Occurrence of Bacillus sporothermodurans in UHT Milk Commercialized in the State of Rio Grande Do Sul, Brazil

Milk produced with Ultra High Temperature process is known as UHT. Milk is the most widely accepted by Brazilian consumers. The presence of mesophilic microorganisms in high levels in UHT products will be able to cause the deterioration and/or the reduction of the shelf life. In this study we determined the counting of viable aerobic mesophilic microorganisms and verified the presence of Bacillus sporothermodurans (BST) in 511 samples of UHT milk. Eleven different brands have been collected during the period of August 2005 to July 2008, from different cities of the State of Rio Grande do Sul, Brazil. According to the results obtained, it can be concluded that 100% of the total samples of UHT milk analyzed, independent of the brand, were in accordance with the effective legal standard for the viable aerobic mesophilic microorganisms (maximum of 102 UFC/ml). It was observed that 55 (10.8%) of the total samples showed characteristic colonies of BST. This allows to affirm that BST is one mesophilic well adapted, exceptionally resistant, being able to survive UHT milk treatments.