Effect of Air-Rest Treatment on Rice Malt

Abstract

To improve the malting qualities of rice grain, paddy rice (Jasmine 85) was air-rested for 2 to 8 h while in steep and malted for 12 days at 28 ± 1°C. Out-of-steep moisture content, germination energy, shoot length, and diastatic activity of the rice grains were evaluated to determine the efficiency of the air-rest treatment. Air-rested rice grains absorbed 0.5 to 5% moisture more than the untreated (control). Six-hour air-rested grains absorbed the highest moisture content of 36.6% after 48 h of steeping. The highest germination energy (93%) and diastatic activity (1002 U/g dry malt) were recorded in the 6-hour air-rested grains. Moreover, malts resulting from this treatment had their optimum diastatic activity (2086 U/g dry malt) on the 8th day after germination, occurring earlier than the control (2001 U/g dry malt) which peaked at the 10th day. Applying air-rest treatment during rice malting improves its hydrolytic potential.