Lipase-catalyzed interesterification of Sunite sheep tail fat and flaxseed oil provides a fat having a unique fatty acid content and favorable physicochemical and nutritional properties.

The aim of this study is to combine flaxseed oil (FO), rich in α-linolenic acid (ALA), with Sunite sheep tail fat (STF) through a lipase-catalyzed transesterification reaction, in order to produce an edible oil with a fatty acid ratio suitable for human needs. Initially, the optimal conditions for esterification were determined using the Box-Behnken design, with the measurement criterion being the content of ALA at the sn-2 position. The results indicated that the highest content of sn-2 ALA was obtained under the conditions of using 6.8 wt% Lipozyme®RMIM as the catalyst, a reaction temperature of 57°C, a reaction time of 3.3 h, and a substrate mass ratio of 5.6:4.4 for STF and FO. This led to the rapid breaking and recombining of molecular bonds, resulting in the interesterified fat (IF) with the highest content of ALA at the sn-2 position. Comparing STF and FO, IF exhibited excellent fatty acid composition and content. Furthermore, IF had a lower melting point and crystallization temperature compared to STF, and its solid fat content decreased with increasing temperature, completely melting at temperatures above 30°C. Thus, IF is a synthesized fat with excellent properties from both animal and vegetable sources.