An investigation of the bacteriological quality of retail vanilla slices

Abstract

SUMMARY: One hundred and thirty-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 °C was > 10³/g in 67/133 (50%) of the samples examined,Bacillus cereusbeing found at that concentration in 21·8%, coliform bacilli includingE. coliin 5·3%,Staphylococcus aureusin 3·0% andStreptococcus faecalisin 0·8%. Thirty-four strains ofB. cereuswere serotyped and 11 (32%) of these were typable with the sera available.Preparation of custard mixes in the laboratory suggests that the milk or milk powder used in the mix may be the major source ofB. cereusin 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.