Antioxidant capacities of heat‐treated wheat germ and extruded compounded bran

Abstract

AbstractBackground and objectivesPure wheat bran and wheat germ are the by‐products of sieved flour. Pure wheat bran contains a substantial amount of dietary fiber, vitamins B and D, and other nutrients; lipases in the wheat germ induce lipid oxidation and break down vitamins. The present study used heat treatment to stabilize the wheat germ and then compounded it with the extruded pure wheat bran and compared it with the extruded bran. The antioxidant capacity and soluble polyphenols of the compounded wheat bran and extruded wheat bran were subsequently measured, to select a method to improve the antioxidant capacity of wheat bran.FindingsThe optimized heating temperature of wheat germ was 110°C. The half‐maximal inhibitory concentration value of the total antioxidant capacity showed that the compounded wheat bran had a higher antioxidant capacity than the extruded wheat bran. It was hypothesized that the operations of extrusion and heat treatment increased the antioxidant capacity of compounded wheat bran. In addition, after the extrusion treatment, a variety of flavonoid glycosides in the wheat bran was released while the content of various phenolic acid types was decreased. However, the content of the phenolic acid types and flavonoids in the compounded wheat bran was increased. Hence, compounded wheat bran is more suitable for producing functional foods.ConclusionThe results of this study revealed that extruded pure wheat bran and heat‐treated wheat germ can effectively increase the antioxidant capacity and the content of the phenolic acid types and flavonoids; hence, it is more suitable for producing functional foods.Significance and noveltyThis study developed a fast and inexpensive detection method that uses a combination of heat and extrude to process compounded wheat bran, which provides the optimal process method for extending the yield and shelf life of wheat bran products.