CRITICAL MOISTURE-CONTENT FOR FISSURES IN ROUGH RICE

Determinations were made of the critical moisture content (CMC) in sel ected IR varieties and other rough rices after harvest in both dry and wet seasons at the International Rice Research Institute. Below the C MC, the grain becomes susceptible to fissuring. The rices were dried t o moisture contents of 10-20%, wb, stressed by soaking in water for 2 hr, and redried before milling. Susceptible variety IR42 had a CMC of 16% in both crops, whereas resistant variety IR60 had a CMC of 14% in the dry season and 12% in the wet season. Grain for the moisture-adsor ption stress test was shade-dried to 14% moisture, verified as optimum . The CMC obtained from dried grains, adjusted to higher moisture cont ent by moisture adsorption before stressing, did not effectively disti nguish among IR rices. Flash-drying of all freshly harvested grain to a target moisture content of 20 +/- 5% may be employed without danger of grain cracking.