The aim of this study was to develop a convenient method to assist the food industry in de-veloping a process protocol for the production of ready-to-eat powders using a microwave pasteuriza-tion system.The analytical model was used to estimate the temperature rise in the cold zone of pack-aged food during the heating process of a 921 MHz single-mode microwave system.The model was validated in a pilot-scale four-chamber plot using mashed potato or cold-gelled gelatinous foods of varying thickness(22～36 mm)and salt content(0～1.0%).Motion sensors are placed in the package to measure a pre-determined cold spot temperature.When the microwave power is 5 kW and 8.7 kW respectively,the 921 MHz microwave heating for 2.48 min,the cold spot temperature rise of the test food with a thickness of 22 mm and a salt content of 0.6%is the highest at 33.2℃,a thickness of 36 mm,and a salt content of 1.0%.The lowest temperature rise of the tested food was 10.3℃.The deviation between the experimental value and the estimated value was 1.9±1.2℃,and the goodness-of-fit R2 was 0.89.Based on the validated analytical results,a simplified diagram was developed to allow a rapid prediction of the temperature rise in affected by the dielectric properties of the food and the thickness of the package.An example is given of how the diagram can assist process scheduling.This chart can help evaluate the heating rate of various prepackaged food prod-ucts in a specific industry operation map,as well as guide product development to obtain the re-quired uniformity of heating.
维普
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