Combining refrigeration and predictive models for beef carcases

Summary

Simplified models of carcase chilling, that provide a prediction of temperature and water activity over the entire carcase surface, were developed in the project PRMS.043A: "Modelling of Beef Carcass Chilling".
Similarly, models for microbial growth based on temperature and water activity have been developed such as the E.coli model underlying the Refrigeration Index - RI.
Models also exist for microorganisms responsible for spoilage of meat that could also be combined with models for prediction of temperature and water activity changes on carcasses.
The objectives of this project were to:determine whether the RI, which makes a calculation of E. coli growth based on temperature data from the slowest cooling point on the carcase and for constant and conservative levels of water activity, pH and lactacte leads to unnecessarily conservative estimates of RIassess the reliability of the carcase chilling modelcompare predicted changes in E.coli and pseudomonad levels under different cooling regimes and at different sites on the carcase to determine whether there is scope for optimisation of cooling regimes that minimise levels of both organisms
Any process that decreases the overall temperature experienced by the carcase during chilling will reduce pseudomonad growth. The inhibition of growth appears to be greatly enhanced by reduction in water activity at the same time.