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Linscombe: Long-grain rice quality problems being tackled

Linscombe: Long-grain rice quality problems being tackled

Long-grain rice producers warned quality concerns on the rise. LSU AgCenter rice breeder explains quality worries in conjunction with growing environment and rice physiology.  

Mid-South mills are warning producers that the quality of U.S. long-grain rice is increasingly at the top of customer concerns. Following several extremely difficult growing seasons that produced uneven rice crops, quality has been a hot topic during winter meetings.

An LSU AgCenter report on a Jan. 26 meeting in north Louisiana quoted rice breeder Steve Linscombe. “The mills are starting to look at the quality of these different varieties,” he said, adding that farmers with better quality rice may get a premium for their crop.

For the full report, see here.

Several weeks later, on Feb. 9, Linscombe, who runs the AgCenter’s Rice Research Station in Crowley, La., spoke with Delta Farm Press about the reasons for the rise of quality concerns, how they’re being addressed by researchers and crop physiology. Among his comments:

On current quality worries...

“The quality issue with Southern long-grain rice that everyone is talking about has been on the radar screen for a while. I was at a grower meeting last night and gave a talk on ‘rice quality 101.’

“It came to a head in 2010 with the grain problems seen in the Arkansas, Mississippi, north Louisiana and Missouri region due to excessive heat. Those growing conditions had a real impact on the crop. Because of the issues in that rice crop, people began to talk much more about it.

“Then, in 2011, we had some problems in (south Louisiana) because of climatic conditions.

“Really, though, there have been quality questions over the last few years despite the weather. Certain lines of rice have quality issues, period.”

On what ‘rice quality’ actually is…

“When you talk about ‘rice quality’ you’re casting a very wide net.

“Most people in the industry first mention milling yield or milling quality. How much breakage do you have in the milling process? That’s what growers are paid on. They get premiums for having head-rice yields above a standard and face deductions if they’re below the standard. In many minds, that’s the primary quality factor – and it is very important.

“However, ‘quality’ is all-encompassing and one thing that’s included is chalkiness. It’s best for rice grains to be almost clear, translucent. A bag of rice with a high percentage of chalky grains isn’t aesthetically pleasing.

“Chalky grains also have a greater potential for breakage during the milling process. However, many don’t break and then end up bagged.”

On chalkiness and grain characteristics…

“What I’ve learned through the years is that it’s very important to understand that chalkiness is a grain characteristic that’s very much influenced by genetics and also by environment. To illustrate that, you have certain genotypes of rice that have a pretty high resistance to chalk. Even under severe environmental conditions normally such types of rice won’t have a tremendous amount of chalk.

“Other varieties, regardless of the environmental conditions during the growing season, will typically have a lot of chalk. An example of that is Milagro that’s been grown primarily in Texas for a specific Mexican market.

“Most of our rice varieties fall in between those extremes. They tend to be less chalky under ideal environmental conditions. But as those conditions are more adverse, more chalk occurs.

“What environmental are worst for causing chalk? Heat, no doubt. High temperatures – especially, I believe, high nighttime temperatures – increase chalk.”


On the physiology of chalk…

“There are actually several different kinds of chalk in the grain. The one that is more environmentally-influenced is primarily air particles trapped within the kernel during its development and maturation process.

“A rice plant heads and after that fertilization occurs. The kernel then begins to develop. As it has been growing, the rice plant has accumulated ‘non-structural carbohydrates.’ After the plant heads and the grain begins to fill, the stored carbohydrates begin to migrate from the leaves and stem and stack up to create the kernel.

“Ideally the grain is filled at the optimum rate under moderate temperatures. But as temperatures increase, the plant’s functions speed up. That means under hot conditions, the plant’s grain-filling happens more quickly. The faster the cells stack up in the kernel, the less uniform they are.

“The non-uniformity creates areas where air can be trapped. That trapped air is what causes a lot of chalk in the grain.”

On rice breeding and grain quality…

“Some say breeders aren’t paying attention to grain quality. That isn’t true. Grain quality is a huge part of what we do when developing varieties.

“Everything we put in a yield trial is milled. Almost every plot in a yield trial has a milling sample harvested. Not only do we look at the head-rice yield, the total yield, but we also visually give a qualitative evaluation of the grain appearance. We look at chalk and grain length.

“We also look at the uniformity of grain length. You can have a variety that averages 6.9 millimeters in grain length. But it can lack uniformity – there can be a lot of longer kernels and a lot of shorter kernels. Ideally, you want very little variation.

“So, all the breeders treat quality issues as a very significant part of their efforts.”

On varietal differences…

“In my program, certain varieties have a reputation for having a bit higher quality. Others have a reputation for a bit lower quality.

“Louisiana millers really like the quality of Cheniere. They consider it ‘package quality.’

“Even so, that doesn’t mean there won’t occasionally be a sample, or lot, of Cheniere that is less than optimum quality. That goes back to (the aforementioned) relationship between genetics and environment. A field of Cheniere grown under extremely adverse conditions won’t have as good a quality as a field grown under better conditions.”

On steps taken to address quality…

“This has become enough of an ongoing issue that the USA Rice Federation has created the Rice Marketability and Competitiveness Task Force. Basically, they’re looking at rice quality and are charged with looking at the whole picture and how it can be addressed long-term.

“More short-term, the task force got samples from a number of varieties grown in 2010. They had those milled uniformly as the first step to see exactly what the mills are looking for. The mills qualitatively evaluated the samples and the USDA lab in Stuttgart, Ark., did some quantitative evaluations. The lab actually measured grain dimensions, looked at some of the cereal chemistry aspects, the amount of chalk and other things.

“The study wasn’t perfect because ideally all the different varieties would be grown under the same environmental conditions. But it was a solid first step in trying to get a handle on what the quality problem actually is, what the mills are looking for. Are all the mills looking at the samples the same?

“We’re now trying to build upon that study to get a stronger database.

“Ultimately, it will lead to a very beneficial controlled study. Right now, we’re set up to conduct the study in Mississippi, in Louisiana, in Texas and, hopefully, in Arkansas. We’re still in discussions about how many varieties will be included – but we want to grow the finalized list under the same environmental conditions. In Louisiana, I’ll probably grow the varieties with two planting dates just like they’ll do in the other states. To a large extent, that will take environmental variation out of the picture.

“After that work is done, the millers and end-users will be able to say if there are specific varieties that fit their needs better. If there are, we’ll see more and more 'IP’ing' (Identity Preservation). Customers would say ‘I want (X) variety’ and, ideally, very similar varieties could be co-mingled.

“Right now, in many mills it is common for a number of long-grain varieties to be co-mingled. This often leads to good quality rice mixed with poor quality creating a smorgasbord of mediocre quality rice.

“The industry must look more and more to identify varieties that, perhaps, users prefer. And they’ll have to move toward IP’ing those varieties. I’m not sure whether that will necessitate a premium for growers or the expectation of a discount if they grow a different variety. But that’s where I see the market moving.”

On the California rice industry…

“California rice doesn’t have the same quality issues as Mid-South rice. This is primarily a long-grain issue and California grows primarily medium-grain rice.”

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