Dissertations / Theses: 'Blanching on'

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Fakhouri, May O. "Microwave blanching and reheating of foods." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=57010.

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Microwave and water blanching of carrots and sweet potatoes were evaluated with respect to peroxidase inactivation, texture degradation and color changes for obtaining stable frozen stored products. Carrot slices and french fry style sweet potatoes were blanched in a 700 W domestic microwave oven as well as in boiling water for different treatment times. Blanched and unblanched samples were packaged in retort pouches and frozen stored at $-$20$ sp circ$C, and evaluated for peroxidase activity, texture and color before and after blanching, and after 3.5 and/or 7 months frozen storage. Kinetics of peroxidase activity and texture softening due to blanching was described by semi-logarithmic models. All frozen products, except unblanched samples, were of good quality at the end of 7 months storage. Small quality differences were detected in the blanched frozen samples during storage; samples blanched for intermediate times were superior.
Temperature distribution profiles were determined for model foods consisting of a starch gel with different concentrations of protein and fat, as well as commercial frozen and refrigerated prepared foods. Microwave heating of model foods showed considerable nonuniformity in temperature distribution and alarmingly low center temperatures. Prolonged lower power heating or holding after microwave heating did not always elevate center temperatures to safe levels. Addition of protein to the starch gel reduced temperature uniformity and heating rate, while added fat resulted in an opposite trend.
For the commercial foods, center temperatures reached after heating according to manufacturer's instructions were below 70$ sp circ$C indicating some safety concerns. However, longer heating time at lower power levels improved the temperature uniformity as well as the quality and appearance of these foods.

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Duval, Hugo. "Investigation on blanching on cryogenic engines combustion chamber inner liner." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0059.

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Les conditions thermodynamiques et cinétiques dans les moteurs cryogéniques sont sévères, en particulier pour la mince paroi interne de la chambre de combustion. Bien que peu résistant mécaniquement, un alliage de cuivre est utilisé pour maximiser les transferts thermiques à travers cette paroi et ainsi améliorer l’efficacité du moteur. Cependant, les fluctuations de concentration et de pression des propergols (tels que l’oxygène ou l’hydrogène liquide) à la surface de la paroi favorisent l’endommagement de l’alliage, en particulier si la paroi n’est pas en permanence couverte d’une pellicule d’hydrogène (barrière contre l’oxydation). Ce phénomène est connu sous le nom de « blanching », qui est la succession de courts cycles d’oxydation et de réduction dues à l’exposition de la paroi de la chambre de combustion aux atmosphères oxydants et réducteurs. Le blanching mène à la diminution de l’épaisseur de la paroi de la chambre, pouvant même conduire à la rupture de la paroi.Les alliages de cuivre peuvent, en fonction de leur composition, apporter une protection à l’oxydation et à la réduction. Comme le cuivre est indispensable grâce à sa conductivité thermique élevée, des éléments d’addition sont souvent ajoutés à l’alliage pour augmenter ses résistances mécaniques et chimiques. Cette étude met en avant les différences de comportement aux cycles d’oxydoréduction de trois matériaux (Cuivre OFHC, et deux alliages Cuivre-Chrome) à des hautes températures. Elle permet de cibler l’endommagement thermochimique qui se produit dans les « vraies » chambres de combustion.Les essais réalisés consistent en l’oxydation et la réduction d’échantillons pendant 40 cycles successifs dans des atmosphères contrôlées à 600, 750 ou 900°C. L’oxydation est obtenue par l’air artificiel (O2+N2) et la réduction est obtenue par l’introduction de monoxyde de carbone. Les différences obtenues entre les échantillons des différents essais peuvent être due à la croissance d’oxydes secondaires, qui ne sont pas réduits pendant la phase de réduction, alors que le cuivre et ses oxydes simples le sont. Les couches d’oxydes doivent être identifies, car leur exploitation pourrait renseigner sur le comportement à l’oxydoréduction des matériaux pendant le blanching. Les analyses RAMAN et MEB confirment bien la présence d’oxydes secondaires sous la couche principale d’oxyde de cuivre, montrant que ce type d’endommagement est probablement lié à la composition des matériaux et de leur comportement à haute température
Conditions in combustion chambers of liquid rocket engines are severe, especially for the inner liner of the chamber wall. The copper alloys used in the thin inner liner of the chamber wall ensure an efficient cooling. However, concentration fluctuations of the propellants such as H2 and O2 on the surface of the inner liner of the chamber wall can lead to a damage of the alloys, especially if the wall is not permanently protected by H2. This phenomenon is known as Blanching, which is a quick redox cyclic, leading to a physical-chemical reduction of the width of the wall, even up to fracture. Copper alloys can - depending on their composition - provide a protection to oxidation and reduction. As copper is mandatory because of its high thermal conductivity, some addition elements are usually used in order to optimize the mechanical and chemical resistance of the alloy. This study shows the differences of the behavior between three copper alloys (OFHC copper and two Copper-Chromium alloys) under oxidation-reduction cycles at 750°C. The experimental investigations aim at assessing blanching in the range of real liquid rocket engines combustion chambers conditions.The performed tests consisted in oxidizing and reducing of samples 40 cycles under controlled atmospheres at 600°C, 750°C or 900°C. Oxidation is obtained by industrial quality air (O2+N2), and reduction by CO as low safety risk replacements for the O2+H2 atmosphere in the engine. The differences between the different conditions may be caused by the growth of secondary copper oxides, which are not reduced during the reduction phases.Oxide layers have to be identified, as their exploitation may lead to a principal understanding of the behavior of the chamber wall material during blanching, and may help to determine oxidation and reduction law parameters. RAMAN and SEM analyses confirm the presence of secondary copper oxide layers below the reduced copper on the surface of the sample

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Schirack, Andriana Vais. "The Effect of Microwave Blanching on the Flavor Attributes of Peanuts." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-07052006-113250/.

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The use of microwave technology as an alternative blanching method for peanuts could potentially reduce energy costs and processing time, and lead to products with better nutrient retention. However, an off-flavor was found in peanuts which were microwave-blanched at high temperatures. As a result, the objective of this research has been to determine the impact of different microwave blanching parameters on the properties of roasted peanuts, and to characterize the off-flavor observed during high-temperature microwave blanching using a descriptive sensory panel and analysis of volatile flavor compounds. The processing parameters best suited for microwave blanching of peanuts were determined based on energy absorbed during processing, internal and surface temperatures, loss in moisture content, and blanchability. The best blanchability resulted from higher process temperatures and lower final moisture content. However, peanuts which reached the highest internal temperatures during blanching also developed an off-flavor, which was characterized by increased intensities of stale/floral and burnt/ashy notes. Solvent extraction / solvent assisted flavor evaporation (SAFE), gas chromatography-olfactometry (GC/O), gas chromatography-mass spectrometry (GC/MS), aroma extract dilution analysis (AEDA), threshold testing, and model systems were used to examine the chemical compounds which may be responsible for this microwave-related off-flavor. Analysis revealed an increased formation of guaiacol, phenylacetaldehyde, and 2,6-dimethylpyrazine in the off-flavored peanuts as compared to a process control, which led to the burnt and stale/floral characteristics noted by descriptive sensory panel. These compounds were only a small fraction of over 200 aroma-active compounds which were found to contribute to roasted peanut flavor using GC/O. This research illustrates the importance of the relative concentrations of the many aroma-active compounds found in peanuts. These findings could aid in training sensory panels to evaluate processing-related off-flavors, because guaiacol and phenylacetaldehyde could be used as chemical standards to define the burnt/ashy and stale/floral off-flavors which can occur during high temperature processing. Through this project, it was determined that it is possible to achieve acceptable blanchability in peanuts using microwave blanching while minimizing the possibility of an off-flavor.

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Clements, Megan Alexander. "Almond Seed Coat, Surface Area, and Kinetics of Removal via Blanching." Thesis, University of California, Davis, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3565492.

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This research aims to provide a more complete understanding of almond seed coats, including microscopic development and structure, the relationship of measurable properties to surface area, and the kinetics of seed coat separation from the underlying almond kernel in response to a range of temperatures.

Immature almond samples of Nonpareil and Padre varieties were microscopically examined in the 16th-20th weeks after flowering (13 through 7 weeks prior to commercial harvest). The highly vacuolate and thin-walled diploid maternal tissues and triploid support tissue that sustain the embryo during development begin to rupture and compress down above a base monolayer of distinctly intact cells to form the mature seed coat. Over the course of blanching, no substantial swelling or dissolution of microscopic tissue layers was visible, however the junction between the base layer of the seed coat and the underlying almond cotyledon moved apart until they were no longer in contact with one another.

Surface areas of Nonpareil, Monterey, and Butte-Padre almonds were measured by manually peeling rehydrated nuts and analyzing images of their seed coats. Ninety-five percent of the 1,545 almonds measured in this study had surface areas between 515.96 mm²-942.24 mm². Surprisingly, individual dimensions (length, width, and thickness) did not increase with increasing surface area, nor they did scale in proportion to one other. An empirical model was created to predict surface area (r²=0.74), which depends on the almond variety, as well as length, width, and mass after rehydration.

The progression of blanching was examined by quantifying the degree of seed coat separation at dozens of intermediate time-points during the blanching process, using this empirical model. Experimental temperatures were 70°C, 80°C, 90°C, and 100°C; at each temperature, seed coat separation occurred in a sigmoidal logarithmic fashion. Rates of blanching were calculated using non-linear two-parametric regression. Rates of blanching at 100°C and 90°C were not significantly different, however, blanching rates decreased semi-logarithmically with decreasing blanching temperature between 70°C and 90°C. D-values representing 90% seed coat separation were calculated as 30 seconds at 100°C, 35 seconds at 90°C, 120 seconds at 80°C, and 443 seconds at 70°C. From these, a z value for decimal reduction times between 70°C and 90°C was calculated at 18.48C degrees.

The novel empirical model for surface area could be used to improve the accuracy of mass transfer and energetic transfer calculations in almond processing. Quantifying the rate of seed coat separation could be used to explore any aspect of almond physiology dependent on or resultant from seed coat integrity, such as germination, rehydration kinetics, processing damage, or blanching efficacy. It could also potentially be used to compare the relative blanching propensity of different almond varieties, as well as evaluating the impact on skin separation of various growing, harvesting, and processing conditions. D- and z values characterizing the almond blanching process may be useful in optimizing almond processing conditions to reduce the chances of accidental seed coat separation, or to more efficiently achieve it.

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Varnalis, Angelos. "Dehydration of potato cubes using puffing as an intermediate step." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325216.

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Santhanam, Menon Abhay. "Effects of blanching and drying on the production of polyphenols rich cocoa beans and product quality." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43219/.

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The high potential of health beneficial polyphenols and antioxidants in cocoa beans has been a major topic for research in recent years. The large-scale application of cocoa beans for health beneficial compounds is relatively unexplored and it needs to be widely utilized by pharmaceutical and nutraceutical industries. Processing methods such as fermentation and drying are major deterrents for recovering high polyphenols in cocoa beans. Hence, it was the intention of this work to introduce the application of hot water blanching pre-treatment and various drying methods for producing polyphenols rich cocoa beans by using unfermented beans. The studies incorporated the application of various drying methods such as oven, adsorption, vacuum, freeze and sun drying methods on cocoa beans. The studies compared the ability of these drying methods to preserve the bioactive capacities namely, total polyphenolic contents and antioxidants activity after hot water blanching. The potential of adsorption, vacuum and freeze drying methods for recovering high polyphenols content are useful in comparing it with the conventional cocoa drying methods such as oven and sun drying methods. For the studies on oven drying of cocoa beans, the drying parameters (T= 60°C, 70°C and 80°C) used were similar to the conventional hot air drying parameters used in industries. The total polyphenolic contents of fermented cocoa beans dried at 70°C was found to be the highest. The polyphenols degradation kinetics for oven drying method of cocoa beans was determined using first-order reaction kinetics model based on various drying temperatures and durations of drying. The studies on drying kinetics of fresh cocoa beans dried using oven, vacuum, adsorption and sun drying methods were successfully analysed. It was found that adsorption drying and vacuum drying methods dried cocoa beans faster than oven and sun drying methods. Two respective falling rate periods were recorded by adsorption and vacuum drying. The effective diffusivities were determined and were found to be in accordance to that of published literatures. Hot water blanching pre-treatment were performed for fresh and fermented cocoa beans (whole beans and half cut). Blanching pre-treatment method was found to show significantly higher total polyphenolic contents when compared with unblanched cocoa samples. The optimal blanching parameter (90°C for 5 min) obtained for fresh beans were subsequently used for experiments involving fresh cocoa beans. The total polyphenolic contents and antioxidant activity of blanched and unblanched cocoa beans were analysed. Results showed that both adsorption and vacuum drying methods showed high recovery of polyphenolic compounds and antioxidants on comparison with freeze dried cocoa samples, which was used as a benchmark in quality analysis of food products. High polyphenols contents were achieved after the blanching and drying treatments and were noted to be significantly higher on comparison with published literatures. Sensory analysis of both blanched and unblanched cocoa beans were analysed after drying using various drying methods. The results for unfermented cocoa beans showed high astringency flavour attributes which further confirmed the high contents of polyphenols in cocoa beans. The cocoa and acidic flavour attributes were recorded to be less owing to the unfermented nature of cocoa beans. The results obtained provides a gateway towards the use of advanced drying technology in cocoa industry. The potential of blanching pre-treatment to mediate high recovery of cocoa polyphenols after drying has been proven through this work. The processing methods used in the current study can be implemented in on-farm cocoa processing, making it a more sustainable farming option.

