Physical and chemical properties of randomly interesterified blends of soybean oil and tallow for use as margarine oils

Refined, unhydrogenated soybean oil and edible beef tallow were interesterified with sodium methoxide. This was done as an alterna-tive to hydrogenation for the production of plastic fats for use as margarine oils. Using 0.5% sodium methoxide at 80 C, interesterifi-cation was complete in 30 min as determined by lipase hydrolysis. A blend of 60% soybean oil and 40% edible beef tallow was found to have physical characteristics (melting point, solid fat index) similar to those of commercial tub margarine oils. The level of poly-unsaturated fatty acids was slightly lower and the level of saturated fatty acids slightly higher than the commercial margarine oils. Iodine value andtrans fatty acid determinations indicated no dis-cernible effect on the degree of unsaturation or the level of isomeric fatty acids by the interesterification process. The interesterified blend did contain 3.0%trans fatty acids which were originally present in the tallow. Oxidative stability of the interesterified oils was estimated by peroxide value determinations over several days on samples stored at 60 C. Experimental blends treated with 0.1% citric acid had poorer stability than the partially hydrogenated margarine oils; however, 0.01% BHA significantly delayed oxidation of the experimental samples. Presented at the JOCS/AOCS annual meeting, 1979, San Francisco. Paper No. 6797, Journal Series, Nebraska Agricultural Experiment Station.