Les systèmes d’élevage allaitants peuvent être diversifiés par leurs pratiques d’élevage (type d’animaux, races, nature des rations, durées de pâturage, etc.) pour produire des carcasses et de la viande répondant à la demande des différents marchés et satisfaire les consommateurs. Les pratiques d’élevage sont définies comme étant la combinaison de plusieurs facteurs d’élevage ayant une variabilité propre. Cette diversité de pratiques d’élevage appliquées tout au long de la vie de l’animal est l’une des causes de la variabilité observée au niveau des caractéristiques de la carcasse et de la viande. L’objectif de ce travail a été d’étudier plus précisément l’influence des pratiques d’élevage sur les caractéristiques de la carcasse et de la viande, et d’envisager un pilotage conjoint de ces caractéristiques à partir des pratiques d’élevage. Pour réaliser cela, deux sources de données complémentaires ont été utilisées : les bases de données expérimentales et les enquêtes en élevage. Ce travail a montré qu’il était possible d’expliquer et de prédire les caractéristiques de la carcasse (poids, rendement, conformation et état d’engraissement) et les propriétés de la viande (descripteurs sensoriels et force de cisaillement) à partir de la combinaison de plusieurs facteurs d’élevage. Il a été également montré que différentes pratiques d’élevage permettaient d’atteindre des caractéristiques similaires de carcasse ou de viande mais que celles-ci devaient être adaptées selon le type de l’animal ou de la race. En effet, lors de la prédiction des caractéristiques de la carcasse ou de la viande, des facteurs d’élevage peuvent être spécifiques à un type de l’animal (jeunes bovins vs vaches de réforme) ou d’un type de race (viande vs rustique) et un même facteur d’élevage peut également avoir des effets différents selon le type de l’animal ou la race considéré. Les modèles établis à partir de la période de finition sont robustes mais ils sont plus précis pour prédire les paramètres individuels caractérisant la carcasse par rapport à ceux de la viande. La qualité de prédiction des propriétés de la viande a été améliorée en prédisant des classes de qualité. De plus, que ce soit pour les propriétés de la carcasse ou de la viande, la qualité de prédiction des classes de qualité a été améliorée en considérant la période de pré-sevrage en plus de la période de finition. En revanche, les facteurs d’élevage ne permettent pas une prédiction satisfaisante de l’abondance des biomarqueurs de la tendreté ou de l’adiposité. Enfin, l’ensemble des résultats de ce travail a montré que, bien que cela nécessite des compromis, il est possible de piloter conjointement les caractéristiques de la carcasse et de la viande. / The beef rearing system could be diversified by their rearing practices (animal categories, breeds, diet composition, grazing duration, etc.) to produce carcasses and beef meat reaching the different market expectations and to satisfy the consumers. The rearing practices were defined as the combinations of many rearing factors, each with its own variability. This diversity of applied rearing practices during the whole life of the animal was one of the causes of the carcass and beef variability observed. The aim of this work was to more precisely study the rearing practices impacts on the carcass and the beef characteristics, and to consider a joint management of these characteristics from the rearing practices. To achieve this, two complementary data sources were used: experimental data set and rearing surveys. This work displayed that it was possible to explain and to predict the carcass characteristics (weight, dressing, conformation and fat scores) and the meat properties (sensorial descriptors and shear force) from the combination of many rearing factors. It was also observed that different rearing practices allowed to reach similar carcass or meat characteristics but those must be adapted according to the animal category and the breed. Indeed, for the prediction of the carcass or meat characteristics, rearing factors can be specific to an animal category (young bulls vs cull cows) or a breed type (beef vs hardy), and a same rearing factor may also had different impacts according to the animal category or the breed considered. The established models from the fattening period were robust but prediction was more precise for individual parameters characterizing the carcass compared to those of the meat. The clustering of meat quality improved the prediction quality of the meat properties. Furthermore, for the carcass or the meat properties, by considering the pre-weaning period in addition to the fattening period the prediction quality of the quality clusters was improved. However, the rearing factors did not allowed a satisfactory prediction of the tenderness or adiposity biomarkers abundances. Finally, all results of this work displayed, although it requires trade-off, it was possible to jointly manage the carcass and meat characteristics.

<p>U okviru disertacije ispitani su i upoređeni pokazatelji kvaliteta integralnog p&scaron;eničnog i integralnog heljdinog bra&scaron;na dobijenog mlevenjem netretiranih (netretirano integralno heljdino bra&scaron;no) i autoklaviranih zrna heljde (autoklavirano integralno heljdino bra&scaron;no). Nakon ispitivanja nutritivnih i funkcionalnih svojstava pomenutih bra&scaron;na, kreirane su i proizvedene integralne taljatele sa različitim sadržajem integralnog heljdinog bra&scaron;na (10&ndash;30%).<br />Pokazatelji senzorskog, nutritivnog i funkcionalnog kvaliteta proizvedenih taljatela sa integralnim heljdinim bra&scaron;nima ispitani su u poređenju sa kontrolnim uzorkom taljatela od integralnog p&scaron;eničnog bra&scaron;na.<br />U ispitivanim uzorcima bra&scaron;na i taljatela određeni su osnovni hemijski sastav, sadržaj mineralnih materija, sadržaj ukupnih rastvorljivih polifenola, utvrđen je kvalitativni i kvantitativni sastav polifenolnih jedinjenja, ispitana je antiradikalska aktivnost na DPPH˙ i određen je sadržaj fitinske kiseline i 5-hidroksimetilfurfural.<br />Pored analize nutritivnih i funkcionalnih svojstava, na taljatelama su sprovedena ispitivanja fizičkih osobina (dimenzije) i svojstva taljatela pri kuvanju. Instrumentalno su izmereni boja i teksturna svojstva nekuvanih i kuvanih taljatela. Senzorska ocena taljatela sprovedena je uz primenu panela utreniranih ocenjivača, metodom bodovanja i panela potro&scaron;ača, testom dopadljivosti.<br />Dobijeni rezultati ukazuju da se supstitucijom dela integralnog p&scaron;eničnog bra&scaron;na integralnim heljdinim bra&scaron;nom (autoklaviranim ili netretiranim) postiže unapređenje nutritivnog i funkcionalnog profila uzoraka obogaćenih taljatela, uz manje ili vi&scaron;e izraženo naru&scaron;avanje senzorskog profila, u zavisnosti od stepena supstitucije i vrste integralnog heljdinog bra&scaron;na.</p> / <p>This study investigated quality parameters of wholegrain wheat flour and wholegrain buckwheat flour from non-treated buckwheat grains (non-treated wholegrain buckwheat flour) and autoclaved buckwheat grains (autoclaved wholegrain buckwheat flour). After investigation of nutritional and functional properties of aforementioned flours, new wholegrain tagliatelle formulations, with different wholegrain buckwheat flour content (10&ndash;30%) have been developed.<br />Sensory, nutritional and functional quality parameters of buckwheat containing tagliatelle samples were analysed and compared with control tagliatelle sample from wholegrain wheat flour.<br />Proximate composition, content of minerals, content of total polyphenols and quantitative and qualitative composition of polyphenols were investigated in both, flour samples and produced uncooked and cooked tagliatelle samples. Antiradical activity on DPPH radicals, and content of less favourable compounds, phytic acid and HMF, have been tested, as well.<br />Tagliatelle physical properties, dimensions, cooking properties, colour and textural properties were determined by instrumental and sensory methods. Tagliatelle acceptability was evaluated by the consumers. The obtained results indicate that wholegrain buckwheat flour (autoclaved or non-treated) incorporation into tagliatelle formulation led to an improvement of nutritional and functional profiles of tagliatelle samples, followed by greater or lesser deterioaration of sensory profile, depending on substitution level and type of wholegrain buckwheat flour.</p>

Tiger nuts (Cyperus esculentus L) are recognized as a high potential, alternative source of food nutrients. However, there is limited scientific literature on the technological possibilities for developing value-added foods, such as fermented products from tiger nut milk. Therefore, strategies for producing and improving the properties of fermented tiger nut milk were investigated for generating lactose-free, nutritious yogurt-like products with acceptable sensory properties and a prolonged shelf life quality. A wet-milling procedure was standardized for extracting tiger nut milk from tiger nuts, and the effects of the extraction process on nutrient distribution, colour properties and colloidal stability of the milk were analyzed. Next, tiger nut milk was enriched with proteins and/or hydrocolloids and the impact of the additives on the physical properties of the milk were determined. Enriched tiger nut milk was fermented by using classical yogurt cultures and the obtained products were analyzed for the microbiological, physico-chemical and sensory characteristics. Additionally, effects of enriching tiger nut milk with microbial transglutaminase cross-linked proteins on the microbiological and physico-chemical properties were evaluated. Higher wet-milling intensity improved the nutrient composition, colloidal stability and colour of the milk. Enrichment of tiger nut milk with milk proteins and xanthan gum enhanced the viscosity and stability, and after fermentation, led to homogenous gel-like products with superior microbiological, physico-chemical and different sensory properties compared to the fermented plain tiger nut milk. Microbial transglutaminase cross-linked proteins improved the physical characteristics of the fermented product, especially during storage. This product would be relevant in many developing countries with high prevalence of lactose intolerance, limited access to nutritious food but show a high distribution of tiger nut vegetation. / Erdmandeln (Cyperus esculentus L) haben ein hohes Potential als alternative Quelle Lebensmittelinhaltsstoffen. Allerdings gibt es nur in begrenztem Ausmaß Literatur über technologische Möglichkeiten zur Entwicklung von Mehrwert-Lebensmitteln wie fermentierter Erdmandelmilch. Daher wurden Strategien zur Herstellung und Verbesserung der Eigenschaften von fermentierter Erdmandelmilch zur Erzeugung laktosefreier joghurtähnlicher Produkte mit akzeptablen sensorischen Eigenschaften untersucht. Für die Extraktion der Erdmandelmilch wurde ein Nassmahlverfahren standardisiert und der Einfluss des Verfahrens auf die Nährstoffverteilung, die Farbeigenschaften und die kolloidale Stabilität der Milch analysiert. Als nächstes wurde Erdmandelmilch mit Proteinen und/oder Hydrokolloiden angereichert, und der Einfluss der Additive auf die physikalischen Eigenschaften des Extrakts bestimmt. Angereicherte Erdmandelmilch wurde mit klassischen Joghurtkulturen fermentiert, und die mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften der Produkte wurden untersucht. Zusätzlich wurden Effekte der Anreicherung von Erdmandelmilch mit enzymatisch vernetzten Proteinen auf die mikrobiologischen und physikalisch-chemischen Eigenschaften bewertet. Eine höhere Nassmahlintensität verbesserte die Nährstoffzusammensetzung, die kolloidale Stabilität und die Farbe der Milch. Die Anreicherung erhöhte die Viskosität und Stabilität und führte nach der Fermentation zu homogenen gelartigen Produkten mit verbesserten mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften im Vergleich zur fermentierten Erdmandelmilch. Mikrobielle Transglutaminase-vernetzte Proteine verbesserten die physikalischen Eigenschaften des fermentierten Produkts, insbesondere während der Lagerung. Dieses Produkt wäre in vielen Entwicklungsländern mit hoher Prävalenz von Laktoseintoleranz und begrenztem Zugang zu nahrhaften Lebensmitteln als Alternative von Interesse.

Les résultats montrent que la teneur en cendres, protéines brutes, sucres disponibles, oxalates totaux, amidons et phosphore augmente significativement (p<0,05) avec la maturité. En revanche la teneur en amylose baisse avec la maturité. La capacité d'absorption d'eau, l'indice de solubilité, la température et l'enthalpie de gélatinisation (delta H) des farines et amidons augmentent significativement (p<0,05) en fonction du degré de maturité. Quel que soit le degré de maturité, les granules d'amidon ont présenté un diffractogramme caractéristique de type "A". Les précurseurs de brunissement augmentent significativement (p<0,05) avec le degré de maturité. Le paramètre L* des farines et des pâtes augmente alors que a* diminue en fonction du degré de maturité. Le paramètre L* est plus élevé et a* moins élevé dans le cas du séchage électrique que le séchage solaire. Les caractéristiques sensorielles des pâtes de taro Sosso sont affectées positivement par le degré de maturité et le séchage électrique. L'acceptabilité générale des pâtes de taro Sosso est corrélée à la couleur de celles-ci. Cette étude suggère que 10 mois de maturité de taro Sosso et le séchage électrique (40°C) sont des conditions favorables à l'obtention des pâtes de qualité acceptable / Results showed that the ash content, crude proteins, available sugars, total oxalate, starch and phosphorus content increased significantly with the maturity stage. On the other hand the amylose content decreased as function of the maturity. The water adsorption capacity, the water solubility index, the temperature and the enthalpy of gelatinization of the flour and starch increased significantly with the maturity stage. Irrespective of the degree of maturity the starch granules diffractogramm were exhibited an "A" type cristallinity. The browning indicators increased significantly (p<0.05) with the maturity stage of the tuber. The color coordinate L* of the flours and that of its dough increased while a* decreased with the maturity stage. These two coordinates lend themselves better with electric drying than solar drying. The sensory characteristics of the taro Sosso dough were positively affected by the maturity stage and electric drying. The overall acceptability of taro Sosso dough was correlated with its color. These results suggest that 10 months of the taro Sosso maturity and the electric drying (40°C) are the best conditions to obtain the acceptable pastes. These optimum conditions might be used to produce the taro flour at industrial scale

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this study was to evaluate the effects of partial replacement of pork fat for emulsion containing canola oil in Italian type sausage. Three treatments were developed, including: control (100% pork fat, no fat replacement), T1 (15% fat was replaced by emulsion) and T2 (30% of the fat emulsion was replaced by emulsion). The parameters of pH, water activity, instrumental color, TBA and weight loss of the salami and the quantification of lactic acid bacteria, Staphylococcus coagulase negative, total coliforms, fecal coliforms, Salmonella sp. and Staphylococcus coagulase positive were studied during the processing. After, the fermented sausages were stored for 90 days, being evaluated the same parameters analyzed during processing, with the exception of water activity and weight loss. Furthermore, were analyzed sensory properties, chemical composition and fatty acid profiles of salami. After 28 days of processing, it was found that the incorporation of the emulsion with canola oil did not affect the attributes of pH, water activity and color of the salami, but resulted in a greater amount of TBARS in T2. Higher moisture content and lower weight loss were observed in treatments with the presence of canola oil. On the other hand, during the 90 days of storage was observed that the addition of oil resulted in lower pH values in salami and changes in color of the products, when compared with control. Concerning the oxidative stability, the T1 had the lowest level among the treatments, with values of 1.87 mg MA / kg sample, while the T2 had TBARS values above 4.00 mg MA/kg and the control sample 2,83 mg MA /kg sample. The microbiological analysis performed during the processing and the storage periods showed that the presence of the canola oil did not affect the development of lactic bacteria, in contrast to Staphylococcus coagulase negative that were higher than control. The microbiological safety of the sausage was maintained independent of treatment, since the acidification by fermentation ensured the elimination of total coliforms and non-detection of fecal coliforms, Salmonella sp. and Staphylococcus coagulase positive. There was also that the treatments with addition of canola oil pre-emulsified did not differ in the percentage of protein, but showed differences in fat content compared with control. Moreover, we observed the reduction in the composition of saturated fatty acids and an increase of polyunsaturated fatty acids, and changes in the ratio of polyunsaturated /saturated, which contribute to improve the nutritional profile of the salami. Furthermore, the incorporation of the canola oil emulsion did not alter the sensory properties of the products. Therefore, the substitution of pork fat by canola oil pre-emulsified is a viable alternative for diversification of products, and the substitution of 15% fat resulted in products with better nutritional quality and showed values similar to salami with incorporation of 30% of the canola oil emulsion. / Este trabalho teve por objetivo avaliar os efeitos da substituição parcial da gordura suína por emulsão contendo óleo de canola em salames tipo Italiano. Foram elaborados três tratamentos, entre eles: controle (100% de gordura suína), T1 (15% do toucinho foi substituído pela emulsão) e T2 (30% do toucinho foi substituído pela emulsão). Durante o período de processamento, foram