Inhibitory effect of four types of tea on the in vitro digestion of starch

Phenolic compounds have been shown to decrease the rate of starch hydrolysis by inhibiting digestive enzymes for starch. Tea, rich in phenolic compounds, has been widely reported for its beneficial health effects. This study explored the inhibitory abilities of four types of tea, that is, green tea (GT), oolong tea (OT), black tea (BT), and white tea (WT), on the in vitro enzymatic digestion of potato starch (PS) and high‐amylose maize starch (HAMS), using two in vitro digestion methods. All teas significantly inhibited the digestion of both starches, with a few exceptions at some time points. The resistant starch content was increased by all four teas in HAMS, but only by BT and WT in PS. The total phenolic contents in the teas could not predict the inhibitory ability of the teas, possibly due to the structural diversity of phenolic compounds and the presence of other compounds that could also alter enzymatic activity. Our results suggested that tea, regardless of its type, can slow down the enzymatic digestion of starch and therefore imply a potential benefit for controlling postprandial hyperglycemia.