Process optimization using response surface design and pilot plant production of dietary diacylglycerols by lipase-catalyzed glycerolysis.

Two approaches to shift the acylglycerol equilibrium were tested as follows: addition of monoacylglycerols and lowering of the temperature. None of these approaches were able to shift the equilibrium toward higher diacylglycerol (DAG) contents. The glycerolysis reaction was optimized with five factors using response surface methodology. Evaluation of the resulting model enabled the determination of optimal reaction conditions for glycerolysis aiming at high DAG yield. However, verification of the model showed that the model was unable to take the molecular equilibrium into account but it provided good insight in how process settings can be chosen to, for example, minimize production costs. Optimal conditions were found to be the following: no extra water, low content of glycerol (molar ratio of 2), temperature of 60-65 degrees C, 4-5 h reaction time, and only 5 wt % lipases. Up scaling of the glycerolysis process was performed and revealed that scale-up to a 20 kg production in a pilot plant batch reactor was possible with a similar DAG yield (60 wt %) as in lab scale. Purification of DAG oil using batch deodorization and short path distillation yielded 93 wt % pure DAG oil.