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Lo, Chun-Min. "The effect of blanching and freezing on the distribution and changes of pectic substances in carrots /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9999306.

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Puwastien, P. "Effects of blanching, soaking and germination on the properties of ? winged bean seeds [Psophocarpus tetragonolobus (L.) DC]." Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353475.

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Meyer, Eric. "A critical evaluation of the human skin blanching assay and comparative bioavailability studies on topical corticosteroid preparations." Thesis, Rhodes University, 1989. http://hdl.handle.net/10962/d1001464.

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Several aspects of the human skin blanching assay were evaluated in an attempt to suggest improvements in the methodology of this assay. Three trials were performed in the unoccluded application mode, using two proprietary creams containing 0,1% betamethasone (as the 17-valerate). Preliminary observations of the influence of ambient temperature and relative humidity on the blanching response did not allow definite conclusions to be drawn. Studies on the number of observers required for reliable results of comparative blanching indicated that at least two trained observers should be employed. Analyses of the results of individual volunteers demonstrated the expected biological variability, and suggest that subjects selected for trials should represent a range of blanching responses. No sex-related differences in blanching responses were found, and both arms exhibited similar sensitivity to corticosteroids. Retrospective analysis of 95 040 observations of blanching responses showed that in the unoccluded application mode blanching is lowest close to the wrist, and in the occluded mode blanching is lowest close to the elbow. Studies on the method of transportation of Betnovate preparations suggest that topical formulations should not be exposed to temperature extremes during transportation. It is proposed that patients should not transport topical formulations in the holds of ships or aircraft, and that exporters and manufacturers should make use of special transportation and storage conditions. In a study of ten topical formulations from three countries it was found that there was no trend of products from one country consistently exhibiting superior blanching to products from the other two countries, or products from one country consistently exhibiting the lowest degree of blanching, although considerable differences in blanching responses were found in some cases. Interpretation of the results of these studies demonstrated the importance of employing a combination of statistical analyses, blanching profiles and AUC values when drawing conclusions regarding comparative bioavailability. A study of the blanching profiles of Betnovate cream included in all 16 trials performed during this work indicated that this preparation behaved in a similar fashion during all trials, thereby giving credence to the results of the trials

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Sensoy, Ilkay. "Ohmic and moderate electric field treatment of foods : studies on heat transfer modelling, blanching, drying, rehydration and extraction /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu148640254459058.

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Button, Kimberly. "Processing sweet potatoes into french fries." Kansas State University, 2015. http://hdl.handle.net/2097/20496.

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Master of Science
Food Science Institute - Animal Sciences & Industry
Fadi M. Aramouni
Sweet potatoes are a significant crop and are popular among consumers, particularly as french fries. Because the processing steps of making white potato french fries may be detrimental to the quality of a sweet potato fry, it is important to understand the impact of processing on quality and consumer acceptability. The variety of sweet potatoes can affect the texture, appearance, and consumer preference. Peeling processes have evolved from harsh lye treatments to more quick and efficient methods such as steam peeling. Blanching is one of the most important steps because it deactivates enzymes, including polyphenol oxidase and amylases, that affect texture and appearance. While hot water blanching is used by majority of french fry manufacturers, novel techniques like microwave blanching may be similarly effective and less detrimental to the texture and nutritional composition. Time and temperature of the blanching method can affect the texture and flavor by weakening cell walls and leaching sugars. Drying of sweet potato fries prepares the product prior to frying. Drying drives moisture off and allows the starch on the surface of the fries to gelatinize. Many types of dryers, including vacuum, hot air, and fluidized bed, have been evaluated for the rate of moisture loss and final product texture. Drying should not be done too quickly because case hardening will occur and make the product have a tough and chewy bite. Frying uses oil at elevated temperatures to develop color, flavor, and a crispy external texture. The type of oil, oil temperature, and time of frying will affect the finished product attributes. Low oil temperature may lead to higher oil uptake into the sweet potato fries. Vacuum frying compared to deep fat frying can create sweet potato fries with less darkening and less oil uptake, but this method would be difficult in large scale manufacturing. Opportunities in creating high quality sweet potato french fries are directly related to consumer acceptability and manufacturing capability.

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Burnstock, Aviva Ruth. "The application of scanning electron microscopy (SEM) to the examination of painting materials with special reference to cleaning and blanching." Thesis, Courtauld Institute of Art (University of London), 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339397.

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Bosi, Francesca. "Determinazione del contenuto di acrilammide mediante HPLC-ESI-MS/MS in campioni di chips di patate trattate con diverse tecnologie." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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L’acrilammide è una sostanza chimica che si forma nei prodotti alimentari amidacei a partire da zuccheri riducenti e amminoacidi (come l’asparagina) in condizioni particolari. In particolare l’innesco dalla reazione di Maillard, l’utilizzo di calore, la bassa umidità, gli zuccheri riducenti e, appunto, l’asparagina naturalmente presenti nella materia prima, portano alla formazione di tale sostanza. Dagli studi svolti negli ultimi anni dall’EFSA (European Food Safety Authority) sono state riscontrate concentrazioni elevate di acrilammide in gruppi di alimenti come pane e prodotti da forno, caffè e suoi succedanei, alimenti per neonati, patatine fritte e chips di patate. Inoltre le ultime analisi svolte portano a catalogare l’acrilammide tra le sostanze genotossiche e potenzialmente cancerogene per l’uomo. Per tali motivazioni l’EFSA ha invitato tutti gli stati membri ad adottare miglioramenti tecnologici volti ad abbassarne il contenuto nei prodotti alimentari in modo da ridurre anche l’esposizione a tale sostanza da parte dei consumatori. Tale lavoro di ricerca ha come obiettivo principale la determinazione del contenuto di acrilammide in diversi campioni di chips di patate fritte, trattate con PEF o blanching, tramite HPLC-ESI-MS/MS. Le analisi sono state svolte su tre tipi di campioni di chips di patate: patate fritte tal quali; patate trattate precedentemente con PEF e poi fritte; patate trattate precedentemente con blanching e successivamente fritte. Da questa ricerca si vuole osservare come, utilizzando diversi trattamenti sullo stesso campione di patata, varia la concentrazione di acrilammide al fine di individuare un metodo che permetta di ottenere alimenti con un contenuto inferiore di tale sostanza.

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Genty, Anaïs. "Les chancis des vernis et des couches picturales des peintures de chevalet à l'huile : Contribution à la caractérisation physico-chimique, à la connaissance des mécanismes de formation et aux traitements de restauration." Thesis, Cergy-Pontoise, 2017. http://www.theses.fr/2017CERG0910/document.

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Le chanci est une altération récurrente des peintures de chevalet à l’huile, induite par l’humidité. Elle affecte les vernis et les couches picturales. Selon le degré d’altération, la couche picturale peut être partiellement ou totalement masquée par un voile blanchâtre. L’analyse d’environ 50 micro-prélèvements altérés et non altérés par microscopie électronique à effet de champ a révélé une structure poreuse dans les vernis et les couches picturales altérées, avec une taille de pores comprises entre 50 nm et 4 µm. Pour les chancis de couches picturales, des investigations complémentaires par nanotomographie X à contraste de phase ont démontré que les pores étaient localisés dans le liant. L’apparence visuelle des couches altérées est due à la diffusion de la lumière par les pores, ce qui a été corroboré par des simulations numériques. Un modèle physico-chimique a été proposé pour expliquer la formation des pores. Il repose sur le fait que les vernis et les liants lipidiques peuvent être assimilés à des ionomères dans lesquels les acides carboxyliques et les carboxylates métalliques ségrègent pour former des clusters ioniques. En présence d’humidité, les clusters s’hydratent entraînant la formation de régions aqueuses. Lors de la phase de déshydratation, les pores initialement remplis d’eau se vident mais subsistent. L’apparition des chancis de vernis et de couches picturales est donc directement liée à la quantité d’acides et à leur capacité à former des clusters.Les traitements de restauration seront efficaces et durables, si et seulement s’ils résorbent ou comblent durablement les pores, dans le but de réduire la diffusion de la lumière. Pour les chancis de couches picturales, les traitements actuels sont peu satisfaisants. Un nouveau traitement innovant a été développé et testé sur des échantillons modèles et des peintures anciennes chancies. Les résultats sont très prometteurs en termes de stabilité, d’efficacité, de durabilité et de réversibilité. Cette recherche aura incontestablement un impact majeur, puisqu’elle pourrait répondre à un véritable besoin pour la restauration et la conservation des peintures de chevalet chancies
Blanching of easel oil paintings is a recurrent alteration, induced by humidity. It affects varnish and paint layers. Depending on the degree of alteration, the paint composition can be partially or totally hidden by a whitish haze. The analysis of circa 50 altered and unaltered paint micro-samples by field-emission gun scanning electron microscopy revealed a highly porous structure in both varnish and paint altered layers, with pores ranging in size from 50 nm to 4 µm. Regarding the blanching of paint layer, in-depth investigation performed by X-ray phase contrast nanotomography highlighted that pores are located in the binder. The visual appearance of altered layers is due to the light scattering by the pores, which was corroborated by computational modeling.A physico-chemical model was proposed to explain the pores formation. It is based on the fact that the varnish and the lipidic binder can be assimilated to ionomers, where carboxylic acids and metal carboxylates segregate to form ionic clusters. In a humid environment, the clusters get hydrated inducing the formation of aqueous regions. During the dehydration, the water is drained out from them, but the pores remains. The blanching emergence is thus directly linked to the quantity of acids and their ability to form clusters. Conservation treatments will be efficient and sustainable only if they resorb or durably fill the pores, in order to reduce the light scattering. For the blanching of paint layers, current treatments are not very effective over time. A new innovative treatment has been developed and tested on mock-ups and ancient altered paintings. The results are very promising in terms of stability, efficiency, durability and reversibility. This research will undoubtedly have a major impact, fullfilling a real requirement for the conservation of blanched easel oil paintings

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Zavatta, Nicolas. "Metodi per il contenimento del contenuto di acrilammide nel caso studio "patate fritte"." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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Il presente elaborato ha lo scopo di trattare, da diversi punti di vista, la tematica dell’acrilammide negli alimenti, con particolare riferimento ad uno dei prodotti più soggetti alla formazione di tale composto indesiderato: le patate fritte. L’acrilammide, come composto di neoformazione nei prodotti alimentari, è stata oggetto di numerosi studi scientifici che hanno ampliato la conoscenza sia per quanto concerne il campo alimentare, sia in ambito clinico-tossicologico. Nel primo capitolo sono discusse le vie di formazione dell’acrilammide negli alimenti, gli effetti che si presume possa avere sulla salute umana e gli interventi in ambito legislativo per gestire questa problematica, con particolare riferimento al Regolamento (UE) 2017/2158. Successivamente, è presentato un “focus” sulla formazione dell’acrilammide nel caso studio “patate fritte”, con attenzione specifica ai principali interventi agronomici e/o tecnologici nelle fasi di preparazione del prodotto volti a contenere la formazione di questa molecola. In particolare, nel secondo capitolo, vengono presi in considerazione tutti quegli interventi che interessano la materia prima, partendo dalla scelta della varietà, epoca di raccolta e condizioni di conservazione, fino ad arrivare a discutere dei possibili pretrattamenti che precedono la fase di cottura. Nel terzo capitolo sono invece descritte le ultime fasi del processo tecnologico, intese come pre-frittura e/o frittura, e come la gestione dei parametri tecnologici quali il tempo, la temperatura di frittura, la quantità ed il tipo di olio impiegato possano influenzare la formazione dell’acrilammide.

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16

Au, Wai Ling. "Investigations of the bioavailability/bioequivalence of topical corticosteroid formulations containing clobetasol propionate using the human skin blanching assay, tape stripping and microdialysis." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1003221.

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Currently, clinical trials in patients are required by most regulatory authorities for the assessment of bioequivalence of topical products where the drug is not intended for systemic absorption. Hence there is a dire need for suitable methods for the assessment of bioavailability and bioequivalence of such products since clinical safety and efficacy studies are expensive, time-consuming and require very large numbers of patients. Except for topical corticosteroid products where the human skin blanching assay/vasoconstrictor assay has been approved by the US FDA for bioequivalence assessment of those products, no other method has been “officially” approved for use in those investigations. However, a few alternative methods such as tape stripping and microdialysis have been pursued and considered to have the potential for use in ioequivalence/bioavailability studies. The human skin blanching assay was used to assess the bioequivalence of commercially available topical products containing 0.05% clobetasol propionate. Both visual and chromameter data were obtained and a commercially available topical corticosteroid product, Dermovate® cream was used as both the “Test” and the “Reference” product. The results indicated that both visual and chromametric assessments were comparable to each other and that either could be used for the assessment of the bioequivalence of topical products containing clobetasol propionate. The screening procedure was optimized to identify potential “detectors” for inclusion in the bioequivalence studies. This resulted in fewer subjects being required in a bioequivalence pivotal study, still having the necessary power to confirm bioequivalence using the human skin blanching assay. Another objective of this research was to re-visit tape stripping and other possible alternative methods such as dermal microdialysis and to optimize these procedures for bioequivalence assessment of topical formulations where the drug is not intended for systemic absorption. In the past few decades, tape stripping has been used to investigate bioavailability/bioequivalence of various topical formulations. This technique involves the removal of the stratum corneum to assess drug penetration through the skin. A draft FDA guidance for tape stripping was initially published but was subsequently withdrawn due to high variability and poor reproducibility. This research project used an optimized tape stripping procedure to determine bioavailability and establish bioequivalence between three commercially available formulations containing 0.05 % m/m clobetasol propionate. Furthermore, tape stripping was validated by undertaking a study to assess the bioequivalence of a 0.05% topical cream formulation (Dermovate® cream) using the same cream as both the “Test” and “Reference” product, in which bioequivalence was confirmed. The findings highlight the potential of tape stripping as an alternative method for the assessment of bioequivalence of clobetasol propionate formulations and may possibly be extended for use in other topical products. Microdialysis is another useful technique that can assess the penetration of topically applied substances which diffuses through the stratum corneum and into the dermis. Microdialysis has previously been successfully used for in vivo bioavailability and bioequivalence assessments of topical formulations. However, the drugs which were under investigation were all hydrophilic in nature. A major problem with the use of microdialysis for the assessment of lipophilic substances is the binding/adherence of the substance to the membrane and other components of the microdialysis system. As a result, this necessitates the development of a microdialysis system which can be used to assess lipophilic drugs. Intralipid® 20% was investigated and successfully utilized as a perfusate to recover a lipophilic topical corticosteroid, clobetasol propionate, in microdialysis studies. Hence, the bioavailability of clobetasol propionate from an extemporaneous preparation was determined in healthy human volunteers using microdialysis. These findings indicate that in vivo microdialysis can be used to assess lipophilic drug penetration through the skin. A novel approach to investigate drug release from topical formulations containing 0.05% clobetasol propionate using in vitro microdialysis was also undertaken. The in vitro findings were found to be in agreement with the results obtained using tape stripping to assess bioequivalence of the same commercially available products, namely Dermovate® cream, Dovate® Cream and Dermovate® ointment. These results indicate the potential to correlate in vitro with in vivo data for bioequivalence assessment of such topical dosage forms.

