De grande importância para o preparo dos produtos panificáveis, a levedura utilizada na panificação ganhou relevante interesse comercial e tecnológico nos últimos anos, através de produtos elaborados com fermentação natural. Este fermento é um sistema natural formado por leveduras e bactérias láticas, que convivem numa associação complexa, gerando um fermento natural que pode ser desenvolvido por fermentação espontânea ou iniciado através da adição de cultura starter. O objetivo principal deste estudo foi isolar, selecionar e liofilizar leveduras de frutas orgânicas a fim de obter uma alternativa mais prática e rápida à produção de pão francês de fermentação natural (levain). Foram isoladas 7 leveduras de frutas orgânicas e destas, 3 foram selecionadas por apresentarem maior volume específico nos pães formulados (X1, maçã gala, X2, figo roxo e X3, uva moscato). Foi realizado planejamento de misturas envolvendo as 3 leveduras selecionadas em porcentagens pré-determinadas e as análises realizadas foram o volume específico, cor, textura da crosta e do miolo e espessura da crosta. As leveduras apresentaram boa estabilidade após a liofilização, sendo que a levedura N5 (maçã gala) obteve a menor porcentagem de redução microbiana. Para a análise de cor, os pães elaborados com a mistura ternária (X1, X2, X3) e a mistura binária com as frações X1 e X3 corresponderam a melhor resposta. Para a textura da crosta, os melhores resultados foram obtidos para a mistura binária de X2 e X3 e para a textura do miolo os melhores resultados foram verificados para a fração unitária da levedura X1 e para a mistura ternária (X1, X2, X3). A fração unitária da levedura X1 e a mistura binária entre X1 e X3 e X2 e X3 representam os melhores resultados para a espessura da crosta. Conclui-se com o presente estudo que é possível a utilização de leveduras isoladas a partir de frutas orgânicas formando um levain natural comercial, para a elaboração de pães com características similares aos elaborados através de fermentação natural, entretanto, de forma mais prática e rápida. / Having great importance to the preparation of bread products, the yeast used in bread making has gained significant commercial and technological interest in recent years through products made from natural fermentation. This yeast is a natural system formed by yeasts and lactic acid bacteria, which inhabit a complex association, creating natural yeast that can be developed by spontaneous fermentation or initiated by the addition of a starter culture. The main objective of this study was to isolate, select and freeze-dry yeast made with organic fruit in order to get a more practical and rapid alternative to the production of natural fermentation (levain) french bread. For this, 7 organic fruit yeasts were isolated, and 3 of those were selected for having higher specific volume in the breads that were prepared (X1, Gala apple, X2 purple fig, X3, moscato grape). Also, mixture plans were made, involving the 3 selected yeasts in pre-determined percentages, and the analysis performed was related to specific volume, color, texture of crust and crumb and crust thickness. The yeasts showed good stability after freeze-drying, and the yeast N5 (Gala apple) obtained the lowest percentage of microbial reduction. Regarding the color analysis, breads prepared with the ternary mixture ( X1 , X2 , X3 ) and the binary mixture with the fractions X1 and X3 corresponded to the best answer. In relation to the texture of the crust, the best results were obtained by the binary mixture of X2 and X3, and the best results of crumb texture were observed in the yeast fraction of the unitary X1 and the ternary mixture (X1, X2, X3 ). The unitary fraction of the X1 yeast and the binary mixture between X1 and X3 and between X2 and X3 represented the best results regarding the thickness of the crust. In conclusion, this study shows that it is possible to use yeasts isolated from organic fruits to form a commercial natural levain for the preparation of breads with similar characteristics of those made through natural fermentation, in a faster and more practical way, though.

