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Induced Postharvest Yellowing in Southern U.S. Rice Cultivars

¹USDA-ARS, Dale Bumpers National Rice Research Center, 2890 Hwy 130 E, Stuttgart, AR 72160. ²Corresponding author. Phone: 870-672-9300 ex 228. E-mail address: Helen.Miller@ars.usda.gov

Rice can yellow during storage if moisture levels and temperatures are allowed to increase. This postharvest yellowed (PHY), or stackburn, rice is reduced in value but no study has investigated the inherent potential within rice germplasm for limiting PHY. To screen a large number of cultivars for propensity to PHY, a laboratory method for PHY using a small amount of rice was used. Ninety-eight popular southern U.S. rice cultivars were yellowed under laboratory conditions. Additional samples of the low-yellowing and high-yellowing cultivars were retested after two and three years of storage as rough rice using higher amounts and larger containers. All cultivars showed greater color change with the higher amounts of rice and when yellowed as milled rather than as rough rice. Length of time of storage and storage temperature did not affect the degree of PHY. The low- and high-yellowing groups remained distinguishable but the overall high level of coloring in southern U.S. rice cultivars indicates that a more diverse germplasm should be investigated to increase the likelihood of identifying low-PHY cultivars.