Adaptation of Escherichia coli O157:H7 to acid in traditional and commercial goat milk amasi

Food Microbiol. 2009 Feb;26(1):58-64. doi: 10.1016/j.fm.2008.07.007. Epub 2008 Aug 22.

Abstract

Acid resistance of Escherichia coli O157:H7 strains UT 10 and UT 15 were determined in traditional Amasi fermented for 3 days at ambient temperature (ca 30 degrees C) and commercial Amasi fermented at 30 degrees C for 24h and stored at 7 degrees C for 2 days. Escherichia coli O157:H7 counts in commercial Amasi were detected at 2.7 log(10)cfu/ml after 3 days while those in traditional Amasi could not be detected after the same period. There was no significant difference (p< or =0.05) in the survival of acid adapted (AA) and non-adapted (NA) E. coli O157:H7 in traditional Amasi, while in commercial Amasi, the NA strain survived significantly (p< or =0.05) better than its AA counterpart. Regardless of prior adaptation to acid, E. coli O157:H7 can survive during fermentation and storage of fermented goat milk Amasi. Also, the fermentation time, pH and storage temperature affects the survival of E. coli O157:H7 in the fermented milk.

MeSH terms

  • Adaptation, Physiological*
  • Animals
  • Colony Count, Microbial
  • Consumer Product Safety
  • Escherichia coli O157 / growth & development
  • Escherichia coli O157 / physiology*
  • Fermentation
  • Food Microbiology
  • Food Preservation / methods*
  • Goats
  • Humans
  • Hydrogen-Ion Concentration*
  • Milk / microbiology*
  • Temperature
  • Time Factors