FACTORS AFFECTING THE COLOR AND APPEARANCE OF SORGHUM STARCH

Seven cultivars of grain sorghum with various seed colors were studied for the presence of light-absorbing substances in the grain and starc h. A corn sample was used for comparison. Starch was isolated from bot h sorghum and corn. Corn starch was bright in appearance and had a yel lowish tinge. Sorghum starch from the cultivars Dorado, UANL-1-V-187, and Blanco 88 was also bright in appearance and white; the seed color was pale yellow. Although Sorghum cultivar Dekalb 42Y had a pale yello w seed color, it yielded a dull-appearing starch. Kansas local, Bajio, and Tamaulipas cultivars had reddish-brown seed color and also yielde d dull-appearing starch that had a reddish tint. It appears that the p resence of certain alcohol-soluble components contributes to the dulln ess of some sorghum starches, because extraction of dull starch with m ethanol resulted in a brighter starch. Dehulling the grain before star ch isolation improved the appearance of starch. A simple alkali test o n the grain was effective in predicting the dullness of starch.