46C-30 |
The effect of naturally occurring damaged kernels in rough rice on milled rice free fatty acid levels |
H. S. LAM, Department of Food Science, University of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72704 and A. Proctor. Free fatty acids (FFA) forms on milled rice due to lipid hydrolysis in surface bran streaks. Since FFA forms rapidly on bran disruption and oxidizes rapidly to form off-flavors, they are a key quality factor in determining suitability of milled rice for brewing (<0.1% FFA). Rough rice damage occurring during harvest and handling that results in hull removal and bran damage may impact milled rice FFA levels, but has not yet been studied. The objective of this study is to determine the effect of rough rice damage produced during harvesting and handling on milled rice FFA levels. Two batches of rough rice that produced milled rice with FFA levels in excess of 0.1% and were rejected for brewing, were obtained from a rice mill. Random samples from both batches of rice were milled and milled rice FFA determined. Rough rice, with damaged kernels removed, was milled and the milled rice FFA determined, for both batches. Damaged brown rice kernels in the rough rice were removed and extractable FFA levels were compared with that of brown rice from sound rough rice, for both batches. The rough rice batches contained 2.9% and 3.2% damaged kernels that had hulls removed and damaged bran layers. Milled rice obtained by random sampling contained 0.10% and 0.11% FFA, which is too high for brewing application. The milled rice FFA levels from sound rough rice, with damages kernels removed, was 0.05% and 0.08%, which is acceptable. The damaged rice kernels had 0.13% and 0.27% FFA, as compared with 0.04% and 0.06% from sound brown rice. The study shows that the removal of damaged kernels from rough rice can have a significant impact on the acceptability of milled rice for the brewing industry, which is the largest rice user.
Session 46C, Food Chemistry: Lipids, antioxidants and emulsifiers
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