avaliados os parâmetros de pH, atividade de água, cor, TBARS e quebra de peso das peças, além das quantificações de bactérias lácticas, Staphylococcus coagulase negativa, coliformes totais, coliformes fecais, Salmonella sp. e Staphylococcus coagulase positiva. Após o término da fabricação, os embutidos fermentados foram armazenados durante 90 dias em temperatura ambiente, sendo analisados os mesmos parâmetros verificados durante o processamento, com exceção da atividade de água e perda de peso. Além disso, foram analisadas as propriedades sensoriais, a composição química e o perfil de ácidos graxos dos embutidos prontos. Ao final de 28 dias de processamento, verificou-se que a incorporação da emulsão não afetou os atributos de pH, atividade de água e cor dos embutidos, mas resultou em maior valor de TBARS no T2. Além disso, maior umidade e menor perda de peso foram verificadas nos tratamentos com a presença do óleo de canola. Por outro lado, durante os 90 dias de armazenamento, foi observado que a adição do óleo resultou em menores valores de pH nos salames e alterações nos parâmetros que avaliam a coloração dos produtos, quando comparados com o controle. Quanto a estabilidade oxidativa, o T1 apresentou o menor nível entre os tratamentos, com valores de 1,87 mg MA/Kg amostra, enquanto que o T2 teve valores de TBARS acima de 4,00 mg MA/kg amostra e o controle 2,83 mg MA/kg amostra. As análises microbiológicas realizadas durante o período de processamento e estocagem dos embutidos indicaram que a presença do óleo de canola não interferiu no desenvolvimento das bactérias lácticas, ao contrário do Staphylococcus coagulase negativa, que apresentou valor maior que o controle. A segurança microbiológica dos salames foi mantida, independente do tratamento, já que a acidificação do meio garantiu a eliminação dos coliformes totais e a não detecção de coliformes fecais, Salmonella sp. e Staphylococcus coagulase positiva. Verificou-se, também, que os tratamentos com adição de óleo de canola pré-emulsionado não diferiram estatisticamente na porcentagem de proteína, mas apresentaram diferença no teor de gordura, quando comparado com o controle. Foi observada a redução na composição de ácidos graxos saturados e a elevação dos ácidos poli-insaturados, além de alterações na razão de poli-insaturados/saturados, as quais contribuem para a melhoria do perfil nutricional dos embutidos. Além disso, a incorporação da emulsão com óleo de canola não alterou as propriedades sensoriais dos produtos. Dessa forma, a substituição de gordura suína por emulsão com óleo de canola em salame é uma alternativa viável para a diversificação de produtos, sendo que a substituição de 15% da gordura resultou em produtos com melhor qualidade e apresentou valores nutricionais semelhantes ao embutido elaborado com a incorporação de 30% de emulsão com óleo de canola.

L’objectif de la thèse est de caractériser la poudre du kishk libanais, un lait fermenté traditionnel, et d’optimiser sa technologie de transformation dans une démarche d’industrialisation. Des échantillons de poudre de kishk traditionnel ont été collectés, et leurs propriétés physico-chimiques, rhéologiques, microbiologiques et sensorielles ont été étudiées, en fonction du type de lait utilisé. Il en résulte que le kishk préparé à base de lait de chèvre est plus riche en matières grasses que les autres types. La distribution granulométrique est très large, quel que soit le type de lait, avec présence simultanée de fines particules à forme irrégulière et d’agrégats de grande taille. Les particules de poudre sont revêtues d’une épaisse couche de lipides leur conférant un caractère cohésif et une grande résistance au cisaillement. Il s’avère aussi que la soupe de kishk présente un comportement rhéofluidifiant, et ses propriétés sensorielles sont fortement liées à la région de production et au type de lait. L’effet des conditions de production optimisée sur les propriétés de la poudre et de la soupe de kishk a été également étudié. Les résultats sont prometteurs et montrent que la structure de la poudre de kishk et son comportement rhéologique n’ont pas été altérés. En effet, les deux poudres de kishk présentent des propriétés rhéologiques quasi similaires, avec une faible aptitude à l’écoulement, malgré des différences au niveau de la composition chimique et la taille des particules. Au niveau rhéologique et sensoriel, la soupe de kishk issue de la production optimisée semble plus épaisse et consistante que la soupe traditionnelle, sans dépréciation notable des qualités organoleptiques du kishk. / The aim of this thesis is to characterize Lebanese kishk powder, a traditional fermented milk, and to optimize its processing technology. Samples of traditional kishk powder were collected, and their physicochemical, rheological, sensory and microbiological properties were studied based on the type of milk. As a result, kishk prepared with goat milk is richer in fat than other types. The particle size distribution is very wide, regardless of the type of milk, with simultaneous presence of fine irregularly shaped particles and large aggregates. Powder particles are coated with a thick layer of fat conferring a cohesive character and a high shear strength. Kishk soup has a shear-thinning behavior, and its sensory properties are strongly related to the production region and the type of milk. The effect of optimized production conditions on the properties of kishk powder and soup was also studied. The results are promising and show that the structure and rheological behavior of kishk powder were not altered. Indeed, the two kishk powders exhibit almost similar rheological properties, with low flowability, despite slight differences in chemical composition and particle size. Finally, kishk soup resulting from the optimized production seems thicker and consistent than traditional soup, without significant loss of the organoleptic properties of kishk.

