The Biological Validation of Thermal Processing Using Food Alginate Simulated Particles Inoculated with Bacterial Spores

摘要

In biaxial rotation processing of liquid particulates cans, biological validation is necessary in order to estimate process lethality, F_0, because of the difficulty in using temperature measuring devices to collect time-temperature history at the particle centers. The objectives of the study were: (1) to fabricate an carrot and meat based alginate particle whose heating behaviour matches the heating behaviour of Nylon spheres previously used in heat transfer studies (2) to predict time temperature profile at the alginate fabricated particle in order to calculate the process times using the numerical integration method (3) using initial and final spores count for carrot and meat fabricated particles inoculated with spores of C. sporogenes and G. stearothermophilus, respectively, to determine the number of log reductions, n, in order to calculate process lethality, and to compare the latter with the model predicted values, which were obtained through simulated time temperature profiles of the alginate fabricated particles. Process times were calculated to achieve an accumulated lethality of 3 and 15 min for carrot and meat alginate fabricated particles, respectively. These ranged from 19.5 to 36.4 min for carrot and from 19.3 to 40.1 min for meat alginate particles. The resulting process lethality, F_0, values ranged from 2.8 to 3.2 min for carrot alginate fabricated particles inoculated with C. sporogenes spores and from 12.5 to 15.4 min for meat alginate fabricated particles inoculated with G. stearothermophilus spores. The evaluated F0 values were in general slightly lower than the selected targets (3 min for carrot particles with C. sporogenes and 15 min for meat particles with G. stearothermophilus). However, there were no significant differences (p>0.05) in the computed F0 values between those obtained from biological validation and numerical simulation under the experimental conditions.