LAUSR

Abstract One of the reasons for “underutilization” of the tropical legume winged bean ( Psophocarpus tetragonolobus (L.) DC.) is the presence of certain anti-nutrients in its seeds. This may be one of the impediments for the adoption and routine cultivation of this plant. The natural-variation of P. tetragonolobus manifests in its seed-coat colour. The present paper characterizes and evaluates the physico-chemical properties of the seed-oil extracted from white, light-brown, dark-brown seeds of P. tetragonolobus. The refined seed-oils of these lines are suitable and comparable with soybean seed-oil. Additionally, as compared to soybean oil, the oil of P. tetragonolobus is thermally stable due to the presence of saturated (21.2–22.7%), monounsaturated (39.3–40.2%) and polyunsaturated (37.0–38.2%) fatty acids. Variation in acid value (0.4 to 0.6 mg/g), free fatty acid (0.2–0.3%), saponification value (172.2–173.5 mg/g), iodine value (118.9–121.5 g/100 g), refractive index (1.44–1.48) and density (0.91–0.92) was reported upon analysis. Safety evaluation of this refined oil on 4-weeks feeding trial on albino mice revealed non-significant changes in terms of body weight, organ weight, haematological and serum biochemical changes. Furthermore, the seed-cake of P. tetragonolobus contained proteins to a range of (34.7–35.6%), carbohydrates (21.4–23.1%), polyphenols (0.45–0.49%), L -DOPA (0.35–0.38%) and phytic acid (0.18–0.2%). These values are closely comparable with the soybean seed-cake. Graphic abstract