Department of Food Science and Technology / MSCPNT

Tiger nuts (Cyperus esculentus L) are recognized as a high potential, alternative source of food nutrients. However, there is limited scientific literature on the technological possibilities for developing value-added foods, such as fermented products from tiger nut milk. Therefore, strategies for producing and improving the properties of fermented tiger nut milk were investigated for generating lactose-free, nutritious yogurt-like products with acceptable sensory properties and a prolonged shelf life quality. A wet-milling procedure was standardized for extracting tiger nut milk from tiger nuts, and the effects of the extraction process on nutrient distribution, colour properties and colloidal stability of the milk were analyzed. Next, tiger nut milk was enriched with proteins and/or hydrocolloids and the impact of the additives on the physical properties of the milk were determined. Enriched tiger nut milk was fermented by using classical yogurt cultures and the obtained products were analyzed for the microbiological, physico-chemical and sensory characteristics. Additionally, effects of enriching tiger nut milk with microbial transglutaminase cross-linked proteins on the microbiological and physico-chemical properties were evaluated. Higher wet-milling intensity improved the nutrient composition, colloidal stability and colour of the milk. Enrichment of tiger nut milk with milk proteins and xanthan gum enhanced the viscosity and stability, and after fermentation, led to homogenous gel-like products with superior microbiological, physico-chemical and different sensory properties compared to the fermented plain tiger nut milk. Microbial transglutaminase cross-linked proteins improved the physical characteristics of the fermented product, especially during storage. This product would be relevant in many developing countries with high prevalence of lactose intolerance, limited access to nutritious food but show a high distribution of tiger nut vegetation.:1. Introduction and aim 1 2. Literature review 4 2.1 Tiger nut, origin, nutritional value and food use 4 2.2 Tiger nut milk, preparation and nutrient composition 7 2.3 Colloidal characteristics of tiger nut milk 9 2.4 Factors accounting for the dispersion stability of tiger nut milk 10 2.5 Enhancing tiger nut milk stability 12 2.6 Properties of fermented tiger nut milk 17 2.7 Microbial transglutaminase and properties of fermented tiger nut milk 18 3. Methodology 21 3.1 Extraction and characterisation of tiger nut milk 21 3.1.1 Sample collection and preparation 21 3.1.2 Tiger nut milk extraction 21 3.1.3 Nutrient analysis of tiger nuts 22 3.1.4 Analysis of tiger nut products 23 3.1.5 Particle size distribution 24 3.1.6 Colloidal stability 25 3.1.7 Colour measurement 25 3.2 Stabilisation of tiger nut milk dispersion 26 3.2.1 Tiger nut milk preparation 26 3.2.2 Preparation of tiger nut milk enrichments 26 3.2.3 Gravitational stability of enriched tiger nut milk 27 3.2.4 Accelerated gravitational stability of enriched tiger nut milk 28 3.2.5 Viscosity of TNM mixtures 29 3.3 Extraction and characterisation of globular tiger nut proteins 29 3.3.1 Protein extraction and fractionation 29 3.3.2 Molecular mass of globular tiger nut proteins 31 3.3.3 Denaturation temperature of globular tiger nut proteins 32 3.3.4 Isoelectric point of globular tiger nut protein 33 3.4 Properties of fermented tiger nut milk enriched with proteins 34 3.4.1 Materials and Reagents 34 3.4.2 Preparation of plain and enriched tiger nut milk 34 3.4.3 Fermentation of plain and enriched tiger nut milk 35 3.4.4 Viable counts of starter cultures in fermented tiger nut milk systems 36 3.4.5 Chemical analysis of unfermented and fermented tiger nut milk 36 3.4.6 Physical analysis of fermented tiger nut milk products 37 3.4.7 Sensory analysis of fermented tiger nut milk products 38 3.5 Microbial transglutaminase and fermented tiger nut milk property 38 3.5.1 Preparation of plain and enriched tiger nut milk 38 3.5.2 Fermentation of plain and enriched tiger nut milk 39 3.5.3 Analysis of the enzymatically cross-linked proteins 39 3.5.4 Viable counts 40 3.5.5 pH and titratable acidity 40 3.5.6 Syneresis and viscosity 41 3.5.7 Colour of fermented tiger nut products 41 3.6 Statistical analysis 41 4. Results and discussion 43 4.1 Extraction and characteristics of tiger nut milk 43 4.1.1 Material recovery, mass transfer and yield of tiger nut solids 43 4.1.2 Nutrient composition of tiger nut products 45 4.1.3 Physical properties of tiger nut milk 48 4.1.3.1 Particle size distribution of extracted tiger nut milk 48 4.1.3.2 Colloidal stability of tiger nut milk 49 4.1.3.3 Colour stability of tiger nut milk 51 4.2 Stabilisation of tiger nut milk 53 4.2.1 Effects of enrichments on the stability of tiger nut milk 53 4.2.2 Effects of pH and temperature on the stability of enriched TNM 56 4.2.3 Effects of enrichments on the rheology of tiger nut milk 58 4.3 Tiger nut protein extraction and characterisation 60 4.3.1 Protein extraction and fractionation 60 4.3.2 Molecular mass of tiger nut protein 62 4.3.3 Thermal denaturation of tiger nut protein 63 4.3.4 Isoelectric point of tiger nut proteins 66 4.4 Properties of fermented tiger nut milk enriched with proteins 67 4.4.1 Acidification and gel formation during fermentation 67 4.4.2 Microbiological properties of fermented enriched tiger nut milk 70 4.4.3 Physico-chemical properties of fermented enriched tiger nut milk 71 4.4.4 Sensory properties of fermented tiger nut milk products 76 4.5 Microbial transglutaminase and fermented tiger nut milk property 77 4.5.1 Effects on tiger nut milk fermentation 77 4.5.2 Microbiological properties during storage of fermented product 81 4.5.3 Physico-chemical properties during