Effect of Microwave Cooking on Quality of Riceberry Rice (Oryza sativa L.)

Microwaves have been applied for cooking, warming, and thawing food for many years. Microwave heating differs from conventional heating and may cause variation in the food quality. This study determined the quality of Riceberry rice (Oryza sativaL.) after microwave cooking using various rice-to-water ratios at three power levels (360, 600, and 900 W). The texture of all microwave-cooked samples was in the range 162.35 +/- 5.86 to 180.11 +/- 7.17 N and was comparable to the conventionally cooked rice (162.03 N). The total phenolic content (TPC) and the antioxidant activity of the microwave-cooked rice were higher than those of the conventional-cooked rice. Microwave cooking appeared to keep the TPC in the range 241.15-246.89 mg GAE/100 g db and the antioxidant activities based on DPPH and ABTS assays in the ranges 134.24-137.15 and 302.80-311.85 mg center dot TE/100 g db, respectively. Microwave cooking also maintained similar contents of fiber, ash, and total starch to those from conventional cooking. The glycemic index (GI) for all freshly cooked rice samples was not significantly different, and the rice was classified as a high-GI food. Microwave cooking could be recommended as an alternative technique for rice cooking due to its rapid heating regime and the comparable quality and maximized TPC and antioxidant activity of the cooked rice.