This study investigated the effect of kilning condfition on the diastatic power and activities of protease, α-amylase, and β-amylase in rice malt. Common rice (Oryza sativa) was steeped at 30℃ for 50 h, germinated at 30℃ for 7 days, and kilned at 50℃ for 24 h. The moisture content and enzymatic activities were determined under various kilning times. As a result, the moisture content was reduced from 42.1 % to 3.9% after 24 h of kilning at 50℃. The protease activity of rice malt showed lower value than that of barley malt. All enzymatic activities were decreased during the kilning stage. Results indicated that after prolonged kilning at 50℃, the inactivation of hydrolytic enzymes might be occurred. Even though the amylolytic activity of malted rice showed low value, the rice malt shows the potential characteristics as ingredient for the brewing and cereal industries.
The malting process of rice (OM4080 variety from Mekong Delta Rice Research Institute) was studied under pilot condition plan by means of the second-order experimental design. Processing parameters, such as the steeping time (0-60 hrs), steeping temperature (5-45℃), germination time (0-8 days), germination temperature (5-45℃) and gibberellin concentration (0-2 mg/kg) were investigated. As a result, all germination conditions, especially germination time, germination temperature, and gibberellin concentration had a significant effect on the malting loss, amylase activity and starch content. The protein content was not clearly affected by any conditions. The optimum conditions for malting process (with highest amylase activity) were as follows: 30 hrs of steeping time, 30-35℃ of steeping temperature, 5-5.5 days of germination time, 25℃ of germination temperature, and 1.5 mg/kg of giberrellin concentration.