Fermentative behavior of native lactobacilli in goat milk and their survival under in vitro simulated gastrointestinal conditions

Abstract

In this study, goat fermented milk trials were prepared with six potentially probiotic autochthonous cultures ‒ Lactobacillus rhamnosus EM1107, Lactobacillus plantarum (CNPC001, CNPC002, CNPC003 and CNPC004) and Lactobacillus mucosae CNPC007 ‒ in the presence and absence of a starter culture (Streptococcus thermophilus, ST) and in the presence and absence of inulin (IN) or oligofructose (FOS), consisting of 36 trials. The fermented milk without the starter culture only achieved a lactic acid content above 0.6 g/100 g after 24 h, thus requiring the presence of ST culture for a faster acidification. After the fermentation, three trials with the best fermentative performance and visual firmness (EM1107 + ST + IN, CNPC003 + ST + IN and CNPC007 + ST + IN) were exposed to simulated conditions of the gastrointestinal tract (GIT) in vitro. All fermented milk, with Lactobacillus spp. population above 6 log CFU/g before GIT simulation, showed the highest viability losses in the gastric step. In fermented milk with Streptococcus thermophilus plus inulin, L. rhamnosus and L. mucosae performed well in the GIT assay, achieving a viability between 6.50 – 7.24 and 6.50–7.60 log CFU/g in the enteric stage, respectively. Therefore, the combination of EM1107 or CNPC007 strains with S. thermophilus and inulin is promising in the production of goat dairy products.