Prevalence of Bacillus cereus in dried milk products used by Chilean school feeding program

The prevalence of Bacillus cereus, in a total of 381 samples of dried milk products (milk with rice, milk substitute, milk powder, milk-cereal-rice, pudding milk, flan, and mousse) used by the Chilean School Feeding Program, was investigated. The potential of 94 selected isolates of B. cereus to produce diarrhoeal enterotoxin (by the BCET-RPLA test) in BHI culture, as well as the ability of enterotoxigenic-strains to grow at psychrotrophic temperatures were also verified. B. cereus was found in 175 of 381 of the samples analysed (45.9%), reaching levels from 3.0 to 10(4) spores g(-1). As expected, the higher prevalence and counts were observed in those products that contained whole rice, cereals and pulses extruded, and food additives. Of the 94 isolates of B. cereus tested for diarrhoeal enterotoxin production, 28 (29.8%) were positive, and none of these was able to grow at <= 7 degrees C. The prevalence of B. cereus in dried milk products analysed was fairly high, although it was present in low number. However, as they were composed to a large extent of enterotoxigenic mesophilic strains, the potential risk for the safety of reconstituted products held at improper temperature should not be neglected. (c) 2006 Elsevier Ltd. All rights reserved.