Archives

Legume seeds are rich in many nutrient components including protein, starch, dietary fibre, certain fatty acids and micronutrients (vitamins, trace minerals). They are also a rich source of many bioactive non-nutrient compounds including phenolic antioxidants. These antioxidants exhibit a wide range of physiological health promoting properties, such as anti-allergenic, anti-inflammatory, anti-atherogenic, anti-microbial, anti-carcinogenic, cardio-protective and vasodilatory effects. Legume seed coats are rich sources of polyphenolics and natural antioxidants that could replace the synthetic antioxidants in foods. Legumes are decorticated to remove the outer fibrous layer (seed coat) to yield the split cotyledon (endosperm). This milling process significantly changes the phytochemical potential of legumes. In the present study, antioxidant properties of morphological fractions of four improved cowpea genotypes for high yield and early maturity viz. Pant Lobia-2 (PL-2), Pant Grain Cowpea-11 (PGCP-11), Pant Grain Cowpea-12 (PGCP-12), and Pant Grain Cowpea-13 (PGCP-13) were evaluated. The seed samples were dehulled into two fractions i.e. seed coat and cotyledon manually. Total phenol content (TPC) and antioxidant activity was measured by DPPH method using three replicates. The fraction of seed coat varied from 12.22±0.02 (PGCP-13) to 13.91±0.02 g (PGCP-11) whereas cotyledon varied from 86.07±0.03 (PGCP-13) to 87.76±0.02 g (PGCP-11). TPC was highest in PGCP-11 (seed coat: 455.64 mg GAE/ 100g; cotyledon: 258.81 mg GAE/ 100g) and least in PGCP-13 (seed coat: 254.68 mg GAE/ 100g; cotyledon: 163.25 mg GAE/ 100g) on dry weight basis. Similarly, antioxidant activity was highest in PGCP-11 (seed coat: 82.3%; cotyledon: 43.3%) and least in PGCP-13 (seed coat: 32.3%; cotyledon: 15.1%) on dry weight basis. Cowpea genotypes differed significantly with respect to their TPC and antioxidant activity. Seed coat had higher TPC as well as antioxidant activity than the cotyledon fraction of all the cowpea genotypes under study. The antioxidant properties of the seed coat in all the genotypes were manifold higher as compared to the whole legume or its respective cotyledon and removal of seed coat significant reduced the antioxidant activity.
Keywords: Cowpea, Seed coat, Cotyledons, Antioxidant activity, Total phenol content