Hydrothermal treatments affecting the concentration of neochlorogenic acid in dough of tartary buckwheat

Abstract

This study investigated the effects of initial temperature treatments of gluten-free doughs made from Tartary buckwheat flour, and time of methanol extraction from the cooked doughs of neochlorogenic acid, an important polyphenol metabolite. The doughs were hydrothermally treated from 25◦ C to 95◦ C, cooked at 95◦ C for 20 min, and extracted using 80% aqueous methanol at the room temperature for 20 min, 2 h, and 8 h. For the control, nonhydrothermally treated Tartary buckwheat flour samples, the extractable neochlorogenic acid was similar for these extraction times. For the cooked dough samples, the hydrothermal treatments were important in terms of extractability of neochlorogenic acid. The extractable neochlorogenic acid was higher for the control samples in comparison to the hydrothermally treated and cooked dough samples. Among these hydrothermally treated dough samples, the high extractable neochlorogenic acid concentrations were maintained for temperatures of at least 80◦ C. These high-temperature initial treatments during dough preparation appear to prevent degradation of the neochlorogenic acid in Tartary buckwheat flour. During hydrothermal treatment, neochlorogenic acid is bound to grain structures in such a way that prolonged extraction time is needed to extract it.