Made available in DSpace on 2015-03-26T13:51:43Z (GMT). No. of bitstreams: 1 01 - capa_abstract.pdf: 74835 bytes, checksum: 716f5bf894e92efbf5c4b42ff95351ad (MD5) Previous issue date: 2008-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The increase in world population demands ever more food and consumer goods, with a consequent increase in the production of agroindustrial residues natives from logging, alcohol fuel plants and industries for beneficiary eligibility of agricultural products. Several studies have demonstrated the potential of white rot fungi to decompose of lignocellulosic substrates, but the use of such residues in ruminant diets has not been properly examined. The objective of this study was to determine the chemical composition and in vitro digestibility of agroindustrial residues (eucalyptus bark, sawdust, sugarcane bagasse, corn kernels, coffee bark, coconut fiber and lump of cotton) inoculated with white rot fungi (Pleurotus ostreatus and Lentinula edodes), and determine the activity of cellulase, xylanase and laccase in ruminal fluid incubated in vitro with corn kernels or sugarcane bagasse ground at different particle sizes. When the residues were treated with L. edodes the content of CP in eucalyptus bark increased 91 % and 78 % in the treatments added with rice bran or urea, respectively. The content of ADL decreased 70% in fructified sawdust added with rice bran compared to the controls. The NDF of sugarcane bagasse decreased 5 % when added with rice bran and 21 % when added with urea. When the residues were treated with P. ostreatus the levels of CEL and ADL of eucalyptus bark decreased 22 % and 137 %, respectively. With sawdust, the concentrations of NDF and ADF decreased 19 % and 27 %, respectively, after fruit body formation. The EE increased 402 % in sugarcane bagasse treated with P. ostreatus. With corn kernels, the content of ash increased 130 % compared to controls in the treatment showing fruit body formation. There was a reduction of 60 % in the LDA content of coffee barks after fructification. Fungus fructification in the coconut fiber reduced the levels of LDA and CEL in 25 % and 20 %, respectively. There were no significant differences between treatments for CP, ADF, CEL, HEM and ADL contents in the lump of cotton. However, there was significant difference in IVDMD between the enriched fructified substrates treated with L. edodes. An average increase 111 % and 98 % was observed for the fructified fungus added with rice bran or urea, respectively, compared to controls. The biggest increase in IVDMD after fructification in residues treated with P. ostreatus was obtained for the eucalyptus bark (200 %), followed by corn kernels (67 %) and sugar cane bagasse (13 %). The highest cellulase activity in corn kernels residues was obtained when using particles with a diameter of 0.6 mm. The xylanase activity was higher than the activity of cellulase for all treatments and sizes of particles tested. The particle size of 0.6 mm in the inoculated treatment yielded maximum xylanase activity after 48 hours of incubation (118.17 U/mL). The activity of cellulase in sugarcane bagasse was superior for all treatments and particle sizes when compared to corn kernels residues. The highest activity of xylanase (78.89 U/mL) in the fructified sugarcane bagasse was obtained after 48 hours of incubation and particles size of 0.6 mm. The changes in chemical composition and IVDMD showed that L. edodes (UFV 73) and P. ostreatus (PLO 06) could improve the nutritional quality of ruminant rations by increasing the content of CP and IVDMD and reducing the levels of NDF, ADF and ADL of agroindustrial residues, allowing its use in ruminant rations. / O aumento da população mundial demanda cada vez mais alimentos e bens