Composition and Digestion Characteristics of Starch in Endosperm of Glutinous Rice Varieties

Abstract

In this study, the starch components, digestible sugar contents (glucose content produced by starch digestion) and expected glycemic index (eGI) values of 65 glutinous rice varieties were analyzed by an in vitro enzyme digestion method. The results showed that starch composition varied greatly among the 65 varieties, with total starch contents ranging from 70.63% to 76.72%, resistant starch contents ranging from 0.17% to 3.79%, rapidly digestible starch contents ranging from 40.51% to 52.37%, and slowly digestible starch contents ranging from 19.92% to 32.47%. Glucose was released quickly from digested glutinous rice starch and the release process lasted for a long time. The amount of sugar released increased sharply within 30 min after meals and then decreased continuously, and the glucose content was minimum during 60–90 min and increased slightly during 90–180 min. eGI values ranged from 67.1 to 79.1, and 80% of the varieties had eGI values above 70, belonging to high sugar varieties. The eGI value of Bananuo 18 was the highest, and that of Dehui 2290 was the lowest. Starch content was correlated with the amount of released glucose and eGI. Rapidly digestible starch contributed to the rapid increase of blood glucose in the early stage, and slowly digestible starch and resistant starch were beneficial to the slow increase of blood glucose. The results can provide data reference for people who need to control their blood glucose levels and pay attention to the quality of glutinous rice.

Keywords

• glutinous rice varieties; starch components; digestive characteristics in vitro; expected glycemic index; digestible sugar content