Japan Journal of Food Engineering
Online ISSN : 1884-5924
Print ISSN : 1345-7942
ISSN-L : 1345-7942
Survival of Escherichia coli on Polypropylene Surfaces Fouled with Organic Soil of Different Water Contents
Takaharu SAKIYAMAYoichiro HONDAMika FUKUOKATomoaki HAGIWARAHisahiko WATANABE
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2006 Volume 7 Issue 4 Pages 249-253

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Abstract

Knowledge of survival behaviors of microorganisms on solid surfaces is important to assess and control the risk of cross contamination for food being processed on the surface. Here we report the survival behavior of Escherichia coli left on polypropylene coupons with or without nutritious soil subjected to drying at room temperature. When E. coli cells were left on the coupons with 0.85% saline solution, decrease in the viable cell number was observed in two stages, each of which followed the first order kinetics. The specific death rate was 0.21 h-1 initially and reduced to 0.11 h-1 after the water content reached 3.9 g-water/g-solid. When E. coli cells were left with Luria-Bertani broth, as a model soil, of different water contents, the viable cell number did not show a distinct decrease until the water content reached 3-4 g-water/g-solid. After the water content went down below the threshold, the specific death rate was roughly 0.1 h-1 though deviation was large especially at the final stage of drying. E. coli survived on the surface even after 2 days, and coexistence of nutrients enhanced the final level of viable cells.

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