Enzymatic method for preparing transesterified oils

An enzymatic transesterification method for preparing a margarine oil having both low trans- acid and low intermediate chain fatty acid content, together with a broad margarine solids fat index melting profile and a smooth organoleptic consistency, said margarine oil comprising a blend of from about 84 to about 95 weight percent fatty acid triglycerides, from about 5 to about 15 weight percent fatty acid diglycerides and less than about one weight percent of fatty acid monoglycerides, based on the total weight of said blend, less than 3 weight percent of esterified trans- unsaturated fatty acid and less than 6 weight percent of intermediate chain saturated fatty acids, from about 25 to about 45 weight percent of esterified linoleic acid, from about 0 to about 11 weight percent of esterified linolenic acid, from about 5 to about 25 weight percent of esterified oleic acid based on the total weight of esterified fatty acids, said margarine oil also having a non-random fatty acid distribution in which esterified stearic acid is predominantly distributed in the 1-, 3- positions, while esterified unsaturated fatty acid moieties are in higher concentration at the 2- position of said glycerides within the following ranges:

• ______________________________________ 1-,3- Glyceride 2- Glyceride positions position weight percent weight percent ______________________________________ Palmitic acid 5-10 0-2.0 Stearic acid 50-70 0-5.0 Oleic acid 5-15 20-30 Linoleic acid 10-30 60-80 Linolenic acid 0-10 3-12 ______________________________________
• and said margarine oil having a solid fat content profile within the following ranges:
• ______________________________________ Dilatometric Solid Temperature Fat Index, Percent ______________________________________ 10.degree. C. 7-31 21.1.degree. C. 3-25 26.7.degree. C. 0.75-10 33.3.degree. C. 0.5-4 38.7.degree. C. less than 3, ______________________________________
• said method comprising the steps of providing a transesterification reaction mixture containing a stearic acid source material selected from the group consisting of stearic acid, stearic acid monoesters of low molecular weight monohydric alcohols, and mixtures thereof, said stearic acid source material comprising at least about 84 weight percent of stearic acid, based on the total weight of fatty acids in said stearic acid source material, and
• an edible liquid vegetable oil comprising at least about 80 weight percent of esterified eighteen carbon fatty acid moieties based on the total weight of the edible liquid vegetable oil triglyceride, said vegetable oil further comprising less than 7 weight percent of esterified palmitic acid in 2- glyceride position, and less than 4 weight percent of esterified stearic acid in the 2- glyceride position, at least about 20 weight percent of esterified oleic acid in each of the 1, 2 and 3 glyceride positions, at least about 20 weight percent of esterified linoleic acid, at least about 5 weight percent of esterified linolenic acid, and less than 2 weight percent of esterified stearic acid in the 2- position,
• transesterifying said stearic acid source material and said vegetable oil triglyceride using a 1-, 3- positionally specific lipase, at a weight ratio of stearic acid source material to the vegetable oil triglyceride in the range of from about 0.5:1 to about 2:1 to substantially equilibrate the ester groups in the 1-, 3- positions of the glyceride component with non-glyceride fatty acid components of the reaction mixture, separating transesterified free fatty acid components from glyceride components of the transesterification mixture to provide a transesterified margarine oil product and a fatty acid mixture comprising fatty acids, fatty acid monoesters or mixtures thereof released from said vegetable oil, and
• hydrogenating the fatty acid mixture to provide a recycle stearic acid source material for recyclic reaction with said vegetable oil triglyceride.