A RISK ASSESSMENT STUDY OF BACILLUS-CEREUS PRESENT IN PASTEURIZED MILK

Due to the heat resistance of Bacillus cereus, its potential pathogeni c character, the capability to grow in milk and reported diseases upon consumption of dairy products, the organism should be considered as h azardous in pasteurized milk. Human exposure experiments based on (I) enquiring about the storage conditions (time and temperature) of paste urized milk in households in The Netherlands and (2) performing of sto rage tests at 6, 8, 10 and 12 degrees C, respectively demonstrated the following: pasteurized milk is consumed within 2-12 days after pasteu rization and is stored at temperatures varying from <5-13 degrees C. V isually spoiled milk is not consumed anymore. Based on the distributio n of both the storage time and temperature of milk in private househol ds, approximately 7 and 4% of the total portions of milk consumed in T he Netherlands could contain >10(5) and >10(6) B. cereus ml(-1), respe ctively. Taking into account the high portion of milk consumed (approx imately 10(9)-10(10) portions/year) and the absence of epidemiological evidence that milk is causing foodborne diseases due to B. cereus, th e dose-response relationship of this organism may need to be considere d. Results of the storage tests, based on the worst case situation, pr ovided useful information on the effect of the risk factors, storage t emperature and time, to human exposure. However, such information can be obtained more easily by applying predictive models. Models also ena ble us to find out the initial number of spores which can be considere d as a third risk factor. (C) 1997 Academic Press Limited.