No abstract

-Survival of starters of yogurt in the digestive tract of rabbits. Yogurt presents a probiotic interest for the consumer. Most of its properties are linked to the ingestion of living lactic acid bacteria (starters), some of which can survive during the crossing of the digestive tract. Our study is based on this perspective. The results obtained show that Streptococcus thermophilus (Sc. t.) and Lactobacillus delbrueckii ssp. bulgaricus (Lb. b.) were relatively resistant to gastric acid, bile salts and intestinal flora. These starters were found at significant concentrations and at different levels of the digestive tract as the rabbits fed with a standard diet supplemented with yogurt (YB3). After stopping addition of the Sc. t. and Lb. b. yogurt to the diet of the rabbits, the number of Sc. t. and Lb. b. remained at an acceptable level for 24 h; the numbers were about 10 5 , 10 7 cells . mL -1 and 10 7 cells . g -1 wet faeces for the stomach, the duodenum and the large intestine, respectively. Sc. thermophilus / Lb. delbrueckii ssp. bulgaricus / gastric acid / bile salt / intestinal flora Résumé -Le yaourt présente un intérêt probiotique pour le consommateur. La plupart de ses proprié-tés sont liées à l'ingestion des ferments vivants, dont certains peuvent survivre lors de la traversée du tube digestif. C'est dans cette optique que notre étude a été réalisée. Les résultats obtenus montrent que Streptococcus thermophilus (Sc. t.) et Lactobacillus delbrueckii ssp. bulgaricus (Lb. b.) sont relativement résistants à l'acidité gastrique, aux sels biliaires et à la flore intestinale. Ces ferments se retrouvent à des concentrations importantes, à différents niveaux du tube digestif, tant que les lapins consomment du yaourt. Après l'arrêt de l'ingestion du yaourt, la concentration de Sc. t. et de Lb. b. reste à un niveau acceptable, pendant 24 heures, avec une concentration voisine de 10 5 cellules . mL -1 au niveau de l'estomac, 10 7 cellules . mL -1 au niveau du duodénum et 10 7 cellules . g -1 de fèces au niveau du gros intestin.

For the first time, this study presented the use of raw locust bean gum (LBG) as a prebiotic, with one probiotic strain in synbiotic fermented milk or combined with Na-alginate as a biopolymer, for a targeted release of bacteria under colon-like conditions. For this purpose, the fermentative characteristics (biomass, pH), bacterial survival, and developed viscosities of the stored fermented milks were determined. The survival rates of microencapsulated bacteria using the emulsion technique under simulated gastrointestinal conditions (stomach: pH 2 + 0.3% pepsin; colon: pH 6.5 + 1% pancreatin + 0.3% bile) were also evaluated. Results showed that all the tested bacteria maintained better biomass and acidifying activities in the presence of LBG, especially at 2%. During cold storage, the viscosities of the LBG-fermented milks were regulated and better appreciated, especially at 2%. Lactobacillus rhamnosus LbRE-LSAS and Bifidobacterium animalis subsp. lactis Bb12 microencapsulated separately in Ca-alginate-raw carob gum maintained good survival rates (51 - 66%) as compared to free cells (21 - 59%) under simulated digestive conditions, and were released under colon-like conditions. Therefore, the formulation of LBG-enriched fermented milks containing probiotic bacteria could represent a very good candidate for industrial application. Ca-alginate-raw LBG beads for the specific release of probiotics in the colon could benefit consumers with celiac disease or other digestive disorders because LBG is naturally gluten-free.