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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.
51

Influência da adição de subproduto de fruta em produto de soja potencialmente probiótico tipo frozen yogurt sobre o bioenriquecimento com riboflavina / Influence of the addition of a fruit by-product on the bio-enrichment with riboflavin of a frozen yogurt-like soy product

Garutti, Luiz Henrique Groto 14 June 2019 (has links)
As bactérias probióticas, além de diversos possíveis efeitos benéficos à saúde do consumidor, podem apresentar um potencial para bioenriquecer alimentos através da produção de compostos de interesse nutricional e para a saúde durante a etapa de fermentação. Nesse sentido, a produção de vitaminas naturais por bactérias láticas, incluindo as probióticas, emerge como alternativa promissora ao uso de vitaminas sintéticas para a fortificação de alimentos. O uso de substratos vegetais para estimular a produção de vitaminas do grupo B por probióticos compreende uma solução sustentável para o reaproveitamento desse material oriundo, principalmente, do processamento de frutas. Os subprodutos de frutas são compostos por diversas substâncias bioativas e a incorporação desses ingredientes para o desenvolvimento de alimentos com alto valor agregado representa uma solução sustentável para o seu reaproveitamento. Sendo assim, o presente trabalho tem como objetivo avaliar a influência da adição de subproduto de fruta no bioenriquecimento de um produto de soja fermentado tipo frozen yogurt probiótico com riboflavina (vitamina B2). Para este fim, a capacidade de diferentes cepas de Streptococcus thermophilus, Lactobacillus spp. e Bifidobacterium spp. em produzir riboflavina foi avaliada, utilizando-se um meio de cultura desprovido desta vitamina (Riboflavin Assay médium, RAM). Paralelamente, foi avaliada a capacidade dessas cepas em fermentar os subprodutos de uva (Vitis spp.) e de caju (Anacardium occidentale L.). De acordo com os resultados de produção de riboflavina em RAM e de fermentação dos subprodutos de fruta, foram selecionadas as cepas para o desenvolvimento do produto fermentado de soja tipo frozen yogurt (FY). Dentre as cepas testadas, os Streptococcus thermophilus (ST-M6, TA-40 e TH-04) e o probiótico Lactobacillus fermentum PCC apresentaram potencial para produzir riboflavina em meio RAM. As cepas PCC e ST-M6 mostraram-se capazes de fermentar os subprodutos de caju e de uva (atingindo 8,25 e 8,40 log UFC/mL, respectivamente, para PCC e ST-M6 com subproduto de uva e 4,82 e 8,38 log UFC/mL, respectivamente, para PCC e ST-M6 com subproduto de caju em 24h). Por outro lado, as cepas TH-4 e TA-40 fermentaram apenas o subproduto de uva (atingindo 6,87 e 7,24 log UFC/mL, respectivamente, em 24h). Sendo assim, foram selecionadas as cepas de St. Thermophilus ST-M6, TH-4 e TA-40 e a de Lactobacillus fermentum PCC para a aplicação nos produtos visando o seu bioenriquecimento. O FY suplementado com 1% de subproduto de uva foi preparado, utilizando-se as cepas em co-cultura totalizando 3 combinações, ou seja, entre Lb. Fermentum PCC e as 3 cepas de St. Thermophilus. As formulações de FY foram capazes de atingir uma concentração de riboflavina de 8,40 e de 5,18 µg/mL (combinando TA-40 e PCC) em 60 dias, respectivamente, sem e com o subproduto de uva. Já a associação de STM6 e PCC, sem o subproduto, resultou na menor concentração obtida (2,30 µg/mL), atingindo 5,62 µg/mL na presença do subproduto. Dessa maneira aplicação do subproduto de uva para estimular a produção de riboflavina só foi efetiva para a formulação que combinou St. Thermophilus ST-M6 e Lb. Fermentum PCC. / Probiotic bacteria, in addition to several possible beneficial effects on the consumers health, may present a potential to bioenrich food through the production of compounds of nutritional and health interest during fermentation. In this sense, the production of natural vitamins by lactic acid bacteria, including probiotics, emerges as a promising alternative to the use of synthetic vitamins for food fortification. The use of vegetable substrates to stimulate the production of B-group vitamins by probiotics comprises a sustainable solution for the reuse of this material coming mainly from fruit processing. Fruit by-products are composed of various bioactive substances and the incorporation of these ingredients into the development of high value-added foods represents a sustainable solution for their reuse. Therefore, the present study aims to evaluate the influence of the addition of fruit by-product on the bio-enrichment of a probiotic frozen yogurt-like fermented soy product with riboflavin (vitamin B2). For this purpose, the ability of different strains of Streptococcus thermophiles, Lactobacillus spp. and Bifidobacterium spp. in producing riboflavin was evaluated using a culture medium devoid of this vitamin (Riboflavin Assay Medium, RAM). In addition, we evaluated the ability of these strains to ferment the grape (Vitis spp.) and cashew (Anacardium occidentale L.) by-products. According to the results of riboflavin production in RAM and fermentation of fruit by-products, strains were selected for the development of a fermented frozen yogurt-like (FY) soybean product. Among the strains tested, Streptococcus thermophiles (ST-M6, TA-40, and TH-04) and the probiotic Lactobacillus fermentum PCC had the potential to produce riboflavin in RAM medium. The strains PCC and ST-M6 were able to ferment the cashew and the grape byproducts (reaching 8.25 and 8.40 log CFU/mL, respectively, for PCC and ST-M6 with the grape by-product, and 4.82 and 8. 38 log CFU/mL, respectively, for PCC and STM6 with cashew by-product in 24h). On the other hand, TH-4 and TA-40 fermented only the grape by-product (reaching 6.87 and 7.24 log CFU/mL, respectively, in 24h). Therefore, the strains St. thermophiles ST-M6, TH-4, and TA-40 and the strain Lactobacillus fermentum PCC were selected for application in the products for bioenrichment. The FY supplemented with 1% of grape by-product was prepared using the co-culture strains comprising three combinations between Lb. fermentum PCC and the three strains of St. thermophiles. The FY formulations were capable of producing 8.40 and 5.18 µg/mL (combination of TA-40 and PCC) in 60 days, respectively, without and with the grape by-product. However, the association of ST-M6 and CCP, without the by-product, resulted in the lowest concentration obtained (2.30 µg/mL), achieving 5.62 µg/mL in the presence of the by-product. Thus, the application of the grape byproduct in order to stimulate the production of riboflavin was only effective for the formulation that combined St. thermophiles ST-M6 and Lb. fermentum PCC.
52

