Study On The Effect Of Tea Polyphenols On Starch Digestion

Starch is the major energy source of hunman being. The blood sugar of nomal people after starchy meals is related to the botanical source of starch, other nutrient components in foods, and the processing techniques used in food preparation. Human blood sugar and insulin levels are closely related to the occurrence of obesity, diabetes, cardiovascular disease and other chronic diseases.This study proved tea polyphenols could reduce glycemic index (GI) of starch food, decrease the peak value of glycemic response curve with a slow elevation of the blood glucose level.Thus, TP might be beneficial to the prevetion and management of diabetes and its complications. For the mechanism study, a convenient method of in vitro digestion to evaluate the starch hydrolysis rate and extent was established. The in vitro experimental results showed that TP's effect on starch digestion was related to the concertrations of TP, compositions of TP catechins, starch digestive emzymes and the time of reaction. An inhibition ratio of 43.6% was obtained when maize starch was used as substrate and TP was controled, which is the highest among used starches. The inhibitory effect of TP on starch digestion was enhanced as increase of TP concertration. The inhibition ratio reached the peak value (86.2%) when the concertration of TP was 0.6mg/ml and 0.02mg/ml was the lowest availability concertration of TP showing inhibitory effect on maize starch. EGC showed a highest inhibitory effect (22.5%) on maize starch digestion among TP catechins. But the inhibitory digestion effect of TP mixture was better than each individual catechin of TP.The inhibitory effect of TP on amyloglucosidase was weaker thanα–amylase. The inhibition ratio at 120 min when amyloglucosidase (AMG) was added was greater than onlyα–amylase acted on starch.In this study, OSA-starch was prepared from OSA modified waxy maize starch on the alkalescence condition. The OSA modified waxy maize starch was produced on the optimum condition, and the SDS content was enhanced to 43.8% through hot-heat treatment.OSA-starch could depress the peak value of blood glucose and smooth the blood glucose curve, and TP had a further effect.The major inhibitory mechanism of TP on starch digestion was the inhibition effect of TP onα-amylase and amyloglucosidase. Both in vitro simulation test and in human blood glucose response reflected TP could suppress the postprandial glycemic response and reduce the GI of starchy foods, which suggest TP's benefits to blood glucose control and human health.