storage of fermented product 83 4.5.4 Effects on colour of fermented tiger nut product 86 5. Conclusions and outlook 88 Bibliography 90 List of figures 111 List of tables 115 List of Publications 116 Poster and presentations 116 / Erdmandeln (Cyperus esculentus L) haben ein hohes Potential als alternative Quelle Lebensmittelinhaltsstoffen. Allerdings gibt es nur in begrenztem Ausmaß Literatur über technologische Möglichkeiten zur Entwicklung von Mehrwert-Lebensmitteln wie fermentierter Erdmandelmilch. Daher wurden Strategien zur Herstellung und Verbesserung der Eigenschaften von fermentierter Erdmandelmilch zur Erzeugung laktosefreier joghurtähnlicher Produkte mit akzeptablen sensorischen Eigenschaften untersucht. Für die Extraktion der Erdmandelmilch wurde ein Nassmahlverfahren standardisiert und der Einfluss des Verfahrens auf die Nährstoffverteilung, die Farbeigenschaften und die kolloidale Stabilität der Milch analysiert. Als nächstes wurde Erdmandelmilch mit Proteinen und/oder Hydrokolloiden angereichert, und der Einfluss der Additive auf die physikalischen Eigenschaften des Extrakts bestimmt. Angereicherte Erdmandelmilch wurde mit klassischen Joghurtkulturen fermentiert, und die mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften der Produkte wurden untersucht. Zusätzlich wurden Effekte der Anreicherung von Erdmandelmilch mit enzymatisch vernetzten Proteinen auf die mikrobiologischen und physikalisch-chemischen Eigenschaften bewertet. Eine höhere Nassmahlintensität verbesserte die Nährstoffzusammensetzung, die kolloidale Stabilität und die Farbe der Milch. Die Anreicherung erhöhte die Viskosität und Stabilität und führte nach der Fermentation zu homogenen gelartigen Produkten mit verbesserten mikrobiologischen, physikalisch-chemischen und sensorischen Eigenschaften im Vergleich zur fermentierten Erdmandelmilch. Mikrobielle Transglutaminase-vernetzte Proteine verbesserten die physikalischen Eigenschaften des fermentierten Produkts, insbesondere während der Lagerung. Dieses Produkt wäre in vielen Entwicklungsländern mit hoher Prävalenz von Laktoseintoleranz und begrenztem Zugang zu nahrhaften Lebensmitteln als Alternative von Interesse.:1. Introduction and aim 1 2. Literature review 4 2.1 Tiger nut, origin, nutritional value and food use 4 2.2 Tiger nut milk, preparation and nutrient composition 7 2.3 Colloidal characteristics of tiger nut milk 9 2.4 Factors accounting for the dispersion stability of tiger nut milk 10 2.5 Enhancing tiger nut milk stability 12 2.6 Properties of fermented tiger nut milk 17 2.7 Microbial transglutaminase and properties of fermented tiger nut milk 18 3. Methodology 21 3.1 Extraction and characterisation of tiger nut milk 21 3.1.1 Sample collection and preparation 21 3.1.2 Tiger nut milk extraction 21 3.1.3 Nutrient analysis of tiger nuts 22 3.1.4 Analysis of tiger nut products 23 3.1.5 Particle size distribution 24 3.1.6 Colloidal stability 25 3.1.7 Colour measurement 25 3.2 Stabilisation of tiger nut milk dispersion 26 3.2.1 Tiger nut milk preparation 26 3.2.2 Preparation of tiger nut milk enrichments 26 3.2.3 Gravitational stability of enriched tiger nut milk 27 3.2.4 Accelerated gravitational stability of enriched tiger nut milk 28 3.2.5 Viscosity of TNM mixtures 29 3.3 Extraction and characterisation of globular tiger nut proteins 29 3.3.1 Protein extraction and fractionation 29 3.3.2 Molecular mass of globular tiger nut proteins 31 3.3.3 Denaturation temperature of globular tiger nut proteins 32 3.3.4 Isoelectric point of globular tiger nut protein 33 3.4 Properties of fermented tiger nut milk enriched with proteins 34 3.4.1 Materials and Reagents 34 3.4.2 Preparation of plain and enriched tiger nut milk 34 3.4.3 Fermentation of plain and enriched tiger nut milk 35 3.4.4 Viable counts of starter cultures in fermented tiger nut milk systems 36 3.4.5 Chemical analysis of unfermented and fermented tiger nut milk 36 3.4.6 Physical analysis of fermented tiger nut milk products 37 3.4.7 Sensory analysis of fermented tiger nut milk products 38 3.5 Microbial transglutaminase and fermented tiger nut milk property 38 3.5.1 Preparation of plain and enriched tiger nut milk 38 3.5.2 Fermentation of plain and enriched tiger nut milk 39 3.5.3 Analysis of the enzymatically cross-linked proteins 39 3.5.4 Viable counts 40 3.5.5 pH and titratable acidity 40 3.5.6 Syneresis and viscosity 41 3.5.7 Colour of fermented tiger nut products 41 3.6 Statistical analysis 41 4. Results and discussion 43 4.1 Extraction and characteristics of tiger nut milk 43 4.1.1 Material recovery, mass transfer and yield of tiger nut solids 43 4.1.2 Nutrient composition of tiger nut products 45 4.1.3 Physical properties of tiger nut milk 48 4.1.3.1 Particle size distribution of extracted tiger nut milk 48 4.1.3.2 Colloidal stability of tiger nut milk 49 4.1.3.3 Colour stability of tiger nut milk 51 4.2 Stabilisation of tiger nut milk 53 4.2.1 Effects of enrichments on the stability of tiger nut milk 53 4.2.2 Effects of pH and temperature on the stability of enriched TNM 56 4.2.3 Effects of enrichments on the rheology of tiger nut milk 58 4.3 Tiger nut protein extraction and characterisation 60 4.3.1 Protein extraction and fractionation 60 4.3.2 Molecular mass of tiger nut protein 62 4.3.3 Thermal denaturation of tiger nut protein 63 4.3.4 Isoelectric point of tiger nut proteins 66 4.4 Properties of fermented tiger nut milk enriched with proteins 67 4.4.1 Acidification and gel formation during fermentation 67 4.4.2 Microbiological properties of fermented enriched tiger nut milk 70 4.4.3 Physico-chemical properties of fermented enriched tiger nut milk 71 4.4.4 Sensory properties of fermented tiger nut milk products 76 4.5 Microbial transglutaminase and fermented tiger nut milk property 77 4.5.1 Effects on tiger nut milk fermentation 77 4.5.2 Microbiological properties during storage of fermented product 81 4.5.3 Physico-chemical properties during storage of fermented product 83 4.5.4 Effects on colour of fermented tiger nut product 86 5. Conclusions and outlook 88 Bibliography 90 List of figures 111 List of tables 115 List of Publications 116 Poster and presentations 116