De grande importância para o preparo dos produtos panificáveis, a levedura utilizada na panificação ganhou relevante interesse comercial e tecnológico nos últimos anos, através de produtos elaborados com fermentação natural. Este fermento é um sistema natural formado por leveduras e bactérias láticas, que convivem numa associação complexa, gerando um fermento natural que pode ser desenvolvido por fermentação espontânea ou iniciado através da adição de cultura starter. O objetivo principal deste estudo foi isolar, selecionar e liofilizar leveduras de frutas orgânicas a fim de obter uma alternativa mais prática e rápida à produção de pão francês de fermentação natural (levain). Foram isoladas 7 leveduras de frutas orgânicas e destas, 3 foram selecionadas por apresentarem maior volume específico nos pães formulados (X1, maçã gala, X2, figo roxo e X3, uva moscato). Foi realizado planejamento de misturas envolvendo as 3 leveduras selecionadas em porcentagens pré-determinadas e as análises realizadas foram o volume específico, cor, textura da crosta e do miolo e espessura da crosta. As leveduras apresentaram boa estabilidade após a liofilização, sendo que a levedura N5 (maçã gala) obteve a menor porcentagem de redução microbiana. Para a análise de cor, os pães elaborados com a mistura ternária (X1, X2, X3) e a mistura binária com as frações X1 e X3 corresponderam a melhor resposta. Para a textura da crosta, os melhores resultados foram obtidos para a mistura binária de X2 e X3 e para a textura do miolo os melhores resultados foram verificados para a fração unitária da levedura X1 e para a mistura ternária (X1, X2, X3). A fração unitária da levedura X1 e a mistura binária entre X1 e X3 e X2 e X3 representam os melhores resultados para a espessura da crosta. Conclui-se com o presente estudo que é possível a utilização de leveduras isoladas a partir de frutas orgânicas formando um levain natural comercial, para a elaboração de pães com características similares aos elaborados através de fermentação natural, entretanto, de forma mais prática e rápida. / Having great importance to the preparation of bread products, the yeast used in bread making has gained significant commercial and technological interest in recent years through products made from natural fermentation. This yeast is a natural system formed by yeasts and lactic acid bacteria, which inhabit a complex association, creating natural yeast that can be developed by spontaneous fermentation or initiated by the addition of a starter culture. The main objective of this study was to isolate, select and freeze-dry yeast made with organic fruit in order to get a more practical and rapid alternative to the production of natural fermentation (levain) french bread. For this, 7 organic fruit yeasts were isolated, and 3 of those were selected for having higher specific volume in the breads that were prepared (X1, Gala apple, X2 purple fig, X3, moscato grape). Also, mixture plans were made, involving the 3 selected yeasts in pre-determined percentages, and the analysis performed was related to specific volume, color, texture of crust and crumb and crust thickness. The yeasts showed good stability after freeze-drying, and the yeast N5 (Gala apple) obtained the lowest percentage of microbial reduction. Regarding the color analysis, breads prepared with the ternary mixture ( X1 , X2 , X3 ) and the binary mixture with the fractions X1 and X3 corresponded to the best answer. In relation to the texture of the crust, the best results were obtained by the binary mixture of X2 and X3, and the best results of crumb texture were observed in the yeast fraction of the unitary X1 and the ternary mixture (X1, X2, X3 ). The unitary fraction of the X1 yeast and the binary mixture between X1 and X3 and between X2 and X3 represented the best results regarding the thickness of the crust. In conclusion, this study shows that it is possible to use yeasts isolated from organic fruits to form a commercial natural levain for the preparation of breads with similar characteristics of those made through natural fermentation, in a faster and more practical way, though.

