14B-49

W. DU, Food, Nutrition and Health, University of British Columbia, 6650 N.W. Marine Dr., Vancouver, BC V6T 1Z4, Canada and D. D. Kitts.

Polyunsaturated fatty acids, especially n-3 fatty acids, play an important role in the health benefit of oil. However, due to the unsaturated extent, these fatty acids are susceptible to oxidation which in turn could result in rancidity as well as health problem instead of benefit when oil is consumed. Flaxseed oil and fish oil are two major resources of n-3 fatty acids in food supplementation.

Our objective was to use the blending of oil with cholesterol and natural antioxidants to achieve optimization of oxidation inhibition during thermal induced peroxidation of flaxseed oil or fish oil.

Fatty acid profile and cholesterol content were analyzed by gas chromatograph. Peroxidation of oil was evaluated by peroxide value, thiobarbituric acid and formation of conjugated diene. Optimization was performed by ECHIP6 program.

Our results showed that flaxseed oil blended with butter oil led to more oxidative resistance to thermal induced oxidation than the oil blend of fish oil and butter oil. Moreover, the retention of n-3 fatty acid was higher in the blending of flaxseed oil and butter oil. The addition of cholesterol to flaxseed oil to the equivalent level present in the fish oil resulted in protection of n-3 fatty acid. Cholesterol oxidation was somehow prevented as well. The optimization of some natural antioxidants, sage, rosemary and citric acid, could also protect flaxseed oil was achieved by the thermal induced peroxidation.

Our results showed that butter oil effectively protects against the loss of n-3 fatty acid in fish oil and flaxseed oil source, beyond what could be expected by simple dilution by saturated fatty acid derived from butter oil. A blending of sage, rosemary and citric acid could also result in the inhibition of peroxidation of highly unsaturated oil.