Effect and aftereffect of gamma radiation pretreatment on enzymatic hydrolysis of wheat straw.

Irradiation pretreatment of wheat straw was carried out at different doses by using Co-60 gamma radiation. The weight loss and fragility of wheat straw after irradiation, the combination effect of irradiation and mechanical crushing on enzymatic hydrolysis of wheat straw as well as the aftereffect of irradiation were examined. It is shown that irradiation can cause significant breakdown of the structure of wheat straw. The weight loss of wheat straw increased and the size distribution after crushing moved to fine particles at elevated irradiation doses. The glucose yield of enzymatic hydrolysis of wheat straw increased with increasing doses and achieved the maximum (13.40%) at 500 kGy. A synergistic effect between irradiation and crushing was observed, with a glucose yield of 10.24% at a dose of 500 kGy with powder of 140 mesh. The aftereffect of irradiation had important impact on enzymatic hydrolysis of wheat straw. The aftereffect (at 22nd day) of 400 kGy irradiation accounted for 20.0% of the initial effect for glucose production, and the aftereffects of 50, 100, 200 (at 9th day) and 300 kGy (at 20th day) accounted for 12.9%, 14.9%, 8.9% and 9.1%, respectively, for reducing sugar production.