Korea University Food Microbiology Laboratory

Survival of Escherichia coli O157H7 in dried beef powder as affected by water activity, sodium chloride content and temperature
Year of publication 2004년 이전
Author Ryu, J.H., D. Yun., & L. R. Beuchat.
Publication in journal Food Microbiology, 1999, 16, 309−316
Status of publication Published


A study was carried out to determine the rate of inactivation of Escherichia coli O157:H7 in beef pow der as affected by aw (0·34±0·06±0·01), sodium chloride content (0·5, 3·0 and 20%) and temperature (5 and 25°C) over an 8-week storage time. Retention of viability of acid-adapted, acid-shocked, and control cells was determined. Overall, there were no significant differences (P≤ 0·05) in survival  among the three types of cells subjected to the same test parameters, suggesting that mechanisms associated with induction of acid adaptation or acid shock do not result in cross protection against dehydration or osmotic stresses. At each aw and within cell type, an increase in sodium chloride concentration resulted in significant reductions in the number of viable cells after a given storage time.  Regardless of cell type, survival was significantly higher in beef powder containing 0·5 or 3% sodium chloride compared to powder containing 20% salt. The rate of inactivation was enhanced at aw 0·34±0·06 compared to aw 0·68±0·01 and at 25°C compared to 5°C.