Ethanol and glucose was analyzed by HPLC with Bio-red Aminex HPX- 87H (300mm×7.8mm) column (Bio-Rad Laboratories, Hercules, CA) and Waters 410 refractive detector. The flow rate was set at 0.6 mL/min with 5 mmol/L H2 SO4 as the mobile phase. All experi- ments were carried out at least twice.