Surface lipid and free acids (FFA) content of head and broken rice produced by milling after different drying treatments
2004
Monsoor, M.A. | Proctor, A. | Siebenmorgen, T.J.
The surface lipids and free fatty acids (FFA) content of head and broken rice samples generated through milling after various drying treatments were studied. Long grain cultivars Francis, Wells, and Cypress, and medium grain cultivar Bengal were dried under three air conditions (mild 25 degrees C, 50% rh; moderate 45 degrees C, 40% rh; and stressed 65 degrees C, 20% rh) for two durations (10 and 30 min). Immediately after drying, the rough rice samples were placed in a conditioning chamber to continue drying slowly to approximately equal to 12.5% moisture content (MC), which occurred within three to five days. After dehulling, a McGill No. 2 mill was used to mill the samples for 30 sec. The head rice yield (HRY) for all rice samples were within the range of 40-68%. Rice surface lipid was extracted with isopropanol (IPA) and the lipid and FFA content of the IPA extracts were determined. Broken rice kernels had significantly greater surface lipid and FFA content than head rice kernels. The surface FFA contents of broken kernels were within the range of 0.045-0.065% of broken rice mass, while that of head rice was 0.027-0.040%. Broken rice had greater b values indicating greater yellow color than did head rice.
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