknowns. HRMS can only compete with classic MS/MS methods using the targeted approach, even if it allows the simultaneous detection of a higher number of compounds. In contrast, HRMS is a more promising approach when suspect and non-targeted screening analysis is performed, not only because full-scan and retrospective analysis is feasible, but also because the accurate mass of both precursor and product ions and their isotope patterns are provided. Furthermore, a non-targeted approach leads to specific profiling of biological systems through a wide selection of chemical descriptors, and provides the fingerprint of the system under investigation, useful for more easily identifying potential adulteration. The aim of this work was to extend comprehension of the three different HRMS approaches (nontargeted, suspect and targeted screening), examining both their potential and limitations in relation to the analysis of the compounds of interest in different matrices. Initially, the objectives concerned the possibility of developing new methods – one for each HRMS screening approach – for the analysis of glycosides and phenolic compounds, in order to furnish innovative and well-performing analytical tools for food safety and quality control at all stages of food production, processing and distribution. Furthermore, they regarded the possibility of investigating the nature and occurrence of glycosides and phenolic compounds in widely consumed beverage and food commodities, such as grape, wine, spirits, cocoa and honeys. The thesis, which includes both published and in litteris papers, describes newly developed analytical methods and their technological applications in the study of different matrices, focusing on: - Investigation of Neutral Loss experiments as an instrument for non-targeted screening analysis of glycosides, and performance evaluation of this analytical approach in relation to the glycosidic profiling of international monovarietal wines; - Investigation of the distribution of free and glycosylated low-molecular-weight phenolic compounds in skin and seeds of color-rich Vitis vinifera grapes cultivated in southern Uruguay, combining Neutral loss experiment and suspect screening analysis; - Investigation of the selectivity and sensitivity of the HRMS approach for targeted analysis of free and glycosylated low-molecular-weight phenolic compounds and suspect screening analysis of the latter, together with evaluation of the best sample clean-up procedure for reducing matrix interference; - Investigation of the distribution of free and glycosylated low-molecular-weight phenolic compounds in skin, pulp and seeds, focusing on both Vitis vinifera and hybrid grapes; - Investigation of the impact of alcoholic fermentation on the free and glycosylated phenolic profile of wines produced from grapes of hybrid varieties; - Study of the occurrence of glycosylated low-molecular-weight phenolic compounds in tannins of different botanical origin, in order to evaluate the alteration of the phenolic profile of wines after tannin addition; - Study of the free phenolic composition of wood barrels, in order to evaluate phenolic enrichment during ageing, and investigation of the possible impact of different barrel sanitation treatments on the phenolic transfer from wood to wine; - Study of the free and glycosylated low-molecular-weight phenolic profile in Primitivo di Manduria and Negroamaro wines of different vintages and evaluation of the effect of wine ageing; - Investigation of the possibility of considering free or glycosylated low-molecular-weight phenolic compounds as new markers for beverages and food characterization and their geographical traceability, focusing on wine, spirits, vinegar, food tannins, cocoa beans and honeys; - Implementation of investigative methods of suspect screening analysis using naturally rich matrices as available sources of compounds of interest. This approach was applied on plant products for alkaloid identification; - Investigation of the selectivity and sensitivity of the HRMS approach for suspect screening analysis of flavonoids in flowering plant (C. pareira) extracts.

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Nikolova, Yoana. "Développement de matrices alimentaires permettant de protéger des substances actives lors des traitements thermiques." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0102.

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Les produits déshydratés permettent d’optimiser la conservation et le transport des aliments. Les poudres alimentaires distribuées au consommateur affichent des garanties nutritionnelles en termes d’apports qualitatif et quantitatif. Cependant, l’apport nutritionnel du produit après reconstitution et cuisson, n’est pas garanti. Ce travail se concentre sur l’évaluation des pertes en vitamines dues aux procédés de transformation alimentaire en lien avec l’effet de la matrice alimentaire. Ces pertes mesurées après le traitement thermique ne sont pas négligeables, rendant l’encapsulation nécessaire pour répondre à l’objectif de la thèse de garantir une teneur en vitamines suffisante après reconstitution et traitement thermique du produit alimentaire déshydraté. Différentes matrices ont été testées à l’échelle laboratoire et industrielle. Parmi ces matrices, certaines comme les protéines laitières et l’amidon se sont avérées très intéressants et ont permis la préservation de la vitamine C du traitement thermique. Pour finaliser l’étude, il a été indispensable de prendre en compte le stockage des poudres de la vitamine C encapsulée avant et après leur commercialisation. Pour assurer leur teneur suffisante en vitamine C lors ce stockage, un vieillissement accéléré a été effectué. Cette thèse a permis d’apporter des réponses concrètes au problème industriel posé, qui était de garantir la teneur en vitamine C des produits commercialisés après reconstitution et traitement thermique
Dehydrated products make it possible to optimize the storage and transport of food products. Food powder mixes distributed to the consumer display nutritional guarantees in terms of qualitative and quantitative inputs. However, the nutritional value of the product after reconstitution and cooking, is not guaranteed. This PhD work focuses on the evaluation of vitamins losses due to food processing in relation to the effect of the food matrix. Losses measured after the heat treatment were not negligible, making the encapsulation necessary to meet the objective of the thesis to guarantee a sufficient vitamins content after reconstitution and heat treatment of the dehydrated food product. Different matrices have been tested at the laboratory scale and industrial scales. Some of these matrices, such as dairy proteins and starch, have proved to be very interesting and allowed the preservation of vitamin C during heat treatment. To finalize the study, it was essential to take into account that the vitamin C-encapsulating powders will be stored before and after their distribution. To ensure that they maintain a sufficient vitamin C content during storage, accelerated aging has been carried out. Thus this thesis made it possible to provide concrete answers to the posed industrial problem, which was to guarantee the vitamin C content of the commercial products after reconstitution and heat treatment

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Corrêa, Filho Luiz Carlos. "Novel delivery systems for bioactives from tomato (Solanum lycopersicum L.) pomace extracts: characterization and release studies." Doctoral thesis, ISA/UL, 2019. http://hdl.handle.net/10400.5/18332.

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Doutoramento em Engenharia Alimentar - Instituto Superior de Agronomia / UL
The production of functional food products rich in natural bioactive compounds, with the intention of taking advantage of their health benefits, is an important target of the food industry to answer the growing interest of consumers for healthy food. Tomato pomace is rich in carotenoids, mainly lycopene, which have been related to important bioactive properties. Within this context, this work was focused on the stabilization of a tomato pomace ethanolic extract using microencapsulation by spray drying with arabic gum and inulin as wall materials, aiming at its incorporation in food matrices. A first insight on carotenoids microencapsulation with Arabic gum was assessed using model carotenoid molecule (β-carotene). Afterwards, the microencapsulation process of tomato pomace extract using inulin and arabic gum as wall materials was successfully optimized, focusing on the evaluation of the effect of drying temperature and the wall material concentration on drying yield, loading capacity and antioxidant activity of encapsulated bioactives. Both wall materials allowed the production of microparticles loaded with tomato pomace carotenoids. The optimized drying conditions were 10% wall material concentration, and drying temperatures of 160 and 200 °C for inulin and arabic gum, respectively. Finally, particles produced under optimized conditions were evaluated for their storage stability and in vitro release of lycopene. Inulin has shown to be the most efficient wall material in maintaining bioactives stability during microcapsules storage after production. In addition, inulin microcapsules demonstrated a higher bioactives protection ability against simulated gastric conditions, either alone or incorporated in a selected food product (liquid yoghurt), enabling a preferential release in simulated intestinal fluid. Overall, it is envisaged a good potential for the microcapsules of tomato pomace extracts to be incorporated in foods systems with diverse chemical and physical properties
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De, Poi Rossella. "Mass spectrometry as an emerging tool for the detection of proteins in complex matrices: from untargeted to targeted analysis." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425394.