Vitamin B12 and folate enrichment of kefir by Propionibacterium freudenreichii and Streptococcus thermophilus strains

Morkel, Ryan Andrew January 2016 (has links)
Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2016. / In South Africa malnutrition exists due to inadequate dietary intake of micronutrients which is one of the major causes of vitamin deficiencies leading to disease. The treatment of malnutrition over the past years has been a considerable burden on the South African economy. Therefore, food fortification is one of the current strategies used to minimize malnutrition by increasing the nutritional value of staple foods. Commercial dairy products and pharmaceutical nutritional products (food supplements) in South Africa have been developed and produced for affluent consumers. Hence the need to develop an affordable fortified dairy product for the majority of South Africans prompted this study aimed at using a “naturally” fortified kefir beverage with vitamin B12 and folate to increase B-vitamins levels. Since Propionibacterium freudenreichii and Streptococcus thermophilus are known to be good producers of vitamin B12 and folate, respectively, and propionibacteria has the ability to grow symbiotically in the presence of lactic acid bacteria, the inclusion of these organisms with the kefir grains was an achievable objective. In order to conduct the analysis of vitamin B12 and folate in the samples, sample extraction and HPLC assay techniques were developed. The extraction of vitamin B12 and folate were achieved by using KCN extraction buffer and the trienzymatic method, respectively. The samples were also subjected to purification and concentration using solid phase extraction for optimum results. All standards and samples were flushed with nitrogen gas and stored for a maximum of 2 weeks at –20°C to prevent B-vitamin deterioration. The HPLC assembly for the vitamin B12 analysis included a Luna C18 column and a diode array detector (DAD) for the detection and quantification. For the folate analysis it included a Zorbax SB-C18 and Luna C18 columns in tandem and the fluorescence detector (FLD) was used for the detection and quantification of THF, 5-CH3-THF and 5-CHO-THF, while the DAD was used for PGA and pteroyltri-γ-L-glutamic acid concentration in the samples.
53

