Rice research

by Emily Wilson
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The University of Arkansas is much like any other big U.S. university. While the public's attention is focused on the school's football or basketball team, academic programs often go quietly unnoticed.

For instance, many Razorback fans are probably unaware that important research on rice — perhaps the only research of its kind in the world — is being done in the Rice Processing Program in the uni-versity's Department of Food Science.

Although there are other key rice research centers around the world, including the International Rice Research Institute in the Philippines, most deal primarily with rice breeding and production. The Rice Processing Program at the University of Arkansas is unique in that it focuses on post-harvest issues, such as milling, storing, drying and cereal chemistry.

The U.S. Department of Agriculture's Southern regional laboratory in New Orleans, Louisiana, also conducts post-harvest rice research, but focuses primarily on end-use, value-added applications.

If Fayetteville, Arkansas seems an unlikely place for a world-class rice research center, consider that the state produces almost half of the rice grown in the United States each year.

"There is a strong rice industry in Arkansas, and these businesses early on supported our research program," said Terry Siebenmorgen, professor and coordinator of the Rice Processing Program.

The research program grew out of a meeting in the early 1990s between Kellogg, Riceland Foods and the university's Food Science Department. Kellogg, a U.S. breakfast cereal maker, was having problems with internal cracks in rice kernels that affected its puffing operations. Riceland, one of Kelloggs' rice suppliers, joined the cereal maker in jointly funding a research project at the University of Arkansas to examine what was causing the cracks in the rice kernel.

Today, the Rice Processing Program has a strong relationship with several rice processing cooperatives and companies in Arkansas, California, Texas and Louisiana, as well as grain storage and trading companies, equipment suppliers and food and beverage manufacturers. Other funding sources come from rice producers through Arkansas' check-off program and the state's Rice Research and Promotion Board. The university also matches industry donations, dollar for dollar, through its Institute of Food Science and Industry.

"We all have a stake in better understanding the milling process," said Bill Reed, Riceland's vice-president of corporate communications and public affairs.

Riceland was seeking a second opinion of its rice processing techniques. "We wanted to make sure that we weren't missing something that could improve our processing," Reed said.

"The key benefit (of being a sponsor) is that the research is being done, and can be used as a collective tool for the whole industry."

In return for their financial support, corporate sponsors like Riceland Foods are able to provide input into research projects and have early access to research results before the information becomes public domain.

Siebenmorgen said program scientists communicate regularly with sponsors in an attempt to better understand their needs.

"We realized back in the early 1990s that we needed to be looking not just at drying, milling and storage, but expand the program into the whole system of rice and address some of the needs of the food companies," he said. "There needed to be better discussion and research of the whole system, addressing challenges on both ends."

RESEARCH RESULTS. Research is focused in five main areas: drying, storage, milling, quality assessment and cereal chemistry of rice and rice products. The goal is to generate research results that are of significant value to the rice industry, Siebenmorgen said.

"If we are ever going to understand rice drying and milling, we have to understand what happens inside those little kernels," he said.

While a number of research projects are currently in progress (see box on page 23), Siebenmorgen highlighted two recent research successes.

One early research project looked at what caused fissures or stress cracks in milled rice. "We now know it is a moisture migration problem," Siebenmorgen said.

The milled rice kernel, under certain environmental conditions, loses or gains moisture. If the moisture transfer is too rapid, stress cracks can develop. The program's research identified the rice moisture content and air condition combinations that produce stress cracks.

Another research project examined why rice kernels crack during the drying process. Rice typically has a moisture content of between 17% and 20% at harvest, and must be dried to 12% to 13% for long-term storage. Drying the rice too rapidly takes the moisture out too quickly, causing the kernel to crack.

Using glass transition principles (glass transition is the temperature at which the properties of any starch-based material changes dramatically), researchers were able to define where the rice kernel transitions from a glassy to rubbery material.

"We're at the point now where we think we know what's going on in that rice kernel during drying," Sieben-morgen said. "The next step is to test this hypothesis commercially to see how we can build better dryers or better use existing dryers."

GSI, a manufacturer of grain storage and handling equipment and a program sponsor, is very interested in that research from a design standpoint.

Mitch Golleher, vice-president of GSI, said the company was eager to work with rice processors in developing storage and drying equipment. GSI recently acquired dryer manufacturer FFI Corp, Indianapolis, which markets products under the Farm Fans and Zimmerman brand names.

"We want Dr. Siebenmorgen and the rice producers and processors to know that we're in this for the long haul," Golleher said. "We think (our sponsorship) is money well spent."

The research team at the Rice Processing Program is made up of an international group of scientists and engineers as well as research assistants and graduate and undergraduate students.

The principal investigators include Siebenmorgen, who is involved in drying, milling and quality assessment; Jean Francois Meullenet, sensory analysis and instrumental measurement of sensory attributes; Wade Yang, drying, milling and finite element modeling; Terry Howell, storage and quality assessment; Dennis Gardisser, on-farm drying and storage; and Ya-Jane Wang, end-use processing and quality assessment.

Dr. Yang, a carbohydrate chemist, was recently hired to study rice from a molecular level, "to start understanding the true fundamentals of rice processing," Siebenmorgen said.

Other faculty oversee research in rice physiology, rice breeding, statistics and lipid chemistry.

The students who help with the research come from many different disciplines in the university. While a degree in rice processing is not offered as part of the Food Science Department, many students do find jobs in the rice industry as a result of their work in the research program.

The Rice Processing Program's laboratories are equipped with the latest lab and pilot-scale drying and conditioning equipment, commercial and laboratory milling systems, single kernel moisture meters, cleaning and grading equipment, complete laboratory milling analysis systems, a video microscopy system, a large walk-in cooler for storage studies and two walk-in, temperature-controlled storage units.

Researchers also have at their disposal a range of analytical equipment, including a differential scanning calorimeter, thermal mechanical analyzer, dynamic mechanical analyzer, thermal gravimetric analyzer, dynamic rheometer, a near-infrared spectrophotometer, a rapid viscoanalyzer, two amylographs, two image analysis systems, a water activity meter, a fat extraction system and two high-performance liquid chroma-trography systems.

The sensory analysis facilities include a state-of-the-art sensory evaluation room, a gas chromatograph/mass spectroscopy unit, an electronic nose and instruments for texture evaluation.

Siebenmorgen said the program's ultimate goal is to improve the quality and value of rice and rice products.

"We are just now really getting into the beneficial phase of our research program," Siebenmorgen said. "We think that good things will happen with the continued support of our sponsors."

University of Arkansas'

Rice Processing Program sponsors*

Busch Agricultural Resources, Inc., St. Louis, Missouri

Coopar, Montevideo, Uruguay

Farmers Rice Cooperative, Sacramento, California

Farmers Rice Milling, Lake Charles, Louisiana

FFI Corp., Indianapolis, Indiana

FOSS North America, Eden Prairie, Minnesota

GSI Group, Assumption, Illinois

Kraft Foods, Inc., Dover, Delaware

Louis Dreyfus, Inc., New Madrid, Missouri

Producers Rice Mill, Inc., Stuttgart, Arkansas

Riceland Foods, Stuttgart, Arkansas

RiceTec, Inc., Alvin, Texas

Riviana Foods, Inc., Houston, Texas

Satake Corp., Houston, Texas

Syngenta, Cordova, Tennessee

*as of Feb. 9, 2001

Partners