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My PhD was performed in Mérieux NutriSciences, a company which provides analytical services. During my PhD I worked on three projects, whose common determinant was the application of mass spectrometry (MS) to the analysis of proteins. The main study deals with MS as a new tool for the analysis of food allergens. Food allergy is an important health problem involving immunological reactions that arise following exposure to protein allergens. In the absence of a cure, patients need to avoid the offending food to prevent allergic reactions. In the European Union, 14 allergens must be indicated in food labels when intentionally added. However, one of the main causes triggering allergic reactions is represented by undesired contamination of food by allergens in production facilities. Even tiny amounts of allergens can trigger severe manifestations; thus, to protect consumers sensitive analytical methods are required. Recently, methods based on MS have received increasing attention for the quantification of food allergens in complex matrices. In the present study, the development of a method based on MS for the simultaneous detection of egg, milk, tree nuts and peanuts allergens into bakery products is described. The method is based on the detection of specific peptides generated from the enzymatic hydrolysis of the target allergens and employs a technique called Multiple Reaction Monitoring, in which the mass spectrometer is operated to selectively acquire signals deriving from specific couples of m/z values, corresponding to a peptide ion and to one of its fragments. The method developed allows to detect target allergens in a specific way and with acceptable sensitivities and can be considered as a valuable alternative to other common analytical techniques, such as ELISA and PCR. A second topic of this thesis is bovine beta-casein, a polymorphic protein for which 12 genetic variants have been identified, the most common being A1 and A2. Some reports suggested a possible association between the consumption of A1 beta-casein and the etiology of some human diseases, including ischemic heart disease and diabetes. At the basis of the effects caused by A1 beta-casein there would be a bioactive peptide with opioid-like activity, released by proteolytic enzymes upon gastrointestinal digestion. This peptide, called beta-casomorphin-7, was shown to be produced only from certain beta-casein isoforms, having a histidine in position 67, including the A1 variant. On the other hand, variants possessing a proline in position 67, such as the A2 variant, would not be able to generate beta-casomorphin-7. Based on these assumptions, some companies now sell “A2 milk”, a milk containing only A2 beta-casein. In this project, a LC-MS analytical method was developed to discriminate between A2 milk and commercial milk, which typically contains a mixture of A1 and A2 beta-casein. The final purpose is to offer milk producers an analytical tool to certify that a milk labeled as “A2 milk” is really as such, eventually capable to identify possible frauds or contaminations. Finally, in this thesis a minor project is described, having as object the enzyme transglutaminase (TGase) from microbial origin. TGase catalyses the formation of isopeptide bonds between carboxamides of glutamine residues and amine groups of lysine, resulting in protein cross-linking. The action of TGase can determine significant changes in the physico-chemical properties of proteins, leading to changes in viscosity, thermal stability and elasticity. For these reasons, TGase finds application as an additive in the food industry. In this study a TGase from an unknown microbial source has been characterized and identified by applying a bottom-up proteomic approach. The identified enzyme is produced from a bacterial strain different from the one most commonly used in food industrial applications, S. mobaraense. Moreover, a method for the measurement of TGase enzymatic activity by the hydroxamate assay has been set up and has now become a service offered by the Mérieux NutriSciences.
Il mio dottorato di ricerca si è svolto in Mérieux NutriSciences, un’ azienda che fornisce servizi analitici. Durante il mio periodo di dottorato ho lavorato su tre progetti, il cui determinante comune era l'applicazione della spettrometria di massa (SM) all'analisi delle proteine. Lo studio principale riguarda la SM applicata all'analisi degli allergeni alimentari. L'allergia alimentare è una patologia importante, dovuta a reazioni immunologiche che insorgono a seguito dell'esposizione di un soggetto ad allergeni proteici. Poiché ad oggi non esiste cura, per prevenire le reazioni allergiche i pazienti devono evitare di assumere alimenti contenenti allergeni. Nell'Unione Europea, 14 allergeni devono essere indicati sulle etichette degli alimenti se aggiunti intenzionalmente. Tuttavia, una delle principali cause di reazione allergica è rappresentata dalla contaminazione indesiderata degli alimenti con allergeni all'interno degli impianti di produzione. Anche piccole quantità di allergene possono scatenare gravi reazioni; dunque, per proteggere i consumatori sono necessari metodi analitici sensibili. Recentemente, i metodi basati sulla SM hanno ricevuto crescente attenzione per la quantificazione degli allergeni alimentari in matrici complesse. Nel presente studio viene descritto lo sviluppo di un metodo basato sulla SM per il rilevamento simultaneo di allergeni da uova, latte, arachidi e frutta secca in prodotti da forno. Il metodo si basa sull'identificazione di specifici peptidi generati dall'idrolisi enzimatica degli allergeni target ed impiega una tecnica chiamata Multiple Reaction Monitoring, in cui lo spettrometro di massa è utilizzato per acquisire selettivamente segnali derivanti da coppie di specifici valori m/z, corrispondenti a uno ione peptidico e ad uno dei suoi frammenti. Il metodo sviluppato consente di rilevare gli allergeni target in modo specifico e con sensibilità accettabile e può essere considerato una valida alternativa ad altre comuni tecniche analitiche, come l’ELISA e la PCR. Un secondo argomento trattato in questa tesi riguarda la beta-caseina bovina, una proteina polimorfica per la quale sono state identificate 12 varianti genetiche, fra cui le più comuni sono la A1 e la A2. Alcuni studi hanno suggerito una possibile associazione fra il consumo di beta-caseina A1 e l'eziologia di alcune malattie, tra cui l’ischemia cardiaca e il diabete. Alla base degli effetti causati dalla beta-caseina A1 ci sarebbe un peptide bioattivo con attività simil-oppiode, rilasciato da specifici enzimi proteolitici durante la digestione. Questo peptide, chiamato beta-casomorphin-7, viene generato solo a partire da alcune isoforme di beta-caseina, contenenti un'istidina in posizione 67, inclusa la variante A1. Al contrario, le varianti che possiedono una prolina in posizione 67, come la variante A2, non sarebbero in grado di generare il peptide beta-casomorphin-7. Sulla base di queste ipotesi, alcune aziende vendono ora il cosiddetto "latte A2", un tipo di latte contenente solo beta-caseina A2. In questo progetto di dottorato è stato sviluppato un metodo analitico LC-MS per discriminare il latte A2 dal latte commerciale, che tipicamente contiene una miscela di beta-caseina A1 e A2. Lo scopo finale è offrire ai produttori di latte uno strumento analitico per certificare che un latte etichettato come "latte A2" sia realmente tale, ed eventualmente in grado di identificare possibili frodi o contaminazioni. Infine, in questa tesi viene descritto un progetto che ha come oggetto l'enzima transglutaminasi (TGasi) di origine microbica. La TGasi catalizza la formazione di legami isopeptidici tra residui di glutammina e di lisina, determinando la formazione di cross-linking fra proteine. L'azione della TGasi può determinare cambiamenti significativi nelle proprietà fisico-chimiche delle proteine, portando a modifiche nella viscosità, nella stabilità termica e nella elasticità. Per questi motivi, la TGasi trova applicazione come additivo nell'industria alimentare. In questo studio, una specie di TGasi di origine microbica è stata caratterizzata e identificata applicando un approccio proteomico “bottom-up”. L'enzima identificato viene prodotto da un ceppo batterico diverso da quello più comunemente utilizzato nelle applicazioni industriali alimentari, denominato S. mobaraense. Infine, è stato sviluppato un metodo per la misurazione dell'attività enzimatica della TGasi mediante il saggio dell'idrossammato, che è ora diventato un servizio analitico offerto da Mérieux NutriSciences.

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Monié, Aurélie. "Lipolyse enzymatique de triglycérides pour la fabrication de matrices alimentaires dans le cadre d'une stratégie "clean- label"." Thesis, Toulouse 3, 2021. http://www.theses.fr/2021TOU30289.

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Dans cette thèse, nous avons voulu explorer des voies dites "clean-label" qui permettraient d'intégrer des mono- et diglycérides d'acides gras (MDGs ; E471) dans des matrices alimentaires. En effet, les fabricants cherchent des solutions pour remplacer les additifs obtenus par voie de synthèse tout en gardant les mêmes fonctionnalités dans les produits alimentaires. L'utilisation d'auxiliaires technologiques, comme les enzymes, entre parfaitement dans la démarche de produits plus respectueux du consommateur et de l'environnement ; c'est-à-dire "clean-label". Ainsi avec une lipase mise en contact avec de l'huile de colza, nous avons démontré que des MDGs pouvaient être générés in situ avec un bon rendement. Pour mieux comprendre les cinétiques de lipolyse et caractériser l'ensemble des produits formés, des analyses par chromatographie en phase gazeuse et RMN 1H et 13C ont été effectuées. Enfin, les huiles de colza, différemment enrichies en MDGs ont ensuite été utilisées dans la fabrication directe de produits alimentaires. En effet, sur chacun des produits choisis, les MDGs jouent des rôles différents. Des produits tels que des barres pâtissières, des brioches et des crèmes glacées ont donc été formulés et caractérisés afin de mettre en avant les effets technologiques et les différences par rapport à des produits fabriqués avec de l'huile de colza seule. Enfin, la fabrication d'émulsions inverses concentrées réalisée à partir de l'huile hydrolysée a été développée permettant d'entrevoir la possibilité de fabriquer des émulsions doubles
In this project, we wanted to explore "clean-label" strategies to incorporate mono- and diglycerides of fatty acids (MDGs; E471) in food products. Indeed, manufacturers try to find solutions in order to substitute synthetic additives while keeping the same functionalities in the food products. The use of processing aids, such as enzymes, fits perfectly with the approach of products that are more respectful of consumers and the environment; that is to say "clean-label". Thus, by reacting a lipase with rapeseed oil, we demonstrated that MDGs could be generated in situ and with a good yield. To better understand the kinetics of lipolysis and to characterize all the products formed, analysis by gas chromatography and 1H and 13C NMR were carried out. Finally, rapeseed oils with different MDGs rates, were used in the fabrication of different food products. Indeed, on each of the products chosen, the MDGs play different roles. Products like sponge cakes, brioches and ice creams were formulated and characterized to highlight all benefits comparatively to products made with unmodified rapeseed oil. Finally, the fabrication of concentrated reverse emulsions starting from the post-enzymatic oil has been developed that allow the possibility to obtain doubles emulsions

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NOBILE, MARIA. "DEVELOPMENT AND VALIDATION OF METHODS FOR THE DETECTION OF RESIDUES IN UNCONVENTIONAL AND INNOVATIVE MATRICES THROUGH LC-MS/MS ANALYSES FOR SAFETY OF FOOD OF ANIMAL ORIGIN." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/547683.

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Successful animal growth depends on a combination of many factors related to health, management and nutrition. The use of veterinary drugs in food-producing animals for therapeutic purposes is regulated (corticosteroids, antibiotics) or banned (anabolic steroids) in the European Union; however, their use as growth promoters cannot be excluded. Moreover, the eventual presence of residues in food constitutes a fraud and a health issue for the consumers. For these reasons the need to find new accumulation matrices and new sensitive, specific and robust methods that are able to reveal the presence of drug residues is essential, based on the fact that there is a low percentage of non-conformity in the final reports of the National Residues Plan in recent years, although the threat of a disproportionate use of these substances is increasingly on the rise. In the light of these facts, there is the need to implement the framework of controls aimed to food safety, due to the inefficiency of tools for the study of these substances. Often, the use of conventional matrices, such as urine, liver or muscle, recommended for the official controls of illegal treatment are not completely satisfactory due to the fast elimination rate of the compounds or to the difficulties arising from the compounds characterised also by a pseudoendogenous nature. The debate about the presence of β-boldenone II phase metabolites and prednisolone in urine samples, owing to endogenous or illicit treatment, is currently ongoing within the European Union. These compounds have been appropriately defined “grey-zone substances”, for their double origin. The simple detection of some steroids in urine is currently considered to provide insufficient evidence of illicit treatment. Parameters such as cut-off levels, the presence of metabolites, or both, must be accounted for. As regards antibiotics, the overuse, over the last decades, as growth promoters in food producing animal have caused favorable condition about the threat of bacterial resistance. The antibiotics can directly affect the consumer in the form of residues from the food chain, or by accumulation in the environment via the application of manure to land as organic fertiliser, via sludge storage or by direct contamination of illicitly additivated water and feed. The main challenge is to monitor contemporally different antibiotic classes, in different steps of the food chain, trying to control this phenomenon. On the other hand, food contamination by new environmental contaminants should not be neglected. In particular, perfluoroalkyl substances (PFASs) have recently aroused great scientific interest and concern for public health, due to the fact they have been found in appreciable concentrations in human serum. On the basis of EFSA requestes and of analytical problems associated with their determination many studies are recommended to monitor their presence, building a database on PFASs in food, evaluate the contamination levels of the individual compound and finally draw up a reliable risk assesstment of European population. This work was born with the aim to detect residues of the most commonly used drugs in broad sense, and then extended over time, also following requests from public and private entities, based on realistic situations of risk. Therefore, based on the mentionated issues, the development, optimisation and validation of multiresidual methods and the direct application on real unconventional matrices allowed us to have a greater amount of information in terms of number, frequency, and concentration of different classes of veterinary drugs than in conventional matrices. We confirmed the presence of pseudoendogenous compounds and their precursors in the unconventional matrix bile, for example. The study of the unconventional matrices, e.g. bovine teeth, has also allowed us to detect esterified forms of some drugs, discriminating them from the active free forms that could have a double, exogenous and endogenous, origin. Finally, this work demonstrates the utility of an eventual introduction, through the food of animal origin chain, of several monitoring points of different types of residues, consisting of non-edible matrix analyses that are not destructive of the product intended for the consumer. On the other hand, the sensitivity and good performance of the developed LC-HRMS methods for the emerging PFASs, could help further studies and also EFSA to increase the number of quantifiable data useful to extend a risk assessment in its final reports.

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Kaltner, Florian [Verfasser], Michael [Akademischer Betreuer] Rychlik, Karl-Heinz [Gutachter] Engel, and Michael [Gutachter] Rychlik. "Investigations on Behaviour, Occurrence and Risk Assessment of Toxic Pyrrolizidine Alkaloids in Various Food and Feed Matrices / Florian Kaltner ; Gutachter: Karl-Heinz Engel, Michael Rychlik ; Betreuer: Michael Rychlik." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1213447704/34.

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Mat, Damien. "Cinétiques d’hydrolyse des protéines et des lipides lors de digestions in vitro d’aliments modèles : influence des paramètres de structure des matrices." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLA007.

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L’aliment est une source structurée de nutriments. Les différents éléments qui le composent sont arrangés et associés à plusieurs échelles et lui confèrent des propriétés organoleptiques et rhéologiques. Cette structure va être déconstruite par les différents étages de l’appareil digestif et prise en charge par l’organisme et son microbiote. La réponse qualitative et cinétique du système digestif à une structure particulière doit donc être prise en compte pour compléter notre compréhension des attributs nutritionnels de l’aliment et aller vers des formulations à visée de bien-être et de santé.Cette thèse s’est concentrée sur des matrices complexes riches en protéines de type émulsions huile dans eau. Tout en gardant constante la composition (10 % d’huile et 15% de protéines de lactosérum), des matrices de structures diverses et parfaitement maîtrisées ont été définies puis préparées en modulant les conditions des procédés de fabrication. Pour étudier leur comportement lors de la digestion, un protocole de digestion in vitro statique a été mis en oeuvre, associé à la titration par pH-stat. Cette méthodologie a permis de suivre, de façon originale, l’hydrolyse, et des protéines, et des lipides, au cours de la phase intestinale simulée.Son usage a ensuite été étendu à la phase gastrique pour le suivi de la protéolyse par la pepsine. L’étude des matrices solides représente un challenge dans les protocoles in vitro car elles ont un degré de complexité supplémentaire par rapport aux matrices liquides ou semi-solides. Une partie du travail s’est ainsi concentrée sur l’étude de l’effet de la taille des fragments sur la libération des nutriments, ainsi que leur impact sur la qualité de la mesure par pH-stat.Le potentiel de ce travail méthodologique a été démontré sur différents effets de structure des aliments sur la digestion. L’état physique de la phase continue en particulier et la taille des gouttelettes d’huile étaient parmi les plus influents. Des interactions entre protéolyses et lipolyse ont aussi été observés, ce qui démontre que le suivi simultané des cinétiques d’hydrolyse est un aspect important pour une compréhension plus complète des effets de structure.Par ailleurs la collaboration avec des physiologistes et des microbiologistes a permis la conduite de deux études in vivo chez le rat dont les premiers résultats attestent d’un effet structure à la fois sur la composition du microbiote et sur des marqueurs physiologiques
Food is a structured source of nutrients. Its different components are arranged and associated on several scales and provide organoleptic and rheological properties. This structure is going to be deconstructed by the different stages of the digestive tract and managed by the organism and its microbiota. The qualitative and kinetical response of the digestive tract to a specific structure must then be taken into account to complete our understanding of the nutritional attributes of the food and achieve functional formulations aiming to well-being and health.This thesis focused on complex protein-rich oil-inwater emulsion-type matrices. While keeping the composition constant (10 % oil and 15 % whey proteins), matrices with various and perfectly controlled structures have been designed and prepared by modulating the conditions of the fabrication process. To study the behavior during the digestion, a static in vitro digestion protocol has been carried out, associated to pH-stat titration. This method allowed to follow, in an innovative way, concurrent hydrolysis of both lipids and proteins during the simulated intestinal phase.Its use was then further extended to the gastric phase in order to follow the proteolysis by the pepsin. The study of solid matrices represents a challenge in in vitro protocols since they have an additional degree of complexity compared to liquid and semi-solid ones. A part of this work thereby focused on the study of the influence of the size of the fragments on the nutrients release, as well as on their impact on the quality of the pH-stat monitoring. The methodologic potential of this work has been demonstrated on different structure effects of the food onto its digestion. The physical state of the continuous phase in particular and the size of oil droplets were among the most influent parameters. Interactions between proteolysis and lipolysis were also observed, proving that simultaneous following of the hydrolysis kinetics is an important aspect for a more complete understanding of the structure effects.Moreover, collaborating with physiologists and microbiologists allowed the conduct of two in vivo studies with rats, the first results of which attest a structure effect on the microbiota composition and on physiological markers

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Jelena, Živančev. "Napredne spregnute tehnike u analizi ksenobiotika." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2014. https://www.cris.uns.ac.rs/record.jsf?recordId=87039&source=NDLTD&language=en.

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Prisustvo organskih zagađujućih supstanci (farmaceutski aktivnih komponenata i prirodnih toksina‐mikotoksina) u uzorcima životne sredine i namirnicama je u porastu kao posledica novih industrijskih procesa i ostalih antropogenih aktivnosti, kao i klimatskih promena. Takođe veliku pažnju javnosti privlače i neorganske zagađujuće supstance kao što su teški elementi. S obzirom da zagađujuće supstance imaju negativan uticaj na životnu sredinu i zdravlje ljudi, u svetu se preduzimaju mere u cilju smanjenja stepena izloženosti toksičnim jedinjenjma i posledicama izlaganja. Trenutno, jedan od najvećih izazova, jeste procena rizika povezana sa velikim brojem zagađujućih supstanci u tragovima ili u tzv. ultratragovima, uključujući “novo” otkrivena zagađujuća jedinjenja, a jedan od osnovnih trendova je razvoj i primena brzih i efikasnih metoda za njihovu analizu u ispitivanim uzorcima na bazi naprednih hromatografskih i spektrometrijskih tehnika.Tehnike bazirane na tečnoj hromatografiji sa različitim masenim analizatorima zakvantifikaciju organskih zagađujućih supstanci kao i metode zasnovane na atomskojapsorpcijonoj spektrometriji za određivanje ultratragova neorganskih zagađujućih supstanci postale su referentne na međunarodnom nivou. Ovakve napredne spregnute tehnike postale su važne za identifikaciju, kvantifikaciju i praćenje različitih zagađujućih supstanci u uzorcima životne sredine i namirnicama i proceni njihovog štetenog uticaja na zdravlje čoveka. S obzirom da su u literaturi retka istraživanja koja se bave razvojem i primenom metoda zasnovanih na naprednim hromatografskim i spektrometrijskim tehnikama i određivanju organskih i neorganskih zagađujućih supstanci u matriksima životne sredine i namirnicama sa prostora zapadnog Balkana, a uzimajući u obzir njihovu važnost, specifični ciljevi disertacije su:• unutrašnja („inhouse“)provera kvaliteta i pouzdanosti postojeće „multi‐rezidualne“metode zasnovane na UHPLC‐QqLIT‐MS/MS za analizu 81‐e farmaceutski aktivnekomponente (PhAC) u otpadnoj, površinskoj, podzemnoj i pijaćoj vodi i po prvi putdobijanje sveobuhvatnih rezultata njihovog prisustva u različitim tipovima vode sapodručja Srbije;• unutrašnja („inhouse“) provera kvaliteta i pouzdanosti postojeće „multi‐toksin“metode za analizu 8 Fusarium mikotoksina u uzorcima ozime pšenice različitih sortizasnovane na HPLC‐QqQ‐MS/MS radi određivanja regionalnih razlika između žitnihregiona kao i otpornosti ispitivanih sorti pšenice na kontaminaciju Fusariumtoksinima;• modifikacija postojeće „multi‐toksin“ metode zasnovane na UHPLC‐QqQ‐MS/MS zaanalizu 11 osnovnih mikotoksina u uzorcima brašna i njena unutrašnja („inhouse“)provera kvaliteta i pouzdanosti, kao i provera kroz interlaboratorijsko poređenje,radi dobijanja podataka za procenu štetnog uticaja ispitivanih mikotoksina nazdravlje populacije;• razvoj „multi‐toksin“ (višekomponentne) i „multi‐matriks“ (za više matriksa) metodebazirane na UHPLC‐QqQ‐MS/MS za analizu 10 mikotoksina u različitim vrstamakoštuničavog voća čija provera kvaliteta je zasnovana na intralaboratorijskoj proveritačnosti i preciznosti dobijenih rezultata; • primena postojeće analitičke procedure zasnovane na naprednoj tehnici pripreme(mikrotalasnoj digestiji) različitih uzoraka biljnog i životinjskog porekla i proverakvaliteta metode identifikacije i kvantifikacije zasnovane na atomskom apsorpcionom spektrometru sa grafitnom kivetom (GFAAS) radi dobijanja sveobuhavatnih rezultata o prisustvu teških elemenata (arsena, olova i kadmijuma) radi procene izloženosti stanovništva Srbije toksičnim neorganskim elementima.Postignuti rezultati predstavljaju jedinstvene rezultate za područje Srbije dobijeneprimenom naprednih spregnutih tehnika koje imaju značajnu ulogu u praćenju prisustva većeg broja organskih i neorganskih zagađujućih supstanci u izabranim uzorcima životne sredine i namirnica, (regulisanih postojećim zakonodavstvom) radi procene stepena zagađenosti ili u slučaju jedinjenja koja nisu regulisana zakonodavstvom radi sticanja novih saznanja o njihovom prisustvu i proceni mogućeg negativnog uticaja na životnu sredinu i zdravlje populacije.
The presence of organic pollutants in environmental samples and food (pharmaceutically active components and natural toxins‐mycotoxins) is increased as a result of new industrial processes and other anthropogenic activities, as well as climate change. Similarly heavy elements as inorganic pollutants have attracted worldwide attention. Since, these pollutants have negative impact on environment and human health, extremely efforts are undertaken in the world to reduce the level of exposure to these pollutants and consequences of the exposure. Currently, one of the highest challenges is to assess the risk associated with a large number of pollutants in trace or ultra trace levels, including "new" (emerging) discovered pollutants, and one of the main trends is development and implementation of fast and efficient methods for their analysis on the basis of advanced chromatographic and spectrometric techniques. Therefore, coupled techniques have become important for the identification, quantification and monitoring of various pollutants in environmental samples and food and assessment of their hazard impact on human health. Since, there are scarce data about the development and application of advanced methods based on chromatographic and spectrometric techniques for determination of organic and inorganic pollutants in environmental matrices and food from the Western Balkan, and taking into account their importance, specific objectives ofthe dissertation were: • internal ("in‐house") quality control of the existing "multi‐residual" method based on UHPLC‐QqLIT‐MS/MS for analysis of 81 pharmaceutically active components (PhAC) in wastewater, surface, underground and drinking water due to obtained for the first time comprehensive results of their presence in different types of water from Serbia; • internal ("in‐house") quality control of the existing "multi‐toxin" method for the analysis of 8 Fusarium mycotoxins in samples of different winter wheat cultivars based on HPLC‐QqQ‐MS/MS to determine the differences among wheat-growing regions as well as the resistance of the analysed wheat cultivars towards Fusarium toxins; • modification of existing "multi‐toxin" method based on UHPLC‐QqQ‐MS/MS for analysis of 11 principal mycotoxins in samples of flour and its internal ("in‐house") quality control as well as verification through the interlaboratory comparison, in order to obtain data for assessing the hazard effect of these mycotoxins on the health of the population; • the development of "multi‐toxin" and "multi‐matrix" method based on UHPLC‐QqQMS/ MS for the analysis of 10 mycotoxins in various types of nuts based on intralaboratory verification of the accuracy and precision of the obtained results; • application of analytical procedure based on advanced preparation technique (microwave digestion) and atomic absorption spectrometer with a graphite furnace (GFAAS) and its verification in order to obtain comprehensive results on the presence of heavy elements (arsenic, lead and cadmium) in different samples of plant and animal origin to assess the exposure of the Serbian population to toxic inorganic elements. The obtained results are unique for the Serbia. They are obtained by applying advanced coupled techniques that have a significant role in monitoring the presence of a numerous organic and inorganic pollutants in analyzed samples of the environment and food. The presented results contribute to the assessment of pollution degree and in the case of new (emerging) not regulated polutant they might give new information about the possible negative impact on the environment and health of the population.

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Tietze, Stefan [Verfasser], Thomas [Akademischer Betreuer] Becker, Harald [Gutachter] Rohm, Julija [Gutachter] Zavadlav, and Thomas [Gutachter] Becker. "Examination of the influence of different stress states on the rheological behavior of starch containing food matrices / Stefan Tietze ; Gutachter: Harald Rohm, Julija Zavadlav, Thomas Becker ; Betreuer: Thomas Becker." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1238373933/34.

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Tomaschunas, Maja [Verfasser], and Mechthild [Akademischer Betreuer] Busch-Stockfisch. "Sensory and consumer-oriented studies on the effect of fat in different food matrices : a comparison between yoghurt, vanilla custard, Lyon-style and liver sausages / Maja Tomaschunas. Betreuer: Mechthild Busch-Stockfisch." Hohenheim/Stuttgart : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2014. http://d-nb.info/1049249488/34.

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Hartard, Cédric. "Les bactériophages ARN F-spécifiques comme indicateurs du danger viral lié à la pollution fécale des matrices hydriques et alimentaires." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0152/document.

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Les virus entériques sont à l’origine de pathologies liées au péril fécal et dans l’état actuel des connaissances, la recherche des indicateurs de pollution fécale conventionnels (i.e. Escherichia coli, entérocoques) peut s’avérer inefficace pour évaluer le danger viral. La définition d’autres indicateurs pour gérer le danger lié à la présence des virus entériques dans les matrices hydriques et alimentaires est aujourd’hui nécessaire. Parmi eux, les bactériophages ARN F-spécifiques (FRNAPH) présentent plusieurs intérêts. Ces virus d’origine entérique sont présents en quantité importante dans les eaux usées. Très proches des virus entériques en termes de structure, ces microorganismes présentent l’avantage d’être facilement cultivables. Ils sont enfin souvent étudiés pour déterminer l’origine d’une pollution fécale (i.e. humaine ou animale). Certaines limites leur sont cependant fréquemment associées, que ce soit en termes de corrélation avec les pathogènes entériques ou concernant leur potentiel pour discriminer l’origine d’une pollution. Dans ce contexte, l’objectif du travail présenté ici était de préciser l’intérêt des FRNAPH en tant qu’indicateurs de pollution fécale mais aussi en tant qu’indicateurs de pollution virale dans l’environnement et les coquillages. Ces travaux ont permis dans un premier temps d’améliorer la capacité des FRNAPH à identifier les contaminations d’origine humaine. Nos résultats soulignent par ailleurs la plus-value apportée par la recherche des FRNAPH en cas de pollution fécale massive, en particulier si on s’intéresse à la contamination des coquillages. En effet, contrairement aux indicateurs bactériens, l’accumulation des FRNAPH ainsi que leur persistance dans ces aliments est très comparable à celles des virus entériques (i.e. norovirus). Enfin, en utilisant des méthodes de détection comparables, une forte corrélation entre la présence des FRNAPH d’origine humaine et celle des norovirus a été observée dans les coquillages. Compte tenu de ces résultats, une méthode de détection assurant la détection sensible des FRNAPH infectieux d’origine humaine dans différents types de matrices hydriques ou alimentaires (e.g. eaux de surface, fruits de mer, fruits rouges, salades) est proposée pour améliorer la gestion du danger viral
Enteric viruses are a leading cause of fecal-oral route transmitted diseases and currently, conventional fecal indicator bacteria (i.e. Escherichia coli, enterococcus) fail to assess this kind of hazard. In this context, the use of more efficient indicators to assess the hazard linked to viruses in water or foodstuff is required. F-specific RNA bacteriophages (FRNAPH) present numerous benefits for this purpose. Of enteric origin, these viruses are found in high concentrations in wastewater. Sharing many structural similarities with pathogenic enteric viruses, FRNAPH are easily cultivable and their potential to track the origin of the pollution is also often investigated. However, some limits are still associated with these indicators, regarding to their ability to track the origin of the pollution or concerning the lack of correlation with pathogens. In this context, the aim of this work was to make clear the potential of FRNAPH as fecal and as viral indicators in environmental waters and shellfish. As a first step, their ability to track human pollution was optimized. In addition, our results underlined the gains bringing by FRNAPH detection, especially when focusing on shellfish microbiological quality management. Indeed, unlike fecal indicator bacteria, the accumulation of FRNAPH and their persistence in shellfish have been found to be close to that of enteric viruses (i.e. norovirus). Furthermore, when using comparable methods for their detection, high correlation was observed between human FRNAPH and norovirus in shellfish. Taking into account these observations, a sensitive method allowing the detection of infectious FRNAPH of human origin was developed to improve viral hazard management in water and food commodities (e.g. environmental waters, shellfish, soft fruits, leaf)

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Bußler, Sara [Verfasser], Frank Jürgen [Akademischer Betreuer] Methner, Cornelia [Gutachter] Rauh, Henry [Gutachter] Jäger, and Dietrich [Gutachter] Knorr. "Cold atmospheric pressure plasma treatment of food matrices : tailored modification of product properties along value-added chains of plant and animal related products / Sara Bußler ; Gutachter: Cornelia Rauh, Henry Jäger, Dietrich Knorr ; Betreuer: Frank Jürgen Methner." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156184061/34.

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Boubellouta, Tahar. "Apports des spectroscopies infrarouge et de fluorescence couplées à la chimiométrie pour la caractérisation de la structure de matrices fromagères et des relations structure-texture." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00726362.

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Le microbiote intestinal constitue un réservoir d'activités enzymatiques riche et varié dont l'expression fait partie intégrante de la physiologie de l'organisme et influe sur sa santé. La mise en évidence par méthodes culturales classiques des Archaea méthanogènes est difficile et n'a permis à ce jour que la mise en évidence de 2 Methanobacteriales hydrogénotrophes au sein de ce microbiote : Methanobrevibacter smithii et Methanosphaera stadtmanae. Les travaux de cette thèse ont eu pour but d'apporter une vision moléculaire nouvelle de la diversité des Archaea méthanogènes du microbiote et de rechercher l'influence de l'âge sur ces communautés. Ces travaux ont été menés par analyse d'une partie du cistron mcrA, marqueur moléculaire spécifique de la méthanogenèse, et du gène codant pour l'ARNr 16S. Ces études ont révélé une plus grande diversité des Archea colonisant cet écosystème et ont mis en évidence de nouveaux phylotypes ne pouvant être rattachés à aucun des 5 ordres méthanogènes précédemment décrits. Ils correspondent probablement à d'autres espèces méthanogènes affiliées aux Thermoplasmatales ou cohabitent avec des membres encore inconnus des Thermoplasmatales. Une étude réalisée sur 63 individus répartis en nouveau-nés, adultes et seniors a montré que la fréquence de ces nouveaux phylotypes augmente avec le vieillissement. Ces résultats interrogent à la fois sur l'origine de ces divers organismes et leur présence au sein du mcrobiote intestinal du sujet âgé et soulignent notre relative méconnaissance d'un des trois domaines du vivant.

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Angoy, Alice. "Eco-extraction par micro-ondes couplée à un champ centrifuge Development of microwave-assisted dynamic extraction by combination with centrifugal force for polyphenols extraction from lettuce Microwave technology for food applications." Thesis, Avignon, 2019. http://www.theses.fr/2019AVIG0274.

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Les préoccupations environnementales actuelles comme l’épuisement des ressources fossiles, l’émission de gaz à effets de serre ou le réchauffement climatique imposent aux industriels de réduire leur impact sur l’environnement et de s’insérer dans une démarche plus verte. Dans le domaine de l’extraction cela se traduit, depuis quelques années, par le développement de techniques innovantes pour remplacer les procédés actuels utilisant des solvants pétro-sourcés et très énergivores. L’objectif de cette thèse a donc consisté en la recherche et le développement d’un nouveau procédé d’éco-extraction de produits végétaux, grâce à la combinaison d’un effet thermique, le chauffage par micro-ondes et d’un effet mécanique, la centrifugation. L’extraction est réalisée directement sur la matrice végétale fraîche, l’eau intracellulaire de la plante jouant le rôle du solvant extracteur.La première partie de ce manuscrit présentera le pilote expérimental à l’échelle semi-industrielle combinant micro-ondes et centrifugation et son adaptation potentielle pour le domaine de l’éco-extraction.Dans la seconde partie, les essais réalisés à l’aide de ce pilote ont été décrits pour l’extraction de métabolites secondaires choisis. Les résultats, obtenus sur des produits modèles comme la salade et les écorces d’oranges, mettent en évidence que ce pilote est opérationnel pour l’extraction de certains micronutriments. De plus, l’utilisation d’une centrifugation combinée à l’application de micro-ondes permet d’intensifier le rendement d’extraction et un gain de temps. Néanmoins, des questions quant à la compréhension relative à l’aéraulique du système et à la distribution du champ de température au cours de l’extraction sont soulevées pour maîtriser parfaitement tous les paramètres d’extraction.Enfin, ce procédé apparaît comme une réelle innovation dans le domaine de l’extraction et est très prometteur car il peut encore être optimisé. Il peut apporter aux industriels une solution alternative aux procédés classiques
Current environmental concerns such as the depletion of fossil fuels, the emission of greenhouse gases or global warming are forcing industry to reduce their impact on the environment and to be part of a greener approach. In the field of extraction, this has led, for some years now, to the development of innovative techniques to replace current processes using petroleum-based and energy-intensive solvents. The aim of this thesis was therefore to research and develop a new green extraction process for plant products, thanks to the combination of a thermal effect (microwave heating) and an effect mechanical (centrifugal force). The extraction is carried out directly on the fresh vegetable matrix, the intracellular water of the plant acting as the extracting solvent.The first part of this manuscript will present the experimental pilot at the semi-industrial scale combining microwaves and centrifugation and its potential adaptation for the field of green extraction.In the second part, the tests carried out using this pilot have been described for the extraction of selected secondary metabolites. The results, obtained on “model” products such as salad and orange peel, highlight that this pilot is operational for the extraction of certain micronutrients. In addition, the use of a centrifugation combined with the application of microwaves makes it possible to intensify the extraction yield and a saving of time. Nevertheless, questions about the understanding of the aeraulic system and the distribution of the temperature field during extraction are raised to fully control all extraction parameters.Finally, this process appears as a real innovation in the field of extraction and is very promising because it

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Bahri-Hammami, Asma. "Développement d'une nouvelle stratégie d'encapsulation de molécules bioactives hydrophobes basée sur la dynamique des micelles de caséines." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT121.

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De nombreux composés bioactifs hydrophobes sont actuellement mis en avant en raison de leurs propriétés nutritionnelles et fonctionnelles. Une attention particulière est, en conséquence, portée à leur incorporation en tant qu'ingrédients dans des aliments fonctionnels. Cependant, la majorité de ces composés bioactifs sont caractérisés par une faible solubilité en milieu aqueux, une dégradation au cours des procédés de transformation ainsi qu'une absorption limitée au niveau du tractus gastro-intestinal. La micelle de caséines, grâce à ses propriétés fonctionnelles uniques, peut être considérée comme un support d’encapsulation naturel pour ces molécules bioactives hydrophobes. En effet, une des originalités de cette suprastructure est sa dynamique dans le lait se caractérisant par des échanges réversibles de protéines et de minéraux entre le sérum et la structure micellaire interne en fonction des conditions physicochimiques, et notamment avec la température. En particulier, un stockage du lait à 4°C permet la dissociation sélective de la caséine β de la phase micellaire vers la phase soluble et un retour à température ambiante permet sa réintégration. L’objectif de cette thèse est de développer une nouvelle stratégie d’encapsulation de molécules bioactives hydrophobes dans les micelles de caséines via cette dynamique de la caséine β. Dans un premier temps, l’optimisation de la dissociation de la caséine β de la micelle de caséines a été réalisée en modifiant la température et le pH, tout en portant une attention particulière au maintien de l’intégrité des micelles déplétées en caséines β. Un procédé de séparation physique de la caséine β solubilisée a été optimisé par microfiltration à l’échelle pilote. Une étude de la concentration micellaire critique de la caséine β a permis de vérifier son état monomérique à l’issue de cette séparation. Une étude de la cinétique d’interaction entre la caséine β monomérique et deux composés bioactifs hydrophobes, la curcumine et la vitamine D3, a ensuite été réalisée par résonance plasmonique de surface et par spectroscopie de fluorescence. La curcumine a été choisie pour la suite de l’étude au vu de sa bonne affinité pour la caséine β. Le complexe caséine β monomérique-curcumine a ensuite été encapsulé dans des micelles de caséines préalablement déplétées en caséines β. Les résultats de ces travaux montrent l’efficacité de cette stratégie d’encapsulation qui peut présenter un intérêt particulier pour la vectorisation de molécules bioactives hydrophobes afin d’assurer leur protection dans des produits laitiers pauvres en matière grasse.De plus, au cours de ce projet, une méthode de caractérisation des propriétés morphologiques et nano-mécaniques des micelles de caséines par microscopie à force atomique en milieu liquide a été développée. Cette méthode représente un outil intéressant de compréhension de la structure micellaire dans son environnement natif et offre la possibilité d’évaluer l’impact de certaines modifications sur les propriétés de la micelle de caséines, comme sa déplétion en caséine β ou sa réticulation
In the last years, the number of studies highlighting the nutritional and functional properties of several hydrophobic bioactives has markedly increased. Special attention is consequently paid to their addition as ingredients to food. However, most of these hydrophobic compounds display a low aqueous solubility, poor stability during processing and low absorption in the gastrointestinal tract. Casein micelles exhibiting unique set of properties can be considered as a natural nanocarrier for these molecules. Actually, changes in environmental factors namely pH and temperature induce the dissociation of caseins and minerals from the colloidal phase to the soluble phase. Particularly, a selective dissociation of β-casein occurs at low temperatures. This effect is reversed with an increase in temperature, with a transfer of β-casein from the serum to the micelles when equilibrated at room temperature. The aim of this study is to develop a novel encapsulation strategy to incorporate hydrophobic bioactive compounds into casein micelles using the β-casein reversible dissociation. First, the β-casein dissociation from casein micelles was optimized by temperature and pH modifications while preserving the integrity of the β-casein depleted casein micelles. The separation of dissociated β-caseins from casein micelles was carried out by microfiltration at a pilot scale. The β-casein critical micelle concentration was concurrently evaluated to ensure the monomeric state of -casein after separation. Secondly, the binding kinetic between monomeric β-casein and two hydrophobic compounds, curcumin and vitamin D3, was investigated by surface plasmon resonance and fluorescence spectroscopy. Curcumin was then selected thanks to its high affinity to -casein β. The complex monomeric β-casein – curcumin was encapsulated in β-casein depleted casein micelles. The results of this study show the efficiency of this encapsulation strategy of hydrophobic bioactive compounds, which could be used to protect such molecules in low fat dairy products.Besides, during this project, a novel strategy was developed in order to evaluate the casein micelle topography and nanomechanical properties by atomic force microscopy in liquid environment. This method opens a new line of investigation to better understand the casein micelle structure in its native environment but also investigate the impact induced by the modification of physico-chemical conditions on its topography and elastic properties

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Durá, de Miguel Ángela. "EFFECT OF ENZYMATIC TREATMENTS ON CARBOHYDRATE MATRICES TOWARDS HEALTHY GLUTEN FREE FOODS APPLICATION." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/79509.

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Starch is the major energy reserve in plants, extensively present in many food and non-food applications, and is one of the most abundant carbohydrates in human diet. In addition to starch native form currently used as a raw material for industrial applications, modified starches have become very attractive to develop numerous products that have greatly expanded starch use and utility. Enzymatic modifications are carried out to enhance starch functionality with the aim of overcoming technological constraints and to improve final product quality. Above all starches, corn starch is widely produced and consumed, and used as main ingredient to produce gluten-free products. This Thesis focuses to the study of the individual effect of three different enzymes, fungal alpha-amylase, amyloglucosidase and cyclodextrin glycosyltransferase, on the above sub-gelatinization temperature of corn starch, in order to modify its properties and extend its applications. Different analyses have been performed to improve the understanding of functional and structural changes promoted by the enzyme action. Moreover, corn starch modified with cyclodextrin glycosyltransferase was selected to investigate the glycemic response in mice. The presence/absence of hydrolysis products released from the enzyme catalytic activity and gelatinization properties were related to glycemic index. Enzymatically modified corn starch resulted in a diversity of functional starch granules that may be used in food applications for many purposes.
El almidón es la principal fuente de reserva de energía en las plantas, está ampliamente presente en diversas aplicaciones alimentarias y no alimentarias, y constituye uno de los hidratos de carbono más abundantes en la dieta humana. Además del uso frecuente y clásico del almidón nativo como materia prima en la producción de alimentos, los almidones modificados han experimentado gran expansión en el desarrollo de numerosos productos debido a su carácter versátil. Las modificaciones enzimáticas se llevan a cabo para realzar la funcionalidad del almidón con objeto de soslayar las restricciones tecnológicas y mejorar la calidad del producto final. En concreto, el almidón de maíz ampliamente producido y consumido, es apropiado como ingrediente principal en la producción de alimentos libres de gluten. Esta Tesis aborda el estudio del efecto individual de tres diferentes enzimas, alfa-amylasa fúngica, amiloglucosidasa y ciclodextrina glucosiltransferasa, sobre la temperatura de sub-gelatinización del almidón de maíz. Se realizaron diferentes análisis para ampliar el conocimiento de los cambios estructurales y funcionales asociados a la acción de la enzima. Así mismo, se seleccionó el almidón de maíz modificado con ciclodextrina glucosiltransferasa para investigar la respuesta glicémica en ratones. El índice glicémico se relacionó con la ausencia/presencia de productos de hidrólisis liberados por la acción catalítica de la enzima y las propiedades de gelatinización. Los almidones de maíz enzimáticamente modificados presentaron alteraciones funcionales en los gránulos de almidón, lo que les confiere características de interés para diversos usos alimentarios.
El midó és la principal font de reserva d'energia en les plantes, està àmpliament present en diverses aplicacions alimentàries i no alimentàries, i constitueix un dels hidrats de carboni més abundants en la dieta humana. A més de l'ús freqüent i clàssic del midó natiu com a matèria primera en la producció d'aliments, els midons modificats han experimentat gran expansió en el desenvolupament de nombrosos productes a causa del seu caràcter versàtil. Les modificacions enzimàtiques es duen a terme per a realçar la funcionalitat del midó a fi d'esbiaixar les restriccions tecnològiques i millorar la qualitat del producte final. En concret, el midó de dacsa àmpliament produït i consumit, és apropiat com a ingredient principal en la producció d'aliments lliures de gluten. Aquesta Tesi aborda l'estudi de l'efecte individual de tres diferents enzims, alfa-amylasa fúngica, amiloglucosidasa i ciclodextrina glucosiltransferasa, sobre la temperatura de sub-gelatinizació del midó de dacsa. Es van realitzar diferents anàlisi per a ampliar el coneixement dels canvis estructurals i funcionals associats a l'acció de l'enzim. Així mateix, es va seleccionar el midó de dacsa modificat amb ciclodextrina glucosiltransferasa per a investigar la resposta glicémica en ratolins. L'índex glicémic es va relacionar amb l'absència/presencia de productes d'hidròlisis alliberats per l'acció catalítica de l'enzim i les propietats de gelatinización. Els midons de dacsa enzimàticament modificats van presentar alteracions funcionals en els grànuls de midó, la qual cosa els confereix característiques d'interès per a diversos usos alimentaris.
Durá De Miguel, Á. (2017). EFFECT OF ENZYMATIC TREATMENTS ON CARBOHYDRATE MATRICES TOWARDS HEALTHY GLUTEN FREE FOODS APPLICATION [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/79509
TESIS

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Hartmann, Kaitlin Ash. "Cronobacter sakazakii Genes Contributing to Persistencein Low-Moisture Dairy Matrices." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8466.

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Cronobacter sakazakii is a gram-negative opportunistic pathogen known to survive in dry environments and food matrices, such as infant formula. This foodborne bacterium can cause fatal human infections of the blood, central nervous system, and gastrointestinal tract; it is also problematic in wounds and urinary tract infections. Preterm infants and immunocompromised individuals are in higher risk categories related to necrotizing enterocolitis, neonatal sepsis, and meningitis due to this organism. Therefore, there is a need for increased understanding of how this bacterium is able to persist in thermally treated low-moisture products that do not support growth. The objective of this research is to identify genes and mechanisms in C. sakazakii that contribute to its resistance to desiccation and survival in low-moisture food matrices, including powdered infant formula. C. sakazakii sequence type 4 (ST4) is of particular interest as it is often the cause of neonatal infections originating from contaminated feedings of powder infant formula. The method chosen to explore these genetic patterns is massively parallel transposon insertion sequencing (Tn-seq). The E. coli strain MFDpir was used to facilitate transposon insertional mutagenesis to create a library of mutated C. sakazakii. Three different C. sakazakii ST4 isolates of different origins (clinical, environmental, and infant formula-derived) were selected for this study. Once transposon mutagenesis occurred with the aid of E. coli MFDpir, the three mutant libraries were subjected to desiccation stress in a closed system equilibrated to 11.3% relative humidity. The surviving mutant genomes were analyzed with Tn-seq. The sequencing data revealed that, while transposition events did occur successfully within the genomes of each of the selected C. sakazakii isolates, these events were not dense enough to draw biological conclusions nor statistical inferences concerning which genes contribute to this organism’s uncanny desiccation tolerance. However, we concluded that the Tn-seq method is a promising tool with this organism of interest, despite incomplete results in this first round of experimentation.

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Carter, Kristina Kim. "A Comparison of Centrifugal Forces to Reduce the Inhibitory Effects of Food Matrixes on Reverse Transcriptase Polymerase Chain Reaction for the Detection of Food Borne Viruses." Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/984.

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The CDC estimated that foodborne infections resulted in approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths per year in the United States (Mead, 1999). There are over 200 known diseases caused by viruses, bacteria, parasites, toxins, metals, or prions that can be transmitted through food. Of these illnesses caused by foodborne disease, the CDC estimates that 38.6 million cases are from identifiable pathogens and 30.9 million of these cases are caused by viruses. Hence, approximately 80% of foodborne illnesses of known etiology result from viral transmission (Mead, 1999). Viral gastrointestinal illness may be caused by virus families such as: enterovirus, rotavirus, calicivirus, astrovirus, or norovirus. These viruses are highly contagious and are spread through the fecal-oral route; transmission vehicles include contaminated food or beverages, infected food handlers, fomites or close contact with an infected individual (FDA Bad Bug Book, 2003). Until recently, there have been few studies concentrating on viruses found in or on foods. There are several technical difficulties that hinder progress in detecting viral agents from foods. One of these problems is the presence of matrix inhibitors. Substances responsible for matrix inhibition include humic acid, polysaccharides, myoglobins, metal ions, glycogen, and lipids (Monpoeho, 2001). These substances in foods produce smearing of the RT-PCR amplicon bands on agarose gels. Several methods to reduce inhibitory compounds utilize multiple toxic reagents in the procedure. In this study, varying centrifugal forces were tested at different steps of the virus extraction/concentration procedure to reduce matrix inhibitory effects for molecular detection of norovirus and poliovirus seeded onto food surfaces. This method incorporates the rapid detection capabilities of RT-PCR with the ability to reduce or eliminate matrix inhibitors present in food, by altering the centrifugal force. Results for both viruses showed that band intensity decreased as the viral concentration decreased and no one method was superior for all food matrices. This investigation showed that matrix specific modifications to the basic protocol are required to efficiently extract viruses from the surface of foods. Each food should be assessed to determine modifications to the standard method that would be optimal for viral concentration and extraction.

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Lemos, Yuri Pessoa. "Microencapsulação de óleo de buriti por coacervação complexa em matrizes de gelatina/alginato /." São José do Rio Preto, 2017. http://hdl.handle.net/11449/150282.

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Orientador: Vânia Regina Nicoletti Telis
Coorientador: Paulo Henrique Mariano Marfil
Banca: Renato Alexandre Ferreira
Banca: Roger Darros Barbosa
Resumo: A microencapsulação do óleo de buriti pode ser capaz de protegê-lo e promover a sua liberação controlada. Por isso, este projeto investigou a formação de complexos eletrostáticos entre gelatina e alginato de sódio como um possível sistema para microencapsular óleo de buriti por coacervação complexa. Óleo de buriti foi homogeneizado em solução de gelatina a 15000 rpm por 3 minutos, misturado à solução de alginato de sódio e o pH de coacervação ajustado em 3,5 ± 0,1. Nessa etapa foi testada a influência da frequência de agitação durante a mistura da emulsão óleo/gelatina com a solução de alginato e também a influência da concentração dos componentes de formação das microcápsulas. Os coacervados obtidos foram decantados por 24 horas, resfriados e então congelados a -40 °C e liofilizados A morfologia das partículas foi analisada em microscópio ótico e eletrônico de varredura (MEV), e a concentração de óleo de buriti presente externamente foi determinada através da extração com acetona e quantificada em espectrofotômetro. As análises em microscópio ótico demostraram que houve a complexação e a formação das microcápsulas. Análises de MEV mostraram o formato irregular e a estrutura contínua dos coacervados, os quais apresentaram boa retenção de óleo de buriti (<80%). Foi observado que a frequência de agitação tem grande influência no tamanho das microcápsulas e que seu tamanho influencia diretamente no comportamento reológico das suspensões de cápsulas obtidas após a coacervação
Abstract: The microencapsulation of buriti oil may be able to protect it and promote its controlled release. Therefore, this project investigated the formation of electrostatic complexes between gelatin and sodium alginate as a possible system for microencapsulating buriti oil by complex coacervation. Buriti oil was homogenized in gelatin solution at 15000 rpm for 3 minutes, mixed to a sodium alginate solution and coacervation pH was adjusted to 3.5 ± 0.1. At this stage the influence of stirring speed during blending of oil/gelatin emulsion with alginate solution, as well as the effect of concentration of the microcapsule-forming components were evaluated. The obtained coacervates were decanted for 24 hours, cooled and then frozen at -40 °C, and lyophilized. The morphology of the particles was analyzed by optical and scanning electron microscopy (SEM). The concentration of buriti oil present in the external surface of microcapsules was extracted with acetone and quantified in a spectrophotometer. Optical microscopy analysis showed that there was complexation and formation of the microcapsules. SEM analyzes showed the irregular shape and continuous structure of the coacervates, which had good retention of buriti oil (<80%). It was observed that the agitation speed has a large influence on the size of the microcapsules, and that particle size directly affected the rheological behavior of the microcapsule suspensions obtained after coacervation
Mestre

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Bordier, Guillaume. "Développements de composants millimétriques pour la caractérisation de la polarisation du fond diffus cosmologique." Paris 7, 2014. http://www.theses.fr/2014PA077192.

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Le fond diffus cosmologique (CMB), première lumière émise par l'Univers est un rayonnement observable aujourd'hui dans le domaine de longueur d'onde millimétrique. L'un des défis de la cosmologie observationnelle est la détection des modes B de polarisation du CMB. Leur caractérisation précise constitue une étape majeure pour contraindre les modèles d'inflation, phase d'expansion très rapide durant les premiers instants de l'Univers. Ce signal très faible nécessite une nouvelle génération d'instruments combinant une très grande sensibilité et un très bon contrôle des bruits instrumentaux. Ce manuscrit décrit les développements de composants millimétriques réalisés durant ma thèse. Pour le projet QUBIC, télescope basé sur le concept de l'interférométrie bolométrique, j'ai contribué à l'étude de grandes matrices de cornets réalisées à partir d'une technique d'assemblage appelée platelets. J'ai également participé au développement d'une solution originale pour des commutateurs en guide d'onde, éléments essentiels pour l'étalonnage de l'instrument et fonctionnant dans un environnement cryogénique à 4K. Dans le cadre du projet BSD financé par le CNES, j'ai contribué la caractérisation d'un diplexeur de polarisation et au développement d'un commutateur et d'un déphaseur utilisant la technologie planaire supraconductrice. Ces composants sont très intéressants pour le développement d'une architecture de détection intégrée au plan focal pour les futurs instruments dédiés à la caractérisation des modes B
The Cosmic Microwave Background (CMB), the first light emitted by the Universe is a radiation observed today in the millimeter wave range. One of the major challenges of modern cosmology is the detection of the B-mode polarization anisotropies in the CMB. Their precise characterisation constitutes a major step towards to constrain models of inflation, a very fast phase of expansion during the first moments of the Universe. This very weak signal requires a new generation of instruments combining a high sensitivity and a very good control of systematics. This manuscript describes the developments of millimeter wave range components made during my thesis. For the project QUBIC, a telescope based on the bolometric interferometry, I contributed to the study of large horn array made with a fabrication technique called \textit{platelets}. I'm also involved in the development of an original solution for waveguide switches working in a cryogenic environment at 4K, essential components for the calibration of the instrument. With the project BSD funded by CNES, I contributed to the characterization of a diplexer of polarization and to the development of a switch and a phase shifter using the superconducting planar technology. These components are very interesting to develop an integrated detection architecture for the next generation of instruments dedicated to the characterization of CMB B-modes

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Perbost, Camille. "Matrices de bolomètres supraconducteurs pour la mesure de la polarisation du fond diffus cosmologique : application à l’expérience QUBIC." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC283/document.

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Le fond diffus cosmologique (CMB) est la première lumière libérée par l’Univers.À ce titre, elle constitue la photographie la plus ancienne à laquelle nous ayons accès.Ces photons recèlent des trésors d’informations capables de nous renseigner tant sur le contenu énergétique de l’Univers que sur son histoire. En retraçant son évolution jusqu’aujourd’hui, on est capable d’établir des scénarios quant à la période qui a précédé l’émission du CMB, inaccessible aux observations. Plus particulièrement,la plupart des modèles s’accordent à dire que l’Univers aurait connu juste après le Big Bang une période d’expansion exponentielle qualifiée d’inflation. L’un des défis majeurs de la cosmologie consiste à confirmer et contraindre ces modèles en cherchant sur le CMB les empreintes théoriques laissées par l’inflation : un motif de polarisation qualifié de mode B. Cependant, ce signal est attendu à un niveau très faible, sa détection requiert donc la mise en place d’instruments extrêmement sensibles. Cette thèse s’inscrit dans l’effort technologique mené au sein du projet QUBIC pour cette quête. Dans cette optique on s’est intéressé aux détecteurs, des matrices de plusieurs centaines de bolomètres supraconducteurs. Dans un premier temps, on a défini une méthode permettant de dimensionner les détecteurs et la matrice pour répondre au mieux à nos attentes à travers l’ajustement de paramètres pertinents. Puis on a mené pour la première fois dans la collaboration toute la réalisation d’une matrice de 256détecteurs sur laquelle on a par la suite effectué et exposé des tests préliminaires prometteurs pour la future implémentation du plan focal de QUBIC
The cosmic microwave background (CMB) is the very first light of the Uni- verse and thus constitutes the oldest picture of its initial state. These photons carry valuable information constraining both the energy content and the history of the Universe. CMB observations allow us to reconstruct what occurred before the CMB anisotropies were imprinted. The most promising theoretical models all postulate an epoch of exponential expansion known as inflation just after the Big Bang. One of the major challenges of observational cosmology is hence to confirm or falsify inflation as well as to discover how inflation was realized in a particular model by searching for its imprint on the CMB polarization B-mode. This signal is however expected to be extremely weak and its detection requires a very sensitive experiment. This thesis reports on contributions to the technology development for the innovative QUBIC instrument, focusing on the perfection of an array of several hundreds of supercon- ducting bolometric detectors. A method was defined to design the detector array through tuning the relevant parameters to best meet our requirements. Then a 256- detector prototype array was fully manufactured and characterized. The preliminary characterization gave promising results for the forthcoming implementation of the QUBIC focal plane

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Montoya, Huamaní Segundo Timoteo. "Periodización y análisis crítico de las matrices teórico sociológicas en el pensamiento del «primer Quijano» (1948-1968)." Master's thesis, Universidad Nacional Mayor de San Marcos, 2021. https://hdl.handle.net/20.500.12672/16807.

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Propone una reconstrucción de la primera etapa de la vida y obra del sociólogo peruano Aníbal Quijano. Dicha etapa es conocida como el «primer Quijano» y se extiende cronológicamente desde 1948 hasta 1968. La reconstrucción del «primer Quijano» está basada en un marco teórico dividido en cuatro ejes (biográfico-intelectual, temático, cronológico, espacial) y en cuatro pautas de lectura («movimiento de la reflexión», «cuestiones abiertas y horizontes», «desplazamiento epistemológico», «vocación interdisciplinaria»). Asimismo, sobre el «primer Quijano» planteamos una hipótesis de periodización temático-cronológica dividida en tres sub-etapas: 1) el pensamiento «no escrito» (1948-1962), 2) la sociología de la sospecha (1962-1965), 3) la sociología culturalista (1964-1968). La denominación de cada sub-etapa obedece a la «unidadtemática», como hilo conductor en el proceso de reconstrucción, por supuesto sin descuidar la preciada dimensión contextual y geopolítica del conocimiento. De este modo desarrollamos un análisis crítico de las matrices teórico-sociológicas y cuestionamos el afán de simplificación y descontextualización —frecuente en los estudios— sobre la vida y obra de Aníbal Quijano.

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Suarez, Poccorpachi Maria del Pilar. "Proliferación de células madre espermatogoniales de alpaca (Vicugna pacos) en presencia de matrices extracelulares." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2020. https://hdl.handle.net/20.500.12672/15556.

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La importancia de las células madre espermatogoniales (SSC) radica en su capacidad de autorenovación y diferenciación, dando lugar a la espermatogénesis, es por esto que se busca la proliferación In vitro de este tipo de células ya que representan un pequeño porcentaje de la población celular en testículos de machos adultos y poderlas emplear en la preservación de especies. Debido a la problemática reproductiva que presenta la alpaca en sus condiciones naturales, el empleo de SSC de alpaca surge como una alternativa para conservar la genética de individuos de esta especie. En este contexto, el objetivo de este trabajo de investigación fue cultivar células madre espermatogoniales de alpaca en presencia de moléculas como la gelatina y DBA y evaluar cuál de los distintos métodos provee un mayor soporte para la proliferación de las SSC. Se procesaron 12 pares de testículos de alpaca que fueron colectados en el Camal Municipal de Huancavelica (Aprox. 3,600 msnm), seleccionadas según la evaluación de sus parámetros espermáticos (concentración, viabilidad y movilidad espermática). Las suspensiones celulares obtenidas luego del aislamiento fueron purificadas por gradientes de Percoll y se evaluó la población de SSC por medio del marcaje con DBAFITC por Microscopía de Fluorescencia (MF) y Citometría de Flujo (CF), obteniéndose un porcentaje de células madre espermatogoniales post Percoll de 49.68 ± 10.9% y 83.72 ± 8.5% por MF y CF, respectivamente los cuales fueron mucho mayor a sus respectivos iniciales de 22 ± 5.45% (MF) y 46.52 ± 17.84% (CF), siendo esta diferencia estadísticamente significativa por ambas metodologías (p<0.05). Con respecto a la viabilidad celular no se ve afectada por el empleo del Percoll (p>0.05), siendo 94.89 ± 6.73% y 91.33 ± 6.58% antes y después del Percoll, respectivamente. Las células obtenidas antes y después de la purificación fueron cultivadas en placas normales (Grupo control y Grupo Percoll, respectivamente) y en placas cubiertas con gelatina y DBA (Grupo gelatina y Grupo DBA, respectivamente). Durante el monitoreo de los cultivos, la viabilidad celular entre grupos de tratamiento no se vio afectada significativamente (p>0.05), sin embargo, se observó disminución en la viabilidad entre días de cultivo siendo significativamente diferente entre el día 0 y 3 del cultivo para todos los grupos de tratamiento. Además, se observó la formación de colonias de SSC en todos los grupos al día 3 de cultivo, excepto en el Grupo control, donde la formación de estas fue mínima. Sin embargo, estas colonias empezaron a desaparecer al sexto día de cultivo. Luego de 8 días de cultivo se evaluó el porcentaje de SSC entre los distintos tratamientos por MF y CF, obteniéndose un mayor porcentaje de SSC en el Grupo DBA (63.28 ± 5.61% y 66.9 ± 10.34%) y el menor para el Grupo Control (44.48 ± 6.34% y 52.60 ± 23.44%), siendo los porcentajes intermedios para el Grupo Percoll (52.38 ± 5.64% y 57.95 ± 20.2%) y Gelatina (46.36 ± 4.14% y 53.05 ± 17.73%). Siendo el primer porcentaje obtenido por MF y el segundo por CF, se encontró que el Grupo DBA muestra diferencia significativa con respecto a los demás tratamientos por Microscopía de Fluorescencia (p<0.05), sin embargo, por Citometría de Flujo no se encontró diferencia significativa entre tratamientos (p>0.05). Se concluye que el empleo de gradientes de Percoll es un buen método para la purificación de SSC y que el empleo de la lectina DBA puede soportar la proliferación In vitro de SSC de alpaca.
Perú. Universidad Nacional Mayor de San Marcos. Vicerrectorado de Investigación y Posgrado. Programa de Promoción de Tesis de Pregrado. B18100184-PTPGRADO
Tesis

