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Cross-flow rice driers typically use devices known as grain exchangers, which transfer the rice flowing near the air inlet side of the drier to the outlet side. Recent testing has shown that air conditions inside cross-flow driers vary greatly from the air inlet to the outlet side. To simulate the effects of a grain exchanger in a cross-flow drier, rice was exposed to air at typical drier inlet conditions and then immediately exposed to typical outlet side conditions. The conditions used were based on measurements from a commercial cross-flow drier.

Once the rice was dried and then exposed to the outlet side air conditions, it was placed in a temperature and relative humidity controlled chamber to equilibrate to 12.5% wb. moisture content (MC) and was subsequently milled to determine head rice yield (HRY). Testing showed that milling quality was adversely affected by switching the rice from inlet to outlet conditions, if the rice was dried for an extended period of time to produce sufficient MC gradients in the kernels before switching. However, if the rice was switched before these MC gradient levels were reached, head rice yields (HRYs) were not affected.