Total Phenolic and Phytosterol Compounds and the Radical Scavenging Activity of Germinated Australian Sweet Lupin Flour

Abstract

In addition to their favourable nutritional profile, legumes also contain a range of bioactive compounds such as phenolic compounds and phytosterols which may protect against chronic diseases including cancer and cardiovascular disease. Germination of some legume seeds has been previously reported to increase the concentration of the bioactive compounds. In this study, the effect of germination of Australian Sweet Lupin (ASL) seeds for 9 days on the concentration of some bioactive compounds and the radical scavenging activity in the resulting flour was determined. The concentration of total phenolic compounds in methanolic extracts of germinated ASL flour was determined using Folin Ciocalteu reagent and phytosterols in oil extracts were analyzed by gas–liquid chromatography. The methanolic and oil extracts were also used to determine radical scavenging activity toward 2,2-diphenyl-1-picrylhydrazyl. In the methanolic extracts of germinated ASL flour, phenolic contents and the antioxidant activity were significantly increased following germination (700 and 1400 %, respectively). Analysis of the oil extracts of germinated ASL flour revealed that the concentration of phytosterols and the antioxidant activity were also increased significantly compared to ungerminated ASL flour (300 and 800 %, respectively). The relative proportion of phytosterols in germinated ASL flour was: ß-sitosterol (60 %), stigmasterol (30 %) and campesterol (10 %). Germination increases the concentration of bioactive compounds and the radical scavenging activity in the germinated ASL flour.