Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 2, 2008
Publication Date: January 1, 2009
Citation: Miller, H.B. 2009. Induced postharvest yellowing in Southern U.S. rice cultivars. Cereal Chemistry. 86(1):67-69. Interpretive Summary: Rice can yellow during storage if moisture levels and temperatures are allowed to increase. Although postharvest yellowed, or stackburn, rice is reduced in value, no study has looked at the diverse rice varieties available to determine if there are some varieties that will yellow less. The ability of a number of Arkansas and popular southern U.S. rice varieties to yellow was tested under laboratory conditions. Low-yellowing and high-yellowing varieties were retested using different laboratory conditions which ensured that the two groups remained distinguishable. All cultivars showed some level of postharvest yellowing under every condition. The range of yellowing achieved was relatively high and narrow indicating that a more diverse group of cultivars should be investigated to increase the likelihood of identifying non-yellowing varieties.
Technical Abstract: Rice can yellow during storage if moisture levels and temperatures are allowed to increase. Although this postharvest yellowed (PHY), or stackburn, rice is reduced in value, no study has investigated the inherent potential within rice germplasm for limiting PHY. In order to screen a large number of cultivars for their propensity for 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. PHY was equivalent for rice grown in two consecutive years and for rice stored at two different temperatures. Additional samples of the low-yellowing and high-yellowing cultivars were retested following two and three years of storage as rough rice. Using higher amounts and larger containers, the low- and high-yellowing groups remained distinguishable and showed greater color change with higher amounts of rice and when yellowed as milled rather than as rough rice. The 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.