Microbial and senzory quality of raw milk cheeses from the milk vending machines

Abstract

Abstract Changes in microbial quality of lump cheeses manufactured from raw cows’ milk from milk vending machines were studied throughout 7 days of fermentation at 15 °C. The density of lactic acid bacteria, Staphylococcus aureus, Escherichia coli and coliforms were determined, continuously. Also the pH value dynamic was analyzed at the same time intervals. All together, 8 cheeses were prepared from two different vending machines in summer and in winter. Based on the results, growth dynamic of all microorganisms as well as the pH value decrease was slower in cheeses made in winter. No significant differences were observed in the maximal counts of microorganisms related to the season. However, the counts of S. aureus exceeded the EU limit 104 CFU g-1 in 7 out of 8 cheeses, probably due to slow pH value descent. Also the Slovak Food Codex limit for E. coli maximal density of less than 104 CFU g-1 was significantly exceeded. According to sensory evaluation, cheeses prepared in winter were less tasty and their typical odour was less distinctive. Results suggest that raw milk from milk vending machines is not suitable for direct consumption without proper thermal treatment.