Evaluation of the antioxidant activity of lupin seed flour and derivatives (Lupinus albus ssp. Graecus)

In order to investigate natural sources of nutritive and non-nutritive antioxidants, the methanol extracts of lupin (Lupinus albus spp. Graecus) flour (with and without alkaloids) and lupin protein isolate were first examined for their antioxidant activity. The antioxidant activity of these extracts was determined by a rapid spectrophotometric method based on the coupled oxidation of beta-carotene and linoleic acid and also by carrying out stability tests at 63 degrees C with cottonseed oil. The results showed that the methanol extracts of lupin exhibit a marked antioxidant activity, higher than that of soya flour extracts. In a second step, an attempt was made to detect some of the components that may contribute to the overall antioxidant activity such as phenols, flavonoids, amino acids and peptides by using thin-layer chromatography. Finally, the pronounced antioxidant activity was correlated to the presence of total phenolics and phospholipids at high concentrations in the lupin extracts. (C) 1999 Elsevier Science Ltd. All rights reserved.