Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2005
Publication Date: 5/10/2005
Citation: Champagne, E.T., Bett Garber, K.L., Grimm, C.C., Thompson, J., Mcclung, A.M., Mutters, R. 2005. Effects of drain and harvest dates on rice sensory and physicochemical properties. Cereal Chemistry. 82:369-374. Interpretive Summary: Timing of field draining and harvesting of rice with meteorological conditions can allow growers to foster conditions for high head rice yield (HRY). In California, HRY may be reduced by dry north winds that can dry the rice field rapidly and make it difficult to harvest the crop at optimum moisture content. University of California at Davis researchers have investigated crop-environment (dry north winds, dew) interactions affecting HRY at a range of soil and grain moisture levels by varying drain and harvest dates of M-202, the predominant cultivar produced in California. As part of this study, USDA ARS Southern Regional Research Center researchers have examined the effects of varying drain and harvest dates on rice composition, flavor, and texture. In summary, M-202 demonstrated stable composition, flavor, and texture across drain and harvest dates. This provides growers with flexibility in selecting draining and harvest practices that will maximize HRY without sacrificing rice flavor and texture.
Technical Abstract: Timing of field draining and harvesting of rice with meteorological conditions can allow growers to foster conditions for high head rice yield (HRY). The effects of timing of draining and harvesting on rice sensory and physicochemical properties are not well understood. The objective of this study was to determine the effects of varying drain and harvest dates on the sensory and physicochemical properties of M -202 grown in California under controlled field conditions. Drain date had a very small, significant (P < 0.05) effect on amylose and protein contents with amylose highest at the late drain date and protein the lowest at the early drain date. Breakdown and setback were lowest for early and normal drain dates, respectively; however, no significant (P > 0.05) differences in texture were measured as a result of these parameters being low. Drain date did not affect the volatile composition or flavor of the rice. Harvest date had no significant effect (P > 0.05) on amylose content and a very small, significant (P < 0.05) effect on protein content. Harvesting at the earliest date (9/30) resulted in rice with higher setback and lower breakdown than at later harvest dates, and subsequently, the early harvested rice cooked harder, more cohesive, and absorbed less saliva in the mouth. The differences in texture measured by the panelists, although detectable, were small. The lowest levels of the lipid oxidation products 1-pentanol, hexanal, and nonanal occurred in rice having the lowest HMC: that harvested on 10/13 and 10/16. Differences in levels of lipid oxidation products and branched chain hydrocarbons did not lead to significant (P> 0.05) differences in flavor. In summary, M-202 demonstrated stable composition, physicochemical properties, flavor, and texture across drain and harvest dates.