Abstract:In order to study the effect of extrusion in synergy with addition of different exogenous additives on the quality characteristics of black rice powder, black rice was used as the raw material, and extruded with 1% (mass fraction) vitamin C, citric acid, glucose, calcium carbonate and complex (each of the four exogenous substances was added at 0.25%), respectively, into black rice powder. The effects of different exogenous additives on the reconstituability, viscosity, gelatinization degree, sensory quality and active ingredients (dietary fiber, polyphenols, flavonoids and anthocyanin contents) of the black rice powder were evaluated. The results showed that compared with direct extrusion of black rice, the water solubility index of black rice powder increased by 105.53%, the water absorption index and the caking rate decreased by 46.28% and 53.36%, respectively, the viscosity decreased significantly, the fluidity increased, with insignificant change in the gelatinization degree and significant improvement of sensory quality. The addition of glucose or citric acid was beneficial to the increase of insoluble dietary fiber and total dietary fiber contents, while the addition of complex was beneficial to the increase of soluble dietary fiber content. The addition of citric acid was more conducive to the retention of active substances in black rice powder such as free and bound polyphenols, bound flavonoids, and anthocyanins, and the antioxidant power of total phenols increased by 105.60%. In summary, the addition of different exogenous additives during the extrusion process of black rice powder could effectively improve the reconstituability and sensory quality of black rice powder, and increased the retention rate of active ingredients. The aim of this study was to establish a processing technology of instant black rice powder that had high contents of retained nutrients and active substances as well as good taste and application quality.
