Isolation and characterisation of lactic acid bacteria strains from raw camel milk for potential use in the production of fermented Tunisian dairy products

The aim of this work was to study the suitability of camel milk for the production of dairy products by lactic acid fermentation. Sixty strains of lactic acid bacteria (LAB) were isolated from camel milk. The strains were tested for their acidification activity, ability to use citrate, exopolysaccharide production, lipolytic, proteolytic activities and resistance to antibiotics. Ten strains were investigated for their ability to metabolize carbohydrates and that resulted in the identification of 5 Lactococcus lactis, 1 Lactobacillus pentosus, 2 Lactobacillus plantarum, 1 Lactobacillus brevis and 1 Pediococcus pentosaceus strains. Two strains of Lactococcus lactis SCC133 and SLch14 were selected to produce traditional Tunisian fermented dairy products (Lben, Raib, Jben cheese and Smen). These strains were chosen based on their acid production capacity and their ability to produce a high yield of biomass.     

Potent odorants in "Smen", a traditional fermented butter product

 Potent odorants in a sample of traditional Moroccan smen were characterized by an aroma extract dilution analysis. In the acidic fraction, butanoic acid followed by hexanoic acid showed the highest flavor dilution (FD)-factors. Further quantitative determination of both acids in the same sample revealed high concentrations, in the g/kg level. In contrast, the low FD-factors found for the volatiles detected in the neutral fraction suggest that they contribute little to overall flavor. Butanoic and hexanoic acids are likely the key odorants of smen flavor, which is consistent with lipolysis being the primary mechanism of aroma development in the product. Received: 24 January 2000 / Revised: 8 June 2000