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Amaral, Rivia Darla Alvares 1985. "Efeito de inibidores de escurecimento na qualidade de batatas minimamente processadas = Efecto de inibidores del oscurecimiento en la calidad de patatas mínimamente procesadas." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256746.

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Orientador: Benedito Carlos Benedetti, Montserrat Pujolà Cunill
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
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Resumo: A batata (Solanum tuberosum L.) minimamente processada é um produto que vem apresentando crescente aumento na comercialização, embora a indústria de processamento encontre dificuldades na manutenção da qualidade dos produtos, devido a alterações organolépticas, principalmente relativas à suscetibilidade deste tubérculo ao escurecimento enzimático, o que acaba por ser um fator limitante à sua vida útil. Dessa forma, a hipótese deste trabalho é que a aplicação de ácido cítrico, alginato de sódio, ultrassom e branqueamento usados isoladamente ou combinados promovem a redução do escurecimento de batatas minimamente processadas armazenadas sob refrigeração e não promovem alterações indesejáveis na textura após a fritura. A pesquisa teve como objetivo avaliar o efeito de diferentes agentes antioxidantes no escurecimento da batata minimamente processada e seus efeitos na textura após a fritura e durante o armazenamento refrigerado. Para esta finalidade, os tubérculos foram adquiridos de um produtor local, selecionados, lavados em água potável, descascados manualmente, cortados em tiras, submetidos a tratamentos antiescurecimento por imersão, drenados, acondicionados em bolsas de polietileno de alta densidade, selados com seladora à vácuo e armazenados sob refrigeração (3 ± 1 ?C) por 12 dias. Os tratamentos utilizados foram: ácido cítrico, alginato de sódio, banho de ultrassom e branqueamento, além de combinação entre as melhores concentrações. Na primeira etapa foram realizados ensaios para seleção das melhores concentrações das soluções antioxidantes com análises de pH, ácido ascórbico, cor (amostra fresca e frita), matéria seca, absorção de óleo durante a fritura e textura (amostra fresca e frita). Na segunda fase foram realizados ensaios com as melhores concentrações definidas nos ensaios da primeira fase isoladamente e combinados, com análises de açúcares, amido, atividade de polifenoloxidase, aromas voláteis, microscopia eletrônica de varredura, formação de acrilamida, além das análises realizadas na primeira fase. As amostras foram fritas em óleo de girassol a 180 ± 10 ºC por 6 minutos. Os resultados mostraram que a cultivar Agata apresentou os menores valores para as variáveis cor, matéria seca, firmeza das batatas minimamente processadas e fritas, o que permitiu a discriminação desta cultivar e a confirmação de que seu uso é indicado para cocção. Em contrapartida, as cultivares Agria, Caesar e Asterix são mais indicadas para fritura. O tempo de exposição ao banho ultrassom (42 kHz; 200 W) foi inversamente proporcional ao pH das amostras. Além disso, a imersão das batatas por um tempo prolongado alterou a microestrutura da batata, promovendo a ruptura da estrutura celular. O uso de 5 minutos de banho ultrassom (42 kHz; 200 W) não promoveu alterações indesejáveis no teor de matéria seca e firmeza das batatas antes e após a fritura, além de outros componentes e atributos sensoriais. Apesar do branqueamento ser um método efetivo na inativação de microrganismos e enzimas, seu uso não é recomendado para a batata minimamente processada devido aos danos causados ao tecido que promovem alterações indesejáveis de qualidade nesses produtos. O recobrimento das batatas minimamente processadas com alginato de sódio, embora tenha reduzido a taxa respiratória das fatias, não contribuiu para impedir o escurecimento das amostras. A combinação de ultrassom de 42 kHz e ácido cítrico (2 %) por 5 minutos demonstrou ser o tratamento mais efetivo na redução do escurecimento dentre todos os estudados nesta tese, além de não afetar os parâmetros de qualidade das batatas antes e após a fritura e reduzir a contaminação microbiana das batatas minimamente processadas, permitindo a manutenção da vida útil dos produtos pelos 12 dias estudados
Abstract: Fresh-cut potatoes (Solanum tuberosum L.) are products that are coming up with a increasing commercialization, although the processing industry has difficulties in maintaing food quality because of organoleptic changes mainly due the susceptibility of tuber to enzymatic browning, which turns out to be a limitant factor in shelf-life. Thus, the hypothesis of this work is that the application alone or combinated of citric acid, sodium alginate, ultrasound bath and blanching promoted the reduction of browning of refrigerated minimally processed potatoes and do not promote undesirable changes in texture after frying. The research aimed to evaluate the effect of different antioxidants on browning of minimally processed and the effects on texture after frying and during cold storage. For this purpose, tubers were acquired from a local producer, selected, washed in tap water, manually peeled, cut into strips, soaked in antioxidant solutions, drained, packed in polyethylene bags, sealed with sealing vacuum and stored at 3 ± 1 ?C for 12 days. The antioxidants solutions used are: citric acid, sodium alginate, ultrasound bath and blanching, besides the combination between the best concentrations. Samples were fried in sunflower oil at 108 ± 10 oC for 6 minutes. The results show that Agata cultivar had the lowest values for color, dry matter content and firmness variables of fresh-cut and fried potatoes, which allowed discrimination of this cultivar and confirmation that its use is indicated for cooking. In contrast, Agria, Caesar and Asterix cultivars are suitable for frying. The time of exposure to ultrasound bath (42 kHz, 200 W) was inverserly proportional to the pH of the samples. Furthermore, the immersion of potatoes for an extended period altered their microstructure, promoting breakage of the cellular structure. The use of 5 minutes of ultrasound bath (42 kHz, 200 W) did not cause undesirable changes in dry matter content and firmness of the potatoes before and after frying, besides other components and sensory attributes. Despite blanching be an effective method for microorganisms and enzyme inactivation, its use is not recommended to fresh-cut potatoes due to damage to tissue that promote undesirable quality changes in these products. The coating of minimally processed potatoes with sodium alginate, although it reduced the respiratory rate of the slices did not contribute to prevent browning of the samples. The combination of ultrasound and citric acid promoted the reduction of microbial contamination of the fresh-cut potatoes, in addition to not affect the quality parameters of the products before and after frying
Doutorado
Tecnologia Pós-Colheita
Doutora em Engenharia Agrícola

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18

Barbosa, Maysa Carvalho. "Atuação de ácido \'beta\'-naftoxiacético, ácido indolbutírico e ácido giberélico na morfogênese de microplantas de abacaxizeiro \"Gomo-de-Mel\"." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-17032010-105813/.

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Visando avaliar a atuação dos biorreguladores beta-NOA, AIB e GA3 na morfogênese de microplantas de abacaxi Ananas comosus L. (Merrill) cultivar IAC Gomo-de-Mel estabeleceu-se um experimento com a presença isolada e/ou combinada dos respectivos biorreguladores ao meio de cultura MS. As microplantas foram mantidas em condições de cultura in vitro, com temperatura, luminosidade e fotoperíodo controlados (25 ± 2 C, irradiância de 42 µmol.m-2s-1 e 16 horas, respectivamente) durante 3 meses. Os resultados obtidos com a análise de variância evidenciaram que houve interação do biorregulador de crescimento e o tempo de cultivo para a altura, número de raiz e número de folhas. O beta-NOA induziu a rizogênese foliar nas microplantas a partir de células da bainha do feixe vascular e não apresentou toxicidade nas concentrações utilizadas, ao passo que o AIB mostrou-se mais eficaz para a indução da rizogênese adventícia caulinar. Em relação ao crescimento das microplantas, a ação tanto isolada, como combinada em ambas as concentrações avaliadas de GA3 foram mais eficientes. As análises histológicas evidenciaram alterações no número de estratos da epiderme, hipoderme e mesofilo das folhas cultivadas nos tratamentos com biorreguladores, porém não se verificou alterações citológicas em nenhum dos tratamentos. Acredita-se que a utilização de pulsing seja uma alternativa eficaz para a rizogênese e crescimento em altura das microplantas de abacaxizeiro Gomo-de-mel.
In order to evaluate the action of bioregulators beta-NOA, IBA and GA3 in the pineapple Ananas comosus L. (Merril) cultivar IAC gomo-de-mel microplants morphogenesis an experiment was stablished in order to the presence of the bioregulator alone and in combinations. The microplants were kept in culture in vitro conditions, during 3 months under controlled temperature, light and photoperiod (25 ± 2 C, irradiance de 42 µmol.m- 2s-1 e 16 hours). The analysis of variance showed the interaction interaction between the use of bioregulator and the period of cultivation on hight, number of roots and leaves. The beta-NOA induced leaf rhizogensis in the microplants from the bundle sheath and there was no sign of toxicity with the used concentrations. The IBA showed to be more effective in the adventicious steam rhizogenesis. The isolated and combinated actions of GA3 were the most effective treatment to microplants growing. The histological analysis showed alterations on the epidermis, hypodermis and mesophyll number of layers of the cultivated leaves with this bioregulator, but neither of the treatments showed citological alterations. It is believed that the use of pulsing would be an effective alternative for the rhizogenesis and growing of the gomo de mel pineapple microplants.

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Scher, Caroline Fenner. "Estudo do branqueamento e da secagem mediante ar quente do yacon (Smallanthus sonchifolius)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16412.

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O Yacon (Smallanthus sonchifolius) é uma planta que pertence à família Asteraceae, é originário das montanhas dos Andes e no Brasil seu cultivo iniciou-se em 1991. Possui carboidratos solúveis tais como frutose, glicose, sacarose e frutooligossacarídeos (FOS), sendo que os FOS não podem ser metabolizados pelo trato digestivo humano, tendo dessa forma atividade prebiótica. Este trabalho visou estudar o efeito do branqueamento no yacon e posterior secagem mediante ar quente. As raízes foram limpas e selecionadas considerando a ausência de injúrias visuais e infecções. A seguir foram descascadas e cortadas em forma de rodelas (espessuras de 1,75 ± 0,35 mm) e cubos (1,00 ± 0,01cm3). Foi verificada a ocorrência da solubilização dos açúcares durante o branqueamento, onde foram avaliadas as perdas de inulina, glicose e frutose em diferentes condições de tempo e temperatura. Foi observada a maior solubilização nas amostras em rodelas que em cubos na maioria dos tratamentos estudados. O teste de Tukey indicou que no branqueamento do yacon em forma de rodelas e cubos, o tempo, a temperatura e a interação entre eles foi significativa na solubilização dos açúcares, exceto na frutose (nas amostras em rodelas) e na inulina (nas amostras em cubos) onde somente foi significativo o tempo e a temperatura. Os resultados obtidos da superfície de resposta permitiram obter modelos estatísticos para estimar a perda de açúcares no branqueamento das amostras em rodelas, estimando as condições de maior solubilização. Devido a essas perdas, estudou-se o branqueamento a vapor em amostras em rodelas, que foram colocadas dentro de uma autoclave gerando vapor a 100oC nos tempos de 1, 2, 4, 6, 8 e 10 minutos, sendo a melhor condição a 4 minutos, onde foi possível reduzir a atividade enzimática da PER e PPO em 84,6% e 83,7%, correspondendo a perdas de inulina, glicose e frutose de 30,6, 39,4 e 15,8% respectivamente. A seguir foi realizada a secagem nas amostras de yacon, nas temperaturas de 50, 60 e 70°C por 5 horas e 30 minutos sem e com branqueamento, onde verificou-se o efeito do pré-tratamento e da temperatura sobre a redução da umidade e da atividade de água, revelando que o menor tempo de secagem foi obtido a 70°C em amostras com branqueamento. Também foi observado que após 5 horas de secagem a concentração de inulina diminuiu, enquanto que as concentrações de glicose e frutose aumentaram, sendo que os teores desses componentes no final da secagem não diferiram com a temperatura, tanto nas amostras que sofreram ou não branqueamento. No entanto, houve conversão dos FOS em açúcares redutores. O aumento na concentração dos açúcares redutores pode ser devido à presença de atividade enzimática da inulinase.
Yacon (Smallanthus sonchifolius) is a plant belonging to the Asteraceae family and originated in the Andes Mountains, having been cultivated in Brazil since 1991. It contains soluble carbohydrates such as fructose, glucose, sucrose and fructooligosaccharides (FOS), the latter not being metabolized in the human digestive tract and thus presenting prebiotic activity. This work aimed to study the effect of blanching and subsequent hot air drying on yacon. The roots were cleaned and selected considering the absence of visual injury and infections. They were then peeled and cut into slices (1.75 ± 0.35 mm thick) and cubes (1.00 ± 0.01cm2). The sugars were shown to dissolve during blanching, and the losses of inulin, glucose and fructose were determined under different conditions of time and temperature. For the majority of conditions studied, greater dissolution was observed with the slices than with the cubes. Tukey's test indicated that both the time and the temperature and the interaction between them were significant with respect to the dissolution of sugars in the blanching of yacon in the form of both slices and cubes, with the exception of fructose (for the sliced samples) and inulin (for the samples in cubes), where only the time and temperature were significant. The results obtained from the response surface allowed for the production of statistical models to estimate the loss of sugars during blanching for the samples in slices, estimating the conditions for greatest dissolution. Due to these losses, steam blanching of the slices was studied, placing the slices inside an autoclave generating steam at 100ºC for times of 1, 2, 4, 6, 8 and 10 minutes, the best condition being that of 4 minutes where it was possible to reduce the PER and PPO activities by 84.6% and 83.7%, respectively, with losses of inulin, glucose and fructose of 30.6, 39.4 and 15.8%, respectively. Drying of the yacon samples at temperatures of 50, 60 and 70ºC for 5 hours and 30 minutes, with and without blanching, was then carried out, verifying the effect of the pre-treatment and of the drying temperature on the reduction in moisture content and water activity. The shortest drying time was obtained at 70ºC with blanched samples. It was also observed that after 5 hours of drying the concentration of inulin decreased, whereas the concetrations of glucose and fructose increased, the contents of these components at the end of the drying period not varying according to the drying temperature, for either the blanched or non-blanched samples. Thus the FOS were converted into reducing sugars, and the increase in reducing sugars could have been due to the presence of inulinase activity.

