Studies on the physiochemical, thermal, structural and functional attributes of vetch starch (Vicia villosa) and protein from Kashmir valley

Abstract

Vicia villosa (vetch), a leguminous plant and a significant source of starch and protein, is primarily used for animal nutrition, but it also has potential for human consumption. This study aimed to isolate starch and protein from vetch seeds and evaluate them based on various physicochemical, functional, structural, and thermal characteristics. The extracted protein and starch exhibited high purity with a C-type crystalline structure. The chemical composition of starch revealed moisture (7.7 ± 0.20), protein (0.09 ± 0.01), fat (0.02 ± 0.00) and ash (0.03 ± 0.01) contents, while that of protein showed moisture, fat, and ash in the range of 9.2 ± 0.3, 2.3 ± 0.26 and 2.05 ± 0.05 g/100 g. SEM revealed an oval or kidney-shaped starch structure, while a heterogenous lamellar structure with some particle aggregation in the case of vetch starch. The DSC analysis demonstrated early gelatinization with increased enthalpy (6.94 J g⁻¹) in vetch starch, suggesting a stable crystalline region and adequate heat resistance whereas vetch protein displayed two separate denaturation peaks (86.19 °C and 227.86 °C), affirming the existence of vicilin (7S) and legumin (11S) fractions, which provide structural stability and functionality during processing. SDS-PAGE displayed polypeptide sub-units ranging between 25 kDa and 75 kDa in molecular weight with the majority of bands characteristic of vicilin and legumin. The pasting behavior of vetch starch showed an effective swelling tendency with strong gel forming capacity, as evident from the high peak, setback and final viscosities – attributes favorable for thickening, texturizing, and film production. Also, vetch protein demonstrated promising functional properties (emulsifying, gelling, and foaming), highlighting its potential applications in food, packaging and various industrial sectors.