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, andheated-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 to26% from two locations (Stuttgart and Keiser, Arkansas). The rough rice was dried under three conditions: 43.5C, 38%relative humidity (RH), 9.5% equilibrium moisture content (EMC); 51.7C, 25% RH, 7.3% EMC; and 60C, 17% RH,5.8% EMC. The results indicated that variety, HMC, drying condition, and drying duration had significant interactiveeffects on the HRYR during drying. Medium-grain Bengal rice exhibited more HRYR than did long-grain Cypress orKaybonnet rice under a given drying condition. The results further indicated that a decrease in MC of rice at the earlydrying stages did not substantially affect the HRY until a certain MC level was reached. It appeared in this study that theamount of moisture that could be removed without affecting HRY increased as harvest MC increased.