OCCURRENCE OF Staphylococcus aureus IN PROTEIN POWDER SUPPLEMENTS

The increase in demand for high-protein food resulted in the popularization of protein powder supplements, such as whey protein and vegetable protein powder. Since  these products are relatively new, few studies have assessed their microbiological quality. A recall due to contamination of Staphylococcus aureus in protein powder occurred recently in Brazil. S. aureus is a pathogenic microorganism which can produce endotoxins associated with foodborne illness. Thus, this study evaluated the occurrence of Staphylococcus aureus in commercially available vegetable protein powder (pea, rice, almond, and sunflower seed) and whey protein powder samples in Brazil. A total of 62 commercial samples of whey protein and 10 commercial samples of vegetable protein were assessed for S. aureus. The whey protein samples were diluted in a 2% K₂HPO₄ solution, and the vegetable protein samples were diluted in 0,1% Peptone water solution (APHA 2015). The samples were decimal-diluted and plated on Baird-Parker (BP) agar, and then incubated at 37 °C for 48 hours. After incubation, the typical colonies were counted, and biochemical tests were performed. Coagulase-positive Staphylococci were detected in one commercial whey protein sample (1,6%), with a count of 2 log CFU/g, exceeding the maximum level permitted by Anvisa. A total of 11% (n = 62) of the whey protein samples exhibited typical colonies, with counts ranging from 1.7 to 3 log CFU/g and an average of 1.9 log CFU/g. All tested positive for the catalase test but negative for the coagulase test. In contrast, none of the vegetable protein powders showed typical colonies of Staphylococcus. Although coagulase was positive for S. aureus in one sample, the counts exceeded 2 log. These findings underscore the importance of ongoing monitoring of the microbiological quality of these supplements and the need to maintain attention to good manufacturing practices.