Physicochemical properties of protease‐treated rice flour

Abstract

AbstractThe physicochemical properties of rice flour treated with protease (Protease‐RF) and a conventional alkali steeping method (Alkali‐RF) were compared with native flour. The physical properties of flour gels were assessed by rapid visco analyzer, texture analysis, and rheology with reference to their composition and impact on their starch structures by the two treatment methods. Alkali‐RF exhibited shorter pasting time to peak with higher breakdown but lower setback. However, the textural parameters of both treatments were not significantly different (p > 0.05). The storage modulus for both treatments increased to a greater extent was compared to native flour. Low‐MW polypeptides (5–30 kDa) had less effect on gel‐forming properties, since similar texture qualities were obtained either in their presence or absence. The granule‐bound SS or GBSS (58–60 kDa) had less effect since it could not be removed either by proteases or alkali. The high molecular weight polypeptides (>77 kDa), which were partly removed either by alkali or protease treatments, played an important role in impairing the gel‐forming property of rice flour. Textural quality was observed to improve after their removal, compared to native flour.