Dissertations / Theses on the topic 'Shelf-life'
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Weber, Rebecca J. "Shelf life extension of corn tortillas." Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/1115.
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Perkins, Catherine. "The Shelf Life of Zora Cross." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15882.
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Zora Cross (1890–1964) is considered a minor literary figure, but 100 years ago she was one of Australia’s best-known authors. Her book of poetry Songs of Love and Life (1917) sold thousands of copies during the First World War and met with rapturous reviews. She was one of the few writers of her time to take on subjects like sex and childbirth, and is still recognised for her poem Elegy on an Australian Schoolboy (1921), written after her brother was killed in the war. Zora Cross wrote an early history of Australian literature in 1921 and profiled women authors for the Australian Woman’s Mirror in the late 1920s and early 1930s. She corresponded with prominent literary figures such as Ethel Turner, Mary Gilmore and Eleanor Dark and drew vitriol from Norman Lindsay. This thesis presents new ways of understanding Zora Cross beyond a purely literary assessment, and argues that she made a significant contribution to Australian juvenilia, publishing history, war history, and literary history.
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Larsen, Ross Allen Andrew. "Food Shelf Life: Estimation and Experimental Design." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1315.pdf.
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El-Khoury, Aniss Adib. "Shelf-life extension studies on pita bread." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ50762.pdf.
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El-Khoury, Anis Adib. "Shelf-life extension studies on pita bread." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21547.
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In this research, three alternative approaches to chemical preservatives to extend the mold free shelf-life and quality of pita bread were investigated namely: Modified Atmosphere Packaging (MAP) involving gas packaging, oxygen absorbents technology and ethanol vapor generators, high pressures, and direct and indirect heating.Gas packaging using 60%CO2 (balance N2) inhibited the growth of Aspergillus niger and Penicillium notatum from 3d (pita bread packaged in air) to 35d at ambient temperature. A longer extension in shelf-life (42d) was possible using an Ageless oxygen absorbent or a Freshmax oxygen absorbent label in conjunction with gas packaging.
Similar results were obtained with 2G--4G sachets of Ethicap, and 100--200S sachets of Negamold, a dual functional oxygen absorbent-ethanol vapor generator.
High pressures (30--400MPa) used to inhibit mold growth, resulted in delamination of the packaging film and textural changes to the pita bread.
Other alternatives, such as direct heating and microwave processing had a minimal effect in increasing the shelf-life of pita bread. (Abstract shortened by UMI.)
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Webster, S. N. "Shelf-life extension of comminuted meat products." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378472.
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Taylor, Aaron. "Shelf life addressing consumption, permanence through adaptability /." This title; PDF viewer required. Home page for entire collection, 2006. http://archives.udmercy.edu:8080/dspace/handle/10429/9.
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Chitundu, Elizabeth Malama, of Western Sydney Hawkesbury University, Faculty of Science and Technology, and School of Food Science. "Studies on the shelf life of macadamia nuts." THESIS_FST_SFS_Chitundu_E.xml, 1994. http://handle.uws.edu.au:8081/1959.7/37.
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Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.Master of Science (Hons) (Food Science and Nutrition)
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Feliciano, Lizanel. "Shelf-life Extension of Seafood Using Sanitized Ice." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1252965039.
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Carpenter, Christopher E. "IMPACT OF ULTRAVIOLET ENERGY ON STRAWBERRY SHELF LIFE." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1885437591&sid=5&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Chitundu, Elizabeth Malama. "Studies on the shelf life of macadamia nuts." Thesis, Richmond, N.S.W. : School of Food Science, Faculty of Science and Technology, University of Western Sydney, Hawkesbury, 1994. http://handle.uws.edu.au:8081/1959.7/37.
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Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.
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ZAMBUCHINI, Barbara. "Shelf-life and Molecular Traceability of Fish Product." Doctoral thesis, Università degli Studi di Camerino, 2008. http://hdl.handle.net/11581/401874.
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The subject of my PhD course regards two aspects of fish products quality and characterization. The first one deals with the evaluation of the effects of natural antioxidants (ellagic acid and L-ascorbic acid) in enhancing fresh sole (Solea solea) shelf life. Quality assurance in the fish sector involves monitoring and documenting defined quality criteria as required by regulations (European Community, 1996), product specifications and consumer demands. Fresh fish products are commonly sold at storage temperature. However, many undesirable changes can occur in the products during storage, due to microbial growth and fish spoilage, affording evident economic loss. From this point of view it is important to develop systems which help to prolong fish shelf life. In this perspective, we have studied the effects of ellagic acid (EA) and L-ascorbic acid (LAA)/ sodium ascorbate (SA), either alone or in combination, on the microbiological quality of fresh finfish Solea solea during storage at 0 °C. The results showed that addition of EA (0.03%) alone or in combination with L-AA (1.71%)/SA (1.98%) significantly delayed the proliferation of aerobic plate counts, psychrotrophic counts and Pseudomonas bacteria extending the product shelf life up to 10 days, versus 8 days for control. During the storage, the pH increase is slowed down when the fish samples are subjected to the treatment with preservative agents. The effect of lowering the pH increase is particularly pronounced when a combination of EA and L-AA/SA is used. Therefore, EA alone or in combination with L-AA and SA can be successfully utilized to reduce the microbial growth, extending the shelf life of fish during storage at 0 °C. The second aspect of fish products quality and characterization studied in this PhD course deals with the identification of ''species-specific genetic markers'' of red mullet (M. barbatus) as useful tools for ''the commercial designation of species''. Consumers demand for a deeper knowledge of the quality and the origin of food is increasing significantly. The UE with the adoption of Reg. (EC) 2065/2001, laying down detailed rules for the application of Reg. (EC) 104/2000, wanted to give a strong push to the " traceability of fish products" through the labelling systems. European Council Regulation (EC) 104/2000, on the common organization of the markets in fishery and aquaculture products, specifies that these products may not be offered for retail use unless they are labelled with ''the commercial name of the species'', ''the production method'' and ''the capture zone''. Particularly, in Italy "the commercial designation" must respect the list present in the enclosure A of the D.M. 27-03-02 and in the following modifications and integrations of the D.M. 25/07/2005. Therefore, the development of analytical methods for species identification is necessary to detect and avoid wilful, as well as unintentional substitution of different fish and shellfish species and to enforce labelling regulations (Mackie et al., 1999). The main aim of this study was the development of a PCR-based assay for the identification of red mullet (M. barbatus) and striped red mullet (M. surmuletus), and was projected on the locus 16S rDNA gene fragment of the 3 Mullid genera (Mullus, Upeneus and Pseudopeneus), widespread in the Mediterranean Sea. The second aim was the investigation of the possible polymorphisms able to detect different populations of red mullet (M. barbatus) in the Mediterranean Sea. The PCR-assay developed can be adequately used for ''species identification'' of red mullet (M. barbatus) and striped red mullet (M. surmuletus). This approach is rapid and offers the potential to detect fraudulent or unintentional mislabeling of seafood, but can be particularly indicated for application to ''processed products''. The randomness of genetic differences among samples indicated that the Adriatic red mullet stock probably belongs to single population unit, according to Garoia et. al., 2004.
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ZAMBRINI, ANGELO STAVRO VITTORIO. "Relationship between Food Waste Probability and Shelf Life." Doctoral thesis, Università di Foggia, 2017. http://hdl.handle.net/11369/362087.
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Obiettivo dello studio
L’allungamento della shelf life dei prodotti alimentari è un tema particolarmente sentito dal sistema agroindustriale italiano ed in particolare dall’industria lattiero-casearia a fronte della crescente richiesta da parte dei consumatori di prodotti freschi ed ultrafreschi.
Il presente studio si pone come obiettivo primario valutare l’esistenza o meno di una correlazione fra estensione della durabilità dei prodotti alimentari, ed in particolare dei latticini freschi prendendo a modello la mozzarella Fior di Latte, e riduzione dello spreco alimentare. Si eseguirà a tal scopo studio statistico di dati di mercato per cercare di correlare, nel comparto lattiero-caseario, la shelf life dei prodotti con lo spreco alimentare, adottando come parametro principale di valutazione la percentuale di prodotto reso da mercato sul prodotto venduto.
Si pone inoltre come ulteriori obiettivi lo studio sperimentale di strategie per l’allungamento della durabilità della mozzarella Fior di Latte (FdL).
Materiali e Metodi
Lo studio statistico è stato condotto utilizzando dati cortesemente messi a disposizione da una grande industria alimentare italiana, relativi a 640 diverse referenze di prodotti lattiero-caseari, che sono stati suddivisi in 17 classi in funzione della shelf life loro assegnata. Come variabili sono state utilizzate il valore di shelf life e la percentuale di reso da mercato (reso/venduto). I dati sono stati sottoposti dapprima ad analisi ANOVA per valutare eventuali differenze fra le 17 classi e il reso% e quindi a modellizzazione per analizzare la correlazione esistente fra le due variabili. Tutte le analisi statistiche sono state condotte con il pacchetto statistico IBM SPSS 20.
Diverse strategie di packaging e le loro relative combinazioni sono state utilizzate per valutare il loro impatto sulla durabilità della mozzarella Fior di Latte mantenuta alla temperatura costante di + 8°C (la temperature media dei frigoriferi domestici in Italia). In particolare si sono utilizzati coating attivi e confezionamento in atmosfera modificata (MAP) per valutarne l’effetto combinato. Ad intervalli regolari di tempo si sono prelevate unità campionarie che sono state valutate per la composizione del gas presente nello spazio di testa della confezione, per il pH del prodotto e del liquido di governo, per I contenuti microbici (conta microbica totale, conta dei batteri lattici e delle pseudomonadacee), nonchè per le caratteristiche sensoriali. Definiti i limiti di accettabilità microbica e sensoriale (MAL and SAL) rispettivamente a 10exp6 ufc/g per le pseudomonadacee e a punteggio 4,0 per la qualità globale dell’analisi sensoriale, è stato possibile calcolare la shelf life della mozzarella Fior di Latte sulla base del minimo valore ottenuto di MAL e SAL.
Risultati principali dello studio
All’analisi ANOVA il parametro reso% non mostra, per i prodotti freschi con shelf life inferiore o uguale a 30 giorni, differenze significative delle medie. Al contrario, per i prodotti aventi shelf life superiore a 30 giorni, le differenze fra i valori medi del reso% appaiono significative. L’ulteriore indagine condotta con un approccio di modellizzazione ha portato ad un modello esponenziale che spiega la correlazione fra shelf-life e reso% da mercato.
Dal lato della sperimentazione di tecniche protettive per l’estensione della shelf life si è evidenziato che la semplice ricopertura della mozzarella Fior di Latte con un strato di alginato polimerizzato in loco protegge solo relativamente il prodotto dallo sviluppo microbico. Il confezionamento in atmosfera modificata (MAP), specialmente ad alte proporzioni di CO2, risulta invece efficace nell’inibizione dei microorganismi alteranti ma impatta negativamente la superficie del formaggio, ciò che non avviene se il formaggio è protetto dalla copertura di alginato. Caricando la copertura di alginato con composti ad azione antimicrobica (active coating) aumenta l’efficacia del sistema: i risultati sperimentali confermano che accoppiando MAP ed active coating (es. potassio sorbato o nanoparticelle di argento) si ottiene un sistema efficace nell’allungamento della shelf life della mozzarella Fior di Latte. Parimenti l’inclusione di cellule di L. reuteri e di glicerolo a formare un coating bioattivo migliora significativamente la shelf life del prodotto in liquido di governo se accoppiato a MAP.
Conclusioni
L’analisi statistica mostra una correlazione di tipo esponenziale fra percentuale di reso da mercato, uno degli indicatori di spreco alimentare, e shelf life assegnata ai prodotti quando questa è superiore a 30 giorni. La differenza fra le medie del reso% in funzione della shelf life non appare invece significativa per i prodotti freschi ed ultrafreschi (DLC < 30 gg). Il dato statistico sembra non concordare con quanto osservato sul campo dagli operatori alimentari, che rilevano benefici, a parità delle altre variabili, in termini di reso da mercato a seguito di allungamento della shelf life.
Il confezionamento in MAP ad elevate proporzioni di CO2 è in grado di controllare lo sviluppo di Pseudomonads spp., il principale agente di alterazione di Fior di Latte e mozzarelle fresche in liquido di governo, ma altera le caratteristiche organolettiche del prodotto, in particolare degradandone la superficie. La presenza di una copertura di alginato protegge la superficie del formaggio dai danni causati dall’acidità del liquido di governo. L’utilizzo combinato di un coating attivo e del confezionamento in atmosfera modificata risulta in grado di allungare la shelf life del prodotto, confermando che è necessario un approccio ad ostacoli multipli per ottenere i risultati attesi.
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Bordin, Ângelo Rafael de Vito. "Estudo do shelf life da quitosana armazenada em diferentes tipos de embalagem, por meio de colorimetria e análise da microdureza dentinária." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/58/58133/tde-22042014-144350/.
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O objetivo do presente trabalho foi estudar, por meio da técnica de titulação colorimétrica e análise da microdureza dentinária, o shelf life da solução de quitosana 0,2% armazenada em frascos de vidro e plástico. Trinta caninos superiores humanos tiveram as coroas desprezadas e a porção cervical das raízes seccionada, obtendo-se 3 cortes. O segundo e terceiro cortes foram divididos ao meio e incluídos em resina acrílica resultando em 4 corpos de prova por dente. A solução de quitosana 0,2% (pH 3,2) foi preparada e distribuída em 3 frascos iguais de vidro (v1, v2 e v3) e em 3 de plástico (p1, p2 e p3) para realização dos testes em triplicata. Os testes de microdureza e colorimetria foram realizados durante seis meses nos períodos de 0, 7, 15, 30, 45, 60, 90, 120, 150 e 180 dias após o aviamento da solução. Para a mensuração da microdureza Knoop utilizou-se carga de 10 gramas por 15 segundos. O corpo de prova recebeu 50 μL da solução teste por 5 minutos e, após lavagem e secagem foi levado para mensuração. A análise foi realizada com as soluções v1, p1, EDTA 17% e água destilada (controle); v2, p2, EDTA 17% e controle; v3, p3, EDTA 17% e controle, para cada tempo proposto. Foram realizadas 3 endentações com espaço de 200 μm. As mensurações foram anotadas e arquivadas em um banco de dados. Para o teste da colorimetria utilizou-se uma solução padrão de carbonato de cálcio 0,3%, na qual gotejava-se por meio de micropipeta a solução de quitosana com volume pré determinado. A alteração da coloração da solução de carbonato, do violeta para azul, indicava quelação dos íons cálcio, detectada por meio de espectrofotometro Ultravioleta Visivel. O aparelho emitia um valor da absorbância para cada análise da coloração, expressa por meio de gráfico (comprimento de onda/absorbância). Empregou-se Análise de Variância (one-Way ANOVA) (α = 0,05) para comparar a microdureza entre as soluções, os diferentes tempos para cada solução, bem como a interação microdureza/tempo para cada solução. Houve semelhança entre as soluções testadas no que se refere ao tempo de estudo (p=0,113), bem como em relação à interação microdureza/tempo (p=0,329). As soluções testadas apresentaram, individualmente, o mesmo efeito sobre a microdureza da dentina, desde o tempo zero até os 180 dias. Quando comparadas entre si foram diferentes (p<0,0001). O teste de Tukey evidenciou que a quitosana (v1, v2, v3, p1, p2 e p3) e EDTA reduziram a microdureza de forma semelhante entre si (p>0,05) e diferente do controle (p<0,001). Os gráficos da análise colorimétrica mostraram que tanto a quitosana em vidro como a em plástico apresentaram valores médios de absorbância no mesmo comprimento de onda (234nm) para todos os tempos, enquanto que para a solução padrão de carbonato de cálcio o comprimento de onde foi de 206nm. Concluiu-se que independentemente da forma de armazenamento a quitosana apresenta propriedade quelante por um período mínimo de 6 meses.The aim of this study was evaluate, through the colorimetric titration method and analysis of the dentine microhardness, the shelf life of the solution of chitosan 0,2% stored in flasks of glass and plastic. Thirty human superior canines had their crown discarded and the cervical portion of the root sectioned, obtaining 3 sections. The second and the third sections were divided in half and included in acrylic resin resulting in 4 specimens per tooth. The chitosan solution 0,2% (pH 3,2) was prepared and distributed in 3 flasks of glass (v1, v2, v3) and in 3 of plastic (p1, p2, p3) to perform the test in triplicate. The tests of microhardness and colorimetry were performed during 6 months in the period of 0, 7, 15, 30, 45, 60, 90, 120, 150 and 180 days after the preparation of the solution. For the measurement of microhardness Knoop, it was used a load of 10 grams for 15 seconds. The test object received 50 μL of the test solution for 5 minutes and after washing and drying, it was taken out for measurement. The analysis was performed with the solutions v1, p1, EDTA 17% and distilled water (control); v2, p2, EDTA 17% and control; v3, p3, EDTA 17% and control, for each proposed time. Three indentations were performed with a 200μm space. Measurements were noted and filed in a database. For the colorimetric test, a standard solution of calcium carbonate 0.3% was used and a predetermined volume of chitosan solution was inserted to it by using a micropipette. The color changes observed in the carbonate solution, from violet to blue, indicated the chelation of calcium Ions, detected through visible ultraviolet absorbance spectrophotometry. The instrument generated a specific value of absorbance for each coloring solution analyzed, expressed through the graphic (wavelength/absorbance). Variation of analysis was used (One-Way ANOVA) (α= 0,05) to compare the microhardness among the solutions, the different time for each solution, as well as the interaction microhardness/time for each solution. The time of study was similar among the tested solutions (p=0,113), as well as the interaction between microhardness/time (p=0,329). The tested solutions showed, individually, the same effect over the dentine microhardness, from time zero until 180 days. When compared among each other the results were different (p<0,0001). The Tukey test demonstrated that chitosan (v1, v2, v3, p1, p2 and p3) and EDTA reduced the microhardness in a similar pattern among them (p>0,05) and different from the control (p<0,001). The graphics of the colorimetric analysis showed that either chitosan in glass or plastic presented medium values of absorbance in the same wave length (234nm) for all the different times, meanwhile the standard solution of calcium carbonate wavelength was 206 nm. It was concluded that independently of storing methods, the chitosan presents chelating property for a minimum period of six months.
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Mohammadbeygy, Tina. "Shelf life extension of preformed pizza using ultraviolet light." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123317.
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Mold is a common post-processing contaminant in pizza. Since contamination could occur in post-baking process, other safety barriers in addition to packaging are needed to ensure the continued safety of preformed pizza. The present research investigated the use of pulsed UV-light for the purpose of decontaminating Penicillium roqueforti on the surfaces of agar media, bread and preformed pizza. In the first step in the present study, the spatial distribution of pulsed UV-light was investigated. The Petri plates inoculated with Penicillium roqueforti were treated for10 min in the first three effective levels in the treatment chamber (5, 10 and 15 cm). 30, 75 and 90 percent of the surface area of the tray was exposed to pulsed light at 5, 10 and 15 cm from pulsed light lamp, respectively. Apple juice inoculated with E. coli was treated with pulsed UV-light at the same distances (5, 10 and 15 cm) from the light source, 3 voltage inputs (400, 750 and 1,000 V) and 3 treatment times (1, 5 and 10 min). The log reduction in E. coli population treated by pulsed UV-light varied from 1.4 to 2.05 log CFU ml-1. In the second phase of the study, the consistency of mold growth on the surface of flat bread was investigated using two different methods of inoculation; random spot and spread. Two different inoculum populations (102 and 103 CFU ml-1) were also used to assess the effect of inoculum concentration on the distribution and consistency of mold growth. Samples inoculated with 102 CFU ml-1 yielded more homogenously distributed colonies. In the third phase of the study, sensory and microbiological analyses were used to evaluate the effectiveness of pulsed light treatment for shelf life extension of pizza and bread. Up to 40 days shelf-life extension was achieved for 8, 32, and 40 percent of samples with minimal, intermediate and maximal pulsed light treatment, respectively. In the fourth phase of the study, the effectiveness of pulsed light was evaluated for the decontamination of Penicillium roqueforti on the surface of solid agar. Process parameters evaluated were treatment time (1, 3, 5, 7 and 10 min) and voltage input (500, 750 and 1,000 V). The population of Penicillium roqueforti was reduced after 10 min of exposure to pulsed light by 3.74, 5.36 and 6.14 log CFU ml-1, respectively for 500, 750 and 1,000 V. The inactivation data were used to construct models to estimate the inactivation. The results presented in this study indicate that inactivation kinetics was best described by the Weibull model with the smallest root mean squared error (RMSE) (R2 ≥ 0.92). Finally in the last phase of study, culture-dependent and independent methods were applied to study the ecology of preformed pizza. The average population of mesophilic aerobic bacteria (MAB), mesophilic anaerobic bacteria (MANB), lactic acid bacteria (LAB), molds and yeasts (M+Y) were 6.6±0.5, less than 2.4, 2.8±0.6 and 5.4±0.4 log CFU g-1, respectively. Molecular methods incorporating conventional PCR targeting the 18S rRNA gene of fungi, TA cloning of PCR-amplified fragments and sequencing were carried out to detect spoilage fungi in naturally spoiled pre-formed pizza. The cloning approach enabled the putative identification of Saccharomyces cerevisiae, Saccharomyces sp. WW-W23, Penicillium expansum, Penicillium freii, Penicillium sp. HSL, Penicillium sp. ljg1, Rhodotorula mucilaginosa, Monascus fuliginosus, Hordeum jubatum, Galactomyces geotrichum strains as well as uncultured fungus and uncultured eukaryote clones. Overall, pulsed UV-light was found to have a potential use for the decontamination of spoilage microorganisms on the surfaces of solid agar and bakery products. However, further investigation using higher treatment voltages is necessary in order to achieve a higher target decontamination of P. roqueforti.La pizza pré-cuisinée est couramment contaminée par la moisissure. Puisque la contamination pourrait se produire durant les procédés d'après cuisson, d'autres mesures, en plus de l'emballage, sont nécessaires pour assurer la sécurité permanente des pizzas pré-cuisinée. Cette recherche a examiné l'utilisation de la lumière UV pulsée pour décontaminer Penicillium roqueforti sur la surface de l'agar solide, du pain et de pizzas préformées.Dans la première étape de la présente étude, les paramètres critiques du procédé ont été optimisés pour améliorer l'efficacité des traitements à la lumière pulsée. Les boîtes de Petri inoculées avec Penicillium roqueforti ont été traitées 10 min dans une chambre de traitement pour les trois premiers niveaux d'efficacité (5, 10 et 15 cm). Les résultats démontrent que 30, 75 et 90 pour cent de la surface du plateau a été exposée à la lumière pulsée à 5, 10 et 15 cm respectivement de la source lumineuse. La réduction en log de la population de E. coli traitée par la lumière UV pulsée varie de 1.4 à 2.05 log UFC ml-1.Dans la deuxième phase de l'étude, la cohérence de la croissance des moisissures (Penicillium roqueforti) sur la surface du pain plat a été étudiée en utilisant deux méthodes différentes d'inoculation : par inoculation ponctuelle aléatoire et par étalement. Deux populations d'inoculum différentes (102 et 103 UFC ml-1) ont également été utilisées pour évaluer l'effet de la densité de l'inoculum sur la distribution et la cohérence de la croissance de moisissures. Les échantillons inoculés avec 102 UFC ml-1 ont donné une distribution des colonies plus homogène. À la troisième phase de cette étude, l'analyse sensorielle et microbiologique, ont été utilisées pour évaluer l'efficacité du traitement à la lumière pulsée pour prolonger la durée de vie de la pizza et du pain. Jusqu'à 40 jours de prolongement de la durée de conservation a été obtenue pour 8, 32 et 40 pour cent des échantillons après un traitement à la lumière pulsée minimal, intermédiaire et maximal, respectivement. Dans la quatrième phase de l'étude, l'efficacité d'une lumière UV pulsée à large spectre a été évaluée pour la décontamination de Penicillium roqueforti sur la surface de l'agar solide. La population de Penicillium roqueforti a été réduite après 10 minutes d'exposition à la lumière pulsée par 3.74, 5.36 et 6.14 log UFC ml-1 respectivement pour 500, 750 et 1000 V. Les résultats présentés dans cette étude indiquent que d'inactivation a été mieux décrite par le modèle de Weibull avec la plus petite erreur de moyenne quadratique (RMSE) (R2 ≥ 0.92). Finalement, dans la dernière phase de l'étude, des méthodes dépendantes ou indépendantes des conditions de culture ont été appliquées pour étudier l'écologie des pizzas pré-cuisinées. La moyenne de la population des bactéries mésophiles aérobies (BMA), des bactéries mésophiles anaérobies (BMNA), des bactéries lactiques (BL), des moisissures et des levures (M+L) étaient respectivement de 6.6 ± 0.5, inférieur à 2.4, 2.8 ± 0.6 et 5.4 ± 0.4 log UFC g-1. Les méthodes moléculaires incorporant la PCR conventionnelle ciblant le gène de l'ARNr 18S des champignons, le clonage TA de fragments amplifiés par PCR et le séquençage ont été réalisées pour détecter les champignons altérant les pizzas pré-cuisinées naturellement contaminées. L'approche du clonage a permis l'identification présumée de souches de Saccharomyces cerevisiae, Saccharomyces sp. WW- W23, Penicillium expansum, Penicillium freii, Penicillium sp. HSL, Penicillium sp. ljg1, Rhodotorula mucilaginosa, Monascus fuliginosus, Hordeum jubatum , Geotrichum galactomyces ainsi que des champignons et eucaryotes non cultivés.Dans l'ensemble, la lumière UV pulsée a démontré avoir un potentiel d'utilisation pour la décontamination des microorganismes altérant les surfaces d'agar solide et les produits de boulangerie.
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Ur-Rahman, Atta. "Negative gamma functions and their relationship to shelf-life." Thesis, University of Hertfordshire, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421262.
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Wynne, Edward McFaddin. "Determination of the Shelf Life of Aluminum Electrolytic Capacitors." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3104/.
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The aluminum electrolytic capacitor is used extensively in the electric utility industry. A factor limiting the storage of spare capacitors is the integrity of the aluminum oxide dielectric, which over time breaks down contributing to a shelf life currently estimated at one nuclear power electric generating station to be approximately five years. This project examined the electrical characteristics of naturally aged capacitors of several different styles to determine if design parameters were still within limits. Additionally, the effectiveness of a technique known as “Reforming” was examined to determine its impact on those characteristics.
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Al-badri, Samir B. Salman. "Extending Saleable Shelf Life Of Selected Perishable Specialty Crops." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1648.
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Farmers are limited in the amount of specialty crops they can plant, harvest and market without adequate cooling to preserve commodities before sale. A cooler available at a farm would allow the farmer to harvest his produce earlier and take it to market at a later time. Cooling available on the farm will help a farmer to harvest commodities during peak harvest times and store it for future sale at multiple farmers markets or over a period of a week or more at a farm market. A cooler will give a farmer more logistical options. An indirect-direct evaporative pad cooling can provide cooling with high humidity which is sufficient to prolong shelf life. A cool room with window air conditioning (AC) was modified by adding indirect-direct evaporative cooling. The cool room was used for comparative study of produce shelf life under AC (with CoolBot), indirect-direct evaporative cooling (EC), residential AC (RES), and farm building (FB) storage. Results showed that FB had a lower shelf life because of non-conditioned space. RES was a table in an office building with a temperature of about 22°C. For produce with medium temperature requirements such as tomato, cucumber, and green pepper the shelf life was prolonged more in the cooler room. Strawberry and blueberry had a much longer shelf life in a cooler. The shelf life of the blueberry stored at Cooler AC was longer about two and a half fold longer than Cooler EC and RES, and five and half fold longer than FB. The shelf life of the strawberry in Cooler AC was longer one-fold than Cooler EC, two and a half fold longer than RES, and five-fold longer than FB. The shelf life of green pepper stored in Cooler AC was longer fivefold than Cooler EC and nine and a half fold longer than RES and FB. The shelf life of cucumber stored at Cooler AC was longer two fold than Cooler EC and 3.3-fold longer than RES and four fold longer than FB. The shelf life of tomato stored at Cooler AC was longer 1.25-fold than Cooler EC, 1.75 fold longer than RES and two and a half fold longer than FB. Generally stored fruits and vegetables in Cooler AC was maintained quality with minimal weight loss that allows a farmer to store their produce while maintaining shelf life. Cooler EC can be used to store produce for a shorter time with higher weight loss. Finally, FB had a shorter shelf life due to the non-conditioned space.
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Bagnato, Annunziata Teresa. "Postharvest improvement of Cavendish banana quality and shelf life /." Title page, table of contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phb147.pdf.
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Joubert, Marisa. "The manipulation of ostrich meat quality, composition and shelf life." Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/16341.
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Thesis (MScVoedselwet)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: Two experiments were conducted in order to manipulate the physical and chemical properties and shelf life of ostrich meat. Experiment 1: The effect of dietary fish oil rich in n-3 fatty acids on the organoleptic, fatty acid and physicochemical characteristics of ostrich meat. The diet of four ostrich groups (15 birds per group), approximately 3 months of age (ca. 41 kg live weight) grazing a predominantly oats pasture, was supplemented with a diet containing 6.7% fish oil. The birds received a supplement of either 0 (diet 1), 800 (diet 2), 1600 (diet 3) or 2400 g (diet 4) DM/day resulting in the consumption of 0 (diet 1), 14.5 (diet 2), 29 (diet 3) and 43.5 (diet 4) g fish oil per day. The ostriches were slaughtered at 10 months of age (ca. 70 kg live weight). An increase in the amount of fish oil consumed was found to have had statistically no significant effect on the sensory characteristics of the M. iliofibularis, although there was a tendency towards an increase in ‘fishiness’, for both aroma and flavour. However, increased concentrations of fish oil had a significant effect on the aroma and flavour of the abdominal fat pads. The muscle pHf and muscle lightness (L*) reflected a significant reduction with increased fish oil levels. The increased feed intake, on the other hand, had no effect on the chemical composition (moisture, protein, fat and ash content) of the meat. The fatty acid profile of both fat and meat was affected by the consumption of fish oil. The SFA concentration increased, while the PUFA concentration decreased, with an increase in feed intake. The MUFA concentration remained constant for all four groups. Experiment 2: The effect of dietary vitamin E and the type of packaging on the sensory quality, physicochemical composition and shelf life of ostrich meat. Two groups of ostriches (35 birds per group; ca. 3 months old) were fed diets containing either 40 mg/kg feed vitamin E (control) or 150 mg/kg feed Vitamin E for nine months. The birds were slaughtered at 12 months of age. The effect of different the levels of vitamin E and heat shrink treatment of vacuum packaging material on the shelf life of refrigerated (0°C) ostrich M. flexor cruris lateralis, was evaluated over 81 days. Vitamin E and heat shrink treatments were found to have had no significant effect on the sensory characteristics; off-meat aroma, sourness, juiciness and mealiness. Rancidity was found to be slightly more pronounced (although not statistical significant) in the vitamin E and heat shrink groups than in the feed control and vacuum-packed groups. A significant decrease in the organoleptic quality of the meat, over a 40 day shelf life period, was observed. The pH and muscle tenderness showed a significant reduction with increased storage time. The purge loss in the package increased over time with no change in muscle drip loss. The colour, conjugated dienoic acid and fatty acid content showed no significant changes over time or with regards to treatment. The total viable counts and coliform numbers in the muscle increased over time, with the coliforms being slightly suppressed by the inclusion of vitamin E in the diet. A microbiological safe shelf life of 40 days at 0°C was obtained.
AFRIKAANSE OPSOMMING: Twee eksperimente is uitgevoer om die fisiese en chemiese eienskappe, asook die rakleeftyd van volstruisvleis, te manipuleer. Eksperiment 1: Die effek van visolie, ryk aan n-3 vetsure, op die organoleptiese, vetsuur- en fisies-chemiese eienskappe van volstruisvleis. Die dieet van vier groepe volstruise (15 voëls per groep), ongeveer 3 maande oud (ca. 41 kg lewende massa) wat ‘n hawer weiding bewei het, is aangevul met ‘n byvoedingsmengsel wat 6.7% visolie bevat en in toenemende hoeveelhede vir die groepe volstruise gevoer is. Die voëls het ‘n aanvulling van 0 (dieet 1), 800 (dieet 2), 1600 (dieet 3) of 2400 g (dieet 4) DM/dag ontvang wat gelei het tot ‘n inname van 0 (dieet 1), 14.5 (dieet 2), 29 (dieet 3) en 43.5 (dieet 4) g visolie per dag. Die volstruise is op ‘n ouderdom van 10 maande geslag (ca. 70 kg lewende massa). ‘n Toename in die hoeveelheid visolie ingeneem, het geen statisties betekenisvolle effek op die sensoriese eienskappe van die M. ilifibularis gehad nie, alhoewel daar ‘n tendens was vir ‘n toename tot ‘n ‘visagtige’ aroma en smaak. ‘n Toename in die konsentrasie visolie het egter ‘n betekenisvolle effek op die ‘visagtige’ aroma en smaak van die abdominale vet neerslae gehad. Die spier pHf en spier ligtheid (L*) het ‘n betekenisvolle afname met toename in voer inname getoon. Die verhoogde olie inname het egter geen effek op die chemiese samestelling (vog-, proteïen-, vet- en asinhoud) van die vleis gehad nie. Die vetsuurprofiel van beide die abdominale vet neerslae en die vleis is deur die inname van visolie verander. Die versadigde vetsuurkonsentrasie het verhoog terwyl die poli-onversadigde vetsuurkonsentrasie verlaag het met ‘n toename in rantsoenvlakke. Die mono-onversadigde vetsuurkonsentrasie het egter konstant gebly vir al vier groepe. Eksperiment 2: Die effek van vitamien E en die tipe verpakking op die sensoriese kwaliteit, fisies-chemiese samestelling en rakleeftyd van volstruisvleis. Twee groepe volstruise (35 voëls per groep, ongeveer 3 maande oud) het voere oor ‘n tydperk van nege maande ontvang wat 40 mg vitamien E/kg voer (kontrole) of 150 mg vitamien E/kg voer bevat het. Die voëls is op 12 maande ouderdom geslag. Die effek van die verskillende vlakke van vitamien E en hitte-behandeling van die verpakkings materiaal op die rakleeftyd van verkoelde (0°C) volstruis M. flexor cruris lateralis, is oor 81 dae geëvalueer. Vitamien E en die hitte-behandeling het geen betekenisvolle effek op die organoleptiese eienskappe (af-vleis aroma, suurheid, sappigheid en melerigheid) gehad nie. Galsterigheid was ‘n bietjie meer gedefinieerd (anie-betekenisvol) in die vitamien E en hitte behandelde groepe as in die rantsoen kontrole en vakuum verpakte vleis. ‘n Betekenisvolle afname is waargeneem in die organoleptiese kwaliteit van die vleis oor ‘n 40 dae rakleeftyd periode. Die pH en taaiheid van die spier het betekenisvol afgeneem met ‘n toename in bergingsperiode. Die drup verlies tydens verpakking het ook oor tyd toegeneem, terwyl geen verandering in die analitiese drup verlies van die spier verkry is nie. Die kleur, gekonjugeerde dieensuur en vetsuursamestelling het geen verandering oor tyd of ten opsigte van behandeling getoon nie. Die Totale Lewendig Seltelling en coliforme het toegeneem oor tyd, terwyl die coliforme deur die byvoeging van vitamien E tot ‘n mate onderdruk is. ‘n Mikrobiologies veilige rakleeftyd van 40 dae is verkry.
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Alcéo, Rita Gonçalves André. "Temperatures and shelf-life duration in the stawberry supply chain." Master's thesis, ISA-UL, 2016. http://hdl.handle.net/10400.5/13359.
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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia - ULStrawberry is a very perishable fruit that requires proper temperature management to reduce losses. Temperature abuses in the strawberry supply chain leads to high losses and dissatisfaction on the part of consumers and retailers. The temperature was monitored in two commercial circuits from harvesting to the final consumer, in June and July of 2016. Temperatures outside and inside of 500 g clamshells and inside the fruits were recorded in the three locations of the pallet. The air temperature inside 5 vehicles trunks and 5 domestic refrigerators were recorded at 60 seconds intervals. Strawberry (Fragaria ×ananassa) packaged in clamshells were stored at 0, 5, 10, 15, and 20 °C. Fruit were evaluated for colour, firmness, soluble solids content (SSC), and titratable acidity (TA). A 10-member panel assessed the fruit for odour, texture, juiciness, flavour, and overall liking at the same sampling dates. In the studied circuits fruits were exposed to an accumulated time-temperature (ATT) of 502.3 and 588.8 °C h. In both the display in store represented the largest contribution to the ATT (273.1 and 281.2 °C h). The maximum temperatures recorded in trunks each day were 47.3, 40.3, 41.4 and 48.2 °C with an outdoor temperature of 24.0, 26.1, 28.2 and 36.6 °C. In refrigerators were recorded average temperatures of 7.2, 4.3, 9.2, 7.4 and 7.7 ° C with reaching temperature fluctuations higher than 5 °C. The temperature had little effect on the physicochemical characteristics and sensory evaluation of the strawberry, but strongly influenced the evolution of the losses. The clamshells have become unmarketable after 3 days at 20 °C and 5 days at 15 °C. Damages development can arise in the retail or just in consumers houses with the ‘last mile’ temperatures being possibly the responsible for the biggest quality depreciation on strawberries
N/A
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Mugadza, Desmond Tichaona. "Bacillus and Paenibacillus spp. associated with extended shelf life milk." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/65919.
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Extended shelf life (ESL) milk combines longer shelf life and better organoleptic characteristics; a combination that is absent in both pasteurised and ultra-heat treated (UHT) milk. Bacterial spoilage remains the main cause of food loss worldwide, which also includes milk and dairy products, despite advances in food preservation technology. The objectives of this study were to identify and characterise the spore-forming population associated with ESL milk during processing and chilled storage as well as characterising Bacillus cereus isolates obtained from ESL milk processing and during storage. Characterisation of spore-formers associated with ESL milk was done by analysing bacteriological quality of milk samples collected at various processing stages and during storage. Isolates were identified with MALDI-TOF-MS. B. cereus strains obtained from ESL milk and filler nozzles were characterised using (GTG)5 Rep PCR fingerprinting; the presence of virulence genes; cytotoxin K (cytK), nonhemolytic enterotoxin A (nheA), emetic toxin cereulide (cer) and enterotoxin hemolysin BL (hblA). The isolates were further discriminated as psychrotrophic and mesophilic strains using 16S rDNA. Furthermore, B. cereus isolates were selected for 16S partial sequencing. Some of the B. cereus strains obtained from ESL milk and filler nozzles were further characterised using rpoB partial sequencing and multilocus sequence typing (MLST). Milk had spore counts < 2 log10 cfu/ml and 4 log10 cfu/ml during processing and storage, respectively. Bacillus pumilus dominated the bacterial population. In addition B. subtilis, B. cereus, B. sonorensis, B. licheniformis and Paenibacillus spp. were among the main spore-formers identified in the study. Bacterial species were inoculated in sterile milk for a shelf life study and population change observed over 42 days at 7 oC. Despite high prevalence of cer, hblA and nheA; cytK was not widely distributed. There was 100% and 8% prevalence of mesophilic and psychrotrophic signatures, respectively in B. cereus isolates. Although ESL milk process was effective in the reduction of bacterial counts and species diversity, the presence of B. cereus shows a potential safety problem in ESL milk. Despite the large diversity of the B. cereus strains in this study, there is evidence that biofilms associated with filler nozzles and raw milk are a source of contamination of B. cereus in ESL milk. Furthermore, the study has also shown that rpoB partial sequencing and MLST can be used as a tool for source tracking in ESL milk processing.Thesis (PhD)--University of Pretoria, 2017.
Food Science
PhD
Unrestricted
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Ramesh, Reddy Yettella Venkata. "Post Harvest Treatment Effects on Crown-Cut Broccoli Shelf Life." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10069.
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The effects of packaging treatments, post harvest cooling delay and storage duration on color, texture, ascorbic acid content, weight loss and glucosinolate retention in crown-cut heads of broccoli were studied. Oxygen and CO2 levels inside shrink wrap packages were also monitored. Shrink wrap packaging had a significant positive effect on hue angle (p<0.05). Packaging and post harvest cooling delay had no effect on hue difference and total color difference. While post harvest cooling delay had no effect on texture, crown-cut heads of broccoli stored in shrink wrap packaging retained firmness significantly better than ice packaged heads of broccoli (p<0.05). Ascorbic acid was retained better in broccoli held in shrink wrap packages and cooling delay had a significant negative influence on ascorbic acid content (p<0.05). Packaging and post harvest cooling delay had a significant positive effect on weight loss (p<0.05). Broccoli stored in shrink wrap film lost about 3.7% of original weight while ice packaging resulted in about 17.4% weight loss (p<0.05). No consistent trends were observed in the levels of O2 and CO2 inside shrink wrap packages. An important glucosinolate, glucoraphanin was retained significantly better in shrink wrapped heads (p<0.05). Between two cultivars, shelf life of cv.Gypsy was better than cv.Everest with respect to color, ascorbic acid retention and weight loss. But cv.Everest retained texture (firmness) better after 35 days of storage. Overall results indicate that shrink wrap packaging and shorter post harvest cooling delays protect quality of broccoli.Master of Science
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Min, Seacheol. "Extending Shelf Life of Juice Products by Pulsed Electric Fields." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1046317424.
