Detection of Bacillus cereus in pasteurized and UHT milk market in Serra Gaúcha, RS

Abstract

The presence of the bacteria Bacillus cereus in milk reflects an important concern to dairy products due to its ability to sporulate and to the possibility of the spore resisting the thermal treatment known as UHT (ultra-high temperature), which can cause deterioration of the product. This study aimed to evaluate the presence of B. cereus in pasteurized and UHT milk samples commercialized in Serra Gaúcha, RS. For that, 50 samples of UHT milk and 10 samples of pasteurized milk from markets of Farroupilha, Nova Prata, Vila Flores, and Veranópolis were evaluated. Samples were inoculated with MYP agar, and the presence of B. cereus was confirmed by Gram staining, α-hemolysis test in 5% sheep blood agar, and rhizoid growth. Overall, 8.3% (5/60) of samples were contaminated by B. cereus. Among them, three were UHT milk, and two were pasteurized milk. The presence of B. cereus in samples of pasteurized and UHT milk presents a risk to public health since the bacteria can resist the heat treatment processes of the plants that produce the milk for consumption and cause foodborne illness outbreaks.