The current analysis of α-amylase/trypsin inhibitors (ATIs) is complicated due to the missing link between inhibition potential and inhibitors. Two on-surface assays (nanoGIT) were developed to quantify the inhibition of α-amylase and trypsin by flour extracts of refined wheat, whole wheat, and einkorn, followed by direct analysis (on the same surface) of the metabolisation products via high-performance thin-layer chromatography (HPTLC). The HPTLC–nanoGIT (amylolysis inhibition)–FLD/Vis revealed a lower α-amylase inhibition of einkorn than refined or whole wheat, whereby both latter wheat types showed no differences. The HPTLC–nanoGIT (proteolysis inhibition)–Vis confirmed only partially the 100% inhibition at high extract concentrations of the three cereal types obtained by the spectrophotometric trypsin inhibition assay. The HPTLC–nanoGIT workflows not only confirmed the inhibitory effects obtained by spectrophotometric assays but also provided substantial resolution of saccharide-specific interactions and specific profile patterns of the released individual metabolisation products.
Müller et al. (Fri,) studied this question.