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Intrinsic and extrinsic factors affecting rice starch digestibility

Toutounji, Michelle R., Farahnaky, Asgar, Santhakumar, Abishek B., Oli, Prakash, Butardo, Vito M., Blanchard, Christopher L.
Trends in food science & technology 2019 v.88 pp. 10-22
blood glucose, carbohydrate content, digestibility, food industry, gelatinization, noninsulin-dependent diabetes mellitus, nutritional intervention, obesity, postharvest storage, retrogradation, rice, rice starch, staple foods, starch granules, storage conditions
The current incidence of obesity and type 2 diabetes is at global epidemic levels. To mitigate their impact, there is a need to develop starch-containing foods that give rise to a low and stable postprandial blood glucose response by increasing the proportion of slowly-digestible and indigestible carbohydrate content. Rice is an ideal target food for such dietary intervention because it is a staple food for over half the world's population.The starch digestion of cooked white rice grains is usually complete or near complete upon consumption, but the rate of digestion is influenced by intrinsic food properties and extrinsic influences. This review provides an overview of the complex interplay between the starch granule and its interaction with non-starch components of the rice grain (intrinsic characteristics) as well as the effects of processing (extrinsic factors) on starch digestibility.The intrinsic properties of white rice grains play a significant role in starch digestibility which can be further enhanced after processing, especially by gelatinisation and retrogradation. Post-harvest storage conditions of rice were found to influence starch digestibility but this effect was temperature-dependent. Limited studies investigated starch-lipid and starch-protein interactions in rice, but changes to substrate accessibility have been implicated. Improving our understanding of the effects of processing on starch digestibility can provide an effective tool for food manufacturers to regulate starch digestibility of existing rice varieties.