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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Caracterização da microbiota latica isolada de queijo de coalho artesanal produzido no Ceara e suas propriedades tecnologicas / Caracterization of the latic microbiota isolated from artisanal coalho cheese preduced in the Ceara and its technological properties

Carvalho, Juliane Doering Gasparin 31 July 2007 (has links)
Orientador: Arnaldo Yoshiteru Kuaye, Laura Maria Bruno / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T22:18:13Z (GMT). No. of bitstreams: 1 Carvalho_JulianeDoeringGasparin_D.pdf: 1954120 bytes, checksum: 4ba23fd784559801ff2b5568f4ba02c0 (MD5) Previous issue date: 2007 / Resumo: O conhecimento da microbiota lática dos queijos de Coalho produzidos de forma artesanal a partir de leite cru, e suas propriedades tecnológicas são fundamentais para preservar as características originais do produto tradicional em queijos de Coalho industrializados, elaborados com leite pasteurizado. Para alcançar este conhecimento, foi realizado um trabalho de pesquisa dividido em três etapas: I) caracterização físico-química de queijos de Coalho artesanais produzidos no Ceará e de sua microbiota lática; II) estudo do comportamento das bactérias ácido láticas (BAL) durante o processamento do queijo; III) caracterização de propriedades tecnológicas das culturas láticas isoladas a partir deles. As análises físico-químicas caracterizaram as amostras avaliadas como sendo queijo de médio conteúdo de umidade (42%), baixa acidez (0,24%), com pH de 6,30; elevada atividade de água (0,959) e teor de NaCl de 2,88%. Dentre as BAL (643) isoladas destas amostras, foram encontrados os gêneros Enterococcus (59,6%), Lactobacillus (22%), Streptococcus (12,8%), Lactococcus (1,7%) e Leuconostoc (0,6%). A identificação de gênero não foi conclusiva para 3,3% de isolados. As espécies prevalecentes foram Enterococcus faecium, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus e Lactococcus lactis subsp. lactis. O acompanhamento da evolução da microbiota lática em amostras de leite cru, massa de queijo e do produto final, coletadas em duas unidades produtoras, revelou a presença de Lactococcus no leite e sua ausência no queijo. A presença de Enterococcus aumentou das amostras de matéria-prima para o queijo, indicando a transferência e multiplicação destes microrganismos ao longo do processamento. Estes resultados evidenciaram uma seleção de microrganismos resistentes às temperaturas elevadas no processamento do queijo, durante o cozimento da massa. Quanto às propriedades tecnológicas avaliadas, 15 isolados foram considerados produtores rápidos de ácido, com predominância dos Lactococcus e Streptococcus (40% cada). Os Lactobacillus exibiram maior variabilidade e extensão proteolítica, além de maior produção de aroma. As culturas analisadas mostraram boa tolerância a 3 e 4% de sal. As cepas de Enterococcus faecium apresentaram a maior produção de bacteriocinas ativas contra Listeria spp., com potencial de emprego na produção de queijo de Coalho, como cultura protetora / Abstract: Understanding the lactic microbiota of the artisanal Coalho cheeses produced from raw milk, and its technological properties, is important to preserve the characteristics of the traditional product in the industrialized Coalho cheeses, elaborated with pasteurized milk. In order to achieve such knowledge, a research work was carried out in three stages: I) the physical-chemical characterization of the artisanal Coalho cheeses from Ceara-Brazil and its lactic microbiota, II) the study of the behaviour of the lactic acid bacteria (LAB) along the processing of cheese, III) characterization of technological properties of the lactic cultures isolated from the cheese. The physical-chemical analyses characterized the evaluated cheese samples with medium moisture content (42%), low acidity (0.24%), pH of 6.30, high water activity (0.959) and 2.88% NaCl content. Amongst the 643 LAB isolated from these samples, Enterococcus (59.6%), Lactobacillus (22%), Lactococcus (1.7%), Leuconostoc (0.6%) and Streptococcus (12.8%) genera were found. The identification was not conclusive for 3.3% of the isolates. The main species were Lactococcus latis subsp. latis, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus and Enterococcus faecium. Following the evolution of lactic microbiota in raw milk, curd and cheese samples collected in two dairies, Lactococcus was found to be present in the milk, but absent in the cheese. The presence of Enterococcus increased from the raw material to the cheese samples, indicating the transference and multiplication of these microorganisms throughout the cheesemaking. Such results evidenced a selection of high temperature resistant microorganisms at the curd cooking stage of cheesemaking. According to the technological properties evaluated, 15 isolates were considered fast producers of acid, with predominance of the Lactococcus and Streptococcus (40% each). The Lactobacillus showed high variability and provided the widest range of proteolytic activity and production of flavour. The lactic cultures also showed good tolerance to 3 and 4 % of NaCl. Strains of Enterococcus faecium produced active bacteriocins against Listeria spp., with potential use in the production of Coalho cheese like protective culture / Doutorado / Doutor em Tecnologia de Alimentos
42