Structural and Interaction Studies of Bacterial Polysaccharides by NMR Spectroscopy

Nordmark, Eva-Lisa January 2004 (has links)
<p>An introduction to bacterial polysaccharides and the methods for structural determination are described in the first two parts of the thesis.</p><p>In a structural elucidation of bacterial polysaccharides NMR experiments are important as is component analysis. A short description of immunochemical methods such as enzyme immunoassays is included. Two NMR techniques used for interaction studies, trNOE and STD NMR, are also discussed. </p><p>The third part of the thesis discusses and summarizes the results from the included papers. The structures of the exopolysaccharides produced by two lactic acid bacteria are determined by one- and two dimensional NMR experiments. One is a heteropolysaccharide produced by <i>Streptococcus thermophilus</i> and the other a homopolysaccharide produced by <i>Propionibacterium freudenreichii</i>. The structure of an acidic polysaccharide from a marine bacterium with two serine residues in the repeating unit is also investigated. The structural and immunological relationship between two O-antigenic polysaccharides from <i>Escherichia coli</i> strain 180/C3 and O5 is discussed and investigated. Finally, interaction studies of an octasaccharide derived from the <i>Salmonella enteritidis</i> O-antigen and a bacteriophage are described which were performed with NMR experiments.</p>
54

Structural and Interaction Studies of Bacterial Polysaccharides by NMR Spectroscopy

Nordmark, Eva-Lisa January 2004 (has links)
An introduction to bacterial polysaccharides and the methods for structural determination are described in the first two parts of the thesis. In a structural elucidation of bacterial polysaccharides NMR experiments are important as is component analysis. A short description of immunochemical methods such as enzyme immunoassays is included. Two NMR techniques used for interaction studies, trNOE and STD NMR, are also discussed. The third part of the thesis discusses and summarizes the results from the included papers. The structures of the exopolysaccharides produced by two lactic acid bacteria are determined by one- and two dimensional NMR experiments. One is a heteropolysaccharide produced by Streptococcus thermophilus and the other a homopolysaccharide produced by Propionibacterium freudenreichii. The structure of an acidic polysaccharide from a marine bacterium with two serine residues in the repeating unit is also investigated. The structural and immunological relationship between two O-antigenic polysaccharides from Escherichia coli strain 180/C3 and O5 is discussed and investigated. Finally, interaction studies of an octasaccharide derived from the Salmonella enteritidis O-antigen and a bacteriophage are described which were performed with NMR experiments.
55

Characterization Of Lactobacillus Delbrueckii Subspecies Bulgaricus And Streptococcus Thermophilus As Lactic Cultures Isolated From Traditional Turkish Yogurts And Subtyping Of Streptococcus Thermophilus Using Crispr Analysis And Mlst

Altay Dede, Neslihan 01 June 2010 (has links) (PDF)
Yogurt is a characteristic fermented dairy product of Turkey and Bulgaria and its popularity has been increasing all over the world. Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lactobacillus bulgaricus) are used together as starter culture in production of yogurt. The objective of this study was to isolate and characterize yogurt cultures from traditionally produced yogurts (i.e. produced without using commercial starter cultures) and to search the genotypic diversity within traditional S. thermophilus isolates. Yogurt cultures were isolated from traditionally produced yogurts collected from different regions of Turkey and identified biochemically. Acidification ability of the isolates was examined and the cultures giving best acidifying rates were further subjected to a selection in terms of their acetaldehyde production ability. Then, phage resistance and proteolytic activity of chosen isolates were tested. Finally, twenty-five L. bulgaricus and twenty-two S. thermophilus isolates were selected as cultures having best technological properties. Furthermore, subtyping studies were carried out to indicate strain diversity among isolates. S. thermophilus was selected as target organism for subtyping in this study. Clustered regularly interspaced short palindromic repeats (CRISPR) loci are highly polymorphic genetic regions, which are composed of partially palindromic direct repeats interspaced by sequences called spacers. In order to characterize S. thermophilus isolates genotypically, CRISPR1 locus of the isolates were analyzed. Additionally, nineteen isolates selected after CRISPR1 analysis were characterized using multilocus sequence typing (MLST). This provided to compare CRISPR1 analysis with MLST as a typing method. According to CRISPR1 analysis S. thermophilus isolates were grouped into 6 main clusters with a total of 15 sub-clusters. MLST results demonstrated an evolutionary relationship among these strains compatible with that derived from the CRISPR1 analysis.
56

