Influences of High Hydrostatic Pressure, Microwave Heating, and Boiling on Chemical Compositions, Antinutritional Factors, Fatty Acids, In Vitro Protein Digestibility, and Microstructure of Buckwheat

The influences of high hydrostatic pressure (HHP), microwave heating (MW), and boiling (BL) on the chemical compositions, phytic acid, tannin, saponin, trypsin inhibitor activity, protein digestibility, and microstructure of buckwheat grains were investigated. All three processes decreased the starch, protein, fat, and ash contents. HHP and MW reduced the total flavonoids by 19 %, lower than that in the BL samples (38 %). HHP lowered the omega-6/omega-3 ratio by 6.4 %, while MW and BL increased the omega-6/omega-3 ratio by 4.9 and 2.6 %, respectively. MW reduced essential amino acids and total amino by 3.1 and 4.8 %, respectively, but the reductions were lower than in other treated samples. Phytic acid was lowered by 45.5 % in HHP samples, by 33.4 % in MW samples, and by 62.7 % in BL samples. Trypsin inhibitor activity decreased by 63 % in BL samples and by 13 % in other treated samples. BL induced the highest losses of tannin (35.7 %) and saponin (27.6 %), followed by MW treatment (27.5 and 20.1 %) and HHP treatment (19.9 and 14.6 %). The protein digestibility increased by 0.8, 3.6, and 6.5 % under HHP, MW, and BL conditions, respectively. Taken together, three treatments offered varying degrees of decreases in the antinutritional factors and increases in in vitro protein digestibility, as well as retention of nutritional components of the buckwheat. Therefore, it might be suggested that special care should be taken when selecting a processing method for the development of health-promoting buckwheat products.