RESUMO A presente comunicação objetivou avaliar a quantificação do caseínomacropeptídeo (CMP), bem como diferenciá-lo (devido à adulteração com soro) do pseudo-CMP (devido à proteólise bacteriana) em amostras de leite cru coletadas nos domicílios do sul do Brasil. Os resultados reforçam a necessidade de práticas higiênicas durante a ordenha e estocagem do leite. As amostras de leite estudadas não estavam adulteradas por adição de soro, mostrando que a análise por cromatografia de exclusão por tamanho deve ser complementada a fim de revelar a identidade do peptídeo (CMP ou pseudo-CMP). A contagem bacteriana total (TBC) também se mostrou útil como indicador da contaminação do leite por micro-organismos proteolíticos, uma vez que uma relação diretamente proporcional entre TBC e pseudo-CMP foi estabelecida.

Bacillus cereusis an ubiquitous, spore-forming bacteria that can survive pasteurization and the majority of the heating processes used in the dairy industry. Besides, it is a pathogen responsible for different types of food poisoning. One type of foodborne disease caused by B.cereusis the diarrheal syndrome, which is caused by the ingestion of vegetative cells producing toxins in the small intestine. One virulence factor for the diarrheal syndrome is the toxin hemolysin BL (HBL), a three-component protein formed by the L1, L2 and B components. In order to evaluate the presence of diarrheal strains isolated from milk and dairy products, 63 B. cereus isolates were obtained from 260 samples of UHT milk, pasteurized milk and powdered milk, sold in commercial establishments and from different brands. The isolates were subjected to the Polymerase Chain Reaction (PCR) for the detection of the encoding genes for the L1, L2 and B components and the toxin production capacity were evaluated with an immunoassay. A total of 23 [36.5%] isolates were identified carrying simultaneously the three tested genes, from which, 20 [86.9%] showed toxigenic capacity. 26 [41.3%] isolates did not carry any of genes tested and the other 14 [22.2%] were positive for one or two of them. The results showed a high toxigenic capacity among the B. cereus isolates able to produce the HBL, indicating a potential risk for consumers.