Optimization of oligoglycerol fatty acid esters preparation catalyzed by Lipozyