Tracking Bacillus cereus in UF-feta cheese processing line

Abstract

Three processing lines for the manufacture of feta cheese from ultrafiltered (UF) milk (UF-feta) and manufacturing conditions were evaluated for product contamination, especially for the probable occurrence of Bacillus cereus. Moreover, enterotoxins from B. cereus, i.e., haemolysin and cereolysin (A and B), were analysed in isolates. Samples were collected from raw milk, after the main processing steps and the silo tanks of three UF-cheese plants. B. cereus and aerobic spores were detected at many points along the processing line. The results showed that the raw milk used to manufacture the UF-feta cheese was the main source of contamination with B. cereus. The storage tanks and UF membrane were two major factors leading to an increase in B. cereus during the process. The presence of enterotoxins in isolates also revealed that the risk of food poisoning caused by B. cereus in UF-feta cheese should not be neglected.