Effets inhibiteurs de l’extrait hydro-méthanolique de Mentha pipérita L Chez Streptococcus thermophillus et Lactobacillus bulgaricus et impact sur la qualité d’un lait fermenté (type yaourt étuvé).

Abstract

The expérimental study is devoted to evaluating the antimicrobial effects of the compounds phenolics of Mentha piperita (peppermint) harvested in the region of Ouargla-Algeria on the growth of Streptococcus thermophillus and Lactobacillus bulgaricus and their impact on the quality of a fermented type yoghurt steamed during fermentation periods and post-acidification storage at 4 ° C. The phenolic compounds were extracted by maceration of the plant in aqueous methanol. The pure extract recovered after evaporation, was concentrated with distilled water at 0, 20, 40, 60, 80 and 100%, respectively. Manufacturing tests a fermented milk supplemented with hydro-methanolic extract of mint at different doses of (0, 2, 4 and 6%) were also performed .The measurements made concerned: inhibitions tests, physicochemical analyzes, microbiological control and organoleptic tests. underwent an analysis of variance (ANOVA) and a comparison of means according to the Newman and Keuls. The hydro-methanolic extract of Mentha piperita L proves to have a bactericidal effect vis-à-vis the two specific yoghurt sprouts; Streptococcus thermophillus and Lactobacillus bulgaricus. The addition of this plant extract in fermented milk has relatively reduced acidity, viscosity and the growth of Streptococcus thermophillus and Lactobacillus bulgaricus germs. In addition, all experimental products supplemented with peppermint extract were poorly appreciated by the tasting panel. Nevertheless, in terms of smell and color, the tests prepared with 2% and 4% extract seem better than the sample yoghurt