<p>U okviru disertacije su razvijeni postupci za iskori&scaron;ćenje sporednog produkta prerade paradajza (tropa) kao polazne sirovine za proizvodnju prehrambenih proizvoda sa dodatom vredno&scaron;ću. Sprovedena istraživanja kretala su se u dva smera: proizvodnja lipofilnih i hidrofilnih ekstrakata od liofilizovanog tropa paradajza, primenom rastvarača koji su dozvoljeni za upotrebu u prehrambenoj industriji (n-heksana i 95% etanola) i njihova karakterizacija u pogledu sadržaja i sastava fitohemikalija i biolo&scaron;ke aktivnosti in vitro; razvoj formulacija i tehnolo&scaron;kih postupaka za kreiranje gotovih proizvoda sa povećanim sadržajem prehrambenih vlakana i njihova karakterizacija u smislu nutritivnih, reolo&scaron;kih i senzorskih svojstava. Proizvedena su tri proizvoda sa povećanim sadržajem prehrambenih vlakana: kečap od svežeg tropa paradajza, kečap od liofilizovanog tropa paradajza u prahu i marmelada od liofilizovanog tropa paradajza u prahu.<br />Proizvedeni lipofilni i hidrofilni ekstrakti pokazali su sposobnost redukcije jona gvožđa, kao i antiradikalsku aktivnost na DPPH, azot (II)-oksid i superoksid-anjon radikale. Karotenoidi detektovani u lipofilnim ekstraktima (likopen i &beta;-karoten) povezani su sa vi&scaron;om antiradikalskom aktivno&scaron;ću na superoksid-anjon radikal, dok su fenolna jedinjenja detektovana u hidrofilnim ekstraktima (hidroksicinamati, flavonoli i dihidrohalkoni) bila efikasnija u redukciji jona gvožđa. Etanolni ekstrakt tropa paradajza pokazao je inhibitornu aktivnost na angiotenzin-konvertujući enzim pri koncentraciji ekstrakta od 10 mg/ml.<br />Kečap proizveden od svežeg tropa paradajza, kečap proizveden od liofilizata tropa paradajza i marmelada proizvedena od liofilizata tropa paradajza su bili okarakterisani povećanim sadržajem prehrambenih vlakana (preko 3 g na 100 g proizvoda), na osnovu kog mogu da se deklari&scaron;u kao izvor vlakana. Marmelada je proizvedena od liofilizovanog tropa paradajza bez dodatka hidrokoloida, sa 20% manjim sadržajem &scaron;ećera u odnosu na komercijalne proizvode.<br />Reolo&scaron;ka svojstva kečapa proizvedenog od svežeg tropa paradajza su prevashodno zavisila od koncentracije nerastvorljivih čestica. Rezultati senzorske ocene sprovedene uz primenu panela treniranih ocenjivača, ukazuju da su miris na paradajz i aroma paradajza bili najvažniji za jasno razlikovanje kečapa proizvedenog od svežeg tropa paradajza od komercijalnih proizvoda.<br />Kečap i marmelada proizvedeni od liofilizovanog tropa paradajza se, kao reolo&scaron;ki sistemi, mogu opisati modifikovanom frakcionom Kelvin-Voigt-ovom jednačinom kao viskoelastična tela. Ispitivanje model sistema sastavljenih od različitih odnosa liofilizata tropa paradajza i vode tretiranih na temperaturi od 60&deg;C i 100&deg;C ukazalo je da su vrednosti modula elastičnosti (G&rsquo;) zavisile od koncentracije liofilizata tropa i da su G&rsquo; vrednosti niže na 100&deg;C u odnosu na 60&deg;C. Test dopadljivosti kečapa i marmelade od liofilizovanog tropa paradajza, sproveden primenom hedonske skale od 1 do 7, ukazuje da su oba proizvoda prihvaćena od strane potro&scaron;ača (prosečna ocena za ukupnu dopadljivost veća od 4).</p> / <p>This dissertation describes processes for utilization of tomato processing byproduct (tomato pomace) as raw material for value-added food products. Research was conducted in two directions: one is production of lipophilic and hydrophilic tomato pomace extracts using solvents that are allowed for use in the food industry (n-hexane and 95% ethanol) and their characterization in terms of content and composition of phytochemicals and their in vitro biological activity; the other one is development of formulations and technological processes for the creation of tomato pomace based products with increased content of dietary fiber and their characterization in terms of nutritional, rheological and sensory properties. Three products with increased dietary fiber content were produced: ketchup was produced from fresh tomato pomace, and ketchup and jam were produced from lyophilized tomato pomace powder.<br />Produced lipophilic and hydrophilic extracts showed ferric ion reducing ability, as well as DPPH, nitric oxide and superoxide anion radical scavenging activity. Carotenoids detected in lipophilic extracts (lycopene and &beta;-carotene) were correlated with higher superoxide anion radical scavenging activity, while phenolic compounds detected in hydrophilic extracts (hydroxycinnamates, flavonols and dihydrochalcones) were more effective in ferric ion reduction.<br />Ketchup produced from fresh tomato pomace, ketchup produced from lyophilized tomato pomace, and jam produced from lyophilized tomato pomace were characterized by increased content of dietary fiber (more than 3 g per 100 g of product). Jam was produced from the lyophilized tomato pomace without addition of hydrocolloids, with 20% lower sugar content in comparison with commercial products. Rheological properties of ketchup produced from fresh tomato pomace primarily depended on the insoluble particles content. The results of sensory analysis indicate that tomato odor and flavor were the most important for clear separation of ketchup produced from fresh tomato pomace from commercial products.<br />Ketchup and jam produced from lyophilized tomato pomace could be described, as rheological systems, by the application of modified fractional Kelvin-Voigt model as viscoelastic solids. The examination of model systems comprised of different lyophilized tomato pomace:water ratios heat treated at 60&deg;C and 100&deg;C indicated that storage modulus (G&rsquo;) values depended on the concentration of lyophilized tomato pomace and that G&rsquo; values were lower at 100&deg;C than at 60&deg;C. Preference test for ketchup and jam, conducted by application of 7-point hedonic scale, indicated that both products were accepted by the consumers (average score for overall acceptability higher than 4).</p>