de consumo, com conseqüente aumento na produção de resíduos agroindustriais oriundos de madeireiras, usinas de álcool combustível e indústrias de beneficiamento de produtos agrícolas. Diversos estudos têm demonstrado o potencial de fungos da podridão branca em decompor substratos ligninocelulósicos, mas a utilização desses resíduos na alimentação de ruminantes ainda tem sido pouco explorada. O objetivo deste trabalho foi determinar a composição bromatológica e a digestibilidade in vitro de resíduos agroindustriais (casca de eucalipto, serragem de eucalipto, bagaço de cana-de-açúcar, sabugo de milho, casca de café, fibra de coco e casca de caroço de algodão desengordurado) inoculados com fungos causadores da podridão branca (Pleurotus ostreatus e Lentinula edodes), assim como determinar a atividade enzimática de celulase, xilanase e lacase em três diferentes tamanhos de partículas dos resíduos sabugo de milho e bagaço de cana-de-açúcar incubados com líquido ruminal in vitro, visando avaliar o potencial hidrolítico das comunidades microbianas do rúmen. Quando os resíduos foram tratados com L. edodes o teor de PB do resíduo casca de eucalipto aumentou 91 % e 78 % no tratamento enriquecido com farelo de arroz e uréia, respectivamente. O teor de LDA diminuiu 70 % na serragem de eucalipto frutificada e enriquecida com farelo de arroz comparada ao controle. A FDN do resíduo bagaço de cana diminuiu 5 % quando enriquecido com farelo e 21 % quando enriquecido com uréia. Quando os resíduos foram tratados com P. ostreatus os teores de CEL e LDA da casca de eucalipto diminuíram 22 % e 137 %, respectivamente, após o tratamento. Na serragem de eucalipto as concentrações de FDN e FDA diminuíram 19 % e 27 % no tratamento frutificado, respectivamente. O EE aumentou 402 % no tratamento frutificado no bagaço. No sabugo o conteúdo de cinzas aumentou 130 % no tratamento frutificado em relação ao controle. Houve redução de 60 % no teor de LDA da casca de café após a frutificação. A frutificação fúngica reduziu os teores de LDA e CEL em 25 % e 20 %, respectivamente na fibra de coco. Não houve diferenças significativas entre os tratamentos para os teores de PB, FDA, CEL, HEM e LDA no resíduo casca de caroço de algodão desengordurado. Houve diferença significativa na DIVMS entre os enriquecimentos dos resíduos tratados com L. edodes, tendo sido observado aumento médio de 111 % e 98 % quando frutificado e adicionado de farelo de arroz e uréia, respectivamente, em relação ao controle O maior incremento de DIVMS no tratamento frutificado nos resíduos tratados com P. ostreatus foi obtido para a casca de eucalipto (200 %), sabugo de milho (67 %) e bagaço de cana-de-açúcar (13 %). As maiores atividades de celulase no resíduo sabugo de milho foram obtidas quando se utilizou partículas com 0,6 mm de diâmetro. A atividade de xilanase foi maior quando comparada à atividade de celulase em todos os tratamentos e tamanhos de partículas testados. O tamanho de partícula 0,6 mm no tratamento inoculado foi o que apresentou atividade máxima de xilanase após 48 horas de incubação (118,17 U/mL). A atividade de celulase no resíduo bagaço de cana-de-açúcar foi superior em todos os tratamentos e tamanhos de partículas quando comparado ao resíduo sabugo de milho. O tamanho de partícula 0,6 mm apresentou as maiores concentrações de xilanase no bagaço de cana-de-açúcar, tendo sido observado valor máximo após 48 horas de incubação de 78,89 U/mL no tratamento frutificado. As mudanças na composição química e na DIVMS indicam que L. edodes (UFV 73) e P. ostreatus (PLO 06) melhoram o valor nutricional dos resíduos tratados, aumentando o teor de PB e DIVMS e reduzindo os teores de FDN, FDA e LDA dos resíduos agroindustriais, com possibilidade de utilização na alimentação de ruminantes.

