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Fermented products by lactic acid bacteria: basic and applied studies

Abstract

The growing demand for functional food justify the importance of searching for new probiotic strains and for appropriate food matrices for maintaining probiotic viability. In addition, it is necessary to determine the effects of functional foods over microbiota and gut health. The aims of this study are to evaluate the probiotic potential of Lactobacillus spp. strains isolated from samples collected during the processing of water-buffalo mozzarella cheese, to verify the best matrix for the incorporation ofthe strain, using in vitro tests, and to evaluate the effect ofstrain and of selected food matrix on the microbiota using a simulator ofthe human microbial ecosystem (SHIME). The study will be divided into three stages. ln phase I, the probiotic potential of 10 Lactobacillus spp. strains will be assessed by verifying the presence or absence of virulent genes, resistance to low pH and bile and in vitro adhesion to Caco-2 cells. The strain with the greatest potential will be tested in phase 2, when it will be incorporated into the three types of food matrices: fermented goat milk, oat fermented product and rice fermented product, added ofbyproducts from orange, banana and guava fruit (5%), separately. A control treatment will also be performed, totaling twelve different treatments. Afier 1, 14 and 28 days of storage, the products will be subjected to the following analysis: viability ofthe selected LAB, resistance ofselected LAB to simulated gastrointestinal tract (GI) conditions and antioxidant capacity. In phase 3 ofthe project, the matrix that provides the best results in the previous phase will be evaluated using SHIME system. At this stage, the following parameters will be evaluated: the interaction of LAB and the selected food matrix over the intestinal microbiota community, the dynamic of Lactobacillus population, the changes introduced by the metabolism ofthe LAB as well as by the fruit byproduct on the amount of fatty acids and ammonium ions. Ali results will be analyzed by Tukey's test considering a significance levei of 5%. We expected to select a strain with probiotic potential and adequate food matrix for its incorporation, as well as to determine the biological effects caused by symbiotic fermented product in the intestinal microbiota. (AU)