Microwave reheating of cold-stored cooked rice partially disrupts B-type starch crystallites and nanoscale order without affecting V-type crystallites or short-range order, resulting in an increase in resistant starch content to approximately 30.06% due to reduced susceptibility of remaining structural domains to enzymatic digestion.

When rice is cooked and then cooled, its starch molecules lock into tight, crystalline structures. Microwaving this cooled rice breaks apart some of these tight structures but leaves other dense parts untouched. These remaining dense parts form a physical barrier that blocks digestive enzymes from breaking down the starch, so more starch passes through the gut undigested.