Background: High oleic sunflower oil (HOSO) and a fatty acid (FA) mixture were inter-esterified in a solvent-free system catalysed by Lipozyme RM IM to produce a cocoa butter equivalent (CBE). The effects of reaction conditions on the percentage of saturate-oleoyl-saturate (SOS) and saturate-saturate-oleoyl (SSO) triacylglycerols (TAGs) were studied. The process was further optimised by response surface methodology. A five-factor response surface design was used to investigate the influences of the five major factors and their mutual relationships. The five factors were substrate ratio (A, FA/HOSO, mol mol⁻¹), enzyme load (B, wt% based on substrates), water content (C, wt% based on substrates), reaction temperature (D,°C) and reaction time (E, in hours) varying at three levels together with two star point levels.
Results: The highest yield (59.1% SOS) and lowest acyl migration (2.9% SSO) was obtained at 10% enzyme load, 1% water content, 1:7 substrate mole ratio, 65°C reaction temperature and 6 h reaction time. All the investigated factors except substrate ratio had significant effect on acyl migration.
Conclusion: The quadratic response models sufficiently described the acidolysis reaction. All parameters had significant effect on the percentage of SOS TAGs. Based on the models, the reaction was optimised to obtain a maximum yield of SOS TAGs.
Keywords: acidolysis; acyl migration; cocoa butter equivalent; lipase; response surface methodology; triacylglycerol positional isomers.
© 2013 Society of Chemical Industry.