⋅ BY RONNIE LEVY ⋅
U.S. long-grain rice has long been considered the quality standard of the world. In recent years, however, a number of both domestic as well as international customers have complained about the quality of some southern U.S.-produced long-grain rice.
The complaints have focused primarily on the high levels of chalk in much of the recently produced long-grain rice. However, there have also been negative comments about milling, non-uniformity of grain size and problems with cooking characteristics.
The causes of the quality issues in U.S. long-grain rice are complex and not due to one specific factor. Rice that matures under very high temperatures will typically have more chalk issues in the milled grain, resulting in lower milling yields and other quality issues; so environmental conditions can be a big part of the problem. However, another factor is an increasing percentage of rice acreage in this region has been planted with rice types that have very high yield potential but inherently poorer milling attributes and other quality issues.
Another factor can be the commingling of long-grain varieties. Commingling is when quantities of rice from different varieties are mixed together and not kept variety specific. Mixing of varieties is not much of an issue when the varieties are similar in grain attributes, such as size, shape, uniformity, color, cereal chemistry, bran thickness and others. However, when there is considerable variation in some of these characteristics, commingling can lead to substantial quality issues in the final milled product. To illustrate why this problem has evolved, consider the number of different varieties grown.
In 2023 in Louisiana, we grew 25 different long-grain varieties/hybrids, seven of which accounted for at least 5% of the state’s acreage. Many of these quality characteristics are primarily genetically controlled; others are primarily environmentally controlled. Many are genetically controlled but also highly influenced by environmental factors.
Chalk
One attribute in this latter category is grain chalk. Chalk is an opaque area of the rice kernel that is visually similar to the appearance of blackboard chalk. Chalky rice occurs when part of the grain is whiter than the rest because in this area the starch has not developed properly. Chalk can vary from being present in a small portion of a rice kernel to encompassing virtually the entire kernel. Chalk can be a point of weakness in the grain, and when chalky rice is milled, it is more likely to break. However, many chalky grains make it through the milling process intact, and a high level of chalky whole grains are certainly considered an unfavorable trait.
Because chalk is greatly influenced by environmental growing conditions, high temperatures during grain-filling stages can lead to this characteristic. Some varieties are fairly resistant to chalk and will not display high levels even when that variety is grown under high temperatures.
An example would be an older variety, Cypress. Some varieties always have very high levels of chalk even when grown under ideal conditions. Most of our varieties are in a middle group, always showing a moderate amount of chalk but with increasing levels when grown under high temperature conditions. Even in this middle group, some of these varieties are always more prone to higher levels of chalk. Many of these have a higher inherent yield potential and thus are being grown on an increasing percentage of the long-grain acreage in the region.
As these types of rice have become a greater portion of the total long-grain crop in the southern U.S., thus have our overall chalk and perhaps other quality problems become more of an issue. What complicates the issue is that certain markets really don’t discriminate against rice with high levels of chalk, and some actually prefer this characteristic. However, these markets are the exception and not the rule.
While the U.S. Department of Agriculture rice grading system can lead to price discounts when amounts of chalk are excessive, often rice which grades #2 will still have levels of chalk unacceptable to some customers. This is a very complex issue and one that will not be solved overnight. As a rule, Louisiana typically produces a higher percentage of higher quality rice than our neighboring states. There is currently an effort underway to develop mechanisms for farmers to capture price premiums based on higher quality.