The survival of Staphylococcus aureus during the fermentation and storage of yoghurt

The effect of yoghurt culture Rx on the survival of Staphylococcus aureus CCM 5984 added to milk in various concentrations was observed during the fermentation and storage of yoghurt. The end of the fermentation process (3.5 h) was only accompanied by a slight reduction. During the storage of yoghurt at 4 degrees C a 1-2 log reduction was observed. No Staph. aureus was detected in yoghurt produced from milk contaminated by 10(3) Staph. aureus cells l-1 after 48 h of cold storage. When a concentration of 10(2) Staph. aureus cells was used for milk contamination, the pathogen was not recovered from yoghurt during the fermentation and storage. The fermentation and storage of yoghurt was accompanied by increases in lactic acid and titrimetric acidity, as well as by a decrease in pH value.