An investigation of the bacteriological quality of retail vanilla slices.

One hundred and thiry-three vanilla slices, purchased from shops in the West Yorkshire Metropolitan County, were examined to determine the numbers and types of bacteria present at the time of purchase. The surface colony count at 37 degrees C was greater than 10(3)/g in 67/133 (50%) of the samples examined, Bacillus cereus being found at that concentration in 21.8%, coliform bacilli including E. coli in 5.3%, Staphylococcus aureus in 3-0% and Streptococcus faecalis in 0-8%. Thirty-four strains of B. cereus were serotyped and 11 (32%) of these were typable with the sera available. Preparation of custard mixed in the laboratory suggests that the milk or milk powder used in the mix may be the major source of B. cereus in the final product. Many of the present methods of manufacture, distribution and storage allow organisms present in the custard at manufacture the opportunity to multiply and possibly reach numbers which present a risk of food poisoning.