159 Relationship of sorghum grain size to physicochemical properties.

W. J. LEE (1), D. R. Shelton (2), and J. F. Pedersen (3). (1) Department of Food Science, Kangnung National University, Kangnung, Korea 210-702; (2) Department of Agronomy, University of Nebraska, Lincoln, NE 68583-0915; (3) USDA, ARS, Lincoln, NE 68583-0915.

It is widely believed that increased seed size in sorghum (Sorghum bicolor (L.) Moench) is associated with higher grain quality. Literature, supporting this belief is sparse, and often fails to remove confounding effects, such as genotype. Three genotypes with red seed and three genotypes with white seed were sieved to yield fractions of varying kernel size (less than 4.00, less than 3.35 and less than 2.80 mm). Milling characteristics (milling yield and particle size index) and physicochemical properties (hardness, color, ash content, starch content, water retention capacity, and Rapid Visco Analyser parameters: peak viscosity, holding strength, breakdown, setback, and final viscosity) were determined. Within genotypes, larger seed size was associated increased hardness and higher milling yield. Flour from the larger seed size was associated with lighter color, lower ash content, lower particle size index and higher water retention capacity. Overall, larger grain had significantly higher starch content, higher RVA peak viscosity and higher breakdown, but lower setback viscosity.