Enzymatic interesterification of vegetable oil/ fish oil blend for margarine production

In margarine formulation, oils of different melting points are blended to make a product that is spreadable at room temperature. Usually, the blend would be subjected to modification process, either by interesterification (chemical or enzymatic) or partial hydrogenation in order to achieve the desired properties.

In this study, palm stearin (PS), palm kernel oil (PKO) and fish oil (FO) are blended and modified by enzymatic interesterification. PS functioned as the hard stock, PKO as the soft oil and FO as a source for eicosapentaenoic acid (EPA)/ docosahexaenoic acid (DHA). The purpose is to restructure the triacylglycerol (TAG) of the blend by locating medium chain fatty acids (MCFA) at sn-1 and 3 positions and EPA/ DHA at sn-2 position.

MCFA located at the end positions would be rapidly hydrolyzed by pancreatic lipase, absorbed into intestines, and rapidly carried into the liver where they are consumed as a quick source of energy. The remaining 2-monoacyl- glycerol becomes a source of essential fatty acid, after being absorbed through the intestinal wall.

This would enhance the nutritional value of the enzymatically interesterified product. However, the incorporation of FO into the blend would cause the product to be susceptible to oxidation due to the presence of high content of polyunsaturated fatty acids. Furthermore, FO could also influence the melting properties of the product.

Therefore, in addition to determining the fatty acid position on the glycerol backbone, it is also pertinent to study the oxidative stability and melting properties of the product.