Characterization of Starch in Two Cultivars of Ubi Gadong (Dioscorea Hispida Dennst)

Abstract

The ubi gadong or Dioscorea Hispida Dennst (D. hispida) is a carbohydrate plant that contain about 75.2 % in the form of starch in its tuber. In this study, two cultivars of D. hispida namely yellow tuber or ‘gadong pulut’ and white tuber or ‘gadong beras’ were identified. The starch content in two cultivars of D. hispida was extracted and analyse their chemical and physical properties by comparing their thermal analysis, granule morphology and others physicochemical properties. Observation on the texture of starch extract from yellow tuber shows that starch in yellow tuber is stickier and requires a long time for the drying process compared to the white tuber. The colour parameter of tuber was measured the yellowness colour (b*) using choma meter showed the yellow tuber is 52.88 more yellowish than white tuber which is about 34.16. Results showed, for both starch samples solubility and swelling power gradually increased with the increasing of temperature ranging from 75°C to 95°C. SEM analysis of the starch granules indicate the polyhedral shapes with size between 1.3μm to 4.3μm. The results obtained from DSC showed the both starches transition temperature (To, Tp and Tc) were in range 74.53 – 74.58°C, 79.34 – 79.39°C and 83.35 – 83.40°C while, the enthalpy of gelatinization (ΔHgel) was in range 4.11 – 4.16 Jg−1.