Qualities of Rice-Based Home Meal Replacement Products Upon Microwave Cooking

The physicochemical characteristics of five types of rice-based home meal replacement (HMR) products (instant rice, doshirak, kimbab, frozen fried rice, and freeze-dried rice) were measured before and after microwave cooking, and principal component analysis (PCA) was performed. HMR products contained grains from 8.42 to 8.72 mm before and after the microwave cooking. The amylose content and water absorption index (WAI) ranged from 20.10-23.15% and 0.50-2.87%, respectively. Frozen fried rice showed high amylose content but low WAI, and dry rice showed low amylose content but high WAI. There was a change in the moisture content of freeze-dried rice: moisture increased from 1.3 to 60.3% after cooking. The rehydration rate of freeze-dried rice was about twice higher than that of other HMR products, while instant rice showed a low rehydration rate. The texture profile's hardness and cohesiveness respectively were 306.1 g/cm2 and 47.9% before cooking, but 209.6 g/cm2 and 66.0% after cooking. The lightness value decreased from 72.5 to 68.9 after the microwave cooking, while there was little change in the lightness value of instant rice, and that of the frozen fried rice decreased. PCA revealed that, microwave cooking apparently affected WAI and rehydration rate in the freeze-dried rice yellowness in the frozen fried rice, and stickiness and lightness in the instant rice, respectively.