STUDIES ON THE PHYSICOCHEMICAL AND PASTING PROPERTIES OF OXIDIZED SWEET POTATO (Ipomoea batatas L. (Lam) STARCH

Abstract

Starch isolated from sweet potato (Ipomoea batatas L.) was chemically modified by sodium hypochlorite (NaOCl). The physicochemical and pasting properties of the native and oxidized sweet potato starches (NSPS and OSPS) were investigated and they were also characterized by Fourier Transform Infrared Spectroscopy. In addition to the pH change from 6.40-7.40 on oxidation, other physicochemical properties such as; foaming capacity, water and oil absorption, moisture content, dispersibility, peak viscosity (PV), trough holding viscosity (TV) and final viscosity (FV) values increased by 2.27%, 0.83 and 0.46mL, 2.02%, 0.76%, 44.34 RVU, 138.34 RVU and 120.33 RVU respectively. However, the breakdown viscosity (BV) and setback viscosity (SV) experienced a decreased in value by 94.7 RVU and 18 RVU respectively following the oxidation process. In all, higher stability and reduced retrogradation to the starch characterized the oxidation process. The improved properties of the oxidized sweet potato starch (OSPS) are some of the essential properties in starch for its application in the pharmaceutical and other biodegradable industries which are lacking in native sweet potato starch (NSPS).