De grande importância para o preparo dos produtos panificáveis, a levedura utilizada na panificação ganhou relevante interesse comercial e tecnológico nos últimos anos, através de produtos elaborados com fermentação natural. Este fermento é um sistema natural formado por leveduras e bactérias láticas, que convivem numa associação complexa, gerando um fermento natural que pode ser desenvolvido por fermentação espontânea ou iniciado através da adição de cultura starter. O objetivo principal deste estudo foi isolar, selecionar e liofilizar leveduras de frutas orgânicas a fim de obter uma alternativa mais prática e rápida à produção de pão francês de fermentação natural (levain). Foram isoladas 7 leveduras de frutas orgânicas e destas, 3 foram selecionadas por apresentarem maior volume específico nos pães formulados (X1, maçã gala, X2, figo roxo e X3, uva moscato). Foi realizado planejamento de misturas envolvendo as 3 leveduras selecionadas em porcentagens pré-determinadas e as análises realizadas foram o volume específico, cor, textura da crosta e do miolo e espessura da crosta. As leveduras apresentaram boa estabilidade após a liofilização, sendo que a levedura N5 (maçã gala) obteve a menor porcentagem de redução microbiana. Para a análise de cor, os pães elaborados com a mistura ternária (X1, X2, X3) e a mistura binária com as frações X1 e X3 corresponderam a melhor resposta. Para a textura da crosta, os melhores resultados foram obtidos para a mistura binária de X2 e X3 e para a textura do miolo os melhores resultados foram verificados para a fração unitária da levedura X1 e para a mistura ternária (X1, X2, X3). A fração unitária da levedura X1 e a mistura binária entre X1 e X3 e X2 e X3 representam os melhores resultados para a espessura da crosta. Conclui-se com o presente estudo que é possível a utilização de leveduras isoladas a partir de frutas orgânicas formando um levain natural comercial, para a elaboração de pães com características similares aos elaborados através de fermentação natural, entretanto, de forma mais prática e rápida. / Having great importance to the preparation of bread products, the yeast used in bread making has gained significant commercial and technological interest in recent years through products made from natural fermentation. This yeast is a natural system formed by yeasts and lactic acid bacteria, which inhabit a complex association, creating natural yeast that can be developed by spontaneous fermentation or initiated by the addition of a starter culture. The main objective of this study was to isolate, select and freeze-dry yeast made with organic fruit in order to get a more practical and rapid alternative to the production of natural fermentation (levain) french bread. For this, 7 organic fruit yeasts were isolated, and 3 of those were selected for having higher specific volume in the breads that were prepared (X1, Gala apple, X2 purple fig, X3, moscato grape). Also, mixture plans were made, involving the 3 selected yeasts in pre-determined percentages, and the analysis performed was related to specific volume, color, texture of crust and crumb and crust thickness. The yeasts showed good stability after freeze-drying, and the yeast N5 (Gala apple) obtained the lowest percentage of microbial reduction. Regarding the color analysis, breads prepared with the ternary mixture ( X1 , X2 , X3 ) and the binary mixture with the fractions X1 and X3 corresponded to the best answer. In relation to the texture of the crust, the best results were obtained by the binary mixture of X2 and X3, and the best results of crumb texture were observed in the yeast fraction of the unitary X1 and the ternary mixture (X1, X2, X3 ). The unitary fraction of the X1 yeast and the binary mixture between X1 and X3 and between X2 and X3 represented the best results regarding the thickness of the crust. In conclusion, this study shows that it is possible to use yeasts isolated from organic fruits to form a commercial natural levain for the preparation of breads with similar characteristics of those made through natural fermentation, in a faster and more practical way, though.

Neste trabalho, foi realizado um estudo sobre a produção de pães de fermentação natural ou “sourdough”, baseado na hipótese que este processo possa apresentar papel bem definido na melhoria do sabor, da estrutura de pão, na estabilização ou aumento dos níveis de vários compostos bioativos, retardamento da biodisponibilidade do amido (baixo índice glicêmico) e no aumento da biodisponibilidade de minerais.. Elaborou-se pães que foram produzidos via fermentação “sourdough” utilizando os microrganismos Kluyveromyces marxianus, Dekkera bruxellensis e Lactobacillus plantarum como cultura de partida. A partir de sete amostras resultantes de um delineamento de mistura Simplex-Centróide, determinou-se o volume especifico dos pães e o pH, acidez e as células viáveis durante a fermentação “sourdough”. Observou-se que pão produzido com Lactobacillus plantarum foi o que apresentou o menor volume específico e a mistura entre K.marxianus e L. plantarum exerceu influência positiva, acarretando o maior volume específico. Durante