Taking into consideration the importance that yoghurt has been assuming in the Brazilian market, a number of research has been procceded to improve its quality and of other fermented products. The presence of contaminants is today one of the great problems for the industry, causing loss of the product due to alterations of flavour, color and also of package swelling on the refrigerated shelves. The chief purpose of this work was to perform surveys of the microbiological characteristics of yoghurts by means of the enumeration of fungi and yeasts found relating them with the shelf-life of the yoghurt of different marks. Seventy-two samples of yoghurts marketed were submitted to the microbiological analysis of the population of Lactobacillus/Streptococcus, fungus and yeasts count and chemical analysis (pH, % of lactic acid). The yoghurts were produced by four different manufacturers and marketed in the supermarkets of Lavras-MG, Brazil. Both Lactobacillus delbrueckii spp. Bulgaricus and Streptococcus thermophillus were found at the 1:2 ratio, respectively, on 80% of the samples analysed. No significant differences were found in the pH value and lactic acid content in the samples. In 28% of the samples, yeasts population above 100 CFU/g was found where as at 7%, yeast counts over 1000 CFU/g were obtained. The results show that despite all cares and technic innovations both during and after yoghurt manufacture, the product may still be subject to microbial contamination when hygiene and health conditions are not met.
yoghurts; yeasts; quality; lactic-acid bacteria