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Sarang, Sanjay S. "OHMIC heating for thermal processing of low-acid foods containing solid particulates." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1197669208.

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Freitas, Francisca Marta Nascimento de Oliveira. "Obtenção do cubiu (solanum sessiliflorum dunal) em passa por métodos combinados." Universidade Federal do Amazonas, 2011. http://tede.ufam.edu.br/handle/tede/3114.

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Fundação de Amparo à Pesquisa do Estado do Amazonas
The cubiu is a fruit with high moisture, acid and pectin. In osmotic dehydration, the moisture that is associated with the perishability of the process and cost is reduced in the final product. The acidity is a limiting factor for acceptance is masked by the incorporation of sugar. As a bioactive substance, preservation retains the functionality of pectin, however, the partial hydrolysis facilitates the process and ensure the appearance of dehydrated fruit. This study aims to develop technologies for conservation and value addition of cubiu for industrialization in the form of fruit in passes. The ripe fruit of cubiu were subjected to different pretreatments: blanching or not, more natural fermentation or not and rapid or slow osmotic dehydration followed by convective drying at 65 ° C. The natural fermentation process was monitored by the determination of moisture, pH, total acidity, sodium chloride, pectin and texture of the slices of cubiu. After rapid and slow dehydration were determined at equilibrium and initial moisture, pH, acidity, total sugars, mass change, water loss, gain and efficiency of sucrose osmotic process. The experimental data of convective drying models were fitted to the Page, Lewis, simple exponential, with two and three parameters and Wang & Singh. The physic-chemical and sensory characteristics were used to monitor the whole process and final product quality. In relation to fresh fruit, money not increase the moisture and pH, decrease in total acidity and sodium and chloride did not significantly alter the texture. During the process of natural fermentation, the parameters moisture, acidity, texture and pH (control) were reduced from their values for pH (blanched) and sodium chloride was no increase in the values. The highest percentage of mass change, water loss and sucrose gain occurred in SF/DOR, SF/DOL and CF/DOL, respectively. The highest rate of drying was obtained by the treatment before the blanching, with natural fermentation and rapid osmotic dehydration, indicating that fermentation influenced the increase of drying rate and the reduction of process time. The r2 values were above 99% for the settings with the Page and Exponential models with three simple parameters. The natural fermentation process was detected during the immersion of slices in NaCl solutions cubiu, blanched or not. The physical and physic-chemical properties of slices cubiu were modified during the natural fermentation process, being more pronounced in slices pre-treated by blanching. The variation in mass loss of water and process efficiency were higher in the treatments without natural fermentation. The time of osmotic dehydration was reduced rapidly by natural fermentation. The highest and lowest drying time were obtained by treatment before the blanching, natural fermentation, followed by rapid osmotic dehydration. The simple exponential model with three parameters and Page have the best fit to experimental data. Separately, money and natural fermentation improved the organoleptic characteristics of cubiu passes in obtaining the highest percentage of acceptance.
O cubiu é um fruto com elevados teores de umidade, acidez e pectina. Na desidratação osmótica, a umidade que está associada com o custo do processo e a perecibilidade é reduzida no produto final. A acidez que é um fator limitante da aceitação é mascarada pela incorporação do açúcar. Como substância bioativa, a preservação da pectina mantém a funcionalidade, porém, a hidrólise parcial facilita o processo e assegura a aparência do fruto desidratado. Este trabalho tem como objetivo desenvolver tecnologias de conservação e agregação de valor do cubiu para industrialização na forma de fruto em passa. Os frutos maduros de cubiu foram submetidos a diferentes pré tratamentos: branqueamento ou não, mais fermentação natural ou não e desidratação osmótica rápida ou lenta seguido de secagem por convecção a 65 °C. O processo de fermentação natural foi monitorado pela determinação da umidade, pH, acidez total, cloreto de sódio, textura e pectina das fatias do cubiu. Após a desidratação osmótica rápida e lenta foram determinadas a umidade inicial e de equilíbrio, pH, acidez, açúcares totais, variação de massa, perda de água, ganho de sacarose e eficiência do processo osmótico. Os dados experimentais da secagem convectiva foram ajustados aos modelos de Page, Lewis, Exponencial simples, com dois e três parâmetros e Wang & Singh. Análises físico-químicas e sensoriais foram utilizadas para monitorar todo o processo e a qualidade do produto final. Em relação ao fruto in natura, o branqueamento acarretou aumento da umidade e pH, decréscimo da acidez total e do cloreto de sódio e não alterou significativamente a textura. Durante o processo de fermentação natural, os parâmetros umidade, acidez total, textura e pH (controle) sofreram redução dos seus valores, para pH (branqueadas) e cloreto de sódio houve acréscimo dos valores. Os maiores percentuais de variação de massa, perda de água e ganho de sacarose ocorreram em SF/DOR, SF/DOL e CF/DOL, respectivamente. A maior taxa de secagem foi obtida pelo tratamento submetido ao branqueamento, com fermentação natural e desidratação osmótica rápida, indicando que a fermentação influenciou no aumento da taxa de secagem e na redução do tempo de processo. Os valores de r2 foram superiores a 99% para os ajustes com os modelos de Page e Exponencial simples com três parâmetros. O processo de fermentação natural foi detectado durante a imersão das fatias do cubiu em soluções de NaCl, branqueadas ou não. As características físicas e físico-químicas das fatias de cubiu sofreram modificações durante o processo de fermentação natural, sendo mais acentuadas nas fatias pré tratadas pelo branqueamento. A variação de massa, perda de água e eficiência do processo foram maiores nos tratamentos sem fermentação natural. O tempo da desidratação osmótica rápida foi reduzido pela fermentação natural. A maior taxa e menor tempo de secagem foram obtidos pelo tratamento submetido ao branqueamento, fermentação natural seguida de desidratação osmótica rápida. Os modelos Exponencial simples com três parâmetros e de Page apresentaram os melhores ajustes aos dados experimentais. Isoladamente, o branqueamento e a fermentação natural melhoraram as características organolépticas do cubiu em passa obtendo os maiores percentuais de aceitação.

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Schoeninger, Vanderleia. "Otimização de parâmetros de pré-processamento para obtenção de feijão seco com reduzido tempo de cozimento." Universidade Estadual do Oeste do Parana, 2012. http://tede.unioeste.br:8080/tede/handle/tede/398.

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The bean (Phaseolus vulgaris L) is a typical leguminous in Brazil. Its consumption should be encouraged due to the benefits of its quantity of protein, fiber, folic acid and minerals such as iron and potassium. However, its long cooking process consequently makes many consumers often avoid eating this product, which results in a decrease of production and demand. The possibility of offering a product previously processed, as well as keeping its technological characteristics with a short time of preparation, is an option for consumers who look for convenience and quality. Techniques as soaking and bleaching beans are presented as options for grains preprocessing. Thus, this study aim was investigating the effects of grains preprocessing with blanching and soaking applied under salt solutions according to the carioca bean quality parameters in order to obtain a dry product with a short cooking time. The maintenance of technological quality characteristics of in natura grain through the use of experimental design techniques was also considered. A Plackett and Burman experimental design was applied to evaluate the effects of nine factors in preprocessing: soaking time, soaking in sodium chloride concentration, soaking in sodium bicarbonate concentration, soaking temperature, blanching temperature, blanching time, concentration of sodium chloride under soaking, concentration of sodium bicarbonate under soaking and drying temperature based on responses as cooking time, splitting percentage and color difference (Δe*) of preprocessed grains related to control. In the optimization, a DCCR 23 plan was used only with factors of the maceration step which mainly contributed to reduce cooking time. The increased concentration of sodium bicarbonate used in the soaking of beans significantly reduced the cooking time, but it increased the damage level in the product and darkened the bean integument. This contributed to greater differences in color of preprocessed grains when compared to the control treatment. The factors that most influenced the studied answers were soaking time, concentration of sodium bicarbonate under soaking and drying temperature. The desirability technique allowed the answers simultaneous evaluation and the definition of optimal conditions for this process. This process presented overall desirability of 56.53%, thus the factors levels were defined according to the following conditions: soaking time of 13.1 hours, concentration of NaHCO3 under soaking solution of 2.3% and drying temperature of 50 °C. Under these conditions, it is possible to reduce the cooking time by 58% with an index of damaged grains near 9.13% and color difference of 8.39. The obtained results may contribute to future researches that aim at developing bean preprocessing quality in a shorter cooking time.
O feijão (Phaseolus vulgaris L) é uma leguminosa típica para o brasileiro. O consumo do grão deve ser incentivado devido aos benefícios relativos ao seu conteúdo de proteínas, fibras, ácido fólico e minerais, como o ferro e o potássio. Porém, o tempo necessário para o processo de cozimento dos grãos de feijão, faz que muitos consumidores deixem de utilizar frequentemente o produto, implicando diminuição do consumo e da demanda por produção. A possibilidade de oferecer um produto previamente processado, mantendo-se as características tecnológicas com o tempo de preparo reduzido é uma opção para consumidores que buscam conveniência e qualidade. Técnicas como a maceração e o branqueamento do feijão, apresentam-se como opções para pré-processamento dos grãos. O objetivo deste trabalho foi verificar os efeitos do pré-processamento dos grãos com as operações de branqueamento e maceração em soluções salinas nos parâmetros de qualidade do feijão carioca, visando obter um produto seco com tempo de cozimento reduzido e manutenção das características de qualidade tecnológica do grão in natura, utilizando técnicas de planejamento experimental. Foi utilizado um planejamento tipo Plackett e Burman que avaliou os efeitos de nove fatores no pré-processamento: tempo de maceração, concentração de cloreto de sódio na maceração, concentração de bicarbonato de sódio na maceração, temperatura da solução de maceração, temperatura de branqueamento, tempo de branqueamento, concentração de cloreto de sódio no branqueamento, concentração de bicarbonato de sódio no branqueamento e temperatura de secagem, sob as respostas tempo de cozimento, porcentagem de grãos danificados e diferença de cor (Δe*) dos grãos pré-processados em relação ao controle. Na otimização foi utilizado um planejamento DCCR 23, apenas com os fatores da etapa de maceração e que contribuíram principalmente para redução do tempo de cozimento dos grãos. O aumento da concentração de bicarbonato de sódio utilizado na maceração do feijão reduziu consideravelmente o tempo de cozimento, porém, aumentou o nível de dano no produto e escureceu o tegumento do feijão contribuindo para maiores diferenças de cor dos grãos pré-processados em relação ao controle. Os fatores que mais influenciaram nas respostas avaliadas foram o tempo de maceração, a concentração de bicarbonato de sódio na maceração e a temperatura de secagem. A técnica de desejabilidade permitiu a avaliação simultânea das respostas e as condições ótimas para o processo foram definidas. O processo apresentou desejabilidade global de 56,53%, sendo os níveis dos fatores definidos na seguinte condição: tempo de maceração de 13,1 horas, concentração de NaHCO3 na solução de maceração igual a 2,3% e temperatura de secagem igual a 50 ºC. Nestas condições é possível reduzir o tempo de cozimento em aproximadamente 58%, com índice de grãos danificados próximo de 9,13% e diferença de cor de 8,39. Os resultados obtidos poderão contribuir para pesquisas que visem o desenvolvimento de tecnologias de pré-processamento do feijão com tempo de cozimento reduzido.

