Understanding starch digestibility of rice: a study in brown rice

• Published in: International journal of food science & technology 2022-10, Vol.57 (10), p.6699-6710
• Main Authors: Srikaeo, Khongsak, Saeva, Kanyarin, Sopade, Peter A.
• Format: Article
• Language: English
• Subjects: Amylose; Biphasic starch digestogram; Digestibility; Digestion; heterogeneity tests; monophasic starch digestogram; objective logarithm of slope; Rice; Starch; starch digestion
• ISSN: 0950-5423; 1365-2621
• DOI: 10.1111/ijfs.16020

Summary In vitro starch digestibility of 10 Thai brown rice samples was investigated for foundational in‐depth understandings of treated/processed and untreated/non‐processed rice. The samples were uncooked pigmented, non‐pigmented and differed in amylose contents and chemical and functional properties. The starch digestograms were modelled using innovative techniques involving objective logarithm of slope (Sopade Objective Procedure) and one‐term and two‐term exponential and non‐exponential models. The samples significantly (P ≤ 0.05) revealed monophasic and biphasic starch digestograms, and the digestion parameters were sample‐dependent. Using the Sopade Objective Procedure, which better predicted the digestograms, the biphasic samples exhibited rapid‐slow and slow‐rapid in vitro starch digestion phenomena. The estimated glycaemic index (eGI) of the samples ranged from 41 to 95 g/100 g, and the sample with the slow‐rapid digestion pattern exhibited the lowest eGI. The results are discussed as baselines for follow‐up treatments that typify rice as a notable global food commodity. An objective logarithmic of slope procedure, the Sopade Objective Procedure, was employed for in‐depth analyses of starch digestograms from the 10 raw Thai brown rice. The starch digestion parameters revealed how estimates of maximum digestible starches in multiphasic starch digestograms should be defined for practical and universal starch digestion analyses.