Degradation of curdlan using hydrogen peroxide.

Curdlan, a linear glucan interconnected by β-(1→3) linkages, is soluble in alkaline solutions but not in water, which limits its wide application, particularly in the food industry. In this study, curdlan was subjected to oxidative degradation using hydrogen peroxide (H(2)O(2)). The optimal hydrolysis conditions were determined, and the results were as follows: reaction time, 40 min; temperature, 60°C; H(2)O(2) concentration, 1.5% (v/v); and NaOH concentration, 2.5M. Under these optimised conditions, the maximum dextrose equivalent value (13.49%) was obtained. The composition and the structure of the hydrolysates were characterised by high-performance liquid chromatography and Fourier-transform infra-red spectroscopy, respectively. The hydrolysates were filtered, neutralised with HCl, concentrated to ∼12% (w/v), desalted, and freeze dried to yield a water-soluble, white powder. The (1→3)-β-d-glucan oligosaccharide content of the product was 98.6% and the yield was 91.4% (w/w).