Antioxidant properties of hard winter wheat extracts

Extracts from three winter wheat varieties ('Trego', 'Akron' and 'Platte') were evaluated and compared to alpha-tocopherol for their inhibitory effects on lipid peroxidation in fish oils by measuring the oil stability index (OSI). Free radical scavenging capacities and chelating potencies were also measured to better understand the potential mechanism(s) of their effects on lipid peroxidation. Trego extracts showed the greatest capacity to suppress lipid peroxidation in fish oils. The OSI time of the oil sample containing 600 ppm Trego extract was 2.85 h beyond the control sample containing no antioxidant, which is 3.1 times longer than the OSI time of oil containing 300 ppm tocopherol. Dose effects were observed for Trego extract, but not for Akron or Platte extracts. Furthermore, the higher level of Platte extract corresponded to a shorter OSI time. All three wheat extracts directly reacted with and quenched DPPH radicals and showed chelating activity. Akron extract had the greatest radical scavenging and chelating activities. Neither radical scavenging nor chelating activities of the wheat extracts can explain the relative activities of these extracts on lipid peroxidation in fish oils under the experimental conditions. The results of this study indicate possibility of to developing natural food antioxidants from selected wheat varieties, including Trego hard white winter wheat. (C) 2002 Elsevier Science Ltd. All rights reserved.