Au cours des procédés d’appertisation, qui impliquent des traitements thermiques généralement pratiqués à hautes températures, la qualité nutritionnelle des produits alimentaires est souvent altérée. En effet, certaines vitamines, telles que la vitamine C, sont très thermolabiles.L’objectif du projet PREDINUT était de proposer un outil d’aide à la décision afin de prévoir la quantité de vitamine C (marqueur de qualité nutritionnelle) détruite dans des conditions données de durée/température, afin de pouvoir optimiser les procédés.Un thermorésistomètre Mastia®, a été utilisé pour établir des conditions de température et pression représentatives des procédés d‘appertisation. L’impact de la variation de paramètres physico-chimiques tels que le pH, la concentration initiale en acide ascorbique ou encore la pression partielle en oxygène dans l’espace de tête, sur la dégradation de l’acide ascorbique a été étudié en solution modèle. Des études ont également été menées dans des produits alimentaires (purée de pomme, purée de carotte et jus de carotte) afin d’établir un profil de destruction de la vitamine C dans des aliments concrets. Dans ce projet, la plage de température étudiée est de 95 à 125 °C, le pH fixé en solution modèle est de 2,5 à 5,5 en conditions d’anaérobiose stricte, et de 3,5 en conditions d’aérobiose (3,5 étant la valeur de pH de la majorité des fruits), les concentrations initiales en acide ascorbique varient de 15 à 90 mg/100mL, et la pression partielle en oxygène de 30000 à 100000 Pa. Dans les produits alimentaires, les expériences ont été réalisées par enrichissement en acide ascorbique à hauteur de 450 mg/L, la valeur du pH ne subissant pas d’ajustement.Des modèles ont été établis pour décrire le profil cinétique de la dégradation de la vitamine C en aérobiose et en anaérobiose. En l’absence d’oxygène la dégradation de la vitamine C suit une cinétique d’ordre 1 (sauf à pH = 4,5). En présence d’oxygène (conditions aérobies) la vitesse de dégradation croit avec la pression partielle d’oxygène, mais très peu avec la température. Des ordres apparents variant de 0,5 à 0,75 en fonction de la pression partielle en oxygène dans l’espace de tête, s’avèrent mieux ajuster les données que l’ordre 1.Dans les aliments, le mécanisme de dégradation de la vitamine C apparaît beaucoup plus complexe, et la vitesse de réaction n’évolue pas de façon continue avec le temps, avec des phases de plateau suivies de réaccélérations. Une connaissance fine des mécanismes et des espèces chimiques impliquées sera nécessaire pour comprendre cette évolution. / Canning involves thermal treatments performed at high temperatures, which may alter nutrional quality of food products. Indeed, some vitamins, like vitamin C, are very heat sensitive.The aim of the project PREDINUT was to propose a decision support tool that predicts vitamin C (as indicator of nutritional quality) degradation in given conditions of time/temperature, in order to optimise processes.A thermoresistometer Mastia® was used to reach the temperature and pressure conditions encountered during canning. The impact of the variation pH, initial concentration of ascorbic acid or again partial pressure of oxygen in headspace, on ascorbic acid degradation was studied in model solution. Studies were also performed in apple puree, carrot puree and carrot juice in order to obtain a destruction profile of vitamin C in real foods. . The temperature range studied was from 95 to 125 °C, the fixed pH in model solution was from 2.5 to 5.5 in strict anaerobic conditions, and 3.5 in aerobic conditions (3.5 being the pH value of common fruits), initial concentrations of ascorbic acid varied from 150 to 900 mg/100mL, and the partial pressure of oxygen from 30000 to 100000 Pa. Foods were enriched in ascorbic acid (up to 450 mg/mL), and the pH value was not adjusted.Models were established to describe the kinetics of vitamin C degradation in aerobiosis and anaerobiosis. En absence of oxygen ascorbic acid degradation was well described by a first order kinetics (except at pH = 4.5). In presence of oxygen the degradation speed increased with head-space oxygen’s partial pressure but very little with temperature. Apparent reaction orders varying from 0.5 to 0.75, depending on the partial pressure of oxygen in the headspace, fitted the data better than first-order.In foods, degradation kinetics of vitamin C appeared more complex, with eventual presence of plateaus followed by acceleration of the reaction. Definitely more knowledge on mechanisms is needed to predict ascorbic acid degradation in real foods.

Thesis (M.Sc. Agriculture (Animal Production)) -- University of Limpopo, 2022 / Refer to document / National Research Foundation (NRF)

Fort McMurray has experienced significant environmental disruptions, raising concerns about chemical releases that affect the environment, particularly berries. This thesis explores the relationship between environmental factors and the nutritional quality of pin cherry (Prunus pensylvanica L.F.) and common blueberry (Vaccinium myrtilloides Michx) fruits and soil in Fort McMurray (reclaimed and natural lands). Samples were collected in August 2022 and analyzed for chemicals and quality variables. The results revealed concentration variations among samples, with hydrocarbons higher in reclaimed areas and blueberries than others and soil surpassing those in fruits. Copper and iron in fruits exceeded regulatory limits. A strong association between soil chemicals and alkylated hydrocarbons in fruits explained most differences. Soil trace elements and properties were primary environmental drivers, while hydrocarbons were secondary influencers, evident mainly in reclaimed berry environments. Antioxidant-focused nutritional quality in reclaimed berries was predominantly influenced by these key drivers in soil, requiring consistent monitoring.

