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United States Department of Agriculture

Agricultural Research Service

Title: Small-Scale Induction of Postharvest Yellowing of Rice Endosperm

Authors
item Miller, Helen
item Kay, Mark - ARKANSAS RREC
item Lee, Fleet - ARKANSAS RREC

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 15, 2005
Publication Date: N/A

Technical Abstract: Rice endosperm may yellow during commercial storage in conditions of high temperature and moisture, thereby reducing the value of the grain. In order to study the process in a controlled manner, we developed a technique to induce this postharvest yellowing on a small, laboratory scale. Milled rice kernels were rinsed with water and incubated in clear test tubes or microfuge tubes at 65-70oC. This allowed direct visualization and measurement of the color change using a colorimeter. Every rice cultivar tested, which included long and medium grain as well as japonicas and indicas, showed some level of yellowing. Yellowing increased with temperature with a maximum color change occurring at 79oC. Most of the color change occurred in one day. The amounts of water needed for yellowing to occur were measured as well as the changes in relative water contents during yellowing. Using sterilization and culturing, we found no indications of direct fungal involvement in the yellowing process.

Last Modified: 10/24/2014
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