Effet de l’extrait hydro- méthanolique de Mentha piperita L. sur la croissance du germe Streptococcus thermophilus spécifique du yaourt.

Abstract

This study was undertaken to study the antimicrobial effect of Mentha piperita L. hydromethanolic extract from the Ouargla-Algérie region on the growth of a specific yogurt germ, namely Streptococcus thermophilus. During the experiment, extraction of phenolic compounds from peppermint was carried out by cold maceration in aqueous methanol. The filtrate solvent was then concentrated and the recovered extract was finally diluted to 0, 20, 40, 60, 80 and 100%. The measurements and control carried out concerned: determination of total polyphenols, determination of flavonoids, growth test, disc diffusion test, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (BMC). The results underwent a monofactorial variance analysis and a comparison of the Newman and Keuls means. The hydromethanolic extract of Mentha piperita L., appears to be rich in total phenolic compounds (14.53 mgEAG/ml); whereas it is found to contain low proportions of flavonides (0.43 mgEQ/ml). This extract exerted a bactericidal inhibitory effect vis-à-vis Streptococcus thermophilus involved in the fermentation of yogurt. The CMI and CMB of this lactic germ were obtained at 20% and 40% of the plant extract, respectively.