Prescribed fire is commonly used to manage white-tailed deer habitat. However, nutrition is still limited during the summer for deer in the Southeast and prescribed fire is commonly restricted to the dormant season. Knowledge of fire phenology effects on summer nutrient availability is relatively unknown. Stump sprouts may also affect available nutrition, which could be important when managing for summer nutrition. To address this summer nutritional stress period, I examined impacts prescribed fire phenology and mechanical stump sprouting had on summer nutritional carrying capacity for deer. Results indicated implementing prescribed fire in both dormant and growing-seasons led to increased summer nutrient availability on the landscape level by increasing forage quality and quantity. Mechanically creating stump sprouts from woody plants led to increased available nutrition on a localized level. Combining these management actions to target summer nutritional stress periods can better help deer meet nutritional demands and reach their full potential.

Tesis por compendio / [ES] La erosión genética provocada en los cultivos al primar producción sobre calidad ha derivado en pérdida de biodiversidad, lo que compromete la seguridad alimentaria mundial. Los agricultores, a través de un proceso histórico de selección, han ido diferenciando variedades tradicionales de cultivo que sonfuente de biodiversidad agrícola que además favorece el desarrollo de la economía local. Por este motivo, su recuperación, clasificación y cultivo son clave para la economía y futuro alimentario. La conservación de las variedades tradicionales requiere un conocimiento de las mismas a través de la descripción detallada de las características fenotípicas, agronómicas, y de calidad nutricional como valor añadido. La Comunitat Valenciana, cuenta con un extenso patrimonio hortícola constituido por una gran diversidad de variedades tradicionales de hortalizas. Estas son fruto de la adaptación a variadas condiciones agroclimáticas de la geografía valenciana, por un lado, y de la selección aplicada por los agricultores en cada localidad por otro. En este sentido, estas variedades tienen un gran valor como patrimonio etnobotánico y como tal deberían ser conservadas. Asimismo, en la actualidad, el cultivo y el consumo de las variedades tradicionales están creciendo, ya que son especialmente atractivas para los consumidores por su diversidad y su alta calidad nutracéutica. En este contexto, esta tesis doctoral se basa en la caracterización fenotípica y nutricional para valorizar las variedades tradicionales de la comunidad, correspondientes a los cultivos de pimiento, berenjena y lechuga, con la finalidad de promover su conservación y cultivo en las zonas de origen, e impulsando la diversidad. La caracterización morfológica de las variedades autóctonas ha sido objeto de numerosos estudios, necesarios porque proporcionan información sobre los caracteres fenotípicos diferenciadores, y contribuyen a optimizar los programas de mejora vegetal. En este sentido, la caracterización de las variedades hortícolas valencianas seleccionadas se realizó siguiendo las directrices del IBPGR. Además, en esta tesis doctoral se han realizado estudios sobre el valor nutracéutico de las tres variedades seleccionadas por ser uno de los principales intereses del consumidor. Por ello, el contenido de algunos compuestos bioactivos y antioxidantes (fenoles, flavonoides, antocianinas, ácido ascórbico, licopeno, carotenoides, clorofilas y la actividad antioxidante), azucares y minerales fueron monitoreados para establecer parámetros de calidad en las especies mencionadas. También se determinó los parámetros indicativos de estrés oxidativo, para establecer la capacidad de conservación de atributos físico-químicos de la lechuga en el ensayo de post-cosecha. / [CA] L'erosió genètica provocada en els cultius com a conseqüència de posar per davant producció sobre qualitat ha derivat en pèrdua de biodiversitat, fet que compromet la seguretat alimentària mundial. Els agricultors, a través d'un procés històric de selecció, han generat la diferenciació varietats tradicionals de cultiu que hui són font de biodiversitat agrícola. A més, s'afavoreix el desenvolupament de l'economia local. Per aquest motiu, la seva recuperació, classificació i cultiu són clau per a l'economia i el futur alimentari. La conservació de les varietats tradicionals requereix un coneixement de les mateixes mitjançant la descripció detallada de les seues característiques fenotípiques, agronòmiques, i de qualitat nutricional com a valor afegit. La Comunitat Valenciana compta amb un extens patrimoni hortícola constituït per una gran diversitat de varietats tradicionals d'hortalisses. Aquestes són fruit de l'adaptació a diverses condicions agroclimàtiques de la geografia valenciana, d'una banda, i de la selecció aplicada pels agricultors