61A-47 |
The effects of growth location on US rice starch structure and functionality |
A. ABOUBACAR, Whistler Center for Carbohydrate Research and Dept. of Food Science, Purdue University, 1160 Food Science Building, West Lafayette, IN 47907-1160 and K. A. Moldenhauer, RREC, University of Arkansas, Stuttgart, AR 72160. The eating quality and functionality of US rice cultivars vary depending on growing location. There is a lack of knowledge regarding the physicochemical basis of this variability. Our objective was to determine the effects of growth environment on US rice quality and functionality through studies of starch composition/structure and to identify rice varieties that have better stability over growing locations. Nine rice varieties were grown at three US locations (Arkansas, Missouri, Texas) and their starch/flour properties were studied. Our results showed that amylose content of rice grown in Missouri was 3 to 18% higher than that of the same varieties grown in Arkansas or Texas. The proportion of short linear chains of amylopectin of rice grown in Missouri was higher and that of intermediate chains lower than that of rice grown in Arkansas and Texas. The proportion of long chains did not follow the same trends and varied depending on the rice variety. Starch RVA data showed that varieties grown in Missouri have consistently lower peak and breakdown viscosities than those grown in Arkansas or Texas. Peak and breakdown viscosities were 1 to 26% and 3 to 43%, respectively, higher in Arkansas than in Missouri. These values were 6 to 14%, and 0 to 24%, respectively, higher in Texas than in Missouri. Trends in these values between Arkansas and Texas were variety-dependent. Trends in flour and starch RVA data were similar. Flour gel hardness of rice grown in Missouri was 0 to 56% higher than that of rice grown in Arkansas and 29 to 51% higher than that of rice grown in Texas. These results showed that growth locations significantly affected starch/flour properties of US rice varieties. The extent of these locational effects was variety-dependent indicating that some rice varieties had better stability than others over growth environments.
Session 61A, Carbohydrate
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