Abstract:
The experimental study is devoted to the evaluation of the inhibitory effects of the aqueous
extract of Mentha piperita L on the growth of specific yogurt germs, and on the other hand
the impact of the addition of this extract. extracted in different doses as a natural additive
on the evolution of the physicochemical, microbiological and organoleptic parameters of a
fermented milk (parboiled yoghurt type) during the periods of fermentation and post
acidification.
The aqueous extract of the plant under study was obtained by maceration with water. the
recovered extract was then diluted with sterile distilled water at concentrations of
0.20,40.60.80, and 100%.
Incorporation tests of mint extract at 0, 2, 4 and 6% were also carried out in fermented milk
type steamed yoghurt.
The various measurements and controls were carried out in triplicate tests and focused on:
direct contact test, disk diffusion test, minimum inhibitory and bactericidal concentration
(MIC and CMB), pH, acidity, viscosity and organoleptic tests. The results were analyzed for
variance and averaged by Newman and Keuls.
The aqueous extract of Mentha piperita L seems to exert a bactericidal inhibitory effect on
the growth of yogurt lactic bacteria: Sreptococcus thermophilus and Lactobacillus bulgaricus.
The addition of aqueous peppermint extract to the fermented milk has relatively reduced
the acidity, pH, viscosity and even increase of the germs Streptococcus thermophilus and
Lactobacillus bulgaricus.
However, the fermented milk supplemented with 2% and 4% aqueous mint extract was very
well appreciated by the tasting panel, just like the standard yoghurt.
