EFFECT OF MILLED WHEAT PARTICLES FRACTIONATION ON THE ANTIOXIDANT ACTIVITY IN SOME FOOD PRODUCTS

Abstract

The current study was designed to determine the radical scavenging activity (RSA/DPPH), total flavonoid contents (TFC) and total phenolic contents (TPC) capability for the wholegrain, flour and bran layer of some Egyptian wheat varieties. Six different wheat samples of five common wheat and one durum wheat varieties were analyzed. The total phenolic contents of the bran layer was found the highest (4.66-3.15 mg/g), followed by that of grains (3.45 -1.78 mg/g) and the lowest of flour (2.81 - 160 mg/g). The same trend was showed in total DPPH radical scavenging. The total flavonoid of the whole wheat was found the highest, followed by flour and the lowest for bran layer. The three solvent systems included 50% acetone (v/v), 70% methanol (v/v) and 70% ethanol (v/v). Antioxidant activities were tested using free radical scavenging abilities against the stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH), Total flavonoid contents by the aluminum chloride colorimetric methods and total phenolic contents were determined using the Folin-Ciocalteu assay. The results showed that the extraction solvents and wheat varieties significantly altered the total phenolics and antioxidant activity of whole wheat and bran, and 50% acetone is a recommended solvent for extracting phenolic compounds from the tested wheat and bran. Antioxidant ability for coarse, medium and fine wheat bran were measured and compared. The fine fraction exhibited significantly higher antioxidant content compared to the other fraction; except for the RSD/DPPH value, in which fine was significantly lower. The particle size effects on the bran's physical properties were examined. The results showed that particle size could effectively decrease water-holding capacity and oil-holding capacity. The antioxidant activity of extract from roasted and boiled whole wheat was evaluated. Results displayed that the extract exhibited high antioxidant activities when compared with untreated whole wheat and the extract significantly increased the TFC while TPC decreased in both treatments. The effects of whole wheat flour (WWF) and replacement ratios (5-10) with bran on the antioxidant, physical and sensory properties for cookies were investigated. The antioxidant activities of the cookies were significantly weakened by adding wheat bran. The sensory quality was negatively affected by WWF with a decrease over all acceptability.

Key Words: Wheat bran; Antioxidant; Radical scavenging activity; Total phenolic contents; Flavonoid; Milled bran fractions; Physical properties; Technology treatments; Cookies.