Pasting, expansion and textural properties of fermented cassava starch oxidised with sodium hypochlorite

This study investigated the effects of oxidation with sodium hypochlorite on the content of carbonyl and carboxyl as well as pasting, expansion and textural properties of fermented cassava starch. A 23 factorial design with three central points and six axial points was used to investigate the effect of active chlorine concentration, pH and temperature during the oxidation of fermented cassava starch; oven-dried and sun-dried fermented cassava starches were used as controls. Sun-dried fermented cassava starch had a higher content of carboxyls and carbonyls, higher expansion and lower biscuit hardness compared to the oven-dried starch. Interestingly, the effect of oxidation was increased when the fermented cassava starch was oxidised with sodium hypochlorite. The highest values for the sum of carbonyl and carboxyl occurred at pH between neutral to alkaline, at high active chlorine concentrations and high temperatures. Oxidative treatment with sodium hypochlorite increases the expansion of starch and reduces biscuit hardness.