Caractérisation de la variabilité du système protéolytique de surface de la bactérie lactique Streptococcus thermophilus / Characterization of the variability of the proteolytic system of the lactic acid bacteria Streptococcus thermophilus

Galia, Wessam 21 September 2011 (has links)
La variabilité du système protéolytique de surface a été étudiée chez 30 souches de St. thermophilus. Cette variabilité consiste en la présence ou l’absence du gène prtS, en la présence de deux allèles différents de ce gène, en la présence d'une protéase PrtS ancrée et/ou soluble et enfin en l'expression variable, due à une variabilité de la régulation du système protéolytique, du gène prtS et d'autres gènes qui interviennent, pour la plupart, dans le métabolisme azoté. L’expression des gènes prtS, pepX, pepC, pepN, amiA1CDEF, dtpT, livJHMGF, ilvC, ilvDBN, bcaT, ackA, ldh, codY et relA a été quantifiée chez les souches PB302 et PB18O en lait et en milieu M17. La souche PB302 est représentative des souches qui se développent rapidement en lait alors que la souche PB18O l’est de celles qui ont une croissance intermédiaire dans ce milieu. Alors que l’expression des gènes étudiés est peu différente en milieu M17 où les deux souches ont une croissance similaire, cette expression diverge lorsque les deux souches sont cultivées en lait.Globalement, la différence de croissance observée en lait entre les deux souches pourrait résulter d'une variabilité de la capacité protéolytique et de l’expression, entre autres, des gènes codant PrtS, le régulateur CodY, les transporteurs des oligopeptides (Ami), des di-tripeptides (DtpT) et des acides aminés ramifiés (LivJ) et de ceux codant des enzymes impliquées dans la voie de biosynthèse des acides aminés ramifiés (IlvC, IlvB et BcaT), ces derniers étant nécessaires pour la croissance en lait. Tous ces gènes possèdent en amont de leur promoteur une boîte CodY potentielle et pourraient donc appartenir au régulon CodY / The variability of the cell envelope-associated proteolytic system was studied in 30 strains of St. thermophilus. Variations in strains consist in the presence or absence of the gene prtS, the presence of two allelic forms of prtS, the presence of an anchored and/or soluble form of the protease PrtS and in the variable expression of the gene prtS and other genes involved mainly in nitrogen metabolism, thus in the variability of the regulation genetic of this system. Expression of the genes prtS, pepX, pepC, pepN, amiA1CDEF, dtpT, livJHMGF, ilvC, ilvDBN, bcaT, ackA, ldh, codY and relA was quantified in the PB302 and PB18O strains. The strain PB302 is representative of strains which exhibit a rapid growth in milk. The strain PB18O is representative those with intermediate growth in milk. In M17 medium, where both strains have similar growth, little difference in the expression of genes tested was observed. Conversely, the two strains did not express the selected genes in the same way when grown in milk. Overall, the difference in growth observed between strains in milk could result from variable proteolytic activities and variable expression of genes encoding, for example, the proteinase PrtS, the regulator CodY, transporters of oligo- or di-tri- peptides (Ami or DtpT) or branched chain amino acids, or BCAA (LivJ) and enzymes in the biosynthetic pathway of BCAA (IlvC, IlvB et BcaT) which are necessary for growth in milk. All these genes have a potential CodY box at the upstream of their promoter and could therefore belong to the regulon CodY
43

Implication des systèmes à deux composants dans les réponses de Streptococcus thermophilus à des changements environnementaux, dont la coculture avec Lactobacillus bulgaricus. / Involvement of two-component systems in Streptococcus thermophilus response to environmental changes such as mixed culture with Lactobacillus bulgaricus

