Growth of Salmonella Serovars, Escherichia coli O157:H7, and Staphylococcus aureus during Thawing of Whole Chicken and Retail Ground Beef Portions at 22 and 30°C

Abstract

Food regulatory agencies advise against thawing frozen meat and poultry at room temperature. In this study, whole chickens (1,670 g) and ground beef (453 and 1,359 g) were inoculated with Salmonella serovars, Escherichia coli O157:H7, and Staphylococcus aureus on the surface (all products) and in the center (ground beef). After freezing at −20°C for 24 h, products were thawed at 22 or 30°C for 9 h. Pathogen growth was predicted using product time and temperature data and growth values from the U.S. Department of Agriculture Agricultural Research Service Pathogen Modeling Program 7.0 predictive models of pathogen growth. No pathogen growth was predicted for whole chicken or 1,359 g of ground beef thawed at 30°C or 453 g of ground beef thawed at 22°C. Growth (≤5 generations) was predicted for 453 g of ground beef at 30°C. Inoculation study data corroborated the predictions. No growth occurred on whole chickens or 1,359-g portions of ground beef thawed at 30°C for 9 h. Pathogen numbers increased an average of 0.2 to 0.5 log on the surface of 453-g ground beef portions thawed for 9 h at 22 or 30°C. Our results suggest that thawing ≥1,670 g of whole chicken at ≤30°C for ≤9 h and thawing >453 g ground beef portions at ≤22°C for ≤9 h are not particularly hazardous practices. Thawing smaller portions at higher temperatures and/or for longer times cannot be recommended, however. Use of values derived from the Pathogen Modeling Program 7.0 model provided realistic predictions of pathogen growth during thawing of frozen ground beef and chicken.