Application of a Rapid In Vitro Method Based on Glucometer for Determination of Starch Digestibility and Estimated Glycemic Index in Rice

Abstract Measuring the glycemic index (GI) of rice in vivo is time consuming and costly. A simple, reliable, and cost‐effective in vitro digestion assay suitable for use during rice breeding and rice product development is required. The purpose of this study is to propose the use of an in vitro enzymatic starch digestion assay based on a glucometer to determine the estimated GI (eGI) of rice in both raw and cooked forms. Four rice cultivars differing in amylose contents are examined. The known GI rice cultivar, Doongara, is used as the reference. The assay includes the digestion of ground rice using all of the enzymes require to simulate the human digestive tract. The glucose released during digestion is determined using a portable hand‐held glucometer over a 120‐min period. The obtained starch digestograms are modeled using a first‐order kinetic model, and eGI values are calculated. The assay is applicable to both raw and cooked rice samples. It can be used to classify rice according to its eGI as affected by cultivars and cooking methods. The protocol is robust, high‐throughput, and adaptable to non‐laboratory settings. It can benefit rice breeders, farmers, and manufacturers of rice products.