Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 81-90). Also available via the Internet.

Orientadores: Walkiria Hanada Viotto, Mieko Kimura / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-04T02:47:09Z (GMT). No. of bitstreams: 1 Fachin_Luciano_D.pdf: 623874 bytes, checksum: 39038138708fcb9d94eb3e5320272cbb (MD5) Previous issue date: 2005 / Resumo: A produção de iogurtes com Bifidobacterium spp. tem crescido muito nas últimas décadas visando a produção de alimentos funcionais. Contudo, para que o produto possa apresentar tais propriedades, tem sido alegado que o número mínimo de células viáveis de Bifidobacterium spp. presentes no momento do consumo deva ser de 106 UFC/g de produto. Entretanto, vários estudos têm mostrado produtos comerciais com contagens menores do que as recomendadas, durante a estocagem do iogurte. Esse fato é reflexo tanto da dificuldade de incorporação destes microrganismos ao iogurte, devido às condições de processo que não são favoráveis ao desenvolvimento da bifidobactéria, bem como pela dificuldade de enumeração destes microrganismos na presença das culturas do iogurte. Este trabalho avaliou o uso dos meios M-MRS, MRS-NNLP, MRS-LP, RCPB pH5 e RCPB pH5 enriquecido com extrato de fígado, visando a contagem seletiva ou diferencial de Bifidobacterium animalis Bb 12 na presença das culturas do iogurte e estudou o efeito do tratamento térmico do leite, visando o aumento do teor de lactulose e, da adição de Propionibacterium freudenreichii PS-1, sobre o desenvolvimento e manutenção do número de células viáveis de B. animalis Bb 12 durante a fermentação e estocagem do iogurte. Dos meios estudados, o meio RCPB pH5, enriquecido com 150mL/L de extrato de fígado, foi o mais indicado para a contagem de B. animalis Bb 12 em iogurte por ter apresentado uma excelente diferenciação deste microrganismo, após a estocagem refrigerada do iogurte. O tratamento térmico do leite de 142°C/15 segundos não afetou o desenvolvimento de B. animalis Bb 12 durante a fermentação do iogurte e também não influenciou a sua resistência à estocagem refrigerada. Entretanto, o tratamento térmico alterou significativamente a textura, diminuindo consideravelmente a dureza, gomosidade e adesividade do iogurte, resultando em um produto com menor separação de soro. A adição de P. freudenreichii PS-1 aumentou em aproximadamente duas vezes o número de células de B. animalis Bb 12 ao final da fermentação e melhorou a resistência da bifidobactéria à estocagem refrigerada. A presença da propionibactéria também alterou significativamente a textura final do iogurte, aumentando consideravelmente a gomosidade e adesividade do produto final, bem como resultou em um iogurte com menor separação de soro durante a estocagem refrigerada / Abstract: Bifidobacterium spp. has been used to produce probiotic yoghurts due to its therapeutic properties. However, it has been claimed that the number of bifidobactéria in yoghurt at the time of consuming must be 106 CFU /g of product to perform their therapeutic functions. Many studies found a low recovery of bifidobactéria from commercial products during shelf life. The low viability of bifidobactéria can be attributed to the process conditions of yoghurt, which is not favorable to the growth of bifidobactéria, and to the difficulty for enumeration of bifidobactéria in the presence of yoghurt bacteria. The objectives of this work were to evaluate the following media: M-MRS, MRS-NNLP, MRS-LP, RCPB pH5 and fortified RCPB pH5 to enumerate B. animalis Bb 12 in yoghurt, and to evaluate the heat treatment of milk (142°C/15 seconds) and the addition of P. freudenreichii PS-1 on the growth of B. animalis Bb 12 during yoghurt fermentation and during shelf life. RCPB pH5 fortified with 150 mL/L of liver extract was the best media due to its excellent differentiation during refrigerated storage of yoghurt. The heat treatment of milk (142°C/15 seconds) did not have effect on the growth of bifidobactéria during fermentation and it also did not improve the bifidus viability during storage. Heat treatment, however, had a strong effect on yoghurt texture, decreasing the sineresis and some parameters of TPA (hardness, gumminess and adhesiveness). The addition of P. freudenreichii PS-1 increased two fold the bifidobactéria growing during yoghurt fermentation and it also increased the viability of bifidobactéria during yoghurt shelf life. The addition of P. freudenreichii PS-1 also decreased the sineresis and increased TPA parameters of hardness, gumminess and adhesiveness. Addition of P. freudenreichii PS-1 to the yoghurt seems to be a good growth promoter for B. animalis Bb 12 / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

