In vitro digestion and physicochemical properties of wheat starch/flour modified by heat-moisture treatment

• Reduced peak viscosity and increased pasting temperature after HMT of wheat flour were found.
• HMT of wheat flour significantly changed the crystal structure and crystal pattern.
• HMT of wheat flour showed higher resistant and slowly digestible starch contents.

Physicochemical and digestive properties between wheat starch (WS) and wheat flour (WF) which had been modified by using heat-moisture treatment (HMT) were investigated. Reduced peak viscosity and increased pasting temperature were found in both WS and WF after HMT. Samples treated with a higher moisture treatment (25% and 35%) exhibited biphasic endotherms. HMT significantly changed crystal structure of WS and WF, and patterns transferred from A to A + V with moisture content increase indicating a formation of starch–lipid complex. Besides, HMT caused the clumping of starch granules and the aggregation of denatured protein, observed using confocal laser scanning microscopy (CLSM) and light microscopy. The higher moisture contents produced HMT samples with higher resistant starch content. In addition, HMT wheat flour showed a higher resistant and slowly digestible starch content when compared to the other counterpart of WS.