Enzymatic extraction of starch from broken rice using freeze‐thaw infusion with food‐grade protease

Despite the abundance of rice crops, rice starch is not widely utilized owing to the low yield and high cost of industrial production. The objective of this study was to increase the efficiency of starch extraction from broken rice using a freeze‐thaw infusion method, which can rapidly infuse food materials with enzymes, combined with food‐grade proteases. Because the freeze‐thaw infusion method facilitates the rapid entry of enzymes into substrates, enzymatic reactions occur efficiently both inside and outside the substrate. The starch extraction efficiencies were 66.81, 61.74, and 69.31% for the alkaline method, protease treatment, and freeze‐thaw infusion method, respectively. The physicochemical properties of the starches, including shape, pasting, and thermal transition, were not affected by the extraction method. These results indicated that the freeze‐thaw infusion method is efficient for starch extraction from broken rice.