Enzymatic hydrolysis
Digestions with endo--(1, 4)-mannanase were performed in 0.01 M sodium citrate buffer at pH 4.0. After -irradiation, 2 g KGM powder was slowly added to 1000 mL vigorously stirred sodium citrate solution and swelled for about 30 min. Then, 0.2 g endo-- (1, 4)-mannanase was added to the solution. The incubation was carried out in 50 ◦C for 24 h at shaking conditions. After hydrolysis, the enzymes were inactivated (10 min, 100 ◦C), and the hydrolysate was centrifuged (20 min, 7000 rpm, room temperature).