Analyzing the characteristics of degraded glucomannan of Amorphophallus oncophyllus using hydrogen peroxide and ultrasonication

Glucomannan, one of the viscous polysaccharides, has been applied for various purposes in food industries. However, its high viscosity limits glucomannan in some applications e.g., as an injectable material and encapsulant in the spray drying method. Hence, glucomannan modification is needed to fulfill specific characteristics in such applications. This study investigated the modification of glucomannan properties under degradation treatment using hydrogen peroxide and ultrasonication in ethanol solvent. The modifications of glucomannan were conducted in a 35% hydrogen peroxide solution for 4 h and 40 kHz ultrasonication in 50% ethanol solvent. The combination of ultrasonication and oxidation significantly reduced the glucomannan viscosity, molecular weight, and swelling but increased the solubility. The oxidation, ultrasonication, or their combination approach increased carbonyl content, whiteness, and syneresis. The degradation created a coarse surface on the glucomannan particles. Interestingly, although the oxidation or the ultrasonication reduced glucomannan crystallinity, the combination of both methods increased this property. This result confirmed the synergetic treatments of the oxidation using hydrogen peroxide and the ultrasonication could effectively modify the properties of glucomannan including reducing the viscosity to the level that allowed the glucomannan to be spray-dried.