Enzymatic reaction model for the production of symmetrical lipid molecules using the response surface methodology

The purpose of this research was to produce symmetric (Saturated-Unsaturated-Saturated, SUS) triacylglycerol (TAG) using palm stearin fraction oil (PSFO) and high oleic sunflower oil (HOSO) as substrates to replace cocoa butter. PSFO was blended with HOSO (1 : 2 weight ratio), and $lipozyme^{(R)}$ TLIM (20 weight % of the substrate) was added. Interesterification was carried out in a shaking water bath at $55^{\circ}C$ at 220 rpm for 6 hours. The response surface methodology (RSM) through the central composite face design was employed to observe the optimized SUS-TAG. The independent factors were the reaction temperature ($X_1$: 65, 75 and $85^{\circ}C$), reaction time ($X_2$: 1, 3 and 5 hours) and ratio of TLIM ($X_3$: 10, 15 and 20 weight %). The dependent variables were $Y_1$ = Saturated-Unsaturated-Unsaturated (SUU, area %), $Y_2=SUS$ (area %), $Y_3$ = Saturated-Saturated-Unsaturated (SSU, area %), $Y_4$ = Unsaturated-Unsaturated-Unsaturated (UUU, area %), and $Y_5=sn-2$ unsaturated fatty acid (area %). The optimal conditions from the central composite face design minimized acyl migration while maximizing the presence of unsaturated fatty acid at the sn-2 position (73.43 area %). The optimal conditions were $X_1=65^{\circ}C$, $X_2=1hour$, and $X_3=20weight%$. As a result of the response surface analysis, the lack of fits was found as $Y_1=0.622$, $Y_2=0.438$, $Y_3=0.264$, $Y_4=0.526$, and $Y_5=0.215$, and their $R^2$ were 0.897, 0.944, 0.826, 0.857, and 0.867, respectively.