Bacillus cereus in infant foods and dried milk products

Dried milk products and infant food are known to be frequently contaminated with Bacillus cereus. Sources of the organism and its behaviour in the product and in the equipment during processing are discussed. With regard to the incidence of B. cereus in infant food, 261 samples distributed in 17 countries were collected and examined for its B. cereus content. Fifty-four percent of the samples were contaminated with B. cereus reaching levels from 0.3 to 600/g. Counts higher than 10/g were found in only 27 samples (10%). Most of the positive samples (44%) contained 0.3 to 10 B. cereus/g. Four samples (1.5%) were contaminated with more than 100 organisms/g reaching a maximum level of 600 B. cereus/g. When classified into different types of products about 50% of the infant formulae based on milk, the follow-on formulae and the weaning foods were contaminated with B. cereus as well as 69% of those based on soy protein and 92% of the special dietetic foods. Compared to our earlier studies from 1982/83, the percentage of contaminated samples from Germany increased from 31% to 70% in the case of infant formulae, from 28% to 55% in the case of follow-on formulae, and from 40% to 100% in the case of special dietetic food. The percentage of weaning food contaminated with B. cereus remained nearly unchanged. It should be stressed, however, that the numbers of B. cereus were almost the same in both studies with the highest count in 1982/83 being 460 and in 1992 600/g. Samples naturally contaminated with counts of about 100 B. cereus/g were reconstituted and incubated at a room temperature of 27 degrees C. Levels of 10(5) B. cereus/g were reached after 7-9 h. Toxigenicity of B. cereus in dried milk products and infant food as well as food poisoning outbreaks attributed to B. cereus are discussed.