Thevenard, Benoît 23 September 2011 (has links)
S. thermophilus est une bactérie lactique largement utilisé dans l'industrie laitière et, comme toute bactérie, doit s'adapter à des environnements variés tels que le lait, le yaourt et même le tractus digestif, après que le produit ait été ingéré. Les systèmes à deux composants (TCS) constituent un des mécanismes essentiels qu'utilisent les bactéries pour percevoir et s'adapter à des changements environnementaux. D'un point de vue structural, les TCS sont constitués de deux composants: un « senseur » ou protéine histidine kinase (HK) qui s'auto-phosphoryle en réponse à un stimulus puis transfère son groupement phosphate au « response regulator » (RR), le deuxième composant. Celui-ci se comporte alors le plus souvent comme un régulateur transcriptionnel permettant une réponse physiologique adaptée. Afin de mieux comprendre ces phénomènes de régulation impliqués dans la réponse aux changements environnementaux, nous avons étudié la contribution de chacun des 8 TCS de Streptococcus thermophilus LMD-9 à son adaptation dans le lait. Ainsi, des études transcriptionnelles effectuées sur des cultures en lait montrent que tous les RR sont exprimés, à des niveaux et profils d'expression différents. Nous avons noté en coculture avec Lactobacillus bulgaricus, le partenaire de Streptococcus thermophilus dans le yaourt, une induction de l'expression de 4 RR qui atteint, pour rr02 et rr09, un facteur 6. Nous avons construit par ailleurs des mutants négatifs pour 7 des 8 RR de S. thermophilus et montré l'essentialité de RR05, un orthologue de YycF chez B. subtilis ou de or de WalR chez S. aureus. Pour les 7 autres mutants RR, l'absence d'un seul gène rr n'impacte pas suffisamment la croissance du streptocoque en lait. Enfin, la détermination du régulon du TCS06 par des études post-génomiques a permis de montrer que ce système est impliqué dans la résistance à la bacitracine en modulant entre autres la voie de biosynthèse du polysaccharide à rhamnose (RGP). / The lactic acid bacterium Streptococcus thermophilus is widely used in the dairy industry and, as a food bacterium, has to cope with changing environments such as milk, yogurt as well as the digestive tract, after the product has been ingested. Two-component systems (TCS), typically composed of a sensor kinase (HK) that detects a stimulus and of a response regulator (RR) which acts as a transcriptional regulator, are among the most prevalent means for bacteria to adapt to changing environments via fine-tune gene expression. To get a more comprehensive view of the role of all two-component systems in S. thermophilus physiology, we have investigated the contribution of each S. thermophilus LMD-9 TCS to its fitness and adaptation to milk. Transcriptomic studies (RT-qPCR) and construction of negative mutants of the rr genes were performed for LMD-9 S. thermophilus strain. We have shown that all LMD-9 response regulators were expressed in milk, at different levels and with different profiles of expression during growth. In mixed culture with Lactobacillus bulgaricus, the S. thermophilus partner in yoghurt, the expression of four LMD-9 rr increased; for two of them, rr02 and rr09, the increase reached a factor 6. These results indicate that Lb. bulgaricus induces regulatory changes in S. thermophilus and that S. thermophilus is able to adapt to these changes by probable fine tuning regulations. We constructed negative mutants for 7 out of 8 LMD-9 RRs and we showed that RR05 -an ortholog of B. subtilis YycF or S. aureus WalR- was essential for the optimum growth of S. thermophilus. For the 7 other RR, the absence of a single rr gene was not sufficient to notably impact the growth of LMD-9 in milk. The determination of the TCS06 regulon by post-genomics shows that TCS06 is involved in bacitracin resistance through the modulation of the rhamnose polysaccharide pathway.
44

EFFECTS OF AFLATOXIN B₁ AND M₁ ON LACTOBACILLUS BULGARICUS AND STREPTOCOCCUS THERMOPHILUS IN FERMENTED DAIRY PRODUCTS

Mahdi, Hussain Ahmed January 1982 (has links)
No description available.
45

Elektronentransfer zwischen Komplex III und IV der Atmungskette von Paracoccus denitrificans und Thermus thermophilus funktionelle und kinetische Charakterisierung der Interaktionen anhand von löslichen Fragmenten /

Janzon, Julia. Unknown Date (has links)
Universiẗat, Diss., 2007--Frankfurt (Main). / Zsfassung in dt. und engl. Sprache.
46

Caracterización bioquímica de la 4-amino-5-hidroximetil-2-metilpirimidina quinasa de Salmonella typhimurium y Thermus thermophilus

