Developing model food systems with rice based products for microwave assisted thermal sterilization

Model foods are effective tools to evaluate heating patterns and determine hot and cold spot locations in food packages during microwave-assisted thermally sterilization (MATS) processes. Previous research on model food development has focused on high-moisture foods, with limited information on medium-moisture foods (0.2-0.6 g water/g food). This research aimed to develop rice model foods to simulate medium-moisture food during MATS processing. The optimal composition of a rice flour gel (RFG) model food was 0.3 g/g rice flour, 0.135 g/g tapioca starch, 0.001 g/g xanthan gum, 0.005 g/g d-ribose, and 0.559 g/g water, and a rice to water ratio of 1:1.2 g/g with 0.005 g/g d-ribose for the rice grain (RG) model. The temperature sensitivities of the models' color parameters could be applicable for safety and quality attribute modeling; the RFG model had a larger range of z-values (11-31 °C) than the RG model (18-27 °C). Validation results showed that the RG model food received more thermal energy than the RFG model, with thermal treatment equivalents at 121 °C of 60.3 and 6.5 min, respectively. The heating pattern in RFG medium-moisture model food was consistent with high-moisture models in MATS processing. Model foods developed in this research could be helpful tools for microwave process development for medium-moisture foods.