Effect of Chemical Modifications on Pasting Properties of Cocoyam Starch (Xanthosoma Sagittifollium)

Abstract

The present study investigated the effect of chemical modifications on pasting properties of starch isolated from Cocoyam chemically modified to produce oxidized starch. The objective of chemical modification was to tailor and improve the native properties of Cocoyam starch so that it could be used in wide variety of food products. The chemicals used for oxidation is sodium hypochlorite (NaOCl). The pasting characteristics of native and modified (oxidized) cocoyam were analyzed using Rapid Visco Analyser (RVA). The peak viscosity of native cocoyam (304.7⁰C) was reduced after oxidation (290.5⁰C). The trough of native cocoyam (164.9Bu) was increased after oxidation (176.0Bu). The pasting value of native Cocoyam (4.52mins) reduced after Oxidation (4.50mins). The setback value for the native cocoyam (88.42) was reduced after oxidation (87.92).The pasting temperature of native cocoyam (79.65⁰C) was significantly reduced after oxidation(78.35⁰C). The FT-IR showed that the native cocoyam showed hydroxyl peak around 3492.24cm^-1.  On oxidation, the FT-IR spectrum showed a new peak around 1641.48cm^-1 for carbonyl group.

Keywords: cocoyam modified , native starches, pasting properties, RVA, Ft-Ir, carbonyl group.