The calcium content is higher in parboiled rice, even without intentional enrichment, because calcium carbonate is typically used as a milling aid with parboiled rice. Bran removal is more difficult in parboiled rice. So, an abrasive material, like calcium carbonate (ground limestone), is added to the brown rice as it enters the milling process. Most of the calcium carbonate exits with the bran stream, but naturally, some stays on the surface of the milled rice.

Starch changes do occur in rice during storage, but most of this occurs within the first 3 months, or so, after harvest. After that, changes are much, much slower. If the rice is milled before the rapid changes are complete, starch in the milled rice would probably continue to change. However, the impact of these changes on cooking quality do not seem to be as dramatic as when they occur in rought (paddy) rice. These starch changes that occur in paddy rice result in the rice having a firmer texture with less cohesiveness than is the case for freshly-harvested rice.