a cada localitat de l'altra. En aquest sentit, aquestes varietats tenen un gran valor com a patrimoni etnobotànic i com a tal haurien de ser conservades. Així mateix, actualment, el cultiu i el consum de les varietats tradicionals estan creixent, ja que són especialment atractives per als consumidors per la seua diversitat i la seua alta qualitat nutracèutica. En aquest context, aquesta tesi doctoral es basa en la caracterització fenotípica i nutricional per valoritzar les varietats tradicionals de la Ccomunitat, corresponents als cultius de pebre, albergínia i encisam, amb la finalitat de promoure'n la conservació i el cultiu a les zones d'origen, i impulsant la diversitat. La caracterització morfològica de les varietats autòctones ha estat objecte de nombrosos estudis, necessaris perquè proporcionen informació sobre els caràcters fenotípics diferenciadors, i contribueixen a optimitzar els programes de millora vegetal. En aquesta línia, la caracterització de les varietats hortícoles valencianes seleccionades es va fer seguint les directrius de l'IBPGR. A més, en aquesta tesi doctoral s'han fet estudis sobre el valor nutracèutic de les tres espècies seleccionades per ser un dels principals interessos del consumidor. Per això, el contingut d'alguns compostos bioactius i antioxidants (fenols, flavonoides, antocianinas, àcid ascòrbic, licopè, carotenoides, clorofil·les i l'activitat antioxidant), sucres i minerals van ser monitoritzats per establir paràmetres de qualitat a les espècies esmentades. També es van determinar els paràmetres indicatius d'estrès oxidatiu, per establir la capacitat de conservació d'atributs fisicoquímics de l'encisam a l'assaig de postcollita. / [EN] Genetic erosion in crops, gained from prioritising production over quality, has led to biodiversity loss, which compromises global food security. By a historic selection process, farmers have been differentiating traditional crop varieties, which are a source of agricultural biodiversity that also favours the development of local economy, which makes their recovery, classification and cultivation key for food economy and the future. The conservation of traditional varieties requires knowledge of them, obtained from a detailed description of their phenotypical, agronomic and nutritional quality characteristics as added value. The Valencian Community (east Spain) has extensive horticultural heritage that is made up of a high diversity of traditional vegetable varieties. These are the result of adapting to the varied agroclimate conditions of the Valencian geography: on the one hand, the selection applied by farmers to each locality; on the other hand, these varieties are very valuable as ethnobotanical heritage and should be preserved. Moreover, the cultivation and consumption of traditional varieties are currently growing because they are particularly appealing to consumers for their diversity and high nutraceutical quality. In this context, the present doctoral thesis is based on a phenotypical and nutritional characterisation to evaluate traditional varieties in the Valencian Community, which correspond to pepper, eggplant and lettuce crops, to promote their conservation and cultivation in areas of origin, and to boost diversity. The morphological characterisation of landraces has been the subject of many studies, which are necessary because they provide information about differentiating phenotypical characteristics and help to optimise plant-breeding programmes. The characterisation of the selected Valencian vegetable varieties was carried out following IBPGR guidelines. Furthermore, studies were conducted in this doctoral thesis into the nutraceutical value of the three selected crops because this value is one of the main consumer interests. The content of some bioactive compounds and antioxidants (phenols, flavonoids, anthocyanins, ascorbic acid, lycopene, carotenoids, chlorophylls, antioxidant activity), sugars and minerals were monitored to establish quality parameters in the aforementioned species. Parameters indicative of oxidative stress were also determined to establish the conservation capacity of the physico-chemical attributes of lettuce in the post-harvest test. / Martínez Ispizua, E. (2022). Rediscovering pepper, eggplant and lettuce landraces of the Valencian Community; an ancient resource with vast potential for the future [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/191053 / Compendio

Trotz der Schlüsselstellung heterotropher Protisten als Bindeglied zwischen dem mikrobiellen und dem klassischen Nahrungsnetz ist noch wenig über ihre biochemische Zusammensetzung und ihren Nährwert bekannt. In der vorliegenden Doktorarbeit wurde untersucht ob die biochemische Zusammensetzung von Protisten (1) von deren Nahrungsgrundlage (Alge oder Bakterien) und Ernährungsweise (Autotrophie, Mixotrophie oder Heterotrophie) abhängt und (2) ihre Nahrungsqualität für räuberisches Rotatorien (Keratella quadrata) bedingt. Die Fettsäure-, Sterol- und Aminosäurezusammensetzung vier heterotropher Protisten spiegelte generell die ihrer Nahrung wider. Es trat jedoch eine Akkumulation dieser biochemischen Substanzen in den Protisten auf. Auch die Ernährungsweise eines Flagellaten (Ochromonas sp.) beeinflusste stark dessen biochemische Zusammensetzung, insbesondere die Konzentrationen an mehrfach ungesättigten Fettsäuren (PUFAs). Bei der Untersuchung des Nährwertes vier heterotropher Protisten für K. quadrata wurden signifikante Korrelationen zwischen verschiedenen PUFAs, drei Sterolen und einer Aminosäure (Leucin) der Protisten und der Eiproduktion der Rotatorien festgestellt. Auch die experimentelle Supplementierung eines Flagellaten mit einer PUFA (Docosahexaensäure, DHA) erhöhte seinen Nährwert für die Rotatorien signifikant. Die Ergebnisse verdeutlichen die Fähigkeit heterotropher Protisten, die biochemische Zusammensetzung organischer Materie schon auf einer unteren Ebene des aquatischen Nahrungsnetzes zu verändern, nämlich beim Übergang zwischen Algen/Bakterien und dem Mesozooplankton. Hier können biochemische Änderungen weitreichende Folgen für den Stoff- und Energiefluß des gesamten Nahrungsnetzes nach sich ziehen. / Heterotrophic protists are an important link between the microbial and the classical food web. However, little is known about their biochemical composition and nutritional quality as prey. In this thesis, I analysed (1) whether the biochemical composition of the protists depends on their dietary resources (bacterial or algal food) or trophic mode (autotrophy, mixotrophy or heterotrophy), and (2) whether the biochemical composition of protists determines their nutritional quality as prey for a rotifer species (Keratella quadrata). The fatty acid, sterol, and amino acid composition of four heterotrophic protists generally resembled the dietary composition, but the protists accumulated these compounds. Moreover, the trophic mode strongly affected the composition of a flagellate (Ochromonas sp.), especially that of polyunsaturated fatty acids (PUFAs). When investigating the nutritional quality of four protist species for K. quadrata, several PUFAs, three sterols (desmosterol, ergosterol, stigmastanol), and one amino acid (leucine) of the protists were significantly correlated with the rotifer’s egg production. Moreover, the nutritional quality of a heterotrophic flagellate for the rotifer was significantly enhanced by artificially supplementing the flagellate with a PUFA (docosahexaenoic acid, DHA). The thesis highlights the ability of heterotrophic protists to modify the biochemical composition of organic matter at an early stage in aquatic food webs, i.e. at the interface between algae/bacteria and mesozooplankton. Biochemical modifications at this stage may profoundly affect matter and energy transfer through the entire food web.

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Plusieurs fabricants de biscuits et gâteaux français se sont engagés à mettre sur le marché des produits de meilleure qualité nutritionnelle. Ce travail de thèse a eu pour objectif de déterminer si cette amélioration de la qualité nutritionnelle était compatible avec le maintien de la qualité sensorielle. La première étude portait sur l’impact des réductions en lipides et/ou en sucres sur l’appréciation et la perception sensorielle de neuf catégories de biscuits et gâteaux. Les résultats montrent que les enfants perçoivent peu de différences et apprécient généralement autant les variantes réduites que les variantes standards. Pour les produits réduits sans ajout de polyols, les adultes déprécient principalement les variantes qui sont perçues moins sucrées et parfois également moins grasses et/ou différentes d’un point de vue textural. De plus, les réductions en sucres sont plus perceptibles que les réductions en lipides et à taux de réduction proches, les produits réduits en lipides sont moins dépréciés que ceux réduits en sucres. Les produits réduits avec ajout de polyols ne sont pas dépréciés et ne sont pas tous perçus moins sucrés.La deuxième étude s’est intéressée à deux leviers pour faire mieux accepter les produits réduits en lipides ou sucres. En exposant quasi-quotidiennement des consommateurs à des biscuits réduits d’environ 30 % en lipides ou en sucres, l’appréciation de ces produits augmente après un mois, mais davantage pour les lipides. En revanche, une exposition progressive ne montre pas d’effet sur un mois. Par ailleurs, une allégation nutritionnelle indiquant une réduction ne semble pas être un levier pour l’appréciation de biscuits et gâteaux réduits en lipides ou sucres / French biscuit producers are willing to improve the nutritional composition of their products. The objective of this work was to determine whether it was possible while maintaining the sensory quality