Rice Utilization and
Product Development - 98



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Project Leader and Principal UC Investigators

Wallace H. Yokoyama, research chemist, USDA Western Regional Research Center, Albany

Charles F. Shoemaker, professor, Department of Food Science and Technology, UC Davis

USDA's Western Regional Research Center in Albany conducts research that leads to new products for domestic and foreign markets. Last year's work evaluated the textural properties of rice and the antioxidant and cancer-fighting properties of rice bran.

Rice starch evaluations

Researchers characterized the textural properties of freshly cooked and stored cooked California rice using previously developed laboratory methods. Factors such as hardness, stickiness, toughness and color are important quality characteristics that vary by variety, location, environmental conditions and farm practices.

The laboratory has received a number of requests for textural characterization of California rice from Asian food importers and manufacturers who anticipate opportunities to use California rice in 2000. The laboratory also received samples from a rice biotechnology company and established interest in cooperative research with Japanese food companies and the Japanese Food Institute. These research interests will serve the California rice industry by ensuring that the industry is providing varieties appropriate to a particular end use.

In addition to whole-grain textural attributes, the cooking properties of rice flours were examined with a unique viscoamylographic instrument developed by the laboratory. Evaluation of Chinese, Japanese, Indian, Thai and U.S. waxy rice showed this rice type can be grouped into two categories with different cooking properties. Further analysis is under way to determine the size of waxy starch molecules to develop a better understanding of the source of cooking differences.

Rice Bran Nutrition

Wheat bran has been shown to be protective against colon cancer. Since the composition of the dietary fiber fraction of rice bran is very similar, researchers conducted a study of the effect of full-fat rice bran on rats. The lab animals were fed diets containing rice bran, wheat bran or cellulose as sources of dietary fiber for six months. Results show that rice and wheat brans are statistically the same. Processing variables can significantly affect the ability of cereal brans to reduce precancerous colonic cells. The effectiveness of rice bran may be improved by processing.

A study of the effect of potential antioxidants in rice bran on hamsters was completed. Male hamsters were fed diets containing full-fat bran, defatted bran, rice bran oil, a low antioxidant control diet, and a control diet supplemented with vitamin E for two months. Indications are that rice bran contains antioxidants in addition to vitamin E that reduce the amount of fatty streaking in the aorta of test animals. Although the effects of antioxidants were not definitive, researchers determined that the rice bran oil diet significantly reduced cholesterol. Preliminary results indicate that a second study is called for.

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