In general, working with higher initial temperatures will probably increase
errors (producing greater differences between experimental and predicted
values) than with similar experimental conditions but lower initial
temperatures, Tables l-3. Other errors would appear (Hung & Thompson,
1983) because volume and size increase when the phase changes from liquid
to solid. This could produce, in any meat product, an increase in the
freezing time not accounted for in the prediction procedure. Slight
deviations from symmetric conditions (de Michelis & Calvelo, 1983; Bazan
& Mascheroni, 1984) or the evaporation of water from the product during
freezing also affects that prediction. The influence of the specific
composition and temperature of each sample on the thermal conductivity
and specific heat also affects the freezing time prediction. In relation to this,
it should be noted that only one equation was used to determine each
thermophysical property for all the different kinds of meats studied here.
Anywhere, average errors of f 10-U% are acceptable in many engineering
applications (Cleland et al., 1982). In the majority of the cases studied this
error range is higher than that obtained with the method developed in this
paper. Both hypotheses, linear and quadratic temperature changes, provide
good predictions.