Microbiological quality assessment of milk and its fermented derivatives produced in the Sfax region, Tunisia

Abstract

The aim of this study was to evaluate the microbial quality and safety of milk and its derivatives in the Sfax area, Tunisia. Two hundred and forty samples of ultra-high temperature sterilized milk (UHT) and pasteurized milk, and its derivatives (yoghurt, fermented milk, cheese, and butter), collected from in-dustrial sale sites and traditional small-scale dairy processing units, were microbiologically analysed and the results compared to the European commission (EC, 2004) maximum limits. All the UHT steri-lized milks analysed were free of microbial contamination and packaging-stable. However, pasteurized milk by thermal treatment at 63 °C for 30 min showed that 41 and 13% of samples were contaminated with total microbial count (TMC) and Escherichia coli. In the analysed samples, total and faecal coliform bacteria (TC and FC) counts exceeded the EU limits in 17 and 9% of industrial yoghurts; 85 and 54% of traditional yoghurts, and 57 and 29% of traditional butters, respectively. Furthermore, all studied fermented milks (Lben and Raieb) exceeded the EU coliform limits. Considering the traditional soft cheese made with pasteurized milk, 61% of the analysed samples respected EU limits in TC except one sample contaminated with both of E. coli and Staphylococcus aureus. Salmonella spp. and Listeria monocytogenes detection showed that only one pasteurized milk sample was contaminated by L. mon-ocytogenes, without any Salmonella detection. Traditional producers must implement good manufac-turing practices and hazard analysis critical control points (HACCP) to ensure integral safety and quality of dairy products.