Effect of KOH as Deacetylation Agent on Physicochemical Properties of Glucomannan

Abstract Glucomannan is one of the high viscosity polysaccharides with high water absorbing capacity as well as solubility. These properties limit glucomannan applications. Hence the property needs to be modified. Glucomannan has 5-10% acetyl groups which conferred its physicochemical properties. Replacing the acetyl with alkali, transforms the physicochemical characterisation of the glucomannan. This study aimed to determine the effect of deacetylation conditions on the physicochemical properties of glucomannan of Amorphophallus oncophyllus. The effects of concentration of KOH (0.1, 0.25 and 0.5 M) and reaction time (2, 8, 16 and 24 h) on the degree of deacetylation (DD), solubility, and viscosity of the glucomannan were studied. The concentration of KOH and reaction time showed a positive impact on the DD of the glucomannan. Solubility and viscosity decreased with increasing KOH concentration and extending the duration of the deacetylation. It was suggested that the changes in the physicochemical properties were due to the replacement of the acetyl group with the alkali during deacetylation. However, the effect of this replacement was not linear with the variables. This nonlinearity could be due to the various removal distributions of the acetyl groups during the deacetylation.