LIPID CLASSES, FATTY ACID COMPOSITIONS AND TRIACYLGLYCEROL MOLECULAR SPECIES FROM ADZUKI BEANS (VIGNA ANGULARIS)

Abstract

The lipids extracted from adzuki beans grown in Japan were classified by thin-layer chromatography (TLC) into eight fractions. Molecular species and fatty acid distributions of triacylglycerols (TAGs) isolated from the total lipids in the beans were determined from a combination of argentation-TLC and gas chromatography. The major lipid components were phospholipids (PL; 63.5%) and TAG (21.2%), while hydrocarbons (5.1%), steryl esters (7.5%), free fatty acids (0.9%), diacylglycerols (1.3%) and monoacylglycerols (0.5%) were also present in minor proportions. Both major samples had high amounts of total unsaturated fatty acids, representing 62.1% for TAG and 65.9% for PL. Seventeen different molecular species were detected. The major TAG components were SMD (5.0%), S2T (19.3%), SD2 (13.8%), SMT (9.3%), MD2 (4.5%), SDT (7.0%), D3 (8.8%) and ST2 (15.9%), where S, M, D and T denote a saturated fatty acid, a monoene, a diene and a triene, respectively. PRACTICAL APPLICATIONS This article describes the characteristics of lipid components, fatty acid compositions as well as the profiles of triacylglycerol (TAG) molecular species of adzuki beans. α-Linolenic (18:3n-3) acid was detected as 24.8, 21.2 and 15.2% in the TAG, total lipids and phospholipids, respectively. The oil from legumes, except the profitable fatty acid content, could be a potential source of tocopherols. The data obtained in this study would be useful to both consumers and producers for manufacturing traditional adzuki confectionaries (wagashi) in Japan and elsewhere.