Cea Medina, Pablo Antonio 01 1900 (has links)
Seminario de Título entregado a la Universidad de Chile en cumplimiento parcial de los requisitos para optar al Título de Ingeniero en Biotecnología Molecular. / La 4-amino-5-hidroximetil-2-metilpirimidina quinasa (HMPK, EC 2.7.1.49) es una enzima perteneciente a la superfamilia riboquinasa y participa en la biosíntesis de tiamina (vitamina B1) en bacterias. Se ha descrito que esta enzima es capaz de catalizar dos fosforilaciones consecutivas dependientes de ATP altamente específicas sobre el sustrato hidroximetil pirimidina (HMP), generando como producto hidroximetil pirimidina pirofosfato. Esto contrasta notablemente con lo que se ha observado en las piridoxal quinasas de bacterias Gram positivas (HMPK/PLK, EC 2.7.1.35), un grupo de enzimas homólogas cercanas capaces de fosforilar hidroximetil pirimidina, piridoxal, piridoxina y piridoxamina, pero incapaces de catalizar dos fosforilaciones consecutivas, por lo que sólo producen hidroximetil pirimidina fosfato. Las HMPKs no han sido estudiadas tan exhaustivamente como las HMPK/PLKs y sólo hay dos caracterizaciones breves disponibles en la literatura; la de la HMPK de Escherichia coli y la de Bacillus subtilis. Por lo tanto, aún no se conoce si las propiedades observadas en las enzimas descritas son ubicuas para linajes bacterianos distintos, especialmente aquellos filogenéticamente distantes y que han sido sometido a presiones selectivas fuertes, como los extremófilos. Por esta razón, en este trabajo se realizó la caracterización bioquímica de la HMPK de la enterobacteria Salmonella typhimurium (StHMPK) y de la bacteria termófila Thermus thermophilus (TtHMPK). A través de experimentos de estequiometría de reacción y análisis de generación de productos, se demostró que ambas enzimas son capaces de catalizar dos fosforilaciones consecutivas. Experimentos de especificidad de sustrato revelaron que ambas enzimas son altamente específicas por hidroximetil pirimidina. Análisis filogenéticos mostraron que estas enzimas están estrechamente relacionadas con las HMPKs/PLK de organismos gram positivos, y estas últimas parecen ser descendientes directos de las HMPKs. Por lo tanto, para estudiar cómo estos grupos de enzimas han divergido en términos de sus actividades catalíticas, se realizaron simulaciones de dinámica molecular del complejo ternario (Mg·ATP - HMP) de StHMPK, para analizar el sitio de unión a sustrato y compararlo con el de la HMPK/PLK de Staphylococcus aureus (SaPLK). Los resultados mostraron que existe un alto grado de conservación entre ambos sitios, existiendo sólo unas pocas diferencias que podrían explicar la divergencia funcional observada, principalmente la presencia de una treonina adyacente a la base catalítica en StHMPK, que es reemplazada por una alanina en SaPLK, y la presencia de una glutamina en StHMPK que forma puentes de hidrógeno con el HMP. La caracterización cinética de StHMPK y TtHMPK mostró que ambas enzimas poseen una KM similar para HMP (cercana a 30μM) y que la Vmax para TtHMPK es un orden de magnitud menor que para StHMPK a 37 °C. Sin embargo, estos parámetros fueron obtenidos para las curvas de saturación de HMP, las cuales mostraban un comportamiento del tipo Michaelis-Menten, mientras que las curvas de saturación para ATP mostraron una clara desviación de este modelo y por lo tanto, no se pudieron determinar parámetros cinéticos. Finalmente, se realizó una caracterización estructural y biofísica para evaluar diferencias de estabilidad. Ambas enzimas parecen ser monómeros en las condiciones estudiadas, a diferencia de lo reportado para la enzima de E. coli que forma un tetrámero. Experimentos de desplegamiento por temperatura y agentes químicos mostraron que TtHMPK es significativamente más estable que StHMPK. Las bases estructurales de estas diferencias fueron analizadas mediante simulaciones de dinámica molecular, las que revelaron que la proteína termoestable es más