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A rápida perceção dos efeitos benéficos que os microrganismos probióticos possuem na promoção da saúde do consumidor conduziu ao aumento da procura de potenciais veículos para a sua incorporação. As matrizes láteas associam-se, normalmente, ao consumo de probióticos sendo a adição de matrizes de fruta uma alternativa viável à manutenção da sua viabilidade. A fruta é rica em nutrientes, fibras e açúcares, apesar da presença de compostos antimicrobianos que podem constituir a sua principal desvantagem. Assim, urge a formulação de uma matriz de fruta capaz de permitir a estabilidade de culturas probióticas durante o seu processamento e armazenamento. O presente trabalho teve como objetivos, por um lado, avaliar a estabilidade de duas estirpes comerciais - Lactobacillus paracasei subsp. paracasei L. casei 431® e Bifidobacterium animalis ssp. lactis BB-12® (forma liofilizada e congelada) - quando incorporadas em preparados de fruta distintos, em termos de viabilidade celular, pH e ºBrix, e por outro, avaliar o efeito das matrizes de fruta sobre a estabilidade das estirpes probióticas quando submetidas a condições simuladas da passagem pelo trato gastrointestinal (TGI). As estirpes em estudo foram cultivadas, centrifugadas e inoculadas em cada preparado de fruta, previamente pasteurizado, a 1% (m/m). Após homogeneização, o preparado de fruta inoculado foi acondicionado sob refrigeração a 5 ± 2˚C, durante um período de 28 dias. Durante este intervalo foi monitorizado o número de células viáveis aos 0, 3, 5, 7, 14, 21 e 28 dias por sementeira de diluições apropriadas em MRS agar, bem como o pH e o ºBrix dos preparados. Os preparados de morango e de alperce foram os que melhor contribuíram para a estabilidade das duas estirpes e o B. animalis BB-12®, na sua forma congelada, foi a estirpe com maior viabilidade. Os ensaios de estabilidade dos preparados de fruta na passagem pelo TGI foram realizados simulando as condições do estômago (pH entre 1,5 e 2,0) e do intestino (pH entre 6,0 e 6,2), adicionando-se ácido clorídrico 1M e hidróxido de sódio 0,25M com sais biliares a 0,3% (m/v), respetivamente, sendo incubados a 37 ± 1,5˚C num intervalo de 60 e 120 minutos. Entre cada intervalo de tempo foram recolhidas amostras para efeitos de enumeração. Constatou-se que as estirpes estudadas sobrevivem à passagem pelo TGI, sendo assim capazes de exercer os seus efeitos benéficos. Por último, analisou-se o comportamento da estirpe B. animalis BB-12® em iogurtes inoculados com os 3 preparados de fruta. Durante um período de 2 meses a matriz de fruta inoculada foi incorporada mensalmente no iogurte. Após homogeneização, o iogurte foi acondicionado sob refrigeração 5 ± 2˚C, durante 28 dias. Realizou-se a monitorização do número de células viáveis aos 0, 7, 14 e 28 dias, bem como o registo do valor de pH e ºBrix. A matriz de alperce revelou-se ser a mais adequada para a manutenção da viabilidade da estirpe probiótica aquando da sua incorporação no iogurte.