Charakterizace mikroorganismů v jogurtech a probiotických výrobcích / Microbial characterization of yoghurts and probiotic foods.

Kocourková, Hana January 2008 (has links)
Zvýšená konzumace fermentovaných mléčných výrobků v posledních letech vede k zavádění nových výrobků na trh. Funkční a probiotické produkty jsou v dnešní době také hojně rozšířeny. Cílem diplomové práce bylo posoudit mikrobiální kvalitu komerčních jogurtů a nefarmakologických probiotických výrobků. Bylo zkoumáno 24 vzorků jogurtů a 8 vzorků probiotických mléčných výrobků. Pozornornost byla zaměřena zvláště na kvantifikaci mikroorganismů v jednotlivých výrobcích a na sledování viability buněk. Většina mléčných produktů obsahovala počty odpovídající minimální požadované hodnotě 1x107cfu/ml. Nicméně byly objeveny produkty, které neobsahovaly živé bakterie nebo obsahovaly jen jejich menší množství. To platí zejména pro běžné jogurty. Probiotické mléčné výrobky v zásadě obsahovaly větší množství bakterií než jogurty, protože je u nich navíc požadováno 1x106cfu/ml minimálního množství specifických bakterií jiných než jogurtových startovacích kultur. Isoláty z fermentovaných mléčných výrobků byly identifikovány jako Streptococcus thermophilus and Lactobacillus spp. Isoláty byly poté rozlišeny na jednotlivé kmeny pomocí RAPD použitím tří různých primerů. Byla zjištěna velká různorodost mezi kmeny rodu Lactobacillus spp. používaných různými podniky.
57

Identifikace bakterií mléčného kvašení v kysaných mléčných výrobcích s využitím amplifikačních metod / Identification of lactic acid bacteria in fermented dairy products using amplification methods

Tycová, Martina January 2008 (has links)
Polymerase chain reaction (PCR) is molecular diagnostic method which allows the identification of lactic acid bacteria used in food industry. In this work species-specific PCR primers (targeted on highly conserved 16S rDNA region) were used for identification of bacteria of species Streptoccocus thermophilus in 10 randomly commercially accessible fermented milk products and for identification of species Streptococcus thermophilus in 25 lyophilisates collected in Culture Collection of Dairy Microorganisms Laktoflora (CCDM, Tábor, Czech Republic). The PCR products (968 bp) were detected using electrophoresis in 1,2 % agarose gel. Bacterial DNA was isolated from crude cell lysates by magnetic carriers P(HEMA co GMA) containing carboxyl groups. DNA was reversibly bind on their surface in the presence of high concentrations of poly(ethylene glycol) (PEG 6000) and sodium chloride. Phenol extraction of DNA was used as control. Streptococcus thermophilus strains were identificated using PCR in all analysed samples.
58

Développement de méthodes de fouille de données basées sur les modèles de Markov cachés du second ordre pour l'identification d'hétérogénéités dans les génomes bactériens / Data Mining methods based on second-order Hidden Markov Models to identify heterogeneities into bacteria genomes

