Hierarchical Structure of Black Wheat Starch Modified by High Pressure Heat-Moisture Treatment and the Modulation on...

Black wheat starch (BWS) with greater brightness and greenness was isolated in this study, which contained phenolics content of 16.52 mg/100 g. It was modified by high pressure heat-moisture treatment (HPMT). Changes in its physicochemical property were investigated on the basis of hierarchical structure. Enhancing moisture content (MC) of HPMT expedited granules' disruption, crystallinity loss, loosening of semi-crystalline lamellae, debranching of amylopectin, and long chains' breakdown. Besides molecular disordering, it increased chains' flexibility to rearrange into new architecture and interact with phenolics. As a result, modified starch showed enhanced cold-water swelling power (up to 6.91 g/g) and thermal stability (with a peak temperature of gelatinization up to 76.09°C), although its pasting viscosity decreased. Furthermore, HPMT (especially that with higher MC) resulted in softer starch gels (with hardness of 68.92∼106.89 g) with enhanced anti-retrogradation capacity. The modified gels also had greater adhesiveness (-34.36∼-52.09 g·s), which is decisive for starch dough formation. Owing to the presence of phenolics and special functionalities, HPMT-modified BWS exhibited the potential to develop health-promoting gluten-free foods.