La qualité sensorielle des fromages au lait cru est variable selon la nature de l’alimentation des vaches laitières mais les mécanismes sous-jacents sont encore mal élucidés. Cette thèse avait pour objectif d’étudier les rôles respectifs et les interactions des composantes biochimique et microbiologique du lait, modulées par l’alimentation des vaches, dans la construction des caractéristiques sensorielles des fromages. Dans un premier temps, nous avons fait varier à la fois la composition biochimique et la composition microbiologique des laits en nous appuyant sur une expérimentation long terme comparant deux systèmes de pâturage qualifiés « d’extensif » (EXT) et de « semi-intensif » (SEMI). La structure des communautés bactériennes de la peau des trayons des vaches laitières, et dans une moindre mesure, celle des laits et des fromages de type Cantal ont varié selon les systèmes de production. Nos résultats confirment que le trayon est un réservoir potentiel de diversité microbienne, non seulement pour le microbiote du lait mais aussi pour celui du fromage. Les fromages EXT étaient caractérisés par une texture fondante et collante et une croûte moins épaisse comparativement aux fromages SEMI. Cependant, les deux systèmes de pâturage ont eu peu d’effet sur la flaveur des fromages, peut-être en raison de la trop grande similarité de la composition biochimique et microbiologique des laits des deux systèmes. Dans un deuxième temps, nous avons fait varier uniquement et de manière accentuée la composition de la matière grasse laitière via l’alimentation des vaches (herbe pâturée versus ensilage de maïs). Dans cette optique, des fromages de type Cantal ont été fabriqués à partir de deux crèmes pasteurisées de composition en acides gras différente et du même lait écrémé. Nous avons montré que l’effet de l’alimentation des vaches sur la texture des fromages était particulièrement lié à la composition de la matière grasse laitière tandis que celle-ci jouait un rôle mineur dans le développement de la flaveur des fromages. La crème la plus riche en acides gras saturés a été associée à une abondance relative plus élevée des ferments bactériens/fongiques et des OTUs dominants sur la surface des fromages et à la formation d’une croûte plus épaisse. Par comparaison, la croûte des fromages fabriqués avec une crème riche en acides gras insaturés était caractérisée par une plus grande diversité fongique et par la présence d’espèces sous dominantes en abondance relative plus élevée. Cette thèse apporte des connaissances nouvelles sur l’effet de la composition de la matière grasse laitière sur les équilibres microbiens et le développement des caractéristiques sensorielles des fromages, et plus spécifiquement sur l’influence des deux composantes biochimique et microbiologique sur l’aspect de la croûte des fromages affinés. / The sensory quality of raw milk cheeses varies according to cow diet but the underlying mechanisms are still poorly understood. The aim of this PhD work was to understand the respective roles and possible interactions between the biochemical and microbiological milk components, modulated by cow diet, on the development of the sensory properties of cheeses. In the frame of a long term experiment comparing two groups of cows managed in two grazing systems qualified of “extensive” (EXT) or “semi-intensive” (SEMI), we made Cantal-type cheeses using milk varying both in its biochemical and microbial composition. The structure of the bacterial communities of the teat skin of dairy cows, and to a lesser extent, that of milk and cheese varied according to the production systems. Our results confirm that the teat skin is a potential reservoir of microbial diversity not only for the microbiota of milk but also for cheese. The EXT cheeses were characterized by a more melting and sticky texture and a thinner rind compared to the SEMI cheeses. However, due to the similarity of the biochemical and microbiological composition of the milks from both systems, the flavour of the resulting cheeses was little impacted. Therefore, we designed a second trial aiming at controlling the microbial composition of milk and accentuating the difference of milk fat composition, via cow diet (maize silage vs pasture). We made Cantal-type cheeses from two pasteurized creams with different fatty acid profiles added to the same skimmed milk. The milk fat composition had a strong influence on cheese texture but it played a minor role on the development of cheese flavour. The cream rich in saturated fatty acids was associated to a higher relative abundance of bacterial / fungal starter strains and of dominant OTUs on the surface of cheese, and to the development of a thicker rind. By comparison, the rind of cheeses made with the cream rich in unsaturated fatty acids was characterized by a higher fungal diversity and the presence of sub-dominant species in greater relative abundance. This thesis provides new knowledge on the effect of the composition of milk fat on the microbial balance and on the development of the sensory characteristics of cheeses, and more specifically on the influence of both biochemical and microbiological components of milk on the aspect of the rind of mature cheeses.