Effect of oxidation and esterification on functional properties of mung bean (Vigna radiata (L.) Wilczek) starch

The chemical and physicochemical properties of mung bean starch oxidized by sodium hypochlorite and esterified with succinic anhydride were studied. Mung bean starch was modified by oxidation with sodium hypochlorite and esterified with succinic anhydride. The native mung bean starch (NMBS) granules were shown to have an irregular shape, which varied from oval to round to bean shape with a smooth surface. Succinylation led to partial rupture of the granule integrity while oxidation converted the smooth surface of the native granules to a surface with fissures. Swelling capacity improved through succinylation but was reduced after oxidation. Oxidation enhanced solubility; however, succinylation showed no uniform effect throughout the temperature range studied. Both modifications increased hydrophilic tendency and demonstrated decreased gelatinization temperature compared to the NMBS. Oil absorption capacity and syneresis of native starch was enhanced after oxidation but was reduced after succinylation. Both starch types, native and modified, exhibited non-Newtonian behavior, but to a different extent. The gel formation of oxidized starch revealed the highest storage modulus followed by native starch and then succinated starch.