30H-1 |
Analysis of refined oils for residual protein and lipid degradants |
V. C. GORDON, Safety Associates, Inc., 1405 Warner Ave., Tustin, CA 92780 The residual proteins in refined oils are present at very low levels. Their presence has caused concern with respect to labeling and allergenicity. Current methods to measure protein content in refined oils are time consuming and difficult. Our objective was to develop a rapid test for low protein levels in refined oils. Fifty refined oils including soy, corn and sunflower were screened for residual protein levels using a new membrane separation technology. The refined oil was solubilized in an alcohol solution and applied to a membrane which binds proteins. The protein is then released from the membrane into a small volume. Protein is detected using an optimized micro protein assay for 1-50 ppm of protein. Additional tests for lipid peroxides, alkenals and free fatty acids in these oils were also performed using this methodology. Fifty refined oils were screened using this new method and protein levels ranged from less than 100 ppb to 10 ppm. The refined oils exhibited low levels of free fatty acid less than 0.05% except for two samples with levels of 0.1% to 0.15%. These samples exhibited a much wider range of lipid peroxides from 0.7 to 7.0 meq/kg. Alkenals ranged from 100 to 600 nmol/ml and malonaldehyde levels ranged from 0.6 to 13 nmol/ml. This range of degradations was larger than expected with higher levels of primary and secondary oxidants than expected. Protein can be rapidly determined in refined oils using membrane separation technology and this study suggests the values range from less than 100 ppb to 4000 ppm. This same technology can be used to determine other quality indicators in these oils.
Session 30H, Quality Assurance
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