of the reduced product.The first study dealt with the impact of fat and sugar reduction on liking and sensory perception of 9 types of biscuits and cakes. Results show that children perceived almost no difference and liked equally the standard and the fat- and/or sugar-reduced variants for most types of biscuits. For products reduced without adding polyols, adults less liked fat- or sugar-reduced variants than standard ones mainly when they were perceived as less sweet, and to a lesser extent as less fatty and/or as different in terms of textural aspects. Furthermore, a reduction in fat content was more difficult to perceive than a reduction in sugar content. With similar levels of reduction, fat-reduced products were less disliked than sugar-reduced ones. Sugar-reduced biscuits with an addition of polyols were not disliked and some of them were not perceived as less sweet than standard biscuits.The second study was about two strategies to promote consumer acceptance for fat- or sugar-reduced products. On the one hand, some consumers were exposed almost daily to -30 % fat- or sugar-reduced biscuits. After a month of exposure, reduced variants were more appreciated than before exposure, but it was more significant for fat reduction. On the other hand, no difference of liking was observed after a month of stepwise exposure. Besides, a nutritional claim indicating the fat or sugar reduction does not seem to be efficient to increase liking for fat- or sugar-reduced biscuits and cakes

Dans le cadre de la présente thèse, a été étudié l’impact de la texturation par traitement thermo-mécanique DIC (Détente Instantanée Contrôlée) sur le séchage de divers produits alimentaires. Ce prétraitement a induit une amélioration de la cinétique de l’opération de séchage quand elle est limitée par le transfert interne de la matière couplé au rétrécissement du produit. Ainsi, la diminution du temps de séchage a atteint 67% dans le cas de l’oignon et 77% dans le cas du cassis. Quant à la diffusivité effective Deff, elle a augmenté par rapport à la matière première jusqu’à 246% pour les pépins et 795% pour les déchets de canneberge, 336% pour l’oignon et 1223% pour le cassis. Dans le cas des produits étudiés, la pression de vapeur de traitement DIC a généralement un effet significatif positif sur la cinétique de séchage et d’extraction des différentes molécules. Concernant les caractérisatiques des produits, nous constatons l’impact positif du traitement par DIC quant aux principales caractéristiques de la matière. Ainsi, les composés phénoliques apparaissent plus disponibles à la suite du traitement adéquat par DIC. Le contenu en composés phénoliques et la capacité antioxydante étant supérieurs dans les produits traités par DIC, la qualité nutritionnelle s’est ainsi également trouvée améliorée. Avec une dégradation thermique négligeable, le traitement DIC implique un effet mécanique dû à la détente instantanée, ce qui permet la rupture de certaines structures cellulaires de la matière et l’augmentation de la quantité maximale extractible. Les caractéristiques physiques diverses (masse volumique apparente et taux relatif d’expansion), les caractéristiques microstructurelles (mesurées par microscopie électronique à balayage) et fonctionnelles d’interaction avec l’eau (réhydratation, teneur en eau, isotherme de sorption, microbiologie et contenu nutritionnel...) peuvent être optimisées en fonction des conditions opératoires DIC, selon les besoins du consommateur. / The present PhD work concerns the effect of thermo-mechanical texturing by DIC (Instantaneous Controlled Pressure-Drop) on fruit and vegetable drying. This pretreatment dramatically improves drying kinetics when the internal mass transfer coupled to the shrinkage of the product, is the limiting process. Indeed, the drying time decreased by 67% in the case of onion and 77% for blackcurrants, while the effective diffusivity Deff increased up to 246%, 795%, 336%, and 1223% for cranberry seed and waste, onion and blackcurrants, respectively. With these products, the saturated steam pressure generally has a significant positive effect on the drying kinetics.DIC treatment significantly improves the main nutritional and functional characteristics of the fruits and vegetables, with more available phenols and higher antioxidant activity. As thermal degradation is negligible, the DIC treatment involves micromechanical effect linked to the instant pressure drop, which allows cell to break and structure to be more porous such increasing the maximum extractable amount. Various physical, microstructural and functional characteristics of new textured material allow water interaction to be completely modified in terms of rehydration kinetics and capacity, sorption isotherm, microbiological and nutritional content... depending on operating DIC conditions, which can be optimized according to the consumer needs.