rígida, tiene un menor contenido de residuos polares en el núcleo y tiene mayor cantidad de interacciones electrostáticas que su homólogo mesoestable. / 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase (HMPK, EC 2.7.1.49) is a bacterial enzyme that belongs to the ribokinase superfamily and participates in the thiamine (vitamine B1) biosynthetic pathway. It has been described that this enzyme is capable to catalyze two consecutive highly specific ATP dependent phosphorylations on the substrate hydroxymethyl pyrimidine, yielding hydroxymethyl pyrimidine pyrophosphate. This contrast notoriously with what has been observed for the closely related homologous enzymes pyridoxal kinases from Gram positive bacteria (HMPK/PLK, EC 2.7.1.35), which can phosphorylate hydroxymethyl pyrimidine, pyridoxal, pyridoxine and pyridoxamine, but are unable to catalyze two consecutive phosphorylations, thus only produce hydroxymethyl pyrimidine phosphate. HMPKs have not been as extensively studied as HMPKs/PLK, and only two brief biochemical characterizations are available on the literature; the characterization of the HMPK from Escherichia coli and from Bacillus subtilis. Therefore, it is still unknown whether the properties observed in the described enzymes are ubiquitous among different bacterial lineages, especially those that come from a very distinct phylogenetic background and have been subject to strong selective pressures, as the enzymes from extremophilic organisms. For this reason, in this work we address the biochemical characterization of the HMPK from the enterobacteria Salmonella typhimurium (StHMPK) and the thermophilic bacteria Thermus thermophilus (TtHMPK). Through stoichiometric experiments and product generation analysis, it was established that both enzymes are able to perform two consecutive phosphorylations. Substrate specificity experiments revealed that both enzymes are highly specific for hydroxymethyl pyrimidine. Phylogenetic analysis of these enzymes showed that are closely related to HMPKs/PLK from Gram positive organisms, being the later a direct descendant from HMPKs. Therefore, to study how these two groups of enzymes have diverged so much in terms of their catalytic activities, we analysed the substrate binding site of StHMPK by molecular dynamics simulations of the ternary complex (Mg·ATP - HMP) and compared it to the binding site of the PLK from Staphylococcus aureus (SaPLK). The results showed that there is an overall great conservation among the active sites, with just a few differences that could be responsible for the functional divergences observed, mainly the presence of a threonine residue adjacent to the catalytic base in StHMPK which is replaced by an alanine in SaPLK, and the presence of a glutamine that forms hydrogen bonds with the HMP in StHMPK. Kinetic characterization of StHMPK and TtHMPK showed that both enzymes have a similar KM for HMP (around 30 μM) while the Vmax for TtHMPK is one order of magnitude lower than the Vmax for StHMPK. However, these parameters were obtained only for HMP saturation curves, which showed a Michaelis-Menten behaviour, whereas ATP saturation curves displayed a clear deviation from a Michaelis-Menten model and therefore, no kinetic parameters could be deduced from these experiments. Finally, a biophysical and structural characterization to assess stability differences was performed. Both enzymes seem to be in monomeric state under the conditions assayed, in contrast with what was reported for the enzyme from E. coli, which forms a tetramer. Thermal and chemical unfolding experiments showed that TtHMPK is significantly more stable than StHMPK. The structural basis for these differences were investigated through molecular dynamics simulations, which revealed that the thermostable protein is more rigid, has a reduced content of polar amino acids in its core, and has more electrostatic interactions than its mesostable homologous. / Julio del 2019
47