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Pessoa, Thayze Rodrigues Bezerra. "Avaliação do processo de obtenção de farinha da casca de banana (Musa sapientum) das variedades Prata, Pacovan e Maçã." Universidade Federal da Paraíba, 2009. http://tede.biblioteca.ufpb.br:8080/handle/tede/4061.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This work aimed to study the drying process of banana (Musa sapientum) peels (varieties Prata, Pacovan and Apple). The convective drying was performed at various air temperatures (40°C to 60°C) and at an average air speed of 1.0 m/s. It was used a fixed bed dryer with upward flow of air. The tests were conducted until the sample reached equilibrium between its own moisture and the drying air humidity. The drying kinetics was evaluated by the Fick, empirical two parameters exponential and Page semi-empirical models. From these models were found the water diffusivities. They were in the order of 10-10m/s². Overall diffusivities increased with drying air temperature. The highest drying rates were obtained for the banana peels from varieties Apple, Prata and Pacovan, respectively. Final product quality was evaluated through the following analysis: enzymatic activity, minerals and water activity. The best drying condition, which generated a final product with better quality, was at 60°C of air temperature for the three varieties.
O presente trabalho teve como objetivo estudar o processo de secagem das cascas de banana Prata, Pacovan e Maçã (Musa sapientum) in natura. A secagem convectiva foi realizada a várias temperaturas (40°C a 60°C) do ar de secagem com velocidade média (1,0 m/s) do ar. Para tal, foi utilizado secador de leito fixo com fluxo ascendente de ar. Os ensaios foram conduzidos até que as amostras alcançassem o equilíbrio na sua própria umidade e a umidade do ar de secagem. A cinética de secagem foi avaliada através dos Modelos Difusional, empírico exponencial de dois parâmetros e semi-empírico de Page, através desses modelos foram encontradas difusividades da ordem de 10-10 m/s². De maneira geral a difusividade aumentou com o tempo. As maiores taxas de secagem foram obtidas para a casca de banana Maçã, Prata e Pacovan respectivamente. A qualidade obtida do produto foi avaliada através das seguintes análises: atividade enzimática, minerais e atividade de água A condição de temperatura de secagem que gerou um produto final com melhor qualidade foi a de 60°C para as três variedades.

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Akyol, Cagdas. "Inactivation Of Peroxidase And Lipoxygenase In Green Beans, Peas And Carrots By A Combination Of High Hydrostatic Pressure And Mild Heat Treatment." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605655/index.pdf.

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In this study, the efficiency of high-pressure treatment (HHP, 250 - 450 MPa) with the combination of heat treatment (20 - 70oC) on peroxidase (POD) and lipoxygenase (LOX) inactivation in green beans, green peas and carrots was investigated for blanching purposes. Two steps treatments were also performed by pressurization at 250 MPa at 20°
C for 15- 60 min and then by water blanching at 40-70°
C. For green beans, 25 % residual activity was obtained by water blanching at 50°
C for 15 min after the pressurization at 250 MPa for 60 min. The enzyme inactivation in green peas was 78 % with water blanching at 50oC for 30 min after holding at 250 MPa for 60 min. When the carrots were water blanched at 50°
C for 30 min after HHP treatment at 250 MPa for 15min, 13 % residual activity was obtained. During the experiments, the stability gain or the activation of latent form of the enzymes were observed prior to inactivation. For carrots, LOX activity could not be measured. For green beans, 22 % LOX inactivation was obtained by holding at 250 MPa for 15 min and then by water blanching at 40°
C for 5 min. For green peas, the multiple treatment of 250 MPa for 30 min and water blanching at 50°
C for 30 min provided 70% inactivation. To obtain the enzyme inactivation higher than 90 % for blanching purposes, the pressure applied must be increased. Key words: high hydrostatic pressure, green bean, green pea, carrot, blanching, peroxidase, lipoxygenase

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Näsman, Birgitta. "The limbic-hypothalamic-pituitary-adrenal axis in Alzheimer's disease." Doctoral thesis, Umeå universitet, Geriatrik, 1994. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-140822.

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Dysfunction of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis is a common finding in advanced dementia. In this study, the function of the LHPA axis at different levels was investigated in patients with dementia and in healthy elderly. A subtle disturbance in the feedback regulation of the LHPA axis was found in patients with early (i.e., mild to moderate) Alzheimer’s disease (AD). After 0.5 mg dexamethasone, serum cortisol levels were less suppressed in AD patients and plasma adrenocorticotropin (ACTH) levels were lower as compared with healthy elderly. After stimulation with human corticotropin-releasing hormone a blunted ACTH response was found in AD patients while relative serum cortisol, dehydroepiandrosterone, and androstenedione responses were increased. Significant correlations were found between low plasma ACTH levels and temporal lobe atrophy and between low peak plasma ACTH levels and hippocampal atrophy measured with computer tomography. Patients with advanced AD and multi-infarct dementia had lower basal levels of dehydroepiandrosterone sulphate in combination with no difference in cortisol levels, resulting in a high cortisol/DHAS ratio. The difference persisted after adjustments for age and sex in a multivariate analysis. In patients with early AD, basal serum levels of dehydroepiandrosterone and androstenedione were increased, and this increase was accentuated after stimulation with ACTH. Peripheral glucocorticoid sensitivity was examined by skin vasoconstrictor blanching tests. Patients with AD and patients treated with glucocorticoids showed skin blanching at higher clobetasol concentrations than healthy elderly. These findings justify further investigations on the role of LHPA axis dysfunction in Alzheimer’s disease and its possible importance for the pathophysiology of the disease.
digitalisering@umu

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Arevalo, Pinedo Rosalinda. "Estudo da estabilizaçãp da polpa de camu-camu (Myrciaria Dubia (H.B.K.) Mc Vaugh) congelada visando a manutenção de acido ascorbico e de antocianinas." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266678.

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Orientador: Theo Guenter Kieckbusch
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: O camu-camu (Myrciaria dubia H.B.K.) é uma fruta nativa da região Amazônica que apresenta um elevado teor de ácido ascórbico e de antocianinas. O presente estudo investigou o processo de conservação por congelamento da polpa de camu-camu cultivada no Estado de São Paulo visando a manutenção de fatores de qualidade. Frutos do camu-camu foram submetidos a uma inativação enzimática por imersão em água em ebulição por 60, 90, 120 e 180 segundos seguida de esfriamento em água gelada. O tempo limite para manter a integridade do pericarpo foi 120 segundos e nestas condições houve um enriquecimento da polpa com ácido ascórbico extraído da casca, no despolpamento. Polpas tratadas por 30, 60 e 120 segundos e polpa não-inativada foram armazenadas por 180 dias a temperaturas de 5oC, -10oC e ¿20oC. O tratamento por 120 segundos manteve os mais altos níveis de ácido ascórbico em todas as situações. O armazenamento a ¿20oC manteve por pelo menos 135 dias o conteúdo inicial de ácido ascórbico, independentemente da intensidade da inativação térmica. Polpas inativadas por 120 segundos receberam crio-protetores (15% de goma arábica, 20% de maltodextrina DE 10 e 25% de sacarose) e juntamente com polpa sem aditivos foram submetidas às mesmas condições de armazenamento descritas anteriormente. O comportamento da conservação de ácido ascórbico foi semelhante as das polpas não-aditivadas. A degradação de antocianinas é alta e ocorre nos primeiros 50 dias de armazenamento. Na estocagem a ¿20oC a retenção foi em torno de 40% de sua concentração inicial, independentemente do tipo de crio-protetor usado. A cor vermelha refletida não sofreu alteração após 180 dias a ¿20ºC, mostrou uma leve descoloração á -10oC, que foi mais intensa a 5oC. O conteúdo de sólidos solúveis, o pH e a acidez sofreram alteração negligível em todos os ensaios de armazenamento realizados. O estudo foi complementado com um levantamento do comportamento reológico dos produtos, a determinação da condutividade térmica do produto congelado e a Temperatura de Início de Congelamento e o levantamento de termogramas em DSC que permitiram determinar a Temperatura de Transição Vítrea, a Temperatura de Início de Fusão e a Entalpia de Fusão. Os resultados recomendam o armazenamento á ¿20oC por preservar a maior parte dos fatores de qualidade da polpa de camu-camu por um longo período, independentemente do tipo de pré-tratamento ou de adição de crio-protetores
Abstract: Camu-camu (Myrciaria dubia H.B.K.) is a fruit native to the Amazon Region, with very high ascorbic acid and anthocyanin contents. This investigation considers the freezing of camu-camu cultivated in the State of São Paulo during storage, as means of preserving these quality factors. Camu-camu fruits were submitted to enzymatic inactivation by immersion in boiling water for 60, 90, 120 and 180 seconds followed cooling in ice water. The intensity limit that maintained the integrity of the pericarp was 120s, and wider these conditions the ascorbic acid of the was enhanced during pulping, due to transference from the peel to the pulp. Pulps blanched for 30, 60 and 120 seconds, as well as untreated pulp were stored for 6 months at 5ºC, -10ºC and -20ºC. The pulp treated for 120s showed the highest retention of ascorbic acid content under ¿20ºC storage, all samples retained the initial ascorbic acid content for at least 135 days. Cryoprotectants were added to pulp blanched for 120 seconds (20% maltodextrin DE 10, 15% gum Arabic or 25% sucrose) and together with national pulp containing no additives, were submitted to the same storage conditions as previously. Ascorbic acid retention followed the same trend in all samples. High degradation of the anthocyanins was detected during the first 50 days of storage. Under ¿20ºC storage, only 40% of the initial content was retained, independent of the cryoprotectant used. The reflected red color did not change after 180 days at ¿20ºC, faded lightly at ¿10ºC and ever more so at 5ºC. The soluble solids content, pH and acidity underwent negligible variation during all storage tests. This research was complemented with the measurement of the rheological behavior of the products, the determination of the thermal conductivity of the frozen products and the Initial Freezing Temperature. DSC thermograms allowed the determination of the Glass Transition Temperature, the Initial Melting Temperature and the Melting Enthalpy. The results recommend storage at ¿20°C in order to maintain most of the quality factors of the camu-camu pulp for a long period, independent of the pretreatment and of the addition of cryo-protectants
Doutorado
Engenharia de Processos
Doutor em Engenharia Química

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Amoussa, Hounkpatin Waliou B. A. "Évaluation du potentiel de couverture des besoins en vitamine A des jeunes enfants à partir des sauces accompagnant les aliments de base consommés au Bénin." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20160/document.

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L'identification et l'amélioration du potentiel pro-vitaminique A des sauces accompagnant les aliments de base pourraient constituer une voie alimentaire de lutte contre la carence en vitamine A (CVA) chez les jeunes enfants au Bénin. La qualité nutritionnelle et la rétention en provitamines A des sauces lors des procédés traditionnels de préparation ont été évaluées au moyen d'une démarche itérative terrain et laboratoire. Une enquête de consommation alimentaire par pesées et mesures anthropométriques auprès de 420 enfants a permis d'évaluer l'état nutritionnel des sujets et l'adéquation des apports en fer, zinc et vitamine A (VA) et d'identifier les principales sources de VA dans l'alimentation. La mangue, les œufs, l'huile de palme rouge (HPR) ou diverses sauces légumes-feuilles (LF) constituent les principaux aliments locaux riches en VA consommés (34,2% des enfants enquêtés). Lorsqu'elles sont consommées, les sauces participent à la couverture de 71 à 129% des apports journaliers recommandés en VA des jeunes enfants. Le suivi au niveau ménage des procédés traditionnels de préparation des sauces les plus prometteuses notamment les sauces LF-amarante à base d'HPR ou de jus de noix de palme (NP), a permis d'identifier les traitements thermiques appliqués aux LF, aux NP ou à l'HPR comme des étapes critiques. Le chauffage de l'HPR à 180-200°C apparaît comme l'étape la plus préjudiciable à la VA. Elle réduit de plus de 70%, et en moins de 3 min, les teneurs en α-carotène, en β-carotène et en activité équivalent rétinol (AER). La violaxanthine, caroténoïde non pro-VA est le seul composé significativement affecté lors du blanchiment des feuilles d'amarante (100°C) mais l'AER reste élevée avec ou sans ajout de potasse traditionnelle. Les sauces formulées à base des ingrédients LF-amarante, NP ou HPR présentent une bonne acceptabilité, une AER élevée et leur consommation pourrait être promue avantageusement dans le cadre d'approches alimentaires de lutte contre la CVA
The identification and the improvement of the potential in pro-vitamins A of sauces accompanying staple foods could constitute a food-based approach for combating vitamin A deficiency (VAD) among young children in Benin. The nutritional quality and the retention of pro-vitamins A in sauces during traditional home processing has been assessed by using a field-laboratory iterative approach. Anthropometric measurements were used to appreciate subjects' nutritional status. A food consumption survey of 420 young children was conducted to assess the adequacy of iron, zinc and vitamin A (VA) intakes, and to identify the main VA-rich foods eaten by children using the weighed food record method. Mangoes, eggs, red palm oil (RPO), various leafy vegetables (LV) and palm nut juice sauces appeared to be the main VA-rich foods consumed by 34.2% investigated children. When consumed, these LV sauces containing RPO or palm nut juice (PNJ) contributed to the meeting of 71-129% of the recommended VA intake of young children. The traditional processing method of the most promising sauces such as amaranth leaf sauces based on RPO or PNJ was monitored step by step during home visits and allowed identifying the thermal treatments applied to LV, to palm nut or to RPO as critical steps. Heating the RPO at 180-200°C appears as the more prejudicial step to VA. It decreased more than 70% and in less than 3 min, α-carotene, β-carotene and Retinol Activity Equivalent (RAE) contents. Violaxanthin, a non pro-VA carotenoid, was the only compound to be significantly affected by the thermal treatment (100°C) of amaranth leaves. RAE remained high after blanching even when alkaline traditional potash was added. The formulated sauces on the basis of the ingredients LV-amaranth, palm nut or RPO present a good acceptability, a high RAE and their consumption could be promoted favorably in food-based strategies to alleviate VAD

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Баса, Ікпе Вільфріед, and Ikpe Vilfried Basa. "Використання лактококів в технології сквашування капусти (броколі)." Thesis, Тернопільський національний технічний університет імені Івана Пулюя, 2017. http://elartu.tntu.edu.ua/handle/123456789/19463.

