Enzymatic Synthesis of Lipophilic Caffeoyl Lipids Using Soybean Oil as the Novel Acceptor

Soybean oil-based caffeoyl lipids are the novel lipophilic derivatives of caffeic acid, which can be used as UV absorbers and antioxidants in the food and cosmetic industries. In the work, the novel lipophilic structured lipids were prepared using soybean oil as the novel caffeoyl acceptor by enzymatic transesterification. The effects of the reaction variables on the transesterification were investigated, and response surface methodology was used to optimize the reaction variables. Reactions were monitored by HPLC-UV. Different enzymes (Novozym 435, Lipozyme RMIM, and Lipozyme TLIM) were used as biocatalysts, and Novozym 435 showed the best performance for the reaction. The results showed that a high lipophilic soybean oil-based caffeoyl lipids yield (73.5 ± 1.2%) was achieved under the optimal conditions (reaction temperature 85°C, substrate molar ratio 1:6 (ethyl caffeate (EC)/soybean oil), enzyme load 25% (w/w), and 60 h at atmosphere pressure). The activation energies of EC conversion, hydrophilic glyceryl caffeates (GC) and lipophilic caffeoylated acylglycerol (CAG) formations were 32.92 kJ/mol, 17.21 kJ/mol and 57.36 kJ/mol, respectively. Km and Vm were 0.022 mol/L and 0.033 × 10^-3 mol/(Lmin), respectively.