Effect of gamma irradiation on physicochemical properties, proximate composition, vitamins and antinutritional factors of the tribal pulse Vigna unguiculata subsp. unguiculata

Abstract

Effect of gamma irradiation on Vigna unguiculata subsp. unguiculata seeds (maroon-coloured seed coat) at various doses (2, 5, 10, 15 and 25 kGy) on the physicochemical properties, proximate composition, vitamins (niacin and ascorbic acid) and antinutritional factors were analysed. No significant changes were recorded in the physicochemical properties of irradiated seeds. Gamma irradiation resulted in a significant increase in crude protein, while the crude lipid, crude fibre and ash contents resulted in a dose-dependent decrease. Gamma-irradiated seeds presented a significant decrease in the ascorbic acid and niacin content. Irradiation processing significantly reduced the level of L-DOPA, phytic acid, hydrogen cyanide, trypsin inhibitor activity, oligosaccharides and lectins. The total free phenolics, tannins and in vitro protein digestibility on irradiation showed a significant dose-dependent increase. Gamma irradiation seems to be a good procedure to improve the quality of legume seeds from the nutritional point of view.

Cowpea (Vigna unguiculata L. Walp), a renewed multipurpose crop for a more sustainable agri‐food system: nutritional advantages and constraints

“…This phytochemical compound is a characteristic and abundant constituent of legume seeds. The phytic acid content of cowpea seeds, pods, and leaves is comparable to that of many other legumes, ranging from 2.6 to 15.2 g kg −1 and representing between 29.0 and 52.0% of total inositol phosphates . Most of the phytic acid in cowpea seeds is located in the cotyledons …”

“…Eight sugars have been reported in cowpea, namely, stachyose (17–60 g kg −1 ), sucrose (11–19 g kg −1 ), verbascose (6–13 g kg −1 ), raffinose (5–10 g kg −1 ), glucose (4–5 g kg −1 ), fructose (1–2 g kg −1 ), galactose (≤15 g kg −1 ), and maltose (≤11 g kg −1 ) . It is widely known that the oligosaccharides stachyose, verbascose and raffinose are causative agents of flatulence in humans, due to the lack of α ‐1,6‐galactosidase in the intestinal mucosa .…”

“…Apart from a relevant source of essential macronutrients, cowpea constitutes an interesting source of micronutrients . The major vitamins present in cowpea are those belonging to the B complex, being reported in the following decreasing order: niacin (7.0–40.0 × 10 −3 g kg −1 ) > panthothenic acid (17.0–22.0 × 10 −3 g kg −1 ) > thiamine (2.0–17.0 × 10 −3 g kg −1 ) > pyridoxine (2.0–4.0 × 10 −3 g kg −1 ) > folic acid (1.0–4.0 × 10 −3 g kg −1 ) > riboflavin (1.0–3.0 × 10 −3 g kg −1 ) > biotin (0.2–0.3 × 10 −3 g kg −1 ) > cobalamin (traces) . It is important to mention that the segregation of cowpea varieties into groups on the basis of the seed coat shows the ‘brown type’ with a higher content from B complex vitamins as compared with the ‘black type’ and ‘blue‐eye type’ .…”

“…Cowpea appear to be a particularly good source of vitamin C, with levels in seeds and pods ranging from 52.0 to 554.0 × 10 −3 g kg −1 , and in leaves from 292.0 to 4100.0 × 10 −3 g kg −1 . It is important to note that the total vitamin C content in leaves at the maturity stages (4 and 6 weeks) is mostly in the form of dehydroascorbic acid, an oxidation product of l ‐ascorbic acid, which exhibits a lower biological activity …”

Particle size-starch–protein digestibility relationships in cowpea (Vigna unguiculata)

“…The pH drop three-enzyme (trypsin-chymotrypsin-peptidase or trypsin-chymotrypsin-protease) method of Hsu et al (1977) is widely used in estimating apparent in vitro protein digestibility (Ainsworth et al, 2007;Wang et al, 2008;Zhang et al, 2010;Pastor-Cavada et al, 2011;Tresina and Mohan, 2011). However, like other in vitro protein techniques, it is mainly used as a single-point measurement when the pH at 10 min (pH 10 min ) is used to calculate the in vitro protein digestibility (IVPD, %) with Eq.…”