a fermentação “sourdough” houve redução dos valores de pH e aumento da acidez. Através da análise sensorial verificou-se a boa aceitabilidade para os pães produzidos com a mistura entre D.bruxellensis e K.marxianus e para a mistura entre os três micro-organismos. Estes resultados indicam que o tipo de cultura de partida influência nos parâmetros de qualidade dos pães avaliados. No entanto, novos estudos, envolvendo outras variáveis do processo de fermentação “sourdough” devem ser feitos para melhor avaliação. / In this work it was studied the formulation and production of natural-fermentation breads, also known as “sourdough”, based upon the fact that this process may play a well-defined role in the improvement of flavor, the structure of bread, in the stabilization or increase of the levels of several bioactive compounds, the bioavailability of slow starch (low glycemic index products), and in improving the bioavailability of minerals in this highly consumed product. Breads were produced by fermentation "sourdough" using Kluyveromyces marxianus, Dekkera bruxellensis, and Lactobacillus plantarum as starting cultures. The seven samples derived from a design mix-Simplex Centroid determined the specific volume of breads and pH, acidity, and viable cells during fermentation "sourdough." It was observed that bread produced with Lactobacillus plantarum presented the lowest specific volume, while the mix of K.marxianus and L.plantarum exerted positive influence, leading to the high specific volume. During fermentation "sourdough" there was a reduction in the pH and an increase in acidity. For the sensorial analysis, there was high acceptability for the bread produced with the mixture of D. bruxellensis and K. marxianus and the mix between the three microorganisms. These results indicate that the type of starting culture have strong influence on the quality of bread parameters evaluated. However, further studies involving other process variables fermentation "sourdough" must be carried out in order to better understand this technical product.

Neste trabalho, foi realizado um estudo sobre a produção de pães de fermentação natural ou “sourdough”, baseado na hipótese que este processo possa apresentar papel bem definido na melhoria do sabor, da estrutura de pão, na estabilização ou aumento dos níveis de vários compostos bioativos, retardamento da biodisponibilidade do amido (baixo índice glicêmico) e no aumento da biodisponibilidade de minerais.. Elaborou-se pães que foram produzidos via fermentação “sourdough” utilizando os microrganismos Kluyveromyces marxianus, Dekkera bruxellensis e Lactobacillus plantarum como cultura de partida. A partir de sete amostras resultantes de um delineamento de mistura Simplex-Centróide, determinou-se o volume especifico dos pães e o pH, acidez e as células viáveis durante a fermentação “sourdough”. Observou-se que pão produzido com Lactobacillus plantarum foi o que apresentou o menor volume específico e a mistura entre K.marxianus e L. plantarum exerceu influência positiva, acarretando o maior volume específico. Durante a fermentação “sourdough” houve redução dos valores de pH e aumento da acidez. Através da análise sensorial verificou-se a boa aceitabilidade para os pães produzidos com a mistura entre D.bruxellensis e K.marxianus e para a mistura entre os três micro-organismos. Estes resultados indicam que o tipo de cultura de partida influência nos parâmetros de qualidade dos pães avaliados. No entanto, novos estudos, envolvendo outras variáveis do processo de fermentação “sourdough” devem ser feitos para melhor avaliação. / In this work it was studied the formulation and production of natural-fermentation breads, also known as “sourdough”, based upon the fact that this process may play a well-defined role in the improvement of flavor, the structure of bread, in the stabilization or increase of the levels of several bioactive compounds, the bioavailability of slow starch (low glycemic index products), and in improving the bioavailability of minerals in this highly consumed product. Breads were produced by fermentation "sourdough" using Kluyveromyces marxianus, Dekkera bruxellensis, and Lactobacillus plantarum as starting cultures. The seven samples derived from a design mix-Simplex Centroid determined the specific volume of breads and pH, acidity, and viable cells during fermentation "sourdough." It was observed that bread produced with Lactobacillus plantarum presented the lowest specific volume, while the mix of K.marxianus and L.plantarum exerted positive influence, leading to the high specific volume. During fermentation "sourdough" there was a reduction in the pH and an increase in acidity. For the sensorial analysis, there was high acceptability for the bread produced with the mixture of D. bruxellensis and K. marxianus and the mix between the three microorganisms. These results indicate that the type of starting culture have strong influence on the quality of bread parameters evaluated. However, further studies involving other process variables fermentation "sourdough" must be carried out in order to better understand this technical product.