The fast perception regarding the beneficial effects that probiotic microorganisms have to promote consumer’s health has led to an increased demand of potential vehicles for their incorporation. Diary matrices are normally associated with consumption of probiotics and the addition of fruit matrices is a viable alternative to the maintenance of its viability. Fruit is rich in nutrients, dietetic fibers and sugars, despite the presence of antimicrobial compounds which constitute their main disadvantage. In this context, it is extremely important to formulate a universal fruit matrix capable of enabling the stability of probiotic cultures during processing and storage. The aims of this study were the stability evaluation of two commercial stains - Lactobacillus paracasei subsp. paracasei L. casei 431® e Bifidobacterium animalis ssp. lactis BB-12® (lyophilized and frozen state) – when incorporated in distinct fruit preparations, in terms of viability evolution, pH and ºBrix, and the evaluation of the fruit matrices effect in the strains stability when subjected to simulated conditions of passage through the gastrointestinal tract (GIT). The strains were cultivated, centrifuged and inoculated in each fruit preparation, previously pasteurized, at 1% (w/w). After homogenization, the matrix was stored under refrigeration at 5 ± 2˚C, during 28 days. During this period, the numbers of viable cells were monitored at 0, 3, 5, 7, 14, 21 and 28 days by plating dilutions on appropriate MRS agar, as well as the pH and ºBrix of fruit preparations. The fruits which better contributed to the stability of both strains were strawberry and apricot and also B. animalis BB-12® was the strain that showed greater viability in its frozen form. Gastrointestinal assays were performed by simulating the stomach (pH between 1.5 and 2.0) and intestinal (pH between 6.0 and 6.2), conditions adding hydrochloric acid 1M and sodium hydroxide 0.25M with bile salts at 0.3% (w/v), respectively, incubating at 37˚C within 60 and 120 minutes intervals. Between each interval samples were taken for enumeration purposes. It was found that the strains under study are capable of exerting their beneficial functions in the host, since they can withstand exposure to GIT conditions. Finally, it was analyzed the behavior of strain B. animalis BB-12® in yoghurts inoculated with 3 fruit preparations. For a period of 2 month, the fruit matrix inoculated was monthly incorporated in the yogurt. After the yogurt homogenization, the matrix was stored under refrigeration at 5 ± 2˚C over a period of 28 days. Then, the number of viable cells was monitored at 0, 7, 14 and 28 days, with pH and ºBrix registration. The apricot matrix proved to be the most suitable for maintaining the viability of the probiotic strain upon its incorporation into the yogurt.
The fast perception regarding the beneficial effects that probiotic microorganisms have to promote consumer’s health has led to an increased demand of potential vehicles for their incorporation. Diary matrices are normally associated with consumption of probiotics and the addition of fruit matrices is a viable alternative to the maintenance of its viability. Fruit is rich in nutrients, dietetic fibers and sugars, despite the presence of antimicrobial compounds which constitute their main disadvantage. In this context, it is extremely important to formulate a universal fruit matrix capable of enabling the stability of probiotic cultures during processing and storage. The aims of this study were the stability evaluation of two commercial stains - Lactobacillus paracasei subsp. paracasei L. casei 431® e Bifidobacterium animalis ssp. lactis BB-12® (lyophilized and frozen state) – when incorporated in distinct fruit preparations, in terms of viability evolution, pH and ºBrix, and the evaluation of the fruit matrices effect in the strains stability when subjected to simulated conditions of passage through the gastrointestinal tract (GIT). The strains were cultivated, centrifuged and inoculated in each fruit preparation, previously pasteurized, at 1% (w/w). After homogenization, the matrix was stored under refrigeration at 5 ± 2˚C, during 28 days. During this period, the numbers of viable cells were monitored at 0, 3, 5, 7, 14, 21 and 28 days by plating dilutions on appropriate MRS agar, as well as the pH and ºBrix of fruit preparations. The fruits which better contributed to the stability of both strains were strawberry and apricot and also B. animalis BB-12® was the strain that showed greater viability in its frozen form. Gastrointestinal assays were performed by simulating the stomach (pH between 1.5 and 2.0) and intestinal (pH between 6.0 and 6.2), conditions adding hydrochloric acid 1M and sodium hydroxide 0.25M with bile salts at 0.3% (w/v), respectively, incubating at 37˚C within 60 and 120 minutes intervals. Between each interval samples were taken for enumeration purposes. It was found that the strains under study are capable of exerting their beneficial functions in the host, since they can withstand exposure to GIT conditions. Finally, it was analyzed the behavior of strain B. animalis BB-12® in yoghurts inoculated with 3 fruit preparations. For a period of 2 month, the fruit matrix inoculated was monthly incorporated in the yogurt. After the yogurt homogenization, the matrix was stored under refrigeration at 5 ± 2˚C over a period of 28 days. Then, the number of viable cells was monitored at 0, 7, 14 and 28 days, with pH and ºBrix registration. The apricot matrix proved to be the most suitable for maintaining the viability of the probiotic strain upon its incorporation into the yogurt.