Composition and some physicochemical properties of microwaved starch blends from cocoyam (Xanthosoma sagittifolium) and bambara groundnut (Voandzeia substerranean)

Abstract

The extracted cocoyam starch (100CYS) and bambara groundnut starch (100BBS) were blended in three ratios (70CYS/30BBS, 50CYS/50BBS, 30CYS/70BBS) (%, w/w) and all the starch samples were microwave(MW) irradiated. The compositional and some physicochemical properties of the starch samples were evaluated to study the changes made as a result of MW irradiation. There was reduction in moisture and ash content, but an increased in the lipid and protein content of MW-irradiated native starches (NSs) and starch blends (SBs). A new trend was developed in apparent amylose (AAM) content. With just one exception (M70CYS/30BBS blend), the AAM content of the NSs increased and that of the SBs decreased as a result of MW irradiation. For the MW-treated SBs, the values for dispersibility, bulk density and pH ranged from 85-98%, 0.79-0.90gmL-1 and 6.9-7.3, respectively. With the exception of the 50CYS/50BBS blend, there was increased in the swelling power of the remaining starch samples due to MW irradiation. Alterations were also observed in water solubility index of the starch samples micro waved as a result of their different chemical constitution. The non-irradiated starches manifested different trend in pasting properties as a result of MW irradiation when compared to the SBs as observed in peak, breakdown and final viscosities.