Occurrence of Bacillus cereus in Instant Cereal Products and Their Hygienic Properties

SHAO-WEI FANG*, SU-YI CHU AND DANIEL YANG-CHIH SHIH

National Laboratories of Foods and Drugs, Department of Health, Executive Yuan, 161-2, Kuen Yang Street, Nankang, Taipei, Taiwan, R.O.C.

ABSTRACT

   From July 1992 to June 1993, 155 instant cereal products were purchased from 24-hour stores, supermarkets and grocery stores in Taipei area and examined for Bacillus cereus, coliform bacteria, Escherichia coli and aerobic plate count. The results showed that B. cereus was found on 32% of instant cereal products examined. The isolation rates of B. cereus in regular instant cereal and cereal mix were 26% and 38%, respectively. Count range of B. cereus in all positive samples was 3 - 93 MPN/g. Aerobic plate counts of these two categories ranged between 5 - 2.3×104 CFU/g and 5 - 4.2×103 CFU /g, respectively. Among all samples, only one cereal mix sample was illegally contaminated with E. coli , while 8 samples contained coliform bacteria. Coliform was isolated from 2 of 74 (2.7%) regular instant cereal products, but isolated from 6 of 81 (7.4%) cereal mix products, except those of only one cereal mix were beyond sanitary standard. All of 44 B. cereus isolates had strong hemolysin activity, but only 4 isolates were capable of producing diarrheagenic enterotoxin.

Key words: Bacillus cereus, hygienic property, instant cereal product,regular instant cereal, cereal mix