Influence of the variability of processing factors on the F-value distribution in batch retorts

The F-value distribution in a batch retort processing of in-pack conduction heating foods resulting from the variability of four processing factors (i nitial temperature, heating time, headspace and external heat transfer coef ficient) was determined by mathematical modelling. Three hundred combinatio ns were generated from normally distributed values for each factor, followi ng the Monte Carlo approach. The retort temperature was assumed the same fo r all containers and the F-value at the geometrical centre of containers of different dimensions was calculated by solving the governing heat transfer equations using finite elements. It was found that in the range tested the variability of the heating time and of the external heat transfer coeffici ent had the biggest impact on the F-value distribution and that the head sp ace variability had a negligible impact. It was also found that although ea ch influencing factor had a normal distribution, the F-value distribution w as not normal, showing a significant tailing, being well described by a gam ma function. (C) 2000 Published by Elsevier Science Ltd. All rights reserve d.