Neste trabalho, foi realizado um estudo sobre a produção de pães de fermentação natural ou “sourdough”, baseado na hipótese que este processo possa apresentar papel bem definido na melhoria do sabor, da estrutura de pão, na estabilização ou aumento dos níveis de vários compostos bioativos, retardamento da biodisponibilidade do amido (baixo índice glicêmico) e no aumento da biodisponibilidade de minerais.. Elaborou-se pães que foram produzidos via fermentação “sourdough” utilizando os microrganismos Kluyveromyces marxianus, Dekkera bruxellensis e Lactobacillus plantarum como cultura de partida. A partir de sete amostras resultantes de um delineamento de mistura Simplex-Centróide, determinou-se o volume especifico dos pães e o pH, acidez e as células viáveis durante a fermentação “sourdough”. Observou-se que pão produzido com Lactobacillus plantarum foi o que apresentou o menor volume específico e a mistura entre K.marxianus e L. plantarum exerceu influência positiva, acarretando o maior volume específico. Durante a fermentação “sourdough” houve redução dos valores de pH e aumento da acidez. Através da análise sensorial verificou-se a boa aceitabilidade para os pães produzidos com a mistura entre D.bruxellensis e K.marxianus e para a mistura entre os três micro-organismos. Estes resultados indicam que o tipo de cultura de partida influência nos parâmetros de qualidade dos pães avaliados. No entanto, novos estudos, envolvendo outras variáveis do processo de fermentação “sourdough” devem ser feitos para melhor avaliação. / In this work it was studied the formulation and production of natural-fermentation breads, also known as “sourdough”, based upon the fact that this process may play a well-defined role in the improvement of flavor, the structure of bread, in the stabilization or increase of the levels of several bioactive compounds, the bioavailability of slow starch (low glycemic index products), and in improving the bioavailability of minerals in this highly consumed product. Breads were produced by fermentation "sourdough" using Kluyveromyces marxianus, Dekkera bruxellensis, and Lactobacillus plantarum as starting cultures. The seven samples derived from a design mix-Simplex Centroid determined the specific volume of breads and pH, acidity, and viable cells during fermentation "sourdough." It was observed that bread produced with Lactobacillus plantarum presented the lowest specific volume, while the mix of K.marxianus and L.plantarum exerted positive influence, leading to the high specific volume. During fermentation "sourdough" there was a reduction in the pH and an increase in acidity. For the sensorial analysis, there was high acceptability for the bread produced with the mixture of D. bruxellensis and K. marxianus and the mix between the three microorganisms. These results indicate that the type of starting culture have strong influence on the quality of bread parameters evaluated. However, further studies involving other process variables fermentation "sourdough" must be carried out in order to better understand this technical product.

Résumé confidentiel / Résumé confidentiel

Lactococcus lactis est une bactérie lactique couramment utilisée dans l’industrie laitière. Elle assure en tant que ferment des fonctions technologiques multiples qui impactent la flaveur et la texture finale des produits. Cependant, la diversité fonctionnelle constatée au sein des levains de cette espèce impose de mettre en place un processus de sélections des souches. Ces travaux ont pour objectif d’identifier les déterminants de la spécificité organoleptique dite « crème » de la souche industrielle L. lactis ssp. lactis. Dans un premier temps, un diagnostic macro-cinétique de l’activité de ce ferment a été réalisé en lait pour évaluer l’impact sur la physiologie cellulaire (l’acidification, le stress oxydatif, et la thermisation différentielle du lait). Définir la singularité de notre souche d’intérêt nécessite d’évaluer la diversité fonctionnelle de levains laitiers de L. lactis ssp. lactis. Cette démarche s’est appuyée sur une approche de biologie intégrative du génotype au phénotype. Pour réduire le temps d’expérimentation, une sélection des variables discriminantes à été conduite. L’un de ses composés clef de cette typicité a fait l’objet d’une étude approfondie afin de tester les différents paramètres pouvant influencer sa synthèse. La dernière partie, plus applicative, s’est articulée sur la modélisation de la signature en fonction de quatre facteurs industriels (matière grasse, sèche, oxygénation et température) par utilisation de la méthodologie des surfaces de réponse. / The lactic acid bacterium Lactococcus lactis is widely used in dairy industry. Used as a starter, L. lactis subsp. lactis is in charge of many functional characteristics which determine the final texture and flavour of fermented products. However, the