CHARACTERIZING RNA TRANSCRIPTION AND DNA REPLICATION VIA RAMAN CRYSTALLOGRAPHY

Antonopoulos, Ioanna H. 03 June 2015 (has links)
No description available.
48

Identification of tRNA modifications in T. thermophilus: wild type HB8 and mutant DTTHA1897 by LC-UV-MS/MS

Fu, Lihua January 2015 (has links)
No description available.
49

Étude du dialogue hôte/bactéries lactiques du yaourt chez des rats gnotobiotiques

Ben Yahia, Leila 22 March 2012 (has links)
L'amélioration de la digestion de lactose est une allégation "santé" liée aux ferments viviants du yaourt : Streptococcus thermophilus (S. thermophilus) et Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) validée par l'EFSA en 2010. La physiologie de S. thermophilus et de L. bulgaricus est connue dans le lait et particulièrement le yaourt, alors qu'elle n'a été que peu étudiée dans le tractus digestif (TD). Mon travail de thèse est basé sur l'hypothèse de travail suivante : l'utilisation de modèles animaux gnotobiotiques permet de mieux connaître la physiologie des bactéries lactiques et de proposer des mécanismes d'action de leurs effets "santé". La stratégie a donc été d'obtenir des animaux mono-associés avec chacune des deux bactéries du yaourt ou les deux en même temps. Les principaux résultats obtenus sont : 1/ S. thermophilus colonise le TD en s'adaptant progressivement à l'environnement colique et y induit une glycolyse massive et une production de lactate. La glycolyse est la signature majeure de S. thermophilus dans le TD et le lactate pourrait être est la molécule "signal" qui induit une réponse chez l'hôte par une augmentation des transporteurs de mono-carboxylates (SLC16A1 et SLC5A8) et d'une protéine impliquée dans l'arrêt du cycle cellulaire p27kip1. 2/ L'apport de lactose stimule la colonisation du TD, la glycolyse ainsi que la production de L-lactate par S. thermophilus in vivo. 3/ Contrairement à ce qui est observé pour S. thermophilus, L. bulgaricus ne s'implante pas en absence de lactose. Quand les deux bactéries sont en co-culture, S. thermophilus est toujours avantagé numériquement par rapport à L. bulgaricus aussi bien in vitro qu' in vivo. Au niveau nutritionnel, tous nos résultats sont cohérents avec les allégations "santé" du yaourt avec un effet prébiotique du lactose. L'étude d'animaux gnotobiotiques a permis de proposer des nouvelles voies de régulation du métabolisme des sucres de bactéries lactiques et de nouvelles voies moléculaires (via le lactate) par lesquelles des bactéries lactiques et de nouvelles voies moléculaires (via le lactate) par lesquelles des bactéries lactiques pourraient influencer la physiologie de l'hôte. / *
50

Desenvolvimento de alimento probiótico à base de soja com polpa de fruta / Development of probiotic soy food with fruit pulp

