Synthesis and Characterization of Canola Oil-Stearic Acid-Based Trans-Free Structured Lipids for Possible Margarine Application

Authors: LUMOR, STEPHEN - UNIV OF GEORGIA; Jones, Kerby; Ashby, Richard - Rick; Strahan, Gary; KIM, BYUNG HEE - UNIV OF GEORGIA; LEE, GUAN-CHIUN - NATL TAIWAN NORMAL UNIV; SHAW, JEI-FU - NATL CHUNG HSING UNIV; Kays, Sandra; CHANG, SHU-WEI - CHUNG-CHOU UNIV OF TECH; Foglia, Thomas; AKOH, CASIMIR - UNIV OF GEORGIA

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2007
Publication Date: 12/26/2007
Citation: Lumor, S.E., Jones, K.C., Ashby, R.D., Strahan, G.D., Kim, B., Lee, G., Shaw, J., Kays, S.E., Chang, S., Foglia, T.A., Akoh, C.C. 2007. Synthesis and Characterization of Canola Oil-Stearic Acid-Based Trans-Free Structured Lipids for Possible Margarine Application. Journal of Agricultural and Food Chemistry. 55(26):10692-10702.

Interpretive Summary: Structured lipids (SLs) are lipids whose molecular composition has been altered to achieve desired nutritional, physical or chemical properties. Over the past decade, concerns have arisen over the consumption of trans fatty acids because of their link to an increased risk of cardiovascular disease. In order to ease these concerns, the food industry is working to develop processes that will reduce trans fat content. In this study, a series of SLs were synthesized by incorporating stearic acid, a saturated fat, into canola oil through the use of both enzymatic (lipozyme RM IM from Rhizomucor miehei) and chemical (sodium methoxide) means. Different stearic acid:canola oil ratios were used for the study, which resulted in new SLs with varied chemical content. Based on their composition and properties, the SLs formed were deemed to be suitable for use in light margarines as an alternative to partially hydrogenated fats, thus allowing the formulation of margarines with lower (negligible) trans-fat content.

Technical Abstract: Incorporation of stearic acid into canola oil to produce trans-free structured lipid (SL) as a healthy alternative to partially hydrogenated fats for margarine formulation was investigated. Response surface methodology was used to study the effects of lipozyme RM IM from Rhizomucor miehei and Candida rugosa lipase isoform 1 (LIP1) and two acyl donors, stearic acid and ethyl stearate, on the incorporation. Lipozyme RM IM and ethyl stearate gave the best result. Gram quantities of SLs were synthesized using lipozyme RM IM, and the products were compared to SL made by chemical catalysis and the fat from commercial margarines. After short-path distillation, the products were characterized by GC and RPHPLC-MS to obtain fatty acid and triacylglycerol profiles, 13C NMR spectrometry for regiospecific analysis, X-ray diffraction for crystal forms, and DSC for melting profile. Stearic acid was incorporated into canola oil, mainly at the sn-1,3 positions, for the lipase reaction, and no new trans fatty acids formed. Most SL products did not have adequate solid fat content or beta-prime crystal forms for tub margarine, although these may be suitable for light margarine formulation.