EFFECT OF ACETYLATION AND CARBOXYLATION ON SOME PHYSICOCHEMICAL PROPERTIES OF CASSAVA STARCHES

Abstract

Starch from five cassava varieties; 97/4414, 97/3982, 97/4489, 97/4962, and Afisiafi was modified with acetic anhydride and sodium hypochlorite solutions. The study was carried out to determine the effect of acetylation and carboxylation on some physicochemical properties of the native starches. The physicochemical properties studied were moisture content, pH, solubility, swelling power, granule size and water binding capacity. The moisture content, pH, water binding capacity, and swelling power of the native starches were generally higher than those of the modified starches. Native 97/4414 had the highest moisture content of 11.31% and acetylated 97/3982, the lowest value of 7.21%. The pH ranged from 4.23 for carboxylated 97/4414 to 6.96 for native 97/3982. The solubility of the carboxylated starches was comparatively lower than those of the native and acetylated starches. The native 97/4414 had the lowest solubility of 11.77% whereas acetylated 97/4414 and Afisiasi, the highest value of 31.91%. The native Afisiafi had the highest swelling power of 40.42% and carboxylated 97/4489 the lowest value of 21.58%. The water binding capacity ranged from 93.79% for native 97/4414 to 51.46% for 97/4489. The granule size ranged between 4.33μm and 6.67μm. Statistical analysis revealed significant effect (p < 0.05) of acetylation and carboxylation on the physicochemical properties of the native starch.