Abstract
Previous studies conducted in our laboratory revealed that Escherichia coli O157:H7 cells capable of producing colanic acid (CA), the acidic polysaccharide of mucoid slime, had increased tolerance to sublethal heat and the extreme pH of microbiological culture media. This study was undertaken to determine the effect of CA on the fate of E. coli O157:H7 during the processing and storage of an acid food: yogurt. Pasteurized and homogenized whole milk was inoculated with a wild-type E. coli O157:H7, its CA-deficient mutant, or a mixture (1:1) of the two strains. Set yogurt was processed from the contaminated milk and stored at 4° and 15°C for 3 weeks. Samples of milk and yogurt were withdrawn during processing and storage and analyzed for total plate counts and populations of E. coli O157:H7 and starter cultures. The results showed that E. coli O157: H7 survived longer in yogurt stored at 15°C than at 4°C. Cells of E. coli O157:H7 deficient in CA production died off more rapidly than those of the parent strain. This suggests that CA plays a role in protecting cells of E. coli O157:H7 from stress during the processing and storage of set yogurt.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