beta-Glucans are a kind of non-digestible carbohydrate (NDC) that are known for their benefits for human gut health, but there are very few studies on their fermentability by human colon microbiota. In this study four beta-glucans were selected for in vitro fermentation by three bifidobacteria. The beta-glucans included those from a seaweed called Laminaria digitata (laminarin), barley, a bacterium called Alcaligenes faecalis (curdlan), and a mushroom sclerotia from Pleurotus tuber-regium. Inulin from Dahlia tubers was used as control. / The content of beta-glucan in the NDCs prepared from the mushroom sclerotium of Pleurotus tuber-regium was 80.8 % with proteins less than 1.0 %, while that of curdlan, barley and laminarin all have more than 95% beta-glucan. All the beta -glucans contained almost purely glucose as their sugar components with only trace amount of mannose ( < 2%) being found in laminarin. beta-glucan from barley had a MW of 590 kDa and a linear chain with mixed 1→3 and 1→4 beta-linkages in the ratio of 1:3. Curdlan had a beta-(1→3) linked unbranched linear chain with a MW of 10 to 30 kDa. Laminarin had a beta-(1→3) linked backbone with beta-(1→6) branches, having a MW of 6 kDa. beta-Glucan from mushroom sclerotia had a highly branched main chain with mixed glycosidic 1→3, 1→4 and 1→6 beta-linkages with a MW of 96 kDa. / Batch systems of in vitro fermentation of individual NDCs by B.longum subsp. infantis ( B. infantis), B. longum and B. adolescentis were carried out for 24 h under anaerobic condition. All the systems showed a significant drop (p< 0.05) of at least 0.5 units in their pH values. The populations of B. infantis increased by 3 log10 CFU on all the NDCs while those of B. longum and B. adolescentis increased by about 1 to 1.5 log10 CFU and 2 to 2.3 log10 CFU, respectively. Utilization of the NDCs by the bifidobacteria evaluated by organic matter disappearance ranged from 4.52% in barley to 41.3% in inulin. The total short chain fatty acid (SCFA) produced by B. infantis was higher than that in B. longum and B. adolescentis for all the beta -glucans. The SCFA profile of inulin and all beta-glucans produced by all the bifidobacteria was dominated by acetate (96%). The ratio of acetic : propionic : butyric acid in the SCFA profile of the fermentation of all the beta-glucans by B. infantis was 8: 1: 1, which was very different from that of B. longum and B. adolescentis. / Based on the in vitro fermentation results, B. infantis was selected for a mechanistic study on the fermentation of the Pbeta-glucans from different sources by proteomic and molecular biology approaches. In the proteomic study, the gels of the two-dimensional difference gel electrophoresis (2D-DIGE) containing the total proteins from the B. infantis cells fermented with beta-glucans from barley, seaweed and mushroom sclerotia were compared with each other to isolate the differentially expressed protein spots. In all the comparisons, a total number of 198 protein spots were identified based on their mass spectra. These proteins were classified according to their functional annotation, including ABC transporters, phosphotransferase system (PTS), transketolase and others. Several genes encoding the proteins that probably play a role in the transport and degradation of beta-glucans including the ABC transporter gene, PTS gene and membrane protein gene underwent real time RT-PCR for transcriptional analysis. Hydrolytic enzyme activity assay showed that intracellular beta-1, 3 glucanase activity was present when B. infantis was incubated with beta-glucans from seaweed and mushroom. / Based on the above results, a model for beta-glucan catabolism in B. infantis was proposed. The fbeta -glucan molecules might be captured and imported inside the bacterial cells either by ABC transporters or PTS. They were then subjected to hydrolysis by glucan beta-1, 3 glucosidase. The released glucose molecules were readily incorporated into the central fermentation pathway, the 'bifid shunt', in which the hydrolyzed residues were further degraded or exported. This study has deepened our understanding on the fermentation of beta-glucans by bifidobacteria and demonstrated the potential of beta-glucans to be used as a novel prebiotic. / Zhao, Jinyang. / Source: Dissertation Abstracts International, Volume: 73-08, Section: B, page: . / Adviser: Peter Chi-Keung Cheung. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 147-162). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thèse (M.Sc.)--Université Laval, 2007. / Bibliogr.: f. [85]-90. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Thèse (Ph.D.)--Université Laval, 2008. / Bibliogr.: f. [150]-162. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 89-102). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Typescript. Vita. Includes bibliographical references (leaves 89-102). Also available on the Internet.