Grain and air properties

Rice is a hygroscopic material.

• When dry rice is exposed to air with high relative humidity (RH) the rice grains will absorb water from the air (re-wetting).
• When wet rice is exposed to air with low RH the rice grains will release water to the air (drying).

The equilibrium moisture content (EMC) is the final moisture content of the grain or seed after being stored for some time with surrounding air of a certain temperature and RH.

During storage, the final moisture content of grain will be determined by the temperature and RH of the air that has surrounds the grain. If the grain is not protected against the humidity in the air, particularly during the rainy season when the RH is very high, the grain moisture content will rise and this will lead to deterioration in both grain and seed quality.