Assessment of bacterial growth on the surface of meat under common processing conditions by combining biological and physical models

A water transfer model and a bacterial model were combined to study the effects of process parameters (air temperature, velocity and relative humidity (RH)) on the drying of the food surface and their indirect consequences on bacterial growth. They were tested on experimental growths of Pseudomonas spp. inoculated on pork meat: small variations in a parameter can have a considerable effect on bacterial growth. Sensitivity calculations showed how the meat properties (diffusivity, sorption isotherm, thickness) affected the calculated results. The combined models were applied to study the impact of air velocity and RH on the increase in the bacterial population after 96 h of storage at 12 °C. Thus, no more than a two log unit increase is obtained (1) if the air velocity is equal to 0.2 m/s and RH below 82% or (2) if RH is as high as 90%, air velocity must be equal to 0.9 m/s.