Matias, Natalia Silva 21 October 2011 (has links)
Alterações favoráveis na composição da microbiota intestinal podem ser observadas com o consumo regular de alimentos funcionais contendo probióticos. Os probióticos são micro-organismos vivos que conferem benefícios à saúde do hospedeiro, quando administrados em quantidades adequadas. Tradicionalmente, são incorporados aos leites fermentados e a outros produtos lácteos fermentados. Atualmente, a idéia de redução dos componentes lácteos como veículos para agentes probióticos tem sido promovida, em razão da alta proporção de indivíduos que apresentam intolerância à lactose, além da busca por alternativas vegetarianas. Nesse contexto, a soja aparece como um substituto ideal para o consumo, promovendo a saúde através de características nutricionais intrínsecas. O presente trabalho visou desenvolver um produto semelhante ao queijo petit-suisse, mas à base de soja, com polpa de fruta, e adicionado de micro-organismos probióticos, bem como avaliar a aceitabilidade do produto sob o ponto de vista sensorial e suas características físico-químicas, microbiológicas e de textura instrumental durante o seu armazenamento a 4±1 °C por até 28 dias. Três formulações foram produzidas (com três repetições cada): F1- formulação de queijo petit-suisse probiótico elaborado com massa-base de queijo quark, como controle (produto lácteo); F2 - formulação com \"queijo\" de soja e com creme de leite (produto misto à base de soja e de leite); F3 - formulação com \"queijo\" de soja e com creme de soja (produto de soja). Em todas as formulações, foi empregada a cultura probiótica ABT-4, constituída dos micro-organismos comprovadamente probióticos Bifidobacterium animalis subsp. lactis Bb-12, Lactobacillus acidophilus La-5 e da cultura starter Streptococcus thermophilus. Os produtos foram armazenados a 4±1 °C e avaliados sensorialmente (teste de aceitabilidade, utilizando escala hedônica estruturada), após 7, 14 e 21 dias, por 50 consumidores em cada período. Adicionalmente, foram analisados semanalmente durante o seu armazenamento por até 28 dias quanto à viabilidade dos probióticos e da cultura starter e quanto ao seu pH e o seu perfil instrumental de textura (teste de dupla compressão de amostras, em analisador de textura TA-XT2). Paralelamente, foi realizado um monitoramento microbiológico das amostras quanto à presença de contaminantes e a partir de amostras mantidas congeladas, foi determinada a composição centesimal dos produtos. A viabilidade de La-5 mostrou-se satisfatória até o 28º dia de armazenamento das formulações F1 e F2, com populações variando de 8,29 a 7,56 log ufc/g e de 8,17 a 6,49 log ufc/g, respectivamente. Entretanto, para F3, as populações de La-5 mostraram-se satisfatórias até o 21º dia (8,18 a 6,84 log ufc/g), não atingindo o mínimo recomendado na última semana. Por outro lado, a viabilidade de Bb-12 manteve-se acima de 8 log ufc/g até o 28º dia de armazenamento de F1, F2 e F3. A cultura starter apresentou populações sempre entre 9,73 e 8,86 log ufc/g. O pH manteve-se estável para todas as formulações, mas foi significativamente menor (p<0,05) para F2, em relação a F1 e F3. Nos parâmetros dureza e gomosidade, F1 apresentou comportamento antagônico em relação ao de F2 e F3. Todos os parâmetros de textura de F1 diferiram significativamente de F2 e F3 (p<0,05). Não houve diferença significativa (p>0,05) na análise sensorial de uma mesma formulação entre os períodos de armazenamento. No entanto, na comparação entre as formulações, foram observados escores médios superiores (p<0,05) para F3 aos 21 dias (6,4), quando comparada a F2 (4,6). Os alimentos à base de soja, F2 e F3, mostraram-se bons veículos para os micro-organismos probióticos, com populações adequadas para caracterizá-los como probióticos, sendo que F3 mostrou uma tendência a um melhor desempenho sensorial após 14 e 21 dias de armazenamento. / Favorable changes in the composition of the intestinal microbiota can be observed with the regular consumption of functional foods containing probiotics. Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. They are traditionally incorporated into fermented milks and other fermented milk products. Currently, the idea of reducing milk components as vehicles for probiotic agents has been promoted due to the high proportion of people who have lactose intolerance, and the search for vegetarian alternatives. In this context, soy appears as an ideal replacement for consumption, promoting health through intrinsic nutritional characteristics. This work aimed to develop a product similar to petit-suisse cheese, but soy based, with fruit pulp, and with probiotic micro-organisms, as well as evaluating the acceptability of the product from the point of view of its sensory and physico-chemical characteristics, microbiological and instrumental texture profile during storage at 4 ± 1 °C for up to 28 days. Three formulations were produced (in triplicates): F1 - formulation of probiotic petit-suisse cheese prepared with quark cheese, as control (milk product) F2 - formulation with soy \"cheese\" and milk cream (mixed product with soy and milk), F3 - formulation with soy \"cheese\" and soy cream (soy product). The three formulations were produced with the probiotic ABT-4 culture, consisting of the probiotic microorganisms Bifidobacterium animalis subsp. lactis Bb-12, Lactobacillus acidophilus La-5 and the starter culture Streptococcus thermophilus. The products were stored at 4 ± 1 °C and subjected to sensory evaluation (acceptability test, using an hedonic scale), after 7, 14, and 21 days, by 50 consumers in each period. Additionally, the products were monitored weekly during storage for up to 28 days regarding the viability of the probiotics and starter culture and their pH profile and the instrumental texture (double compression of samples test, using a TA-XT2 texture analyzer). Also, samples were monitored for the presence of contaminants, and, the chemical composition of the products was determined from samples kept frozen. The viability of the La-5 was satisfactory until the 28th day of storage for F1 and F2, with populations ranging from 8.29 to 7.56 log cfu/g and from 8.17 to 6.49 log cfu/g respectively. However, for F3, the population of La-5 proved to be satisfactory until the 21st day (8.18 to 6.84 log cfu/g), not reaching the minimum recommended in the last week. On the other hand, Bb-12 viability remained above 8 log cfu/g throughout the 28 days of storage for F1, F2, and F3. The starter culture populations were always between 9.73 and 8.86 log cfu/g. The pH remained stable for all formulations, but was significantly lower (p<0.05) for F2, compared to F1 and F3. As for the texture parameters hardness and gumminess, F1 showed antagonistic behavior in relation to F2 and F3. All texture parameters evaluated differed significantly for F1, F2, and F3 (p<0.05). There was no significant difference (p>0.05) in the sensory scores obtained for the same formulation, when different storage periods were compared. However, when the 3 formulations were compared, higher average scores (p<0.05) were obtained on day 21 for F3 (6.4) than for F2 (4.6). The soy-based foods, F2 and F3, proved to be good vehicles for probiotic microorganisms, with appropriate populations to characterize them as probiotics, and F3 showed a trend towards a better performance in sensory evaluation on days 14 and 21 days of storage.

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