phenotypic diversity observed within the species requires strain selection development. This PhD aims at identifying the determinants of the creamy sensory specificity of the industrial strain L. lactis subsp. lactis. Firstly, a diagnosis of macro-kinetic activity of ND5F was carried out to assess the impact on cellular physiology of three environmental parameters (acidification, oxidative stress, and milk heat treatments). In order to assess the uniqueness of our strain of interest, a system biology approach from genotype to phenotype was implemented to study the functional diversity of L. lactis subsp. lactis starters. A group of nine strains representative of the genetic diversity of this subpopulation was made up. 82 variables selected as important dairy features; including physiological descriptors, production of metabolites and volatile organic compounds (VOCs); were monitored. This study demonstrated the phenotypic uniqueness of each of these genetically closely related strains, allowing strain discrimination in dairy products. To reduce the time-consuming experimentation, we developed a method of variable selection. Twenty VOCs were therefore identified as major phenotypic determinants of this diversity. They define four robust stain clusters depending on their metabolic orientations: lipolysis, proteolysis, glycolysis and unexpressed. Inclusion of genotypic diversity in addition to phenotypic characters led to adjust the functional classification by integrating strain unexpressed genotypic potentialities. Comparative proteomics analysis in milk identified protein markers of this specificity. After selecting a subset of forty-six proteins the three levels (genotype, phenotype and proteomics) involved in this diversity expression were integrated to provide a predictive classification of starter diversity.The Integration of our strain to this model enabled the identification of fourteen phenotypic determinants and seven proteins to explain ND5F specificity. The pentane-2,3-dione, a key aromatic compounds of this typicity was subjected to a comprehensive analysis to point out the different factors that may influence its synthesis. On a more applied aspect, the last part was focused on the signature modelling based on four industrial factors (milk fat and total solid level, oxygen and temperature) using the response surface methodology. It enabled to enhance the “creamy” organoleptic characteristics of the fermented products.

Les microorganismes sont essentiels au maintien et au fonctionnement des écosystèmes. Dans certains produits alimentaires, la communauté microbienne, composée principalement de levures et de bactéries lactiques, fermente les sucres, affecte positivement les qualités organoleptiques du produit et augmente sa durée de conservation. C’est le cas du levain de panification. Cette thèse visait principalement à décrire les patterns de diversité des levures de levains français produits à partir de farine issue de l’agriculture biologique et à conserver une partie de cette diversité. Grâce à des méthodes d’analyses culturales et non culturales de la diversité des levures, nous avons mis en évidence une diversité spécifique caractéristique de chaque levain étudié. Nous avons aussi montré la dominance du genre Kazachstania et la convergence des souches isolées de levain pour la capacité à consommer du raffinose et du saccharose. Bien que la densité et la composition en espèces varient entre deux levains, aucune structuration spatiale de la diversité n’a été mise en évidence. Les pratiques de panification et leurs effets sur la diversité des communautés microbiennes ont également été analysés. Deux typologies de pratiques de panification (plutôt « intensives » et plutôt « extensives »), affectant l’espèce dominante des populations de levures, ont été révélées. / Microorganisms are essential for the maintenance and functioning of the ecosystems. In some food products, microbial community, mainly composed by yeasts and lacid actic bacteria which ferment sugars, positively affects organoleptic qualities and shelf life of the product. It is the case of bread sourdough. This PhD aimed at describing yeast diversity patterns of organic French bread sourdoughs and conserving a part of this diversity. Using cultural-Based and non-Cultural based analyses of yeast diversity, we highlighted a unique specific diversity of each sourdough. We also shown the predominance of Kazachstania genus and a convergence of sourdoughs’ yeasts isolates for the ability to consume raffinose and sucrose. Although density and species composition varied between sourdoughs, no spatial pattern was highlighted. Bread-Making practices and their effects on microbial communities’ diversity were also analyzed. Two bread-Making practice typologies (quite « intensive » and quite « extensive »), affecting dominant yeast species were also revealed.