Numerous studies have demonstrated the protective effect of food constituents on the survival of spores and vegetative cells of B. cereus in simulated gastric media (GM) enriched with food
component [16,37e39]. The studies of the B. cereus strain F4430/73 (B4ac) in GM at pH 1.0 revealed that a decrease in the B. cereus spore count not exceeding 1.5 log CFU/mL was obtained only in the case of GM with vegetables (pea pur ? ee). No change in the spore count was observed in GM-milk or GM-chicken [16]. At pH 5.0, a 10-fold increase in the bacteria count was observed, which means that the spores were able to germinate and the vegetative cells were able to multiply regardless of the type of food added to the GM. The resistance of B. cereus spores to the conditions simulating passage through the stomach (the pH ranges from 2.0 to 5.0) was
also demonstrated in the studies carried out by Ceuppens et al. [17] and Wijnands et al. [40]. Experiments performedon vegetative cells show different results. In GM at pH < 3.5, a considerable decrease (by > 4 log CFU/mL) in the bacteria population was observed irrespective of the nature of the GM. Both the vegetative cells and the spores showed a similar survival in GM-milk at pH > 4.5 [16]. The protective effect of milk can probably be attributed to its content of lipids and proteins, which can “trap” the bacteria by forming protein-lipid complexes. As a result, the bacteria are not directly exposed to the influence of low pH levels. Similar results were obtained in the studies of B. cereus strains isolated frommilk [37,39]
and from the cases of food poisoning and food contamination [40]. The number of vegetative cells (B. cereus ATCC 14579) in the simulated gastric fluid (SGF), which had a pH 4.4 value and
contained fresh cheese, decreased by 3 log CFU/mL during a 60-minute exposure time. In the case of SGF with chicken and rice baby meal at the same pH value and exposure time, the decrease observed in the B. cereus count was higher by over 1 log CFU/mL. The examined strain showed an even lower survival rate when cultivated in the SGF with food and 16% red wine [39]. Similar results were obtained for the B. cereus NVH 1230-88 strain. About 14% (±9%) of the vegetative cells could survive in the medium simulating the stomach environment at pH values > 4.0