Enhancing the quality of steamed oat cake by partially gelatinized starch in oat flour and its molecular mechanism

Abstract

The aim of this study was to investigate the effect and mechanism of partially gelatinized starch in oat flour on the rheological characteristics of the oat batter and the quality of steamed oat cakes. The results showed that an increase in the gelatinization degree of oat flour destroyed the starch granular structure and the long-range molecular order of starch, accompanied by a decrease of crystallinity from 22.28 % to 8.72 % and the formation of a starch-lipid complex. The increased gelatinization degree of oat flour destroyed the protein network and promoted the formation of the starch gel network in oat batter. Meanwhile, the addition of gelatinized oat flour enhanced the elastic behavior of the oat batter and the gas retention ability of the fermented oat batter, while decreased the total gas volume from 1075.5 mL to 827.0 mL. The steamed oat cake containing 50 % gelatinization degree of oat flour (G50) showed moderate hardness, springiness and chewiness, as well as the largest cell area fraction (37.35 %), due to the formation of a dense starch gel-protein double network and the enhancement of long/short-range molecular order of starch. Thus, this study provided the feasibility of improving the quality of oat-based fermented products by changing the gelatinization degree of oat starch.

Keywords: Microstructure; Starch gelatinization degree; Steamed oat cake.