Contribution à l’étude de la qualité et la stabilité d’un lait fermenté alicament (type yaourt étuvé) additionné d’extrait a l’hexane de Thymus vulgaris(Thym)récolté dans la région de SETIF

Abstract

The purpose of this study is to monitor the effect of the extracts of thyme. (thymus vulgaris) on the quality of a fermented milk (type yogurt) over the post phase acidification of sample preservation in positive cold to 4° C. for 21 days. From beginning to end of the period of post acidification, the average values of pH (6.46 à 4,49) and viscosity in fermented milks are characterized by a remarkable reduction. The fermented milk acidity knows the contrary a significant increase during the experiment (17,80D° en 1day) and (84,66 en 21day), it is also observed a proportional relationship average acidity values with embedded phenolic extract rate. It seems that the addition of thyme extract product stimulates the growth of specific organisms inoculated with the number of living bacteria (Streptococcus thermophélus and Lactobacillus bulgaricus) enumerated widely spreads the accepted norm in the product of (107UFC / ml). In the end the best results organoleptic (acidity, cohesiveness and adhesiveness) are found in fermented milk with added ginger phenolic extracts prepared at a dilution of 4 and 6%.