Eng, Catherine 15 June 2010 (has links)
Les modèles de Markov d’ordre 2 (HMM2) sont des modèles stochastiques qui ont démontré leur efficacité dans l’exploration de séquences génomiques. Cette thèse explore l’intérêt de modèles de différents types (M1M2, M2M2, M2M0) ainsi que leur couplage à des méthodes combinatoires pour segmenter les génomes bactériens sans connaissances a priori du contenu génétique. Ces approches ont été appliquées à deux modèles bactériens afin d’en valider la robustesse : Streptomyces coelicolor et Streptococcus thermophilus. Ces espèces bactériennes présentent des caractéristiques génomiques très distinctes (composition, taille du génome) en lien avec leur écosystème spécifique : le sol pour les S. coelicolor et le milieu lait pour S. thermophilus / Second-order Hidden Markov Models (HMM2) are stochastic processes with a high efficiency in exploring bacterial genome sequences. Different types of HMM2 (M1M2, M2M2, M2M0) combined to combinatorial methods were developed in a new approach to discriminate genomic regions without a priori knowledge on their genetic content. This approach was applied on two bacterial models in order to validate its achievements: Streptomyces coelicolor and Streptococcus thermophilus. These bacterial species exhibit distinct genomic traits (base composition, global genome size) in relation with their ecological niche: soil for S. coelicolor and dairy products for S. thermophilus. In S. coelicolor, a first HMM2 architecture allowed the detection of short discrete DNA heterogeneities (5-16 nucleotides in size), mostly localized in intergenic regions. The application of the method on a biologically known gene set, the SigR regulon (involved in oxidative stress response), proved the efficiency in identifying bacterial promoters. S. coelicolor shows a complex regulatory network (up to 12% of the genes may be involved in gene regulation) with more than 60 sigma factors, involved in initiation of transcription. A classification method coupled to a searching algorithm (i.e. R’MES) was developed to automatically extract the box1-spacer-box2 composite DNA motifs, structure corresponding to the typical bacterial promoter -35/-10 boxes. Among the 814 DNA motifs described for the whole S. coelicolor genome, those of sigma factors (B, WhiG) could be retrieved from the crude data. We could show that this method could be generalized by applying it successfully in a preliminary attempt to the genome of Bacillus subtilis
59

Influência da associação de culturas probióticas sobre as características de queijo petit-suisse / Influence of the combination of probiotic cultures on petit-suisse cheese features

