Antioxidative activity of roasted and defatted peanut kernels

Peanut kernels were roasted at 180 +/-2 degreesC for various period of times (0-60 min); then grounded and defatted or further hydrolyzed with proteases to test their antioxidative activity (AOA). Samples roasted for 60 min displayed the most remarkable AOA, determined by Ferric-thiocyanate method, on linoleic acid in emulsions prepared with Tween 20 or 80. In reducing power, the absorbance at 700 nm of enzymatic hydrolysates (1 mg/ml) prepared from a 60-min-roasted sample with Esperase (enzyme/substrate=1/200, 60 degreesC, pH 8.0) and with Neutrase (enzyme/substrate=1/200, 50 degreesC, pH 6.0) was 1.24 and 0.81, respectively. The scavenging activity of Esperase and Neutrase hydrolysates on DPPH (alpha, alpha'- diphenyl-beta -picryldrazyl) radicals was 93 and 89%, respectively, while their chelating activity on Fe+2 was 69 and 52%, respectively. Besides, in vitro, Esperase hydrolysates (greater than or equal to 100 mug/ml) exhibited the remarkable antioxidative effect on the oxidation of low-density lipoprotein (LDL) induced by copper by showing a lag time of longer than 6 h. (C) 2001 Elsevier Science Ltd. All rights reserved.