Arkansas Researchers Identify Cultivar Commingling as Key Driver of Declining Global Rice Milling Yields

University of Arkansas study finds that mixing rice cultivars with different milling rates reduces head rice yield and affects food functionality.

By: AXL Media

Published: Apr 30, 2026, 9:52 AM EDT

Source: Information for this report was sourced from EurekAlert!

The Economic Paradox of Rising Field Yields and Falling Quality

While Arkansas rice farmers have seen a steady increase in grain produced per acre through the adoption of hybrid varieties, the financial returns at the mill are being undermined by a persistent decline in head rice yield. Head rice, defined as the total weight of unbroken kernels after processing, is the primary metric for quality and farmer profitability. According to Griffiths Atungulu, director of the Rice Processing Program at the Arkansas Agricultural Experiment Station, recent investigations indicate that the industry-wide practice of commingling different cultivars during processing is a leading cause of this quality degradation.

The Mechanical Friction of Evolving Milling Rates

Milling rates are not static across varieties, they are constantly evolving as new cultivars are developed for better environmental adaptation and higher field yields. Factors such as bran layer thickness, husk characteristics, and the inherent structural resistance of the kernel dictate how quickly a variety loses its outer layers. The research conducted at specialized centers in Stuttgart and Harrisburg demonstrates that when fast-milling and slow-milling cultivars are processed together, the resulting friction causes significant breakage. This mechanical mismatch leads to over-milling, which Atungulu notes can decrease head rice yield by nearly 2 percent even when surface lipid content changes by only 0.1 percentage point.

Strategic Identity Preservation as a Mill Solution

To protect the structural integrity of the grain, the study suggests that mills must adopt more rigorous identity preservation strategies. By ensuring that only varieties with compatible milling rates are processed in the same batch, facilities can avoid the unintentional destruction of high-quality whole kernels. Atungulu acknowledges that while simultaneous arrivals of multiple varieties at a mill create logistical hurdles, being aware of specific cultivar sensitivities allows millers to make necessary adjustments. This approach serves the interests of the farmer, who receives a higher premium for whole grains, and the food manufacturer, who requires consistent kernel size.