|Rice Utilization and
Project Leader and Principal UC Investigators
Walace H. Yokoyama USDA Western Regional Research Center, Albany
Charles F. Shoemaker Professor, Dept. of Food Science and Technology, UC Davis
Scientists at USDA's Western
Regional Research Center in Albany conduct research that will ultimately lead to new
products for domestic and foreign markets. Last year's work focused on the physical
characteristics of rice starch and the antioxidant properties of rice bran. The narrative
below highlights some of their key findings.
Rice Starch Characteristics
Researchers developed an award-winning laboratory method to determine the molecular size and shape of cereal starches. The characterization of cereal starches, including rice, is difficult partly because of their extremely large molecular size. With the application of size-exclusion chromatography and laser light scattering, researchers were able to measure different forms, sizes and shapes of starch molecules in different rice varieties. The technique shows that different rice varieties have different starch characteristics, each with its own profile or fingerprint. Researchers hope to relate these structural characteristics to eating quality and texture.
A related experiment with this new method examined changes in rice starch after storage. Storage gelatinization is the process of water uptake by starch upon heating to a given temperature. Researchers observed clear changes in the gelatinization of rice starch. This new method may replace current methods to characterize starch gelatinization.
Single kernel texture analysis to compare varieties and lots of rice to standards, which has been in use in Japan, is now being used to characterize California rice varieties. Samples were evaluated for eating quality by the single kernel rice kernel texture analyzer. The hardness/ stickiness measurements for M-202 and M-401 are similar to Koshihikari. These characteristics are important to the Japanese and Korean markets. Another important characteristic of Koshihikari and M-401 are their ability to remain soft, even 24 hours after cooling.
Rice Bran Nutrition
Researchers conducted an experiment to determine whether rice bran contains specific antioxidants that reduce fatty acid deposits that lead to heart disease in animals. Two antioxidants found in cereal brans - vitamin E and catechin - are found in rice at levels normally consumed by humans. The content of vitamin E was determined in different rice ingredients. In this experiment 12 hamsters were fed a special diet that contained stabilized full fat rice bran, defatted rice bran, rice bran oil, and vitamin E or catechin. The study was designed to determine if vitamin E and the other antioxidants unique to rice bran reduced fatty acid formation.
The two month feeding phase of the study was completed in November. Unexpectedly, the crude rice bran oil diet but not the rice bran diet reduced blood cholesterol. The other diets were not different from vitamin E controls. This lead researchers to conclude that rice bran oil can improve cholesterol levels in test animals with high levels of the LDL or so-called bad cholesterol levels. Further work on the unique properties of rice bran will continue.