Thermal destruction of Escherichia coli O157:H7 in sous-vide cooked ground beef as affected by tea leaf and apple skin powders.
We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of white and green tea powders and an apple skin extract. Inoculated meat was cooked using the sous-vide technique, i.e., the meat was packaged in sterile bags and completely immersed in a circulating water bath at low temperature for a period of time. The bags were cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5 degrees C, and then held from 240 min at 55 degrees C to 10 min at 62.5 degrees C. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol-MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time, in minutes, required for the bacteria to decrease by 90%) in the control beef ranged from 67.79 min at 55 degrees C to 2.01 min at 62.5 degrees C. D-values determined by a logistic model ranged from 36.22 (D1, the D-value of a major population of surviving cells) and 112.79 (D2, the D-value of a minor subpopulation) at 55 degrees C to 1.39 (D1) and 3.00 (D2) at 62.5 degrees C. A significant increase (P < 0.05) in the sensitivity of the bacteria to heat was observed with the addition of 3% added antimicrobials. D-value reductions of 62 to 74% were observed with apple powder and 18 to 58% with tea powders. Thermal death times from this study will assist the retail food industry to design cooking regimes that ensure the safety of beef contaminated with E. coli O157:H7.
Microbial Food Safety Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA. vjay.juneja@ars.usda.gov
Vijay K
VK
Juneja
M L
ML
Bari
Y
Y
Inatsu
S
S
Kawamoto
Mendel
M
Friedman
D000818:Animals; D028241:Camellia sinensis; D002417:Cattle; D003296:Cooking / Q000379:methods*; D019453:Escherichia coli O157 / Q000502:physiology*; D005516:Food Microbiology; D005638:Fruit; D006358:Hot Temperature; D027845:Malus; D008460:Meat / Q000382:microbiology*; D010936:Plant Extracts; D018515:Plant Leaves / Q000737:chemistry*
D010936:Plant Extracts