Inconsistency between polyphenol-enzyme binding interactions and enzyme inhibition: Galloyl moiety decreases amyloglucosidase inhibition of catechins

•Catechins with (CGMs) and without (Cs) galloyl moiety inhibit amyloglucosidase (AMG).•Inhibitory activity of each CGMs was weaker than its corresponding Cs.•In digestion system catechins tend to bind with starch-AMG complex, instead of AMG.•Without starch, binding affinity of each CGMs was higher than its corresponding Cs.•GM Tropism to AMG active site weakens binding of A-C-B skeleton with non-active sites.