A study of head rice yield reduction of long- and medium-grain rice varieties in relation to various harvest and drying conditions

In this research, the effects of harvest moisture content (HMC), harvest location, variety difference, and heated-air drying conditions on head rice yield reduction (HRYR) of long-grain (Kaybonnet and Cypress) and medium-grain (Bengal) varieties were investigated. The rice was harvested at moisture contents (MCs) of approximately 16 to 26% from two locations (Stuttgart and Keiser Arkansas), The rough rice was dried under three conditions: 43.5 degreesC, 38% relative humidity (RH), 9.5% equilibrium moisture content (EMC); 51.7 degreesC, 25% RH, 7.3% EMC; and 60 degreesC, 17% RH, 5.8% EMC. The results indicated that variety HMC, drying condition, and drying duration had significant interactive effects on the HRYR during drying, Medium-grain Bengal rice exhibited more HRYR than did long-grain Cypress or Kaybonnet rice under a given drying condition. The results further indicated that a decrease in MC of rice at the early drying stages did not substantially affect the HRY until a certain MC level was reached It appeared in this study that the amount of moisture that could be removed without affecting HRY increased as harvest MC increased.