Effect of Yoghurt Starter Culture and Pasteurization on Some Pathogenic Microorganisms in Domestic Soft Cheese
This work was conducted to determine the microbial contamination in soft cheese processed in laboratory. Pure yoghurt starter culture consists of Lactobacillus bulgaricus and Streptococcus thermophillus and domestic starter of yoghurt were used in making of soft cheese in laboratory. Both starters were individually added to raw and pasteurized cheese milk before adding rennet. Samples of manufactured soft cheeses were stored at 7°C for 1, 7, 14 and 21 days. The results showed an increase in the total aerobic count in all treatments to which the starter cultures were added. Yeasts & molds count was lower in pasteurized milk cheese compared to raw milk cheeses. Coliform count was observed to increase more rapidly in raw milk cheese in comparison with pasteurized milk cheese. Escherichia coli and Staphylococcus aureas were not found in pasteurized milk cheese, in contrast with raw milk cheese in which their counts rose rapidly during storage especially in control raw milk cheese. Influence of pure yoghurt starter culture was higher on microbial load in soft cheese compared to domestic starter.