Hot water immersion to eliminate Escherichia coli O157:H7 on the surface of whole apples: thermal effects and efficacy.
The effect of hot water immersion on both the reduction of Escherichia coli O157:H7 on the apple surface and internal temperatures of the apple was assessed in this study. Microbial reductions were measured experimentally, whereas internal temperatures were calculated through a mathematical analysis of experimental heat transfer data obtained from the apples. A method was developed to provide a purely surface-based inoculation of E. coli O157:H7. Rinsing produced no reduction, and treatments at 80 and 95 degrees C produced reductions of more than 5 logs in 15 s or less. The heat transfer analysis based on experimental data was used to calculate surface heat transfer coefficients and predict temperatures throughout the apple. The analysis indicated a low heat transfer rate. Although it reduces thermal degradation, a low heat transfer rate precludes thermal-based reduction of any internalized microorganisms.
Fleischman
G J
GJ
US Food and Drug Administration, National Center for Food Safety and Technology, Summit-Argo, Illinois 60501, USA. gfleisch@cfsan.fda.gov
Bator
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C
Merker
R
R
Keller
S E
SE
D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000254:growth & development*; D006358:Hot Temperature; D008433:Mathematics; D019685:Rosales / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014867:Water
D014867:Water