Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 9, 2007
Publication Date: July 1, 2007
Citation: List, G.R., Jackson, M.A., Eller, F.J., Adlof, R.O. 2007. Low trans spread and shortening oils via hydrogenation of soybean oil. Journal of the American Oil Chemists' Society. 84:609-612. Interpretive Summary: Trans fatty acids found in many processed foods, spreads and baking shortenings have been implicated as cholesterol elevating agents and are now required to be listed on nutrition labels. This paper describes technology that allows significant reductions in trans fatty acids using existing oil processing methods. Historically, hydrogenation has been used to formulate food oils and takes advantage of the fact that the reaction is carried out under conditions that maximize trans fat formation. By carrying out the reaction more completely, trans fats are actually reduced and the desired functionality is achieved through a combination of reduced trans fats and increased saturated fats. The new process is a distinct advantage over the traditional one and offers the industry options for reduced trans fats in foods.
Technical Abstract: Soybean oil and cottonseed oil were hydrogenated under selective conditions to yield oils with low iodine values, lowered trans fatty acids and increased stearic acid contents. Oils hydrogenated at 175 deg C, 15 psi hydrogen in the presence of nickel catalyst showed a maximum content of trans fatty acids (46%) at an iodine value of about 70, that, upon reduction to an IV of about 40, showed trans fatty acids content in the 28-32% range with stearic acid contents of 42-46%. Solid fat by NMR and Mettler dropping point measurements show that oils in the 40-42 IV range have physical properties much like hard structural fats obtained by fractionation of palm or palm kernel oils. The hydrogenated oils show high solids at 10-55 deg C with melting points of about 55 deg C. Blends of 10-25% of IV 40 oil with 75-90% liquid soybean oil show solid fat contents and melting points suitable for soft spreads or all-purpose shortenings with trans content of about 2% and 8%, respectively.