Effect of postharvest UV-C irradiation as physical elicitor on anti-nutritional factor, B-vitamins and mineral profile of Clerodendrum volubile leaves

Abstract

The effect of postharvest UV-C irradiation on the antinutrients (phytate, saponin, tannin), B-vitamins, and mineral profile of Clerodendrum volubile leaves was evaluated. The leaves were cleaned, detached, divided into two parts, one part was irradiated with UV-C lamp at wavelength 210 nm, average dose of 2.217 J/m2 for 20 minutes while the other was left untreated, the two were stored for 24 hours at room temperature. The phytate, saponin, tannin, B vitamins and mineral content of the leaves were analysed after irradiation and storage using standard methods. Mineral and molar ratios were calculated. UV-C irradiation substantially decreased the phytate contents from 18.12 to 9.02 mg/g but increased the tannin contents from 0.68 to 1.42 g/100g and saponin contents from 1.44 to 1.52 g/100g. The phytate and saponin contents reduced in storage but the tannin content increased. The B vitamins reduced after UV-C irradiation and further in storage with the exception of pyridoxine (B6) which increased significantly. The minerals P, Mn, Na, Ca and Mg content increased while K decreased with UV-C irradiation and no effect on the Fe content of white butterfly C. volubile leaves. After UV – C irradiation the mineral ratios Ca : P, Na : K, Ca : Mg, Ca : K and the miliequivalent ratio K : (Ca + Mg) were still within the required standard for their availability for absorption. [Ca][Phytate]/[Zn] molar ratios (0.0003 – 0.0006 mol/kg) were below 0.5 mol/kg the critical value. Irradiating food just like other food processing methods will depend on what the food has to contribute to the total diet.