Résumé:
The experimental study is devoted to the evaluation of the antimicrobial effects of the polyphenols of the hydro-methanolic extract of Mentha piperita L on the growth of a specific germ of yoghurt, namely: Lactobacillus bulgaricus. The phenolic compounds of Mentha piperita L collected in the wilaya of Mostaganem were extracted by maceration of the plant in aqueous methanol. The pure extract recovered after evaporation was concentrated in distilled water to 0, 20, 40, 60, 80 and 100%, respectively. The measurements and controls carried out in triple tests concerned: dosage of total polyphenols, dosage of flavonoids, growth tests, diffusion test on disc, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (CMB).
The hydromethanolic extract of Mentha x piperita L. is found to be very rich in total poly-phenols (39.48 mgEAG / ml of extract) and relatively poor in Flavonoids (0.47 mgEQ / ml of extract).
It seems to exert at high concentrations of 60, 80 and 100% an inhibitory effect of the bactericidal type vis-à-vis the growth of the lactic acid germ Lactobacillus bulgaricus.
However, at less than 40% the extract had no detrimental effect on the proliferation of the germ studied.
