In some seasons, cracking of the rice grain is a significant problem. Most cracking occurs in the field and seems to be related to changes in grain moisture or to moisture cycles after the rice matures. Hot sunny days that dry the grain are commonly followed by humid or dewy nights that wet the grain. The changes in grain moisture over a 24-hour period can lead to cracking. Cracking may also result from rain on dry grain and storage of grain with variable moisture levels.
Rough handling of grain during harvest operations and during drying and processing will also cause the grain to crack.
Chalk is the opaque area in the rice grain and is undesirable in almost every market. Chalky areas occur because of malformed starch granules with air spaces between them. Chalky areas cook differently from translucent areas, but only a very clever palate could detect the difference. There are small differences in the solubility of the starch and the gelatinization temperature of the chalky and translucent areas, but research has yet to discover