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Магістерська кваліфікаційна робота присвячена дослідженню процесу ферментування капусти броколі з використанням лактококів, для збереження біологічно активних речовин (БАР) та отримання продуктів харчування із хорошими смаковими властивостями. Метою даної роботи є використання лактококів у технології сквашування капусти броколі. На підставі отриманих результатів запропоновано способи попередньої теплової підготовки капусти броколі, які б дозволили максимально можливо зберегти всі БАР сировини, підібрано активні штами лактококів, які доцільно використовувати для ферментування броколі та проведено органолептичну та фізико-хімічну оцінки готової продукції.
Master's qualification work is devoted to the process of fermentation using broccoli laktokokiv to preserve biologically active substances (BAS) and get food with good taste properties. The aim of this work is the use of technology in laktokokiv fermentation broccoli. Based on preliminary results suggested ways to prepare broccoli heat that would most probably keep all BAS raw chosen laktokokiv active strains that should be used for fermentation broccoli and conducted organoleptic and physico-chemical evaluation of finished products.

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Trichet, Véronique. "Photochimie de pâtes à papier blanchies à l'aide de réactifs non chlorés." Bordeaux 1, 1996. http://www.theses.fr/1996BOR10631.

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L'etude de la reversion de blancheur de pates a papier chimiques et a haut rendement blanchies sans reactifs chlores a fait l'objet du travail de these. Nous avons montre que la lignine residuelle dans les pates chimiques est a l'origine de leur sensibilite a la lumiere uv. Par ailleurs, le test de wiesner (phloroglucinol en solution acide) a ete applique aux deux types de pates etudiees (faible et fort taux de lignine) en tant que marqueur de la photodegradation de la lignine. Ainsi, il apparait que des enones de type quinone ou coniferaldehyde, formees par irradiation uv, seraient les chromophores responsables de la coloration des pates. De meme, le role des stilbenes phenoliques dans le photojaunissement des pates a haut rendement a ete aborde in-situ dans le materiau. En parallele, l'origine de la synergie entre un absorbeur uv et un thiol rencontree lors de la photostabilisation des pates a haut rendement a ete determinee

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Cosquer, Claire. "Expat' à Abu Dhabi : blanchité et construction du groupe national chez les migrant.e.s français.es." Thesis, Paris, Institut d'études politiques, 2018. http://www.theses.fr/2018IEPP0040.

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Fondée sur une ethnographie combinant observation et entretiens, cette thèse analyse les expériences migratoires des résident·e·s français·es à Abu Dhabi. Nuançant le portrait d’« expatrié·e·s » fréquemment présenté·e·s comme hypermobiles, elle montre qu’elles et ils empruntent en fait des routes migratoires balisées. Ces routes sont notamment dessinées par la rencontre entre politiques émiriennes et État français transnational, dans un contexte de concurrences postcoloniales qui se traduisent par des stratégies de distanciation vis-à-vis du colonialisme britannique et de l’impérialisme étasunien. La construction du groupe national, encadrée par des institutions migratoires, se déploie dans la délimitation de frontières associant francité et blanchité, au travers des interactions tant avec les nationales et nationaux émirien·ne·s qu’avec d’autres groupes migrants. Si le rapport à la population majoritaire sud-asiatique est marqué par une mise à distance, toutefois perturbée par la fréquence de l’emploi domestique à demeure, le rapport aux citoyen·ne·s émirien·ne·s engage un trouble singulier dans l’ordre postcolonial. Les résident·e·s français·es font ainsi l’expérience d’une vulnérabilité limitée, mais anxiogène, vis-à-vis d’Émirien·ne·s perçu·e·s comme omnipotent·e·s. En cela, les migrations françaises à Abu Dhabi se révèlent le lieu d’une déstabilisation autant que d’une solidification de la blanchité. Mettant en lumière la façon dont ces reconfigurations blanches s’entrecroisent avec un régime de genre où se renforce l’hétéroconjugalité, la thèse apporte une contribution à l’analyse plurielle des rapports sociaux dans les migrations des Nords vers les Suds
Drawing on ethnographic methods (participant observation and interviews), this research analyses the migratory experiences of French residents of Abu Dhabi – generally referred to as ‘expats’ rather than ‘migrants’. It describes their migratory paths, and explores how migration affects their social positions, relations, and representations. While these ‘expatriates’ have been described as ‘hypermobile,’ they actually proceed along marked trails. Their migratory routes are shaped by the encounter of Emirati public policies and the French transnational state, in a context where postcolonial competition involves complex distancing strategies vis-à-vis British colonialism and U.S. imperialism. While the construction of the national group is supported by those migratory institutions, it also delineates symbolic boundaries and blends Frenchness and whiteness, through interactions with Emirati nationals as well as with other migrant groups. Although there appears to be little contact with the majority, South-Asian population, this remoteness is complicated by the massive institutionalization of ‘live-in’ domestic services. Relations to national citizens trigger an interesting trouble in the postcolonial order: French residents experience a limited, albeit anxiety-ridden, vulnerability vis-à-vis omnipotent-reputed Emiratis. To that extent, French migrations to Abu Dhabi enact an ambivalent social theater where whiteness is both destabilized and solidified. Showing how the reconfigurations of whiteness intersect with a gender regime which bolsters heteroconjugality, this research contributes to the analysis of the plurality of power relations in North-South migrations

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Ruffin, Brigitte. "Etudes des chromophores responsables de la photocoloration des pâtes à papier à haut rendement blanchies." Bordeaux 1, 1999. http://www.theses.fr/1999BOR10576.

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Le role des stilbenes phenoliques lors du photojaunissement des pates a papier a haut rendement blanchies a ete aborde. La quantite de ces unites presentes dans la pate a pu etre estimee suite a la mise au point d'une hydrogenation selective de la double liaison stilbene. L'etude photochimique de composes de type stilbene-para-hydroquinone a ete realisee sur des modeles de lignine en solution et adsorbes sur papier de cellulose. La detection des structures biphenyles phenoliques a ete entreprise in situ dans la pate. Des essais de photostabilisation par reactions chimiques ou par addition d'absorbeurs uv ont ete realises.

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La, Chapelle Virginie de. "Etude du jaunissement à la chaleur des pâtes papetières chimiques blanchies par des séquences sans chlore." Grenoble INPG, 1999. http://www.theses.fr/1999INPG0155.

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La stabilite de blancheur est une propriete frequemment requise pour les pates a haute blancheur comme les pates chimiques blanchies. Certains facteurs sont connus pour leur effet sur la reversion de blancheur a la chaleur des pates cellulosiques mais les mecanismes du jaunissement sont mal connus. Une etude de pates chimiques blanchies industriellement montre que, pour une meme usine, les pates tcf possedent generalement plus de carboxyles et des indices kappa plus eleves que leurs homologues ecf, ces pates sont egalement plus sensibles a la chaleur. Des fonctions aldehyde en c 2 et/ou c 3 du motif anhydroglucose des chaines cellulosiques d'une pate n'affectent que tres peu son comportement a la chaleur, a l'inverse des fonctions cetone qui induisent un fort jaunissement. La presence simultanee de ces deux types de fonctions conduit a un jaunissement a la chaleur plus intense que dans le cas ou ils sont presents separement. Des fonctions carboxyle en c 2 et/ou c 3 ou c 1 et/ou c 6 induisent un jaunissement accelere de la pate a la chaleur mais ceux positionnes en c 6 ont le plus d'effet. Les fonctions carboxyle sont naturellement presentes dans les pates ecrues principalement au niveau des hemicelluloses. Les stades de blanchiment utilisant l'ozone, le dioxyde de chlore ou l'acide peracetique, a l'inverse de ceux utilisant le peroxyde d'hydrogene ou l'oxygene, contribuent a eliminer des structures porteuses de carboxyles. La chaleur induit la creation de fonctions cetone et de doubles liaisons carbone-carbone sur les hydrates de carbone. Sous l'effet de la chaleur, les polysaccharides sont depolymerises par coupures homolytiques donnant naissance a des radicaux organiques. Un mecanisme decrivant la creation de cetone et d'insaturations est propose, des hypotheses sont formulees pour tenter d'expliquer les modifications observees lors du vieillissement a la chaleur des pates chimiques. Des moyens de minimiser le jaunissement des pates chimiques a la chaleur sont exposes.

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Louvion, Alexis. "Blanchir les zones grises de l'emploi : le portage salarial, extension ou détournement des institutions salariales ?" Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLED055.

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Cette thèse étudie l’hybridation des statuts d’emploi à travers le portage salarial, mécanisme qui permet à des travailleurs indépendants de disposer du statut de salarié par la signature d’un contrat de travail avec un tiers employeur. En s’appuyant sur une enquête par entretiens, observations, et analyse documentaire (contrats de travail, jurisprudences, textes de loi, articles de presse), la thèse, qui se situe au carrefour de la sociologie du travail et de l’emploi, de la sociologie économique et de la sociologie du droit, entreprend d’analyser les différentes étapes de la chaîne de production et d’appropriation de ce salariat particulier. Elle retrace ainsi la co-construction juridique et législative du dispositif, étudie la manière dont les entreprises de portage font commerce de cette forme d’emploi, et analyse les bricolages faits par des travailleurs qui tentent de tirer parti de la situation hybride dans laquelle ils se trouvent
Through the umbrella companies’ example, this thesis analyses self-employed and employed work evolutions. Based on interviews, ethnographic material and a document review, this thesis follows retraces how this employment relationship is produced and uses by different actors. The first part focuses on the legal construction of this specific form of employment, and its integration to standard employment. The second part is based on an analysis of third-party employer strategies. The last part shows how this type of employment is used by workers for securing career paths, but helps to consolidate the inequalities

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Perrin, Laurette. "5 ans, 5 jours et 5 nuits : instantané d’une recherche-création sur la blanchité à Salvador (BA)." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCC007.

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Les mots sont des performances. Les actes sont des performances. Une étude académique est déjà un acte performatif en soi. Comment, en tant que personne blanche européenne étudiant à Salvador (Bahia), puis-je participer aux luttes contre les injustices sociales dans une perspective de décolonisation des sciences ? La recherche-création permet de questionner les formes de production de savoirs. Grâce au langage du Soundpainting – langage de gestes créé par Walter Thomson (1974) permettant de composer en temps réel la recherche-création,au-delà de son oralité et de sa pluridisciplinarité, propose une approche des concepts identitaires (genres, sexualités, racisme, identités, etc.) qui considère la particularité de leurs mouvances, de leurs formes évolutives et subjectives. « Recherche-collaborative », cette recherche a évolué au contact des différents performers qui ont participé aux créations, comme aux divers publics rencontrés. Chacun.e a contribué à l’évolution de son objet de recherche : « la blanchité à Salvador ». La première partie de cette thèse propose une présentation du concept de blanchité, tentant de définir certaines caractéristiques récurrentes, tout en tenant compte des particularités liées à chaque contexte socioculturel, ici la France et le Brésil. La seconde partie, quant-à-elle, décrit les différentes étapes du travail de recherche ainsi que son évolution au fil des rencontres
Words are performances. Acts are performances. An academic study is, infact, a performative act in itself. As a white european studying in Salvador (Bahia),can I take a stand against social injustice in a perspective of decolonization of science? Research-creation allows us to question the ways of knowledge production. Thanks to the Soundpainting language – language of gestures created by Walter Thomson (1974) which allow us composing in real time - the research creation,in addition to its orality and pluridisciplinarity, proposes an approach to the concepts of identity (gender, sexualities, racism, identity, etc.) which considers the particularity of their movings and their evolving and subjective forms. As a "collaborative research", this research has evolved in contact with several performers who participated in the creation, as well as the various audiences we met. Each one has contributed to the evolution of its research object, "the whiteness in Salvador." The first part of this thesis proposes an overview of the concept of whiteness, trying to define some recurring characteristics, considering the particularities related to each socio-cultural context, here in France and also in Brazil. The second part describes the different stages of the research project an dits evolution over the meetings
As palavras são performances. Os atos são performances. Um estudoacadêmico já é em si um ato performativo. Enquanto pessoa branca europeia estudando em Salvador (Bahia), posso participar na luta contra a injustiça socialnuma perspectiva de descolonização da ciência? A pesquisa-criação permite questionar as formas de produção de conhecimento. Com a linguagem Soundpainting - linguagem de gestos criado por Walter Thomson (1974) para compor em tempo real - a pesquisa-criação, além de sua oralidade e de su apluridisciplinaridade, propõe uma abordagem dos conceitos de identidade (degênero, sexualidades, racismo, identidade, etc.) que considera a particularidade de suas movências, suas formas evolutivas e subjetivas. "Pesquisa-colaborativa",esta pesquisa tem evoluído em contato com vários artistas que participaram dacriação, como os vários públicos encontrados. Cada um.a contribuiu com aevolução do seu objeto de pesquisa, "a branquitude em Salvador." A primeira parte desta tese propõe uma visão geral do conceito de branquitude, tentando definir algumas características recorrentes, tendo em vista as particularidades decada contexto sociocultural, aqui na França e no Brasil. A segunda parte descreveas diferentes fases do trabalho de pesquisa e sua evolução ao longo dosencontros

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Voccia, Isabelle. "Effets immunomodulateurs des effluents d'usine de pâte blanchie chez la truite arc-en-ciel (Oncorhynchus mykiss)." Lyon 1, 1997. http://www.theses.fr/1997LYO10009.