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48

Altamirano, Pizarro Pedro Cesar. "Implementación del método EPA 8270D para el análisis de hidrocarburos aromáticos policíclicos (PAHs), en matrices de aguas." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2020. https://hdl.handle.net/20.500.12672/16167.

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El análisis de los hidrocarburos aromáticos policíclicos (PAHs) en matrices de aguas, que para efectos de la implementación del método EPA 8270 D Rev 4 han sido agrupados como aguas de uso y consumo humano, aguas naturales y aguas residuales, se realiza aplicando la técnica de cromatografía de gases acoplado al detector de Masas. El límite de detección, precisión, veracidad (exactitud), linealidad y rango de trabajo e incertidumbre son los parámetros estadísticos evaluados para el analito Naftaleno y en la que participaron tres analistas en la implementación del método EPA 8270 D Rev 4. Los hidrocarburos restantes están referidos en un cuadro aparte. En una serie de siete repeticiones y con el concurso de los tres analistas, se determinó el valor del límite de detección y de cuantificación al 99% de confianza. Estos fueron 0.00003 y 0.00009 mg/L. La consistencia de los datos se demuestra mediante las pruebas de Mandel, Cochran y Grubbs cuando, los analistas, realizan corridas con agua de uso y consumo humano, agua natural y agua residual; para tres niveles de concentración o valor teórico del fortificado para cada nivel: 0.00016; 0.00080 y 0.00700 mg/L, respectivamente. Una precisión al 95% de confianza demuestra que los resultados de los datos evaluados son consistentes. Al evaluar la normalidad de los datos, para cada nivel, aplicando la prueba de Anderson Darling al 95% de confianza (p value mayores a 0.05), los valores obtenidos fueron 0.273, 0.344 y 0.218. Como son mayores de 0.05, se demuestra que los datos siguen una tendencia normal. La precisión entre analistas, para los tres niveles de concentración evaluados, se mide al aplicar las pruebas estadísticas de Barlett o de homogeneidad de varianzas y medias de un factor o ANOVA. Los valores de 0.403; 0.709 y 0.765, fueron obtenidos para la primera prueba y de, 0.824, 0.709 y 0.848 para el ANOVA. Con los resultados, obtenidos por los tres analistas, se comprueba la existencia de homogeneidad de las varianzas y las medias. Las repeticiones de cada analista, con el valor teórico del fortificado para cada nivel, sirvieron para evaluar la veracidad mediante la prueba t de una muestra. Los valores de 0.217; 0.541 y 0.885, para el primer nivel, de 0.932; 0.703 y 0.287, para el segundo nivel, y de 0.683; 0.954 y 0.382, para el tercer nivel, muestran que los datos son veraces. Para conocer el rango de la curva de calibración obtenida, se determinó su coeficiente de correlación. La relación es lineal porque el valor de 0.9997 para R2 es mayor que 0.99. Los valores de 0.296 y 0.290, mayores que 0.05, fueron obtenidos al evaluar los valores de p y con ellos se determinaron su grado de correlación, que fue de 2.419. Como este valor es mayor que 0, muestra un buen grado de correlación entre las variables y al proveer, el análisis de residuales, un valor para p de 0.810, lo cual demuestra la homeocedasticidad e independencia de los datos. De ahí que el modelo de Horwitz se valida, porque al graficar los residuos se demuestra la ausencia de tendencia en la gráfica. Para evaluar el rango de trabajo de la muestra se preparó como prototipo un compósito cuya concentración de 0.00800 mg/L, es el valor máximo que puede cuantificar la curva en lo que a la muestra se refiere y para su validación, a este nivel, los analistas corrieron 10 repeticiones. Al realizar las pruebas de normalidad, se obtuvo un valor de 0.121 para p, la precisión de Barlett reporta 0.664 como valor de p y este valor para ANOVA de un factor fue 0.892. El rango quedó validado al obtener, para la veracidad, valores de p de 0.325; 0.426 y 0.560, respectivamente. Para estimar la incertidumbre de las muestras a tres niveles se establecieron los factores que sobre ella influyen: sesgo, analistas, concentración de la curva de calibración del equipo, volumen de concentrado de la muestra y volumen de muestra utilizada en el análisis. A continuación, y utilizando la ley de propagación de incertidumbres, se estimó la incertidumbre combinada. Los valores obtenidos al estimar la incertidumbre expandida son: 0.00016 ± 0.0006, para el agua de uso y consumo humano, 0.00080 ± 0.0009, para el agua natural, 0.00700 ± 0.00063, para el agua residual.

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Zuanon, Sardella Larissa Angélica Cirelli. "Produção, caracterização e aplicação de extrato de beterraba microencapsulado em matrizes de maltodextrina e amido modificado /." São José do Rio Preto, 2016. http://hdl.handle.net/11449/144393.

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Orientador: Vânia Regina Nicoletti Telis
Banca: Wanderley Pereira de Oliveira
Banca: Cassia Roberta Malacrida Mayer
Banca: João Cláudio Thoméo
Banca: Andrea Carla da Silva Barreto
Resumo: O presente trabalho teve como objetivo avaliar a produção, as características físicoquímicas e a aplicação de betalaínas oriundas da beterraba (Beta vulgaris L.) microencapsuladas pelo processo de spray drying, utilizando agentes carreadores. Inicialmente, avaliou-se a influência das condições de processo (temperatura e vazão do ar de secagem, concentração e formulação dos agentes carreadores) sobre a umidade das microcápsulas, rendimento do processo, solubilidade, retenção de betalaínas e parâmetros de cor, através de um delineamento composto central rotacional 24 . Foram produzidas partículas utilizando a mistura de dois agentes carreadores: maltodextrina 10 DE (Md) e amido de milho modificado (Am). A partir dos resultados do planejamento experimental, foi selecionado um grupo de quatro amostras para serem estudadas quanto à morfologia, distribuição de tamanho das partículas, isotermas de sorção, atividade antioxidante, temperatura de transição vítrea e estabilidade à luz e ao pH. Além disso, essas amostras foram aplicadas como corante natural em uma formulação modelo de queijo petit suisse, sendo submetidas a avaliação sensorial por teste de aceitação e intenção de compra juntamente com uma amostra comercial do mesmo produto. Em todos os ensaios de produção de microcápsulas foram obtidos baixos valores de umidade (0,16 a 2,91%) e elevada solubilidade (> 90%). O rendimento variou de 2,96 até 81,34% e a retenção de betalaínas nas microcápsulas variou entre 40 e 46%. As amostras com maior concentração total de carreadores resultaram em partículas maiores e com paredes mais lisas, o que está relacionado ao aumento da viscosidade da mistura a ser seca, além disso foram mais estáveis nos testes de estabilidade à luz, apresentando menor variação da cor ao longo de 98 dias de estudo. O processo de encapsulação ofereceu elevada...
Abstract: This study aimed to evaluate the production, physical-chemical characteristics, and the application of betalains derived from beetroots (Beta vulgaris L.) microencapsulated by spray drying using carrier agents. Initially, we assessed the influence of process conditions (temperature and drying air flow-rate, concentration and formulation of carrier agents) on the water content of the microcapsules, process yield, solubility, betalain retention and color parameters through a central composite design 24 . Particles were produced using blends of two carrier agents: maltodextrin 10 DE (Md) and modified corn starch (Am). Taking into account the results of the experimental design, a group of four samples was selected to be further evaluated regarding morphology, particle size distribution, sorption isotherms, antioxidant activity, glass transition temperature and stability to light and pH. In addition, these samples were applied as natural colorant in a model formulation of petit Suisse cheese, which was subjected to sensory evaluation for acceptance and purchase intention along with a sample of the corresponding commercial product. In all the production trials, the microcapsules presented low water content values (0.16 to 2.91%) and high solubility (> 90%). The yield ranged from 2.96 to 81.34%, and betalain retention in the microcapsules ranged between 40 and 46%. Samples with higher total carrier concentration resulted in larger particles and smoother walls, which are related to increased viscosity of the mixture to be dried; further, they were more stable under light exposure, presenting lower color changes up to 98 days of study. The encapsulation process provided high protection to the antioxidant compounds of betalains, keeping more than 70% of the activity in these samples when compared to the results obtained for the pure extract. The highest antioxidant activity was ...
Doutor

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SISTI, CRISTINA. "Aplicacao de diferentes metodologias na preparacao de matrizes organicas para a determinacao voltametrica de elementos traco." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10891.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Dissertations / Theses on the topic 'Food matrices'

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