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Hasan, Salah. "Methods to extend the mold free shelf life of pizza crusts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29712.pdf.
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Lyver, André. "Formulation, shelf-life and safety studies on value-added seafood products." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0001/MQ29749.pdf.
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Bagdan, Galen Corey. "Shelf-life extension studies on an omega-3 enriched breakfast cereal." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0033/MQ64315.pdf.
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Ḥasan, Ṣalāḥ 1964. "Methods to extend the mold free shelf life of pizza crusts." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27337.
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In this research, initial studies were done to determine the effect of various methods of presentation involving chemical preservatives, water activity ($ rm a sb{w}$), and modified atmosphere packaging (MAP) on mold growth in an agar model system. Results showed that preservatives could completely inhibit mold growth for 2-40d depending on concentration and pH used. Gas packaging (60% or 80% CO$ sb2$), oxygen absorbents, alone or in combination with potassium sorbate, could also inhibit mold growth for $>$40d at ambient storage temperature using a Response Surface Methodology (RSM) approach.The effects of various methods of applying potassium sorbate into pizza crusts via direct incorporation into the batter, surface spraying, and impregnation of packaging material with potassium sorbate to control mold spoilage of pizza crusts were also investigated. Results showed that the antimicrobial effect of potassium sorbate was negligible when the packaging material was impregnated with the inhibitor but more pronounced when it was incorporated directly into the dough or sprayed onto the product's surface. The inhibitory effect of potassium sorbate increased as both the pH and the inoculum level decreased.
Shelf life studies using low concentrations of potassium sorbate (1000 and 2000 p.p.m.) and MAP, alone and in combination with each other, showed that potassium sorbate, gas packaging or oxygen absorbents (Ageless FX) could extend the shelf life of pizza crusts and decrease the growth rate of molds, bacteria and yeast. Furthermore, when pizza crusts were packaged in 60% CO$ sb2$ or with an oxygen absorbent, in combination with potassium sorbate (1000-2000 p.p.m.), a shelf life of 42d was possible without compromising the sensory shelf life of the product. (Abstract shortened by UMI.)
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Grifa, Federica. "Studio di Shelf-life di taralli formulati con miscele lipidiche diverse." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25110/.
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La conservabilità dello snack tipico della panetteria italiana "Tarallini" dipende dalla ricetta e dalle condizioni di cottura e conservazione. In questo lavoro di tesi si è studiata la stabilità ossidativa di taralli formulati con miscele lipidiche diverse durante un periodo di shelf life di circa due mesi e mezzo. I campioni sono stati formulati con olio EVO, con una miscela di olio EVO e olio di riso e il terzo campione è costituito da olio di girasole alto oleico e olio di cocco. Per poter valutare come la diversa frazione lipidica e come anche le interazioni con gli ingredienti propri del campione possano influenzare la conservabilità di taralli, sono state svolte analisi sull'ossidazione lipidica degli olii. In particolare è stata svolta la determinazione dei prodotti primari dell'ossidazione, determinazione dei perossidi; poi sono stati quantificati i prodotti secondari, ovvero i composti volatili, in particolare Esanale che è il composto target per valutare l'ossidazione dell'alimento; ed infine i campioni sono stati sottoposti ad OXITEST, un test di ossidazione accelerata.
Dallo studio effettuato emerge che il campione formulato con EVO nonostante sia più suscettibile all'ossidazione è quello che presenta caratteristiche organolettiche e nutritive migliori, a differenza degli altri due campioni che resistono meglio all'ossidazione lipidica, in particolare il campione formulato con olio di girasole altro oleico e olio di cocco.
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Fattibene, Laura. "Studio di shelf life di biscotti formulati con diverse miscele lipidiche." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Find full textAbstract:
Nel corso degli ultimi anni i bisogni e i desideri dei consumatori verso i prodotti alimentari sono cambiati radicalmente. Il consumatore moderno appare sempre più informato e consapevole della stretta associazione tra alimentazione e salute, basando la propria scelta alimentare su quattro condizioni fondamentali: sapore, salute, sicurezza e sostenibilità. D’altro canto, il crescente utilizzo di prodotti trasformati a lunga conservazione, fonte di praticità e convenienza, ha determinato un forte consumo dei prodotti da forno, aiutando la crescita di nuovi mercati. Uno dei principali settori, al giorno d’oggi, in forte crescita è quello dei biscotti.
Come noto, la produzione di prodotti da forno, in particolare dei biscotti, richiede frequentemente l’impiego di quantità rilevanti di sostanza grassa che contribuiscono alla struttura e quindi alle caratteristiche sensoriali del prodotto, alla sua fragranza e alla sua conservabilità. In generale la sostanza grassa più utilizzata nella preparazione dei prodotti da forno è, allo stato attuale, l’olio di palma, che presenta un largo impiego in ambito alimentare grazie alla buona resistenza al deterioramento ossidativo e alla sua capacità di ottenere prodotti altamente stabili con una lunga shelf life. La sua versatilità ne determina un elevato utilizzo in ambito alimentare, ma allo stesso tempo l’incessante deforestazione, la perdita di biodiversità e la presenza di 3-monocloropropandiolo (3-MCPD) con i suoi derivati, che si vengono a formare durante il processo di raffinazione, ha stimolato nel tempo il progressivo disimpiego di questo olio.
In virtù di queste considerazioni, il principale scopo di questo lavoro è stato quello di identificare e valutare lo stato ossidativo di differenti miscele lipidiche, utilizzate nella formulazione dei biscotti come alternative all’olio di palma per la produzione di prodotti ad elevata qualità nutrizionale, accettabilità sensoriale e shelf life.
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Gibson, Michael W. "Physico-chemical and shelf-life between baked and extruded pet foods." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20410.
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Master of ScienceGrain Science and Industry
Sajid Alavi
The U.S. pet food market was approximately worth $22 billion in 2013. Further growth is predicted at a pace faster than most major human food product categories. More than 60% of pet food products are processed using extrusion, and a significant proportion is produced using baking. However, research is lacking on fundamental process and product differences between extrusion and baking. The current study focuses on this aspect and also in-depth characterization of process and product quality. Three iso-nutritional diets were formulated for dry expanded dog food using 0%, 7% and 15% fresh meat inclusion. Major variations between diets were inclusion rates of mechanically deboned chicken, cereal grains, and poultry fat. Each diet was processed with a single screw extruder using various thermal and/or mechanical energy inputs (obtained by varying pre-conditioner stem injection and/or extruder screw speeds). Diets were also processed by baking using a 30 foot experimental oven at 425°F, although the fresh meat inclusion was at 0%, 10% and 20% levels. Proximate analysis of products was conducted. Products were also characterized for physico-chemical properties such as bulk density, piece density, expansion ratio, degree of gelatinization and textural attributes. As fresh meat inclusion increased (0–15%), expansion ratio (4.1–3.5) decreased irrespective of extrusion treatment. Expansion was not evident in the baked kibbles, and bulk and piece densities were up to 56% higher for baked versus extruded kibbles. Textural analysis of extruded kibbles revealed serrated force-deformation response, typical of cellular products, with peak hardness of 2.9–1.5 kgf. On the other hand, baked products had a ‘smooth’ force-deformation response with higher peak hardness than extruded products (up to 3 kgf). Microbial counts for baked products were higher than extruded products, and rancidity profiles as obtained from gas chromatography also had marked differences. The extrusion process was characterized by detailed mass and energy balance analyses, and compared with baking that lacks mechanical energy input. Results from this study provide a useful bench-mark for dry expanded pet food product quality and commonly used processing technologies.
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Zhang, Dong. "Chemical Composition, Probiotic Survivability and Shelf Life Studies of Symbiotic Buttermilk." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/369.
Full textAbstract:
Cultured buttermilk is becoming popular as an ingredient for bakery applications and for direct consumption in the U.S.. The objective of this study was to develop a symbiotic cultured buttermilk, containing inulin as a prebiotic and the probiotics Lactobacillus acidophilus and Bifidobacterium spp. The cultured buttermilk was prepared using a commercial mesophilic starter CHN22 (Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Leuconstoc mesenteorides subsp. cremoris, Lactococcus lactis subsp. lactis biovar diacetylactis) and the probiotics. The control buttermilk was prepared using CHN22 and the symbiotic buttermilk were analyzed for chemical composition, probiotics survivability, mold, yeast and coliform counts. Changes in pH, titratable acidity and proteolysis were also determined during storage at 4℃ for 12 weeks. The chemical composition of the control and symbiotic buttermilk were: protein 3.29±0.05 and 3.30±0.02%; fat 3.28±0.04 and 3.26±0.06%; carbohydrate 4.55±0.05 and 5.16±0.06%; total solids 11.81±0.05 and 12.42±0.03%; ash 0.69±0.03 and 0.70±0.01%, respectively. The populations of both Lactobacillus acidophilus and Bifidobacterium spp. were initially above 107 cfu/ml and remained 106cfu/ml during the 12-week study and no mold or yeast were detected. There were significant differences in pH and titratable acidity between the control and symbiotic buttermilk (p<0.05). There was no considerable difference in proteolysis between the two samples. Results indicated that the symbiotic buttermilk might be considered as a functional food as survival of probiotics was significantly higher compared to other fermented foods.
Key words: Buttermilk, Symbiotic, Inulin, Functional foods, Lactobacillus acidophilus, Bifidobacterium spp.
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Pretorius, Cornelia. "The influence of road condition on the shelf life of tomatoes." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/61266.
Full textAbstract:
In the modern era consumer awareness on quality aspects has been a growing concern for the fresh produce market due to the fact that consumer perspective defines the bottom line of all agricultural businesses. External damage to produce does not only render fruit less attractive but damaged locations serve as entry points for pathogens resulting is food safety issues.
Because tomatoes have a limited shelf life, it is vital to control the factors that lead to earlier deterioration of the quality of the product. Shipping, handling and distribution can cause numerous forms of cuts and bruises on harvested tomatoes which compromise their quality and appearance. Furthermore the economic value to the retailer and grower is reduced (Chonhenchob et al., 2009).
Post-harvest science focus mainly on the quality of fresh produce. One of the areas of interest is the shipment of tomatoes using road transport. Trucks are one of the best methods for transporting perishable products because of shorter transport times and the ability to reach more inland destinations than any other mode of transport (Jarimopas et al., 2005; Chonhenchob et al., 2009). Although the flexibility of road transport is an advantage, previous studies have indicated that fruit and vegetables suffer mechanical damage due to in-transit vibrations which is caused by the road condition (Jarimopas et al., 2005).
The condition of roads in South Africa is dependent on the management plan execution by the managing agent. The National Road Network, maintained by SANRAL is predominantly in a good condition (Ittmann, 2013). In contrast, condition assessment data for provincial roads indicate that roads are deteriorating at an alarming pace, not to mention that the majority of road networks under municipal authorities have no data at all (SAICE, 2011).
To date there is no model that relates tomato damage and loss in shelf life to the road condition, fruit maturity and position in the container. For this experiment the in-transit conditions were monitored on trucks travelling from three farms in Limpopo, owned by the ZZ2 group, to the fresh produce market in Pietermaritzburg. These trucks drive on a variety of roads including gravel or rural roads where higher roughness values are probable along with more produce damage.
The experimental setup consisted of two phases. The first phase was the in-transit monitoring of the conditions to which tomatoes are exposed when shipped from grower to the farmers market. The second phase was the laboratory simulation of in-transit conditions to create a model for the prediction of shelf-life under controlled conditions.
Equipment for the field experiment included a profilometer to determine road conditions, accelerometers to determine in-transit vibrations, pressure sensors to determine in-transit pressures. Equipment for the laboratory experiment included a vibration table to simulate different road conditions, pressure sensors to measure pressures that can be related to in-transit pressures and a colour meter to measure colour changes in damaged and control tomatoes.
From the in-transit pressure analysis it was concluded that the amount of pressure cycles that a tomato experience increase as the roughness of the road increase and the force distribution that is applied to the tomatoes becomes wider to include forces larger in magnitude. Good correlations existed between in-transit and laboratory pressures.
Colour measurements had no strong trends that could be related to damage and an experimental model based on consumer perspective was developed. The experimental model was designed based on a marketability matrix that models the decision of the consumer on whether to purchase a tomato or not. Ultimately it is a subjective matter and each consumer would react differently towards the colour and firmness of the tomato in question.
The model indicated that for roads with high roughness values (International Roughness Index (IRI) > 8 m/km), which mostly consist of farm roads that are poorly maintained, all tomatoes in the first and second layers would acquire significant damage irrespective of the maturity of the fruit. On well-maintained roads with roughness values less than 3.5 m/km red tomatoes in the top layers tend to damage more with an increase in time as compared to tomatoes in the lower layers. Green and pink tomatoes are more resistant to damage in the top layers than the red tomatoes.
From the damage models it is apparent that as the roughness of the road increases the damage to tomatoes increase as well. Tomato maturity and the position of the tomatoes in a container also influence the amount of damage to the fruit.
With this information in hand, logistic planners can make informed decisions during route planning in weighing transportation costs to the cost of losses to produce during transportation. Similar models can be developed to include other fruits and vegetables.Dissertation (MEng)--University of Pretoria, 2017.
Tamatie Produsente Organisasie (TPO)
ZZ2
Post-Harvest Innovation Program (PHI)
Civil Engineering
MEng
Unrestricted
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Magalotti, Lorenzo. "Valutazione dell'effetto di packaging antimicrobici sulla shelf life e sicurezza di smoothies." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16153/.
Full textAbstract:
I succhi vegetali sono attualmente bevande molto popolari, che sono consumate da persone di ogni età per le loro qualità nutrizionali e sensoriali. Uno dei settori in più rapida evoluzione nel mercato dei succhi di frutta è stato quello degli smoothies. La crescente varietà di prodotti lanciati sul mercato ha amplificato la problematica riguardante la sicurezza e la stabilità dei prodotti. Pertanto, attualmente vengono ricercate soluzioni tecnologiche a questi problemi, cercando di preservare anche le caratteristiche nutrizionali e funzionali e, di conseguenza, riducendo il danno termico associato ai trattamenti termici tradizionali. Le prove effettuate in questo elaborato hanno riguardato inizialmente le capacità di diversi gel contenenti lisozima, da addizionare al packaging, di inattivare microrganismi patogeni e degradativi in vitro. La sperimentazione ha identificato nel PvOH il gel più performante. È stata poi determinata l’efficacia del packaging attivo prescelto, PLA+PvOH, sulla shelf life di smoothie di mela e carota trattati con alte pressioni di omogeneizzazione (HPH), confezionati e conservati in pouch a 4°C e 10°C. Il trattamento HPH ha migliorato le caratteristiche tecnologiche del prodotto ed ha anche abbattuto la carica microbica iniziale di 3,5 log UFC/ml. Per quanto riguarda i campioni confezionati in packaging con e senza lisozima stoccati a 10°C, i risultati mostrano un rallentamento della crescita microbica nei campioni con l’enzima. D’altra parte, le prove a 4°C non evidenziano differenze significative tra i campioni, ciò probabilmente dovuto proprio alla temperatura di stoccaggio che non permette né il funzionamento dell’enzima né lo sviluppo microbico. Le prove mostrano come l’effetto combinato di trattamenti HPH, refrigerazione e lisozima nel packaging possa influire positivamente sulla shelf-life del prodotto.
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Benedetti, Martina. "Utilizzo di colture protettive per prolungare la shelf-life di salsiccia fresca." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18598/.
Full textAbstract:
Lo scopo del mio elaborato è stato quello di testare alcune colture protettive per il prolungamento della shelf life di salsiccia fresca. Queste prove si sono inserite in un progetto più ampio, partito dallo studio dei pattern di degradazione del prodotto per individuare le specie responsabili del suo decadimento qualitativo. Successivamente sono state testate alcune colture bioprotettive in grado di rallentare la crescita di queste specie degradative, ma i risultati non sono stati soddisfacenti. Dall’elaborazione di questi dati è stata pianificata una nuova prova che ha previsto l’inoculo nell’impasto di un ceppo di Lactobacillus sakei e di un ceppo di Staphylococcus xylosus ed una riduzione della concentrazione di zucchero comunemente impiegata nella preparazione delle salsicce fresche. I campioni sono stati confezionati in atmosfera modificata e conservati a 4 o 10°C. I risultati hanno mostrato che le colture bioprotettive determinano un abbassamento del pH, molto più marcato a 10°C, a causa dell’accumulo di acidi organici, ma anche un accumulo di composti quali diacetile e acetoino, che derivano da alcuni metabolismi secondari e da conseguenti eccessi di acido piruvico, e che conferiscono note aromatiche estranee al prodotto. Inoltre l’aggiunta di colture bioprotettive ha avuto un effetto limitato sui principali gruppi microbici, se si esclude una riduzione del carico di enterobatteri e pseudomonadacee rispetto al controllo conservato a 10°C. Questi vantaggi sono stati controbilanciati dalla presenza di molecole volatili che impattano sul profilo aromatico del prodotto e quindi non si è assistito ad un effettivo miglioramento della shelf life. E’ evidente che la stabilità del prodotto dipende soprattutto da un corretto mantenimento della catena del freddo e che, in caso di abuso termico, le colture bioprotettive possono limitare lo sviluppo di gruppi microbici potenzialmente pericolosi, determinando però al contempo un impoverimento qualitativo del prodotto.
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Beach, Shannon Elizabeth. "Shipping and nitrogen toning effects on postharvest shelf life of vegetative annuals." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4340.
Full textAbstract:
Vegetative annuals are currently popular in the ornamental horticulture industry.
Many crops are newly domesticated species and little is known about how they perform
during shipping or in the retail environment. Nine species and 21 cultivars were grown
and underwent simulated shipping after harvest or nitrogen toning two weeks before
harvest. Shipping was not found to affect the number of flowers on all but two cultivars
post ship. Nitrogen toning affected vegetative growth of most Bracteantha bracteata
(bracteantha) cultivars at harvest. All species had an effect due to toning postharvest.
Bractenatha and Diascia ÃÂhybrida (diascia) were chosen for further study due to their
performance during these experiments. The effect of thidiazuron (TDZ) as a foliar spray
and nitrogen toning on leaf yellowing and plant growth of bracteantha were evaluated.
The two treatments were then combined to see how the two treatments worked together.
It was found TDZ decreased leaf yellowing but its effects can be negated if the plants
were not toned. Nitrogen toning reduced vegetative growth of the bracteantha without
affecting the number of flowers on the plants. Diascia was found to have flower
abscission in response to shipping. Further trials were conducted using 1-
methylcyclopropene (1-MCP) an ethylene inhibitor. The effects of shipping duration and temperature were investigated. 1-MCP was found to hold flowers on treated plants
longer postharvest than those not treated. Plants shipped for one day had no differences
from the control but shipping for two days had a negative effect on plant quality.
Postharvest shelf life was decreased when diascia was shipped at 24 ðC when compared
to cooler shipping temperatures. These results indicate shipping for no longer than one
day and at less than 24 ðC is recommended for diascia.
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Majoni, Sandra. "Effects of shelf-life on phytonutrient composition in stored non-alcoholic beer." Menomonie, WI : University of Wisconsin--Stout, 2006. http://www.uwstout.edu/lib/thesis/2006/2006majonis.pdf.
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Lütke, Entrup Matthias. "Advanced planning in fresh food industries : integrating shelf life into production planning /." Heidelberg ; New York : Physica-Verlag, 2005. http://www.springerlink.com/content/978-3-7908-1592-4.
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Kaufmann, Veronika [Verfasser]. "Einflussfaktoren auf die Produktcharakteristika von Extended Shelf Life (ESL)-Milch / Veronika Kaufmann." München : Verlag Dr. Hut, 2012. http://d-nb.info/1028784244/34.
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Obande, Matthew A. "Effect of preharvest UV-treatment on shelf life of fruits and vegetables." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7768.
Full textAbstract:
The benefits of low UV dose treatment of horticultural produce – also known as hormetic treatment - have been attested to in numerous studies conducted over the last 15 years. However, commercial growers have not adopted the concept of hormesis. With increasingly stringent controls on the use of fungicides and other chemical agents the time has come to examine how hormetic treatment might be applied in the horticulture sector. The objectives of this work were firstly, to confirm UV-induced hormetic effects applied postharvest for a number of different types of produce, namely, tomatoes, broccoli, strawberries and mangoes. Secondly, to evaluate the use of rollers to ensure full surface treatment of produce, and thirdly to evaluate the possibility of treating produce preharvest. In order to investigate surface UV dose distributions, a polystyrene sphere (Diameter 70 mm) was used to simulate fruits such as tomatoes, apples, peaches etc., that have an approximately spherical form. Biodosimetry based on spores of Bacillus subtilis was employed to experimentally determine UV doses and to compare the results obtained with theoretical predictions. Good agreement was obtained and the modelling approach was extended to other types of produce. This showed the amenability of mechanical rollers to ensure full surface treatment of produce. Postharvest treatment of produce was carried using conventional low intensity UV sources principally emitting at 254 nm and also a commercially available high energy pulsed UV source. Treatment using the conventional UV source was carried out on mechanical rollers within a UV cabinet designed for this work at a fixed distance from the source and at an intensity of 1000 μW/cm2. A 5 minute conventional UV treatment of tomatoes was approximately comparable to fruit given a 3-pulsed treatment using the pulsed source (507 J/pulse of polychromatic light). The colour and texture of both groups of fruit were significantly maintained as compared with controls. The treated tomatoes also showed a significant increase in the ascorbic acid levels during storage. Similarly, a 15 minute conventional UV treatment of broccoli heads was comparable to heads given a 10-pulsed treatment using the pulsed source. Where both treatments gave rise to a statistically significant retention of green colour of treated broccoli. In addition, mangoes given a 10 minute conventional UV treatment were comparable to fruit given a 20-pulsed treatment using the pulsed source with both treatments leading to maintenance of texture as compared to control fruit. This confirmed the UV-hormetic effects. The effects of conventional and pulsed treatments are compared and discussed. Preharvest treatment of tomatoes and strawberries was carried out in commercial glasshouses. Doses of either 3 or 8 kJ/m2 were delivered to the fruits using a treatment device designed for the work, which delivered a combined intensity of 2000 μW/cm2 from two low pressure UV sources. The treated tomatoes showed a delay in development of colour as measured on the vine and after picking. Picked tomatoes were inoculated with P. digitatum and C. gloeosporioides and the results obtained showed a significant inhibition of the development of the fungi in the treated fruit during the storage period. These results suggest that the beneficial response shown by the preharvest treatment is not a localised one but a systematically induced resistance observable throughout the treated plant. This was shown by monitoring tomato fruits on treated plants which themselves where not directly exposed to the UV light. The two doses elicited different responses in the treated strawberries, with the 8 kJ/m2 dose causing the fruit to redden significantly faster than the 3 kJ/m2 treated fruits and controls. This could have significant nutritional benefit as the red colour of strawberries has been correlated with anthocyanin levels. On the other hand, treatment at the lower UV dose led to a lag in colour development. The amenability of the equipment utilised for commercial application is discussed.
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Zhang, Yang. "Roles of flavonoid compounds in determining the shelf life of tomato fruit." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/48096/.
Full textAbstract:
This thesis examines the role of flavonoid compounds in determining the shelf life of tomato fruit. Shelf life is one of the most important traits for tomato industry. Although there are many approaches to enhance the post-harvest performance of tomato fruit, most of them would have side effects such as reducing fruit quality. My work showed that accumulation of anthocyanins in tomato fruit by over expressing Delila and Rosea 1, two transcriptional factors from Antirrhinum majus, can extend tomato shelf life significantly. Compared to WT tomato fruit, the anthocyanin-enriched purple fruit have double the shelf life including delayed over-ripening and reduced susceptibility to the fungal pathogen, Botrytis cinerea. My data indicate that the delayed over-ripening is associated with the high antioxidant capacity of purple tomato and the reduced susceptibility to B. cinerea is due to the high scavenging ability of anthocyanins. Using Aft/Aft atv/atv, a conventionally bred tomato variety which accumulates anthoycanin predominantly in the skin, I showed that accumulation of anthocyanins in tomato skin can be sufficient to extend fruit shelf life. The scientific findings from transgenic crop studies can provide new strategies for conventional breeding improved fruit quality. My research also revealed that, as a general principle, flavonoids extend tomato shelf life. For ripening and over-ripening, increasing total antioxidant capacity by accumulating flavonoids of different types can delay these processes. To reduce susceptibility to B. cinerea, however, the effects of different flavonoids depend on their scavenging abilities, which are determined by their molecular structures. Taken together these findings demonstrate that increasing total antioxidant capacity by accumulating different flavonoid compounds offers a general strategy to delay over-ripening of tomato fruit. However, to reduce susceptibility to B. cinerea, flavonoid compounds with high scavenging activity should be used.
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Bell, Luke. "Rocket science : phytochemical, postharvest, shelf-life & sensory attributes of rocket species." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/69943/.
Full textAbstract:
Rocket species are increasing in popularity with consumers, and in the last ten years scientific interest has also increased due to the potential health benefits of consuming leaves. They are known for pungent and bitter taste components, and the chemical compounds largely responsible for these sensations are also health beneficial. These compounds are called isothiocyanates (ITCs), and they are ubiquitous in the plant family Brassicaceae. Precursor compounds called glucosinolates (GSLs) are converted to ITCs via the action of myrosinase enzyme. This thesis presents data relating to numerous aspects of rocket species, such as differences in GSLs and ITCs. Other phytochemical constituents (flavonols, volatile organic chemicals (VOCs), free amino acids, free sugars, polyatomic ion content, and organic acids) are explored to determine their impacts on human sensory perceptions and consumer acceptance. The data presented highlight significant differences between ‘wild’ accessions of rocket and commercially available varieties, in terms of flavonol and GSL content and sensory attributes. There is great potential to develop underutilised genetic resources in breeding programs, and through collaboration with a breeding company (Elsoms Seeds Ltd., Spalding, UK) and a commercial salad supplier (Bakkavör Group Ltd., Spalding, UK), several accessions were selected for detailed analyses. Analysis of VOC profiles further demonstrated the differences between the selected cultivars, and by combining these data with sensory and consumer studies, it was observed that the diversity of phytochemical components fundamentally underpins taste, flavour, and consumer acceptance. The same accessions of rocket were also tested under commercial growth, processing and storage conditions. It was hypothesised that this would negatively impact GSL and ITC content of leaves, but in fact increased concentrations up to five fold from the point of harvest in all accessions analysed. We also observed a previously undocumented link between GSL, ITC and free amino acid content with bacterial load.
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Kurt, Esra. "Associations between lipid composition, shelf life and sensory quality in ruminant meats." Thesis, University of Bristol, 1999. http://hdl.handle.net/1983/a77d9a0c-f888-4650-b6b8-7c1b8f5cee45.
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Thor, Nandan G. "Using Computer Vision to Build a Predictive Model of Fruit Shelf-life." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1721.
Full textAbstract:
Computer vision is becoming a ubiquitous technology in many industries on account of its speed, accuracy, and long-term cost efficacy. The ability of a computer vision system to quickly and efficiently make quality decisions has made computer vision a popular technology on inspection lines. However, few companies in the agriculture industry use computer vision because of the non-uniformity of sellable produce. The small number of agriculture companies that do utilize computer vision use it to extract features for size sorting or for a binary grading system: if the piece of fruit has a certain color, certain shape, and certain size, then it passes and is sold. If any of the above criteria are not met, then the fruit is discarded. This is a highly wasteful and relatively subjective process.
This thesis proposes a process to undergo to use computer vision techniques to extract features of fruit and build a model to predict shelf-life based on the extracted features. Fundamentally, the existing agricultural processes that do use computer vision base their distribution decisions on current produce characteristics. The process proposed in this thesis uses current characteristics to predict future characteristics, which leads to more informed distribution decisions. By modeling future characteristics, the process proposed will allow fruit characterized as “unfit to sell” by existing standards to still be utilized (i.e. if the fruit is too ripe to ship across the country, it can still be sold locally) which decreases food waste and increases profit. The process described also removes the subjectivity present in current fruit grading systems. Further, better informed distribution decisions will save money in storage costs and excess inventory.
The proposed process consists of discrete steps to follow. The first step is to choose a fruit of interest to model. Then, the first of two experiments is performed. Sugar content of a large sample of fruit are destructively measured (using a refractometer) to correlate sugar content to a color range. This step is necessary to determine the end-point of data collection because stages of ripeness are fundamentally subjective. The literature is consulted to determine “ripe” sugar content of the fruit and the first experiment is undertaken to correlate a color range that corresponds to the “ripe” sugar content. This feature range serves as the end-point of the second experiment. The second experiment is large-scale data collection of the fruit of interest, with features being recorded every day, until the fruit reaches end-of-life as determined by the first experiment. Then, computer vision is used to perform feature extraction and features are recorded over each sample fruit’s lifetime. The recorded data is then analyzed with regression and other techniques to build a model of the fruit’s shelf-life. The model is finally validated. This thesis uses bananas as a proof of concept of the proposed process.
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Matunda, Aldegunda Sylvester. "Pineapple Vinegar to Enhance Shelf Life of Carrot and Mango in Tanzania." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54543.
Full textAbstract:
Fruits and vegetables are highly perishable, produced seasonally, and large quantities (about 50-60% of production) are wasted during high season due to poor handling and lack of cold storage in Tanzania. Processing excess pineapple into vinegar which can be used for preservation of other fruits and vegetables may be a helpful strategy for reducing losses. Vinegar was produced from pineapple juice supplemented with sugar to produce different degrees of Brix (13, 20 and 30) and was fermented with Saccharomyces cereviciae, Acetobacter pasteurianus, and Gluconobacter oxydans. Levels of acetic acid were measured in the vinegar produced. High production (5.8%) of acetic acid was observed with pineapple juice concentrated to 130 Brix with the combination of Saccharomyces cerevisiae, A. pasteurianus and G. oxydans.
The pineapple vinegar produced was used for preservation of carrot and mango. The pH of carrot pickle and mango chutney was monitored for three months. The pH of preserved carrot and mango was below 4 and no significant changes in pH were observed during three months storage at 29-320C. Chemical analysis of vitamin A and vitamin C showed high losses of Vitamin A in carrot and increased vitamin A in mango, but losses of about 74% and 85% of vitamin C were observed in carrot and mango after processing.
Consumer sensory testing of pineapple vinegar, carrot pickle and mango chutney showed no significance different on overall consumer acceptability of products during storage. Pineapple vinegar can be used to rescue mango and carrots that would otherwise be lost, producing highly acceptable food products in Tanzania.Master of Science in Life Sciences
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Orleans, Kimberly Ann. "Microbiological and Chemical Changes During Shelf-life in Regular and Chocolate Milk." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308253657.
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McMillan, Bradley Ian. "Challenging the Safe Centre: An Exegesis to Support the Screenplay Shelf Life." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/368003.
Full textAbstract:
This exegesis examines the processes used to produce a body of studio work that investigates how screen-based narratives and aesthetics function in relation to, and are able to question, political and cultural hegemony. The final outcome of the studio work – a feature-length screenplay called Shelf Life – has at its thematic core a focus on neoliberal ideology and its cultural manifestations, an exploration of the social exclusion that is a by-product of that phenomenon, and an examination of the emancipatory potential of the cinema. It looks at how a work can engage with, yet also challenge, mainstream modes of storytelling to counter their potentially soporific effects, which may work to obscure deeper counter readings.
The screenplay embodies a bricolage of influences in its final incarnation, as different strategies were developed to deal with the interaction between content, form and conflicting ideologies. A process of iterative writing shifted the work from its beginnings as a narrative exploration of theme to focus on the interplay between aesthetics and ideology, and the ways in which aesthetic choices can contribute to a spectator’s active reading of the work. It finally culminated in an extensive process of improvisational writing, which aimed to shift how the work was engaged with, away from an unquestioned a priori reading to a less stable liminal reading to allow for a more mindful viewing experience.Thesis (Professional Doctorate)
Doctor of Visual Arts (DVA)
Queensland College of Art
Arts, Education and Law
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Cocci, Emiliano <1974>. "Innovative treatments for shelf-life extension of whole and fresh-cut fruit." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1073/1/Tesi_Cocci_Emiliano.pdf.
Full textAbstract:
Maintaining the postharvest quality of whole and fresh-cut fruit during storage and distribution is the major challenge facing fruit industry. For this purpose, industry adopt a wide range of technologies to enable extended shelf-life. Many factors can lead to loss of quality in fresh product, hence the common description of these products as ‘perishable’. As a consequence normal factors such as transpiration and respiration lead ultimately to water loss and senescence of the product. Fruits and vegetables are living commodities and their rate of respiration is of key importance to maintenance of quality. It has been commonly observed that the greater the respiration rate of a product, the shorter the shelf-life.
The principal problem for fresh-cut fruit industries is the relative shorter shelf-life of minimally processed fruit (MPF) compared to intact product. This fact is strictly connected with the higher ethylene production of fruit tissue stimulated during fresh-cut processing (peeling, cutting, dipping). 1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene action and several researches have shown its effectiveness on the inhibition of ripening and senescence incidence for intact fruit and consequently on their shelf-life extension. More recently 1-MCP treatment has been tested also for shelf-life extension of MPF but discordant results have been obtained. Considering that in some countries 1-MCP is already a commercial product registered for the use on a number of horticultural products, the main aim of this actual study was to enhance our understanding on the effects of 1-MCP treatment on the quality maintenance of whole and fresh-cut climacteric and non-climacteric fruit (apple, kiwifruit and pineapple).
Concerning the effects of 1-MCP on whole fruit, was investigated the effects of a semi-commercial postharvest treatment with 1-MCP on the quality of Pink Lady apples as functions of fruit ripening stage, 1-MCP dose, storage time and also in combination with controlled atmospheres storage in order to better understand what is the relationship among these parameters and if is possible to maximize the 1-MCP treatment to meet the market/consumer needs and then in order to put in the market excellent fruit. To achieve this purpose an incomplete three-level three-factor design was adopted. During the storage were monitored several quality parameters: firmness, ripening index, ethylene and carbon dioxide production and were also performed a sensory evaluations after 6 month of storage. In this study the higher retention of firmness (at the end of storage) was achieved by applying the greatest 1-MCP concentration to fruits with the lowest maturity stage. This finding means that in these semi-commercial conditions we may considerate completely blocked the fruit softening. 1-MCP was able to delay also the ethylene and CO2 production and the maturity
parameters (soluble solids content and total acidity). Only in some cases 1-MCP generate a synergistic effect with the CA storage. The results of sensory analyses indicated that, the 1-MCP treatment did not affect the sweetness and whole fruit flavour while had a little effect on the decreasing cut fruit flavour. On the contrary the treated apple was more sour, crisp, firm and juicy.
The effects of some treatment (dipping and MAP) on the nutrient stability were also investigated showing that in this case study the adopted treatments did not have drastic effects on the antioxidant compounds on the contrary the dipping may enhance the total antioxidant activity by the accumulation of ascorbic acid on the apple cut surface.
Results concerning the effects of 1-MCP in combination with MAP on the quality parameters behaviour of the kiwifruit were not always consistent and clear: in terms of colour maintenance, it seemed to have a synergistic effect with N2O MAP; as far as ripening index is concerned, 1-MCP had a preservative effect, but just for sample packed in air.
49
Cocci, Emiliano <1974>. "Innovative treatments for shelf-life extension of whole and fresh-cut fruit." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1073/.
Full textAbstract:
Maintaining the postharvest quality of whole and fresh-cut fruit during storage and distribution is the major challenge facing fruit industry. For this purpose, industry adopt a wide range of technologies to enable extended shelf-life. Many factors can lead to loss of quality in fresh product, hence the common description of these products as ‘perishable’. As a consequence normal factors such as transpiration and respiration lead ultimately to water loss and senescence of the product. Fruits and vegetables are living commodities and their rate of respiration is of key importance to maintenance of quality. It has been commonly observed that the greater the respiration rate of a product, the shorter the shelf-life.
The principal problem for fresh-cut fruit industries is the relative shorter shelf-life of minimally processed fruit (MPF) compared to intact product. This fact is strictly connected with the higher ethylene production of fruit tissue stimulated during fresh-cut processing (peeling, cutting, dipping). 1-Methylcyclopropene (1-MCP) is an inhibitor of ethylene action and several researches have shown its effectiveness on the inhibition of ripening and senescence incidence for intact fruit and consequently on their shelf-life extension. More recently 1-MCP treatment has been tested also for shelf-life extension of MPF but discordant results have been obtained. Considering that in some countries 1-MCP is already a commercial product registered for the use on a number of horticultural products, the main aim of this actual study was to enhance our understanding on the effects of 1-MCP treatment on the quality maintenance of whole and fresh-cut climacteric and non-climacteric fruit (apple, kiwifruit and pineapple).
Concerning the effects of 1-MCP on whole fruit, was investigated the effects of a semi-commercial postharvest treatment with 1-MCP on the quality of Pink Lady apples as functions of fruit ripening stage, 1-MCP dose, storage time and also in combination with controlled atmospheres storage in order to better understand what is the relationship among these parameters and if is possible to maximize the 1-MCP treatment to meet the market/consumer needs and then in order to put in the market excellent fruit. To achieve this purpose an incomplete three-level three-factor design was adopted. During the storage were monitored several quality parameters: firmness, ripening index, ethylene and carbon dioxide production and were also performed a sensory evaluations after 6 month of storage. In this study the higher retention of firmness (at the end of storage) was achieved by applying the greatest 1-MCP concentration to fruits with the lowest maturity stage. This finding means that in these semi-commercial conditions we may considerate completely blocked the fruit softening. 1-MCP was able to delay also the ethylene and CO2 production and the maturity
parameters (soluble solids content and total acidity). Only in some cases 1-MCP generate a synergistic effect with the CA storage. The results of sensory analyses indicated that, the 1-MCP treatment did not affect the sweetness and whole fruit flavour while had a little effect on the decreasing cut fruit flavour. On the contrary the treated apple was more sour, crisp, firm and juicy.
The effects of some treatment (dipping and MAP) on the nutrient stability were also investigated showing that in this case study the adopted treatments did not have drastic effects on the antioxidant compounds on the contrary the dipping may enhance the total antioxidant activity by the accumulation of ascorbic acid on the apple cut surface.
Results concerning the effects of 1-MCP in combination with MAP on the quality parameters behaviour of the kiwifruit were not always consistent and clear: in terms of colour maintenance, it seemed to have a synergistic effect with N2O MAP; as far as ripening index is concerned, 1-MCP had a preservative effect, but just for sample packed in air.
50
Nallan, Chakravartula Swathi Sirisha <1991>. "Optimizing quality losses and shelf-life in bakery products by edible coatings." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8890/1/NallanChakravartula_SwathiSirisha_Tesi.pdf.
Full textAbstract:
Edible packaging is of increasing interest as a technological strategy for preserving quality, improving shelf-life as well as reducing the residual waste associated with food packaging. Alternative packaging systems with coatings and films that are viable have already been proven useful in fresh produce, fresh cuts; meat and milk products. However, in the past decade interest has been renewed in edible packaging application for bakery products to restrict moisture migration, texture changes, mould growth, incorporate functional compounds and reduce overall packaging impact.
The objective of this thesis was to develop edible coatings to mitigate quality losses in bakery products. The coating and product as dynamic systems with different physico-mechanical characteristics were assessed individually by, (i) development and characterization of edible coating matrices for bakery application; (ii) evaluation of the drying of edible coating on bread to optimize temperature and time of drying; (iii) effect of coating during storage as influenced by type of coating and stage of application.
Based on the obtained results, characterization of rheological, mechanical and thermal characteristics of edible coatings and films were found particularly useful to select suitable coating matrices. The use of rapid methods like near infrared spectroscopy enabled the monitoring and modelling of optimal temperature/time combinations to dry coatings. Also, a numerical model to understand the heat and mass transfer dynamics for the coated bread was designed. Furthermore, the study on storage indicated that the use of edible coatings can have a retaining effect on the moisture and textural quality of bread.
The results evidenced in this doctoral project can contribute to the understanding of the role of edible coatings for bread. They could be further designed as potential alternatives to reduce the level of barriers used for packaging, for a more sustainable and eco-friendly production chain.