Influence of intrinsic and extrinsic parameters on Bacillus cereus growth in one REPFED product

Bacillus cereus growth was evaluated in one REPFED in different pH and water activity conditions at three different temperatures (5, 8, 12°C). The product’s initial pH and aw values were 5.6 ± 0.1 and 0.99 ± 0.001 respectively. They were reduced to obtain different combinations in which Bacillus cereus growth was estimated. The combinations were compared to ComBase model, and they showed growth. But, against ComBase prediction, the REPFED did not support Bacillus cereus growth. The inoculum of Bacillus cereus for experimental conditions was equal to 2.6 ± 0.1 Log CFU/g, but it reduced in every sample to less than 1 log CFU/g. The same analysis was conducted in the no inoculated REPFED and the results highlight that the temperature is the main factor affecting Bacillus cereus growth. Also spoilage microorganisms growth and their chemical modifications could affect Bacillus cereus growth. Further research needs to be carried out to confirm these preliminary results and to evaluate if the conditions applied in this study represent a worst scenario for Bacillus cereus growth.