Lucas Campana Pereira 05 October 2007 (has links)
A possibilidade de se obter um produto com grande aceitabilidade nacional, principalmente voltado ao público infantil, com propriedades microbiológicas, nutricionais, físico-químicas e organolépticas ótimas associadas aos benefícios creditados aos probióticos é bastante promissora. Assim, o presente trabalho teve como objetivo verificar a influência do emprego de culturas probióticas compostas pelos microrganismos Lactobacillus acidophilus La-5 e Bifidobacterium animalis subsp. lactis BL04 isolados e em co-cultura, em queijo tipo petit-suisse processado com a adição de Streptococcus thermophilus como cultura starter, sobre as características do produto, ao longo do seu armazenamento refrigerado. Quatro tratamentos de queijo petit-suisse foram estudados (em triplicata): T1 (controle - Streptococcus thermophilus ST), T2 (ST + Lactobacillus acidophilus La-5), T3 (ST + B. animalis subsp. lactis BL04) e T4 (ST + La-5 + BL04) e armazenados a 4±1ºC. Foram avaliados parâmetros microbiológicos (população de probióticos, starter e contaminantes), de textura, físico-químicos e sensoriais (aceitabilidade). As análises sensoriais foram realizadas após 7 e 14 dias e as demais análises, após 1, 7, 14, 21 e 28 dias de armazenamento dos produtos a 4±1oC. As populações dos probióticos estiveram sempre superiores ao mínimo recomendado para um alimento probiótico, tendo variado de 7,22 a 7,60 log UFC/g e de 8,56 a 8,72 log UFC/g durante o armazenamento, para L. acidophilus e B. animalis subsp. lactis, respectivamente. A cultura starter apresentou populações entre 9,20 e 9,61 log UFC/g no mesmo período. As populações máximas para coliformes totais, bolores e leveduras foram de 2,79 e 3,60 log UFC/g, respectivamente. Os valores de pH diminuíram ao longo do armazenamento, devido à atividade dos microrganismos acidificantes presentes. A umidade variou entre 67,16% e 70,26% no mesmo período. Todos os queijos apresentaram queda na dureza e adesividade ao longo do armazenamento. Na análise sensorial, o queijo T4, com a co-cultura, revelou uma aceitabilidade significativamente maior em todos os atributos avaliados (p<0,05). Após 14 dias de armazenamento, o queijo T3 apresentou uma aceitabilidade significativamente inferior aos demais (p<0,05). A suplementação de queijo petit-suisse T4 com Lactobacillus acidophilus La-5 e B. animalis subsp. lactis BL04 em co-cultura com a cultura starter resultou em um produto com excelente potencial comercial, tendo apresentado características sensoriais, microbiológicas e de textura bastante vantajosas. / The possibility of obtaining a product with wide acceptability in Brazil, and which is mainly targeted at children and has excellent microbiological, nutritional, physical-chemical and organoleptic properties associated with the benefits ascribed to probiotic microorganisms is rather promising. Thus, the aim of the present work was to examine the influence of the probiotic cultures of Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp. lactis BL04, isolated and in co-culture, on the characteristics of petit-suisse cheese produced with the addition of Streptococcus thermophilus as a starter culture, throughout the period of refrigerated storage. Four petit-suisse cheese trials were studied (in triplicates): T1 (control - Streptococcus thermophilus ST), T2 (ST + Lactobacillus acidophilus La-5), T3 (ST + Bifidobacterium animalis subsp. lactis BL04) and T4 (ST + La-5 + BL04) and stored at 4±1ºC. Microbiological (population of probiotic bacteria, of the starter and of contaminants), instrumental texture, physical-chemical and sensory (acceptability test) parameters were evaluated. The sensory evaluation was carried out after 7 and 14 days of storage of the products at 4±1ºC, and further analyses were carried out after 1, 7, 14, 21 and 28 days of storage. The populations of the probiotics always remained above the minimum level recommended for a probiotic food, having varied between 7.22 and 7.60 log CFU/g, and between 8.72 and 8.56 log CFU/g during storage, respectively, for L. acidophilus and B. animalis subsp. lactis. The starter culture presented populations between 9.20 and 9.61 log CFU/g in the same period. Coliforms, yeasts and molds presented maximum populations of, respectively, 2.79 and 3.60 log CFU/g. The pH values decreased throughout storage, due to the activity of the acidifying microorganisms present. The moisture ranged from 67.16% up to 70.26% in the same period. All the cheeses studied presented a decrease in hardness and adhesiveness throughout storage. Both after 7 and 14 days, cheese T4 presented the highest sensory acceptance for all attributes evaluated and differed significantly from the other cheeses (p<0.05). After 14 days of storage, cheese T3 presented the lowest acceptance and differed significantly from the other cheeses (p<0.05). The supplementation of petit-suisse cheese T4 with both L. acidophilus and B. animalis subsp. lactis in coculture with a starter culture resulted in a product with excellent market potential, as it presented favorable sensory, microbiological and texture features.
60

Influência da associação de culturas probióticas sobre as características de queijo petit-suisse / Influence of the combination of probiotic cultures on petit-suisse cheese features

