Effet antimicrobien des composés phénoliques des graines de Foeniculum vulgare sur la qualité d’un lait fermenté type yaourt étuvé

Abstract

The objective of this work is to design a new food product, namely a fermented milk such as steamed yogurt based on fennel seed extract rich in bioactive compounds of interest to health and which could be a ready project for anyone wishing to invest in the domain in Algeria. The experimental study was devoted to the evaluation of the antimicrobial effect of the hydroethanolic extract of the seeds of Foeniculum vulgare L., vis-à-vis the growth of specific germs of yogurt and its impact as a natural additive on the evolution of the physico-chemical, microbiological and organoleptic parameters of a fermented milk during 21 days of the post-acidification period. The fennel seed extract object of the study was obtained by maceration of a plant material taken from fennel seeds in a hydroethanolic solution. The extract recovered after filtration and evaporation of the solvent was then incorporated at 0, 6 and 8% in the preparation of a fermented milk such as steamed yoghurt. The various measurements and controls carried out periodically in triple tests during the storage of the products at 4°C concerned the pH, the acidity, the viscosity, the enumeration of Streptococcus thermophilus, the enumeration of Lactobacillus bulgaricus and the organoleptic tests including acidity, freshness , cohesiveness, adhesiveness, color, odor and aftertaste. The experimental data were processed by an analysis of variance and a comparison of the means two by two according to the Newman and Keuls test. The results showed that the addition of hydroethanolic extract of the seeds of Foeniculum vulgare, in particular at severe rates of 8%, improves the acidity and the pH of the medium; whereas, on the contrary, the viscosity of fermented milks is clearly altered. In addition, the growth of the two germs Streptococcus thermophiluse and Lactobacillus bulgaricus specific to yoghurts reinforced with plant extract was not affected throughout the storage period. Apparently, the fermented milk with the addition of 6% aqueous fennel extract was more appreciated by the tasting panel than the standard yogurt.