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Les effets immunomodulateurs des effluents d'usines de pate a papier ont ete testes chez la truite arc-en-ciel. Divers procedes de fabrication (kraft et bisulfite) et de blanchiment (avec ou sans chlore) de la pate, ainsi que le traitement secondaire des effluents ont ete testes sur des parametres de la reponse immunitaire non specifique (phagocytose, flambee oxydative, activite du lysozyme) et specifique (proliferation lymphocytaire et le taux des immunoglobulines totales) nos resultats montrent un effet immunomodulateur pour tous les effluents, plus particulierement pour les effluents de blanchiment sans chlore. Les parametres les plus sensibles sont la flambee oxydative et la proliferation des lymphocytes. Nous avons egalement montre que les parametres du systeme immunitaire peuvent etre utilises comme biomarqueurs de toxicite a d'autres polluants (metaux lourds) ainsi que pour d'autres especes exposees a des polluants (choquemort, fundulus heteroclitus). Finalement, nous avons mis en evidence l'influence de certains systemes physiologiques (le systeme endocrinien et reproducteur) sur le systeme immunitaire des poissons.

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Ravalason, Holy. "Développement de nouveaux outils fongiques respectueux de l'environnement (écoprocédés) pour la production de pâtes chimiques blanchies de résineux." Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11017.

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Les biotechnologies peuvent être utilisées dans le domaine de l'industrie papetière comme alternatives aux procédés chimiques de production de pâtes à papier. Dans le cadre de ces travaux de thèse nous avons souhaité exploiter les avancées technologiques dans le domaine de la génomique et de l'ingénierie des protéines pour améliorer les procédés biotechnologiques appliqués à la production et au blanchiment de pâtes chimiques. Dans une première partie, le secrétome du Basidiomycète Phanerochaete chrysosporium, cultivé sur copeaux de bois de résineux en conditions de biopulping, a été analysé. Une approche protéomique a été choisie, en exploitant le génome de ce champignon. L'analyse protéomique a révélé la production de différentes enzymes impliquées dans la biodégradation des constituants du bois. La sécrétion de certaines des enzymes identifiées a été démontrée pour la première fois. Les copeaux de bois traités ont par la suite été soumis à un procédé de mise en pâte chimique (procédé kraft) et à un blanchiment au dioxyde de chlore. Le traitement fongique a conduit à une augmentation du rendement en pâte kraft, accompagnée d'une augmentation de la blancheur finale de la pâte produite et d'une diminution de la consommation en réactifs de blanchiment. Ces effets peuvent être partiellement expliqués par une production d'enzymes spécifique de dégradation du bois. Dans la deuxième partie de ces travaux, la laccase du Basidiomycète Pycnoporus cinnabarinus a été modifiée par fusion à un module de fixation aux carbohydrates (CBM) fongique. La laccase-CBM obtenue a pu être produite chez Aspergillus niger, et ses capacités de fixation à un substrat cellulosique et à des fibres de pâte kraft de résineux ont été évaluées. La laccase-CBM a été comparée à la laccase de P. Cinnabarinus dans des essais de délignification et de blanchiment d'une pâte kraft de résineux, en présence d'un médiateur d'oxydoréduction (hydroxybenzotriazole). La présence du CBM a permis d'améliorer la biodélignification de la pâte kraft étudiée par la laccase, conduisant à une diminution de la charge enzymatique, une augmentation de la blancheur finale de la pâte, une diminution de la consommation en dioxyde de chlore et une préservation des propriétés mécaniques des fibres. Des analyses microscopiques ont révélé une pénétration de la laccase-CBM dans la paroi des fibres, et sa rétention au sein des fibres à la fin du traitement enzymatique
Biotechnologies can be applied to paper industry as an alternative to chemical processes for pulp and paper production. In this work advances in genomic and protein engineering were used to improve biotechnological processes applied to chemical pulps production and bleaching. In the first part of this work, the Phanerochaete chrysosporium secretome, grown on softwood chips under biopulping conditions was analysed. A proteomic approach was chosen, using the P. Chrysosporium genome. Proteomic analysis revealed the production of several enzymes involved in wood biodegradation. The secretion of some of the identified enzymes was demonstrated for the first time. Biotreated wood chips were further submitted to kraft cooking and chlorine dioxide bleaching. Fungal treatment led to an increase of pulp yield, as well as an increase of pulp final brightness and a decrease in chlorine dioxide consumption. These effects could be partially explained by the production of specific wood-degrading enzymes. In the second part, Pycnoporus cinnabarinus laccase was fused to a fungal carbohydrate binding module (CBM). The laccase-CBM was produced in Aspergillus niger, and binding capabilities of the enzyme on a cellulosic substrate and on softwood kraft pulp fibers were evaluated. Laccase-CBM and P. Cinnabarinus laccase were compared for their softwood kraft pulp biobleaching potential, in the presence of a redox mediator (hydroxybenzotriazole). The presence of the CBM could improve pulp biodelignification with laccase, leading to a decrease in the enzymatic charge, an increase of pulp final brightness, a decrease in chlorine dioxide consumption and a preservation of pulp mechanical properties. Microscopic examinations revealed a penetration of the laccase-CBM in the fiber wall, and retention of the enzyme inside the pulp fibers at the end of the enzymatic treatment

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Ben, Hamouda Anissa. "Des jeunes de la diversité culturelle dans les quartiers dits populaires : une expérience paradoxale de la minorité : d'autres Blancs en France et en Allemagne." Paris 8, 2014. http://www.theses.fr/2014PA084077.

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En France, nous assistons à un renversement des majorités dans des quartiers dits populaires. Des populations Blanches y font l’expérience d’une minorité paradoxale, impensable et impensée. Elle résulte d’une homogénéité fictive des populations non-blanches et de la rencontre entre petite et grande Histoire. Durant la socialisation pubertaire, elle agit sur les modes d’identifications. Les jeunes Blancs sont davantage marqués par une diversité culturelle qui anime l’ensemble des interactions sociales de leur vie quotidienne. Un déplacement sur le contexte allemand permet d’en apprécier les limites situationnelles et relationnelles. Les jeunes en tirent toutefois un ensemble de savoirs. Avec 57 entretiens réalisés auprès de jeunes Blancs des deux pays, j’ai pu mettre en lumière une représentation humaniste du divers directement puisée dans une norme de la diversité active et précocement incorporée. Cela se manifeste chez ces jeunes par une compétence d’adaptabilité sociale exacerbée. De par leur expérience de socialisation, ils savent composer avec l’altérité. Ils disposent ainsi de savoirs informels leur permettant de circuler librement à plusieurs niveaux sociaux (macro et micro, culturels, etc. ). Au final, ces jeunes Blancs sont plus proches de leurs modes de subjectivation, ce qui induit un rapport à soi et au monde original, plus éclairé et plus égalitaire. Par l’effet de l’après-coup, leur minorité se métamorphose en heureuse marge. Ils sont plus libres, plus ouverts au changement, même désireux d’accompagner un renouvellement sociétal. Leurs savoirs informels, non comparables et transformés en système de valeur, sont une ressource pour notre société plurielle
In France, we are witnessing a reversal of majority populations in the so-called popular neighborhoods. White people that live there witness a paradoxical minority experience, which can be considered unthinkable and unthought. This phenomenon is a result of a fictitious homogeneity of non-white populations and the encounter between stories and History. During the nubile socialization, these experiences affect the identification modes. Young Whites are more marked by cultural diversity that influences all their social interactions in their daily lives. A displacement in the German context allows to appreciate the situational and relational boundaries. However, these youths derive a set of new knowledge. Using 57 interviews with young Whites in France and Germany, I highlighted a humanistic representation of the diverse directly drawn from a standard active and precociously integrated diversity. This is manifested in the youth by a vivid social adaptability competency. By their socialization experience, they know how to deal with the incidence of strangeness. They have informal knowledge allowing them to move freely at several social levels (macro and micro, cultural, etc. ). Ultimately, these young Whites are closer to their subjectivation mode, which induces an original relation to oneself and to the world, more enlightened and egalitarian. By the effect of the aftermath, their minority status turns into a happy margin. They are freer, more open to change, and even willing to adapt to societal renewal. Their informal knowledge, non comparable and transformed into value system, is a resource for our plural society

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Belayachi, Larbi. "Pâtes à papiers chimiques blanchies de plantes annuelles sans chlore ni soufre : cas de l'orge et du sorgho sucrier." Toulouse, INPT, 1995. http://www.theses.fr/1995INPT006A.

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Le travail propose concerne la valorisation papetiere de pailles de cereales et de bagasses de sorgho sucrier. Quelques donnees bibliographiques comparatives sur la structure du bois et des plantes annuelles notamment la paille de cereale et la bagasse du sorgho sucrier (disponibilite, production, utilisation), sur le marche mondial des pates a papiers, leur fabrication par les procedes alcalins, et les nouvelles sequences de blanchiment a base de l'ozone et de peroxyde d'hydrogene sont rapportes dans le premier chapitre. Le second chapitre porte sur la mise au point de conditions originales de blanchiment de pates chimiques de paille d'orge obtenues par des procedes alcalins sans l'emploi de soufre et de chlore. L'ozone est le principal agent de blanchiment. Son utilisation necessite la mise au point de conditions operatoires satisfaisantes pour obtenir une reactivite optimale. La selectivite s'est amelioree par le recours aux pretraitements acides notammant l'acide acetique couple a l'acide ethylene diamine tetra-acetique. Le peroxyde d'hydrogene est utilise en phase finale de blanchiment pour son caractere selectif et delignifiant quand l'ozone devient inefficace. Le troisieme chapitre est consacre a l'etude et la mise au point de la cuisson de bagasse desucree et demoellee de sorgho sucrier, par le procede soude-anthraquinone associe au blanchiment de la pate ecrue par l'ozone et le peroxyde d'hydrogene. La pate ecrue presente des caracteristiques physico-chimiques equivalentes voire superieures a celles de pates chimiques de bois ou de plantes annuelles. Le blanchiment de cette pate chimique par le couple ozone - peroxyde avec pretraitement acide confirme l'excellente qualite papetiere de cette matiere pour l'industrie papetiere

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Leone-Colombo, Nadine. "Etude photochimique de molécules modèles de lignine à motif gaiacycle : photostabilisation des papiers de pâtes à haut rendement blanchies." Bordeaux 1, 1990. http://www.theses.fr/1990BOR10541.

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Le role des groupes alpha carbonyles lors du photojaunissement des pates a haut rendement blanchies a ete aborde par l'etude de la photoreactivite en solution et a l'etat adsorbe d'un dimere beta-o-4 phenolique et d'un dimere beta-1 o-methyle, modeles de lignine gaiacyle. La contribution des phenols non carbonyles, dans le processus de photocoloration, a ete demontree par spectroscopie uv-visible sur des pates chimicothermomecaniques blanchies, et par simulation du photojaunissement a l'aide de modeles phenoliques non carbonyles varies, synthetises puis adsorbes sur des fibres carbohydrates exemptes de lignine. Des essais pratiques de photostabilisation des pates a haut rendement blanchies ont ete entrepris parallelement

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Delmas, Delphine. "Dosage des groupements phénoliques et quinoniques dans les pâtes cellulosiques : application à l'étude de pâtes écrues et semi-blanchies." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0074.

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Une méthode de dosage in-situ des groupements OH phénoliques proposée par Behrooz Eshkiki (2005) a été modifiée. Cette méthode de dosage est employable en vue du dosage semi-quantitatif des groupements quinoniques. La méthode a été appliquée sur différentes lignines extraites et les résultats obtenus ont été comparés avec des mesures obtenues par analyse spectroscopique RMN 31P. Les tendances des résultats obtenus sur pâtes écrues sont conformes aux résultats de la littérature, même si en valeur absolue, la méthode in-situ donne des résultats plus élevés. L’influence de différents réactifs de blanchiment a été étudiée. L’examen de données de la littérature a permis d’établir que la relation existant entre l’indice Kappa et le taux de lignine d’une pâte cellulosique est de nature affine
A method initially proposed by Behrooz Eshkiki (2005) for the in-situ titration of free phenolic group modified. This method was employed for the semi-quantitative titration of quinonic compounds. The methO<1 employed with various extracted lignins and the results were compared with datas obtained with JIP Nt spectroscopy. The tendencies of the results obtained with unbleached pulps agreed with literature, even if resuh obtained with the in-situ method were systematically higher. The action of various bleaching chemicals was studied. Examen of literature datas showed that the relationship between the Kappa number and the lignin content of a pulp is not strictly proportional due to an offset

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Rayot, Véronique. "Alterations du centre de l'australie : role des solutions salines dans la genese des silcretes et des profils blanchis." Paris, ENMP, 1993. http://www.theses.fr/1993ENMP0462.

