Growth of Mycobacterium avium subsp. paratuberculosis , Escherichia coli , and Salmonella Enteritidis during Preparation and Storage of Yogurt

Abstract

The purpose of this study was to determine the viability of Mycobacterium avium subsp. paratuberculosis (MAP), Escherichia coli ( E. coli ), and Salmonella Enteritidis ( S. Enteritidis) during preparation and refrigerated storage of yogurt. Three yogurts were prepared using pasteurized commercial milk. Each yogurt was artificially contaminated with (1) MAP, (2) E. coli + S. Enteritidis, and (3) MAP + E. coli + S. Enteritidis. Samples were taken during and after the fermentation process until day 20 after inoculation. MAP was not detected during their preparation and short-term storage but was recuperated after starting at 180 min after inoculation storage. Live bacterial counts of E. coli , and S. Enteritidis increased during the first 24 hours, followed by a slight decrease towards the end of the study. In this study it was shown how MAP, E. coli , and S. Enteritidis resisted the acidic conditions generated during the preparation of yogurt and low storage temperatures. This work contributes to current knowledge regarding survival of MAP, E. coli , and S. Enteritidis during preparation and refrigerated storage of yogurt and emphasizes the need to improve hygiene measures to ensure the absence of these pathogenic microorganisms in dairy products.