Synthesis of 1,3-distearoyl-2-oleoylglycerol by enzymatic acidolysis in a solvent-free system

- Substrate molar ratio and lipase type are key factors affecting SOS yield.
- NS40086 had a higher catalytic activity and lower selectivity than Lipozyme RM IM.
- Acetone fractionation is an effective method for the purification of SOS.
- Purified SOS product can be used as a cocoa butter improver in chocolate industry.

1,3-Distearoyl-2-oleoylglycerol (SOS) is widely used as a cocoa butter improver and an anti-blooming agent in the chocolate industry. In this study, an effective process was developed to prepare SOS by enzymatic acidolysis. Under optimal reaction conditions (substrate molar ratio of 12, NS40086 loading of 10%, a solvent-free system, 75 °C for 4 h), a SOS yield of 70.2% was obtained. Subsequently, two-step purification was applied to purify the crude SOS product. Free fatty acids were completely removed after molecular distillation. After acetone fractionation, the purity of SOS reached 92.2% with an 85.1% recovery. Comparison of various physicochemical properties of purified SOS and a commercial cocoa butter improver showed their properties to be similar. This study provides an effective and sustainable process for the synthesis of SOS product, which is expected to be used as a high-quality cocoa butter improver or an anti-blooming agent in the chocolate industry.