A review of rice starch digestibility: effect of composition and heat-moisture processing

Rice grain as the staple food for more than half the global population provides 20% of global human calorie requirements. Starch digestion rate is an important consideration for rice consumers who are concerned about health, particularly those with diabetes. Understanding the effect of rice grain composition on starch digestion may assist the growing and processing of rice for preferred eating quality and starch digestibility. Amylose content is regarded as the key determinant of rice starch digestibility, however, starch digestibility differs between rice varieties with similar amylose content indicating the possible role of non‐starch components in determining rice starch digestibility. The current understanding of the role of starch and non‐starch compounds in determining rice starch digestion has been reviewed here. Starch digestion rate is dependent upon starch granule size, starch crystallinity, amylose content and amylopectin chain length and non‐starch components such as fibre, protein, lipid and polyphenols. Non‐starch components may complex with starch and inhibit starch digestion by affecting starch properties or by producing a protective layer around starch or by having antagonistic effects on digestive enzymes. Hydrothermal processing of rice can alter the effects of starch and non‐starch components on starch digestion.