Lethality of heat to Escherichia coli O157:H7: D- and z-value determinations in turkey,lamb and pork |
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Affiliation: | 1. University of São Paulo, Department of Chemical Engineering, Escola Politécnica, P.O. Box 61548, 05424-970 São Paulo, Brazil;2. University of São Paulo, FoRC - Food Research Center, São Paulo, Brazil;3. Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Avd. Agustín Escardino, 7, 46980 Paterna, Spain |
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Abstract: | Thermal inactivation of a four-strain mixture of E. coli O157:H7 was determined in lean ground turkey, lamb and pork. Inoculated meat was packaged in bags completely immersed in a circulating water bath and held at 55, 57.5, 60, 62.5, and 65°C for predetermined lengths of time. The surviving cell population was enumerated by spiral plating meat samples on tryptic soy agar overlaid with Sorbitol MacConkey agar. D-values, determined by linear regression, in turkey were 11.51, 3.59, 1.89, 0.81 and 0.29 min at 55, 57.5, 60, 62.5 and 65°C, respectively (z=6.5°C). When a survival model was fitted to the non-linear survival curves, D-values in turkey ranged from 11.26 min at 55°C to 0.23 min at 65°C (z=6°C). When the E. coli O157:H7 four-strain cocktail was heated in ground pork or lamb, D-values calculated by both approaches were similar at all temperatures. Thermal-death-times from this study will assist the retail food industry to design cooking regimes that ensure safety of ground muscle foods contaminated with E. coli O157:H7. |
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