Yaourts probiotiques algériens et ferments commerciaux utilisés dans leur fabrication

Abstract

Fermented milk products are generally regarded by consumers as healthy and as such, they represent an important part of the diet. The incorporation of probiotic bacteria as dietary supplements in various fermented milk-derived products has enhanced their acclaimed healthy properties and lead to increased consumption of these products. However, the efficiency of probiotics depends on their viability which needs to be maintained during the manufacturing, storage and conservation processes. In addition, the probiotic strains must survive the environment of the gastrointestinal tract. The viability of probiotics is therefore a key factor in the ability of commrcialized strains to provide the desired effects. In addition, recent controversies have sparked an international debate with regards to approaches to regulate this new category of food products. This study comprises two main parts: (1) Microbiological quality control and analysis of health claims in the labeling of yogurts marketed in Algeria as "probiotic" and (2) Quality control, evaluation of some probiotic properties and the viability of three samples of commercial cultures collected from an Algerian dairy company. Two of these samples are used as starter cultures and the other as an additive to manufacture probiotic yogurts. We tested the probiotic lactic acid bacteria delivered in two yogurts manufactured in Algeria and commercialized as "probiotics". The effect of the solution used to prepare decimal dilutions for the enumeration of these bacteria on the result of the count was examined. We also examined the labeling of five yogurts which are commercialized as "probiotics". In addition, we assessed various characteristics of probiotics in vitro, namely resistance to acid, bile tolerance and antimicrobial activity of three samples of commercial DVS cultures used in the Algerian dairy industry to manufacture probiotic yogurts: ST-M6 (Streptococcus thermophilus), LB-12 (Lactobacillus delbrueckii subsp. bulgaricus) and LA-5 (Lactobacillus acidophilus). Finally, we assessed the influence of technological conditions (cold storage, acidity, addition of artificial flavors and thickening agents) on the viability of these lactic bacteria samples.