OCCURRENCE OF Bacillus cereus IN WHEY PROTEIN SUPPLEMENTS

Bacillus cereus is a spore-forming pathogen of major concern in the dairy industry. Their spores show high resistance to environmental stressors and physicochemical treatment, and they can germinate at various stages of the production chain. Whey protein powder is a relatively new dairy product whose consumption has increased exponentially in recent years due to the growing pursuit of wellness and healthy lifestyles. However, few studies have assessed the microbiological quality of this product regarding spore-forming bacteria. Thus, this study evaluated the occurrence of Bacillus cereus vegetative cells and spores in commercially available whey protein samples in Brazil. A total of 35 commercial samples were assessed for spores and vegetative cells. The samples were diluted in a 2% K₂HPO₄ solution (APHA 2015) and enumerated on Mannitol Yolk Polymyxin (MYP) Agar. For spore enumeration, the diluted sample was heat-shocked at 70 °C for 15 minutes, rapidly cooled in a 5 °C water bath until room temperature, and then plated on MYP. The plates were incubated at 30 °C for 48 hours. After incubation, the typical colonies were counted. For the vegetative cells, suspected Bacillus cereus was detected in 60% (n=21) of the samples, with an average count of 2.47 log CFU/g, ranging from 1.69 to 3.20 log CFU/g. For the spores, 63% (n=22) contained suspected Bacillus cereus with an average of 2.30 log CFU/g and a range of 1.69 to 2.74 log CFU/g. The samples collected in this study revealed the presence of Bacillus cereus in whey protein samples, with counts ranging from 1 to 3 log CFU/g. Although the counts are relatively low, they indicate the occurrence of the microorganism in the product and reinforce the need for attention to good manufacturing and storage practices. While they do not exceed the limits considered critical for health risk in dry products, such as whey protein, the detection of B. cereus is significant due to its toxigenic potential, particularly under rehydration conditions and subsequent storage at inadequate temperatures. Therefore, continuously monitoring the microbiological quality of these supplements is essential to ensure food safety and quality.