Pereira, Lucas Campana 05 October 2007 (has links)
A possibilidade de se obter um produto com grande aceitabilidade nacional, principalmente voltado ao público infantil, com propriedades microbiológicas, nutricionais, físico-químicas e organolépticas ótimas associadas aos benefícios creditados aos probióticos é bastante promissora. Assim, o presente trabalho teve como objetivo verificar a influência do emprego de culturas probióticas compostas pelos microrganismos Lactobacillus acidophilus La-5 e Bifidobacterium animalis subsp. lactis BL04 isolados e em co-cultura, em queijo tipo petit-suisse processado com a adição de Streptococcus thermophilus como cultura starter, sobre as características do produto, ao longo do seu armazenamento refrigerado. Quatro tratamentos de queijo petit-suisse foram estudados (em triplicata): T1 (controle - Streptococcus thermophilus ST), T2 (ST + Lactobacillus acidophilus La-5), T3 (ST + B. animalis subsp. lactis BL04) e T4 (ST + La-5 + BL04) e armazenados a 4±1ºC. Foram avaliados parâmetros microbiológicos (população de probióticos, starter e contaminantes), de textura, físico-químicos e sensoriais (aceitabilidade). As análises sensoriais foram realizadas após 7 e 14 dias e as demais análises, após 1, 7, 14, 21 e 28 dias de armazenamento dos produtos a 4±1oC. As populações dos probióticos estiveram sempre superiores ao mínimo recomendado para um alimento probiótico, tendo variado de 7,22 a 7,60 log UFC/g e de 8,56 a 8,72 log UFC/g durante o armazenamento, para L. acidophilus e B. animalis subsp. lactis, respectivamente. A cultura starter apresentou populações entre 9,20 e 9,61 log UFC/g no mesmo período. As populações máximas para coliformes totais, bolores e leveduras foram de 2,79 e 3,60 log UFC/g, respectivamente. Os valores de pH diminuíram ao longo do armazenamento, devido à atividade dos microrganismos acidificantes presentes. A umidade variou entre 67,16% e 70,26% no mesmo período. Todos os queijos apresentaram queda na dureza e adesividade ao longo do armazenamento. Na análise sensorial, o queijo T4, com a co-cultura, revelou uma aceitabilidade significativamente maior em todos os atributos avaliados (p<0,05). Após 14 dias de armazenamento, o queijo T3 apresentou uma aceitabilidade significativamente inferior aos demais (p<0,05). A suplementação de queijo petit-suisse T4 com Lactobacillus acidophilus La-5 e B. animalis subsp. lactis BL04 em co-cultura com a cultura starter resultou em um produto com excelente potencial comercial, tendo apresentado características sensoriais, microbiológicas e de textura bastante vantajosas. / The possibility of obtaining a product with wide acceptability in Brazil, and which is mainly targeted at children and has excellent microbiological, nutritional, physical-chemical and organoleptic properties associated with the benefits ascribed to probiotic microorganisms is rather promising. Thus, the aim of the present work was to examine the influence of the probiotic cultures of Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp. lactis BL04, isolated and in co-culture, on the characteristics of petit-suisse cheese produced with the addition of Streptococcus thermophilus as a starter culture, throughout the period of refrigerated storage. Four petit-suisse cheese trials were studied (in triplicates): T1 (control - Streptococcus thermophilus ST), T2 (ST + Lactobacillus acidophilus La-5), T3 (ST + Bifidobacterium animalis subsp. lactis BL04) and T4 (ST + La-5 + BL04) and stored at 4±1ºC. Microbiological (population of probiotic bacteria, of the starter and of contaminants), instrumental texture, physical-chemical and sensory (acceptability test) parameters were evaluated. The sensory evaluation was carried out after 7 and 14 days of storage of the products at 4±1ºC, and further analyses were carried out after 1, 7, 14, 21 and 28 days of storage. The populations of the probiotics always remained above the minimum level recommended for a probiotic food, having varied between 7.22 and 7.60 log CFU/g, and between 8.72 and 8.56 log CFU/g during storage, respectively, for L. acidophilus and B. animalis subsp. lactis. The starter culture presented populations between 9.20 and 9.61 log CFU/g in the same period. Coliforms, yeasts and molds presented maximum populations of, respectively, 2.79 and 3.60 log CFU/g. The pH values decreased throughout storage, due to the activity of the acidifying microorganisms present. The moisture ranged from 67.16% up to 70.26% in the same period. All the cheeses studied presented a decrease in hardness and adhesiveness throughout storage. Both after 7 and 14 days, cheese T4 presented the highest sensory acceptance for all attributes evaluated and differed significantly from the other cheeses (p<0.05). After 14 days of storage, cheese T3 presented the lowest acceptance and differed significantly from the other cheeses (p<0.05). The supplementation of petit-suisse cheese T4 with both L. acidophilus and B. animalis subsp. lactis in coculture with a starter culture resulted in a product with excellent market potential, as it presented favorable sensory, microbiological and texture features.

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