Starch digestibility of cooked rice as influenced by the addition of different tea types (Camellia sinensis): An in vitro study

The stability of tea catechin is influenced by various factors such as tea types, pH and digestive processes. The study aimed to investigate the effect of different tea types on the stability of tea catechin and their impact on starch digestibility and glycemic response to different types of cooked rice. Cooked rices were co-digested with green tea, oolong tea and black tea, and the catechin profiles were correlated with the inhibition of enzymatic digestion.The findings revealed that the green tea exhibited to be the most potent inhibitory effect on starch digestion. In addition, due to its highly porous structure, glutinous rice showed a higher starch hydrolysis rate and glycemic index than jasmine rice. The estimated glycemic index (eGI) of cooked jasmine rice co-digested with green, oolong, and black teas were 61.95 & PLUSMN; 1.07, 64.62 & PLUSMN; 1.12, and 67.14 & PLUSMN; 0.87, respectively, while eGI values of cooked glutinous rice were 77.55 & PLUSMN; 1.15, 79.98 & PLUSMN; 0.98, 81.45 & PLUSMN; 0.75, respectively. The findings indicates that epigallocatechin (EGC) achieves the highest stability. Overall, the results provided compelling evidence that tea types and rice structure affect the regulation of starch digestion and eGI of cooked rice.