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Plusieurs phases d'alterations et de silicifications se succedent et se superposent dans le regolite du nord de l'australie meridionale. Les alterations se caracterisent par un blanchiment general des profils. Des niveaux de silicification de nappe s'intercalent au sein des series blanchies. Les profils sont souvent couronnes par des silicifications d'origine pedologique (silcretes et hardpans). Le blanchiment est amorce par l'oxydation de la pyrite et de la matiere organique de la roche mere qui induit un milieu acide. Les feldspaths et phyllites originels sont alteres par extraction de l'aluminium. Reste en place la silice dont les tetraedres se reorganisent sur place pour former de l'opale. Cette alteration conduit a des profils ou coexistent de la kaolinite, de l'opale, de l'alunite, du gypse et du quartz herite du materiel originel. L'alteration se fait en presence de saumures. La diminution importante de la solubilite de la silice amorphe en presence de sels explique la paragenese opale-kaolinite dont l'association semble a priori antagoniste. La similitude de structure entre l'opale-ct et les couches tetraedriques des mineraux argileux suggere qu'une partie de l'opale soit heritee de l'alteration des argiles. Cette transformation se fait tres probablement par des stades intermediaires d'interstratifies de plans de tridymite et de feuillets d'argile. Les silicifications de nappe se caracterisent par la disparition des argiles, le maintien d'une partie de l'opale-a et l'apparition d'opale-ct. La silicification se fait par impregnation de la matrice et formation de concretions dans les vides. Les concretions sont liees a la percolation d'eaux douces chargees en silice. Lorsque ces eaux douces se melangent aux eaux de la nappe saline, la silice en solution precipite. Les sequences minerales concretionnees vont systematiquement de phases desordonnees (les differentes varietes d'opale) vers les phases les plus ordonnees (cristaux de quartz automorphes)

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Rayot, Véronique. "Altérations du centre de l'Australie : rôle des solutions salines dans la genèse des silcrètes et des profils blanchis /." [Fontainebleau] : Adélaïde : Ecole des mines, Centre d'informatique géologique ; CSIRO, Division of soils, 1994. http://catalogue.bnf.fr/ark:/12148/cb357014896.

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Noutary, Carole. "Photostabilisation des pâtes à papier à haut rendement blanchies et étude photochimique d'un modèle phénolique de lignine à structure stilbénique." Bordeaux 1, 1994. http://www.theses.fr/1994BOR10510.

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Les mecanismes fondamentaux de photocoloration des pates a haut rendement ont ete abordes, d'une part par l'etude de l'emission de fluorescence en phase solide de lignine extraite de pin maritime, d'autre part par l'etude photophysique et photochimique d'une phenylcoumarone, molecule phenolique a structure stilbenique, modele de lignine. Une amelioration notable de la photostabilisation des papiers a ete obtenue, soit par etherification ou esterification des phenols de la lignine en presence d'agents de transfert de phase, soit par l'addition d'absorbeurs uv phenoliques, en presence d'antioxydants incorporant des fonctions thiols

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Dollie, Lucas. "Concepts et développements pour la production de cellulose blanchie, pure ou oxydée à partir de matière lignocellulosique à recycler." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI031.

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Les papiers et cartons récupérés sont aujourd’hui recyclés en nouveaux matériaux similaires, en particulier les vieux cartons sont transformés en nouveaux cartons. Riches en matière lignocellulosique, les cartons récupérés pourraient remplacer le bois dans la production de produits de plus haute valeur ajoutée. Ainsi la thèse a exploré le potentiel de procédés existants de délignification, blanchiment et purification, appliqués sur des mélanges fibreux simulant la composition de différents cartons, pour la production de pâte papetière blanchie et de pâte à dissoudre.Le traitement appliqué est composé d’une cuisson Kraft, suivie d’une séquence de blanchiment classique D0-Ep-D1 puis, dans le cas de la production de pâte à dissoudre, d’une purification de type CCE. Les cartons à traiter ayant des compositions fibreuses variables, toute l’étude a été conduite sur des mélanges fibreux modèles, composés de fibres de pâte Kraft écrue et de pâte mécanique. Dans tous les cas, des pâtes blanchies ont été produites, même si leur degré de polymérisation est parfois en deçà des standards. En revanche, les pâtes sont difficiles à purifier. Par ailleurs, il a été montré que la qualité du produit final, les performances des procédés et leur impact environnemental, dépendent de la composition fibreuse du mélange. Enfin le traitement d’un carton industriel a révélé que les charges minérales contenues dans le matériau limitent sa revalorisation.La faible qualité des pâtes blanchies obtenues a conduit à tester une autre voie de valorisation, la production de cellulose oxydée pour MFC. Un nouveau procédé de pré-oxydation pour les pâtes Kraft écrue a été développé : il combine blanchiment et oxydation du substrat dans un stade unique en utilisant le catalyseur TEMPO avec du dioxyde de chlore et de l’hypochlorite de sodium. Des MFC de qualité équivalente à celles produites à partir de pâte blanchie préoxydée par le système TEMPO/NaClO/NaBr ont été obtenues
Today recovered papers and boards are recycled into similar products; in particular old corrugated boards are transformed into new corrugated boxes. Rich in lignocellulosic material, recovered carton boards might replace wood for the production of hgiher added-value products. The thesis investigated the potential of existing delignification, bleaching and purification processes, applied on fibre mixes simulating the composition of various carton boards, for the production of bleached paper pulp and dissolving pulp grades.The treatment was composed of a Kraft cook, followed by a conventional D0-Ep-D1 bleaching sequence, and in the case of dissolving pulp production, a CCE stage for cellulose purification. Because carton boards exhibit various fiber compositions, all the study has been conducted on model mixes, made of fibres from unbleached Kraft pulp and mechanical pulp. In all cases, bleached pulps have been successfully obtained, although pulp viscosity was sometimes below the standards. However the bleached pulps were found difficult to purify. Moreover, it has been shown that the quality of the final product, the performances of the processes and their environmental impact, depended on the fiber composition of the mix. Finally, the treatment of an industrial carton board revealed that mineral fillers contained in the material limit its upcycling.Because of the low quality of the bleached pulp produced, another valorization way was tested: the production of oxidized cellulose for MFC. A new pre-oxidation process for unbleached Kraft pulp has been developed, combining bleaching and oxidation of the substrate in a single stage combining stage combining the use of TEMPO as a catalyst, chlorine dioxide and sodium hypochlorite. MFC of same quality as those produced from bleached Kraft pulp pre-oxidized by the classical TEMPO/NaClO/NaBr system have been obtained

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Quashie, Hélène. "Ethnicités en miroir. Constructions sociales croisées de la blanchité et de l'africanité au prisme des mobilités touristiques et migratoires vers le Sénégal." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEH089.

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A partir de six terrains d’étude menés dans plusieurs régions du Sénégal (Petite Côte, Saloum, Saint-Louis, Sénégal oriental et Dakar), cette thèse explore l’articulation différenciée des enjeux de classe et de race dans des contextes de mobilités et de migrations issues d’Europe et d’Amérique du Nord. Les trajectoires, pratiques et modes relationnels enquêtés sont liés au tourisme balnéaire et culturel, à l’entrepreneuriat individuel en situation post-touristique, à des mobilités pour étude, et aux parcours professionnels du volontariat et de l’expatriation. Ces configurations sociales mondialisées, souvent inscrites dans des champs de recherche dissociés, favorisent l’analyse croisée de la construction de deux ethnicités, la blanchité et l’africanité, conçues comme notions emic et etic. Leurs productions socio-identitaires se déploient, se croisent et se répondent, selon des mécanismes récurrents de hiérarchisation de classes et de confrontation raciale à l’échelle des interactions individuelles et des dynamiques collectives. Elles font aussi écho à des logiques de stratification et de sélection sociale, intrinsèques à la société sénégalaise, qui vont au-delà du marqueur chromatique et se combinent à des représentations culturalistes et ethniques. Les échelles socio-historiques, les asymétries de classe transnationales, les identifications religieuses, phénotypiques et genrées, présents dans les contextes de mobilités et migrations étudiés, soulignent la valeur heuristique des catégorisations identitaires de la blanchité dans les processus de classification sociale, racialisée et ethnicisée, au regard des définitions plurielles de l’africanité. Analyser ces mécanismes d’assignation et de distinction dans une société africaine telle que le Sénégal permet également de penser la question postcoloniale au cœur des ambivalences du champ social et invite à interroger la positionnalité des chercheur.e.s dans la pratique ethnographique et la production des savoirs sur l’Afrique
Based on six fieldworks conducted in several regions of Senegal (Petite Côte, Saloum, Saint-Louis, Oriental Senegal and Dakar), this thesis explores the social mechanisms which articulate class and race issues in different contexts of mobility and migration from Europe and North America. The trajectories, practices and ways of socializing investigated are related to seaside and cultural tourism, individual entrepreneurship in post-tourist contexts, study abroad programs and professional flows of voluntary service and expatriation. These social and globalized settings, often addressed in distinct fields of research, underlie a cross analysis of the constructions of two ethnicity – whiteness and africaness – considered as emic and etic notions. The social identities they produce respond to one another and reveal recurring patterns in social hierarchy and racial confrontation throughout individual interactions and collective dynamics. They also echo logics of social stratification and selection within the Senegalese society, which are combined with culturalist and ethnic representations, beyond color markers. The contexts of mobility and migration investigated are embedded into specific socio-historical backgrounds, transnational asymmetry of class and process of identification based on religion, phenotype and gender. They all reflect the heuristic value of whiteness and its production of identity in social, racialized and ethnicized categorization, regarding multiple meanings of africaness. Analyzing these mechanisms of social distinction in an African society such as Senegal leads to face postcolonial thinking with the ambiguities of social spheres. It also questions the positionality of researchers through ethnography and in the production of knowledge about Africa

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Arseneault, Éric. "Étude de l'impact de l'azote sur la cinétique de la biodégradation dans une lagune aérée d'une usine de pâte kraft blanchie." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0004/MQ43282.pdf.

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Arseneault, Éric. "Étude de l'impact de l'azote sur la cinétique de la biodégradation dans une lagune aérée d'une usine de pâte kraft blanchie /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1999. http://theses.uqac.ca.

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Villeronce, Johan. "Approches chimique, écologique et règlementaire de la production de pâte à papier blanchie : application aux cas du sorgho sucrier et de l'eucaplyptus." Toulouse, INPT, 1998. http://www.theses.fr/1998INPT007C.

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Ce travail traite, dans son ensemble (chimique, ecologique, legislatif), de la transformation de la matiere vegetale en pate a papier blanchie. Il ressort de cette etude que la fabrication de pate genere necessairement des effluents polluants. Si le traitement des effluents de l'etape de cuisson est globalement maitrise, celui des effluents de l'etape de blanchiment est en revanche plus problematique. Notre travail a consiste a elaborer un procede global de production de pate a papier qui limite ces risques de pollution. Dans ce but, nous avons examine le blanchiment par l'ozone de deux types de pates : une pate de plante annuelle traitee par un procede soude / anthraquinone et une pate de bois a croissance rapide obtenue par un procede kraft industriel. Les resultats obtenus ont montre la bonne aptitude papetiere de ces matieres premieres. L'analyse des effluents issus de l'etape de blanchiment nous a conduit a proposer une methode de traitement par echangeurs d'ions. Un tel dispositif d'epuration permet d'une part le recyclage de l'acide acetique utilise en pretraitement de la pate ecrue et, d'autre part, une disparition quasi-totale de la charge organique des effluents d'ozonisation. La regeneration des resines est effectuee grace aux composes obtenus apres transformation chimique des composes issus de cette meme regeneration. Ce procede permet ainsi d'eviter la formation d'un nouvel effluent polluant lors de la regeneration des resines. Le procede mis au point conduit a l'obtention d'une pate blanchie de bonne qualite avec des effluents non charges en produits chimiques. Ceux-ci peuvent donc etre rejetes, sans aucun risque de pollution, dans les eaux receptrices des rivieres.

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ABBAS, JAWAD. "Chlorophylles de haricots verts (phaseolus vulgaris l. ) congeles non blanchis : cinetiques de degradations et mecanisme de leur co-oxydation sous l'action des lipoxygenases." Paris 6, 1988. http://www.theses.fr/1988PA066691.

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Etude comparee des cinetiques de decoloration et de pheophytinisation des chlorophylles dans les haricots blanchis ou non, en fonction de la duree et de la temperature d'entreposage. Mecanisme de decoloration enzymatique des chlorophylles, isolement des isoenzymes de la lipoxygenase dans le pericarde des haricots. Les resultats sont en faveur d'un couplage de la reaction de decoloration avec les produits d'oxydation de l'acide linoleique (radical)

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Da, Silva Perez Denilson. "Préparations de pates chimiques blanchies à partir du bois d'Eucalyptus grandis et de la bagasse de canne à sucre par cuisson douce organosolv et blanchiment photochimique." Bordeaux 1, 1999. http://www.theses.fr/1999BOR10552.

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Une methode de preparation originale de pates a papier blanchies issues du bois d'eucalyptus grandis et de la bagasse de la canne a sucre qui met en jeu des conditions douces de cuisson organosolv et un blanchiment photochimique est presentee. Les pates sont obtenues par cuisson avec un melange de l'acide formique et du peroxyde d'hydrogene. Les elements constitutifs des lignines extraites et residuelles ont ete caracterises par des methodes chimiques et spectroscopiques. Le blanchiment photochimique mis au point, est base sur l'action de la lumiere uv et visible en presence de photocatalyseurs et de photosensibilisateurs. Les mecanismes du blanchiment photochimique ont ete apprehendes a l'aide de composes modeles et de lignines extraites. L'ensemble du travail constitue une avancee importante vers la production de pate blanchie utilisant la lumiere solaire, abondante dans les pays tropicaux et equatoriaux.

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Dissertations / Theses on the topic 'Blanching on'

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