Physicochemical properties of potato starches oxidised by different concentrations of sodium hypochlorite, and their application in yogurt

Abstract

Potato starch was modified by oxidation with different concentrations of active chlorine (0.5, 1.0, 2.0, 3.0, and 4.0%); and the physicochemical properties of the oxidised potato starch samples and the use of these starches in set yogurt were investigated as a function of their degree of oxidation. The carboxyl content, carbonyl content, and solubility of the oxidised starches increased with increasing sodium hypochlorite concentrations, while the swelling power decreased. Scanning electron microscopy showed that oxidation caused cracks or pores on the surfaces of the starch granules, and these morphological changes were enhanced by increased oxidant concentrations. Analysis with a Rapid Visco Analyser showed that high degrees of oxidation could improve the starch thermodynamic stability and resistance to retrogradation. Set yogurts made with oxidised potato starches had higher water-holding capacities, higher apparent viscosities, and better sensory qualities than those prepared with native starch.