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Milling Characteristics of Rice Cultivars and Hybrids

¹Professor and research associate, respectively, University of Arkansas, Department of Food Science, 2650 N. Young Ave., Fayetteville, AR 72704. ²Corresponding author. Phone: 479-575-2841. Fax: 479-575-6936. E-mail: tsiebenm@uark.edu ³Former research scientist, RiceTec, Inc., 3505 Linwood St., Pearland, TX 77581.

Many rice cultivars and hybrids have unique physical characteristics that affect milling performance. The purpose of this study was to quantify the rate of bran removal during milling for several rice cultivars and hybrids common to the southern United States, and compare the quantity of lipids remaining on the kernel surface to that located throughout the kernel. This was accomplished by analyzing two sample sets. The first comprised cultivars Cocodrie, Cypress, and Lemont, and hybrids XL7 and XL8, which were milled for 0 (brown rice), 20, 30, 40, 50, 60, and 70 sec in a laboratory mill. In the second set, cultivars Cocodrie, Cypress, and Wells, and hybrids XL7 and XL8 were milled for 0, 20, 40, and 60 sec. The surface lipid content (SLC) and color of head rice samples were measured as indications of the degree of milling (DOM). The total lipid content (TLC) of ground head rice was also measured to determine the total amount of lipids present throughout the entire kernel. Results showed that at a given milling duration, SLC and color varied across cultivars and hybrids. In particular, the SLC levels of hybrids were lower than those of cultivars, particularly for Cocodrie, for all milling durations. This research indicated that it may be necessary to mill different cultivars and hybrids for varying durations to attain comparable DOM levels. Milling to a consistent DOM level is necessary to ensure equitable head rice yield comparisons across cultivars and hybrids.