Superheated steam treatment of soft wheat on the physicochemical properties and structure of wheat starch

Abstract

AbstractSoft wheat grains were treated with superheated steam (SS) at 165 and 190°C, respectively for 1–5 min to understand the changes in the structures and properties of wheat starch following SS treatment. The damaged starch contents, amylose ratio, gelatinization properties, surface morphology, viscosity, and crystalline structure of the starch in wheat flour were determined. Damaged starch content, amylose ratio, and starch viscosity significantly increased after SS treatment. The onset temperature (To) and peak temperature (Tp) of wheat starch increased with the extending of treatment time, while an opposite variation trend was observed for (Tc − To). Additionally, the gelatinization enthalpy (ΔH) decreased after 3–5 min of SS treatment. Starch aggregation was observed in scanning electron microscopy (SEM) graphs. Compared to traditional heat treatment methods, SS treatment of wheat grains may be preferable for modifying the starch properties of soft wheat since much time and energy could be saved.Practical ApplicationThe physicochemical properties and structure of soft wheat starch significantly affect the quality of cakes made with soft wheat flour. After SS treatment of wheat kernels, the amylose ratio and damaged starch content in wheat starch significantly increased. Moreover, gelatinization properties and starch viscosity of wheat starch were also significantly affected. The changes in physicochemical properties were mainly due to the changes in the structure of starch granules and starch molecules. The above results in the physicochemical properties and structure of starch led to the increase in the viscosity and gas retention capacity of cake batter, which might be the reason why the specific volumes and texture of cakes could be improved after SS treatment of wheat. This research verified SS treatment may be preferable for improving cake quality compared to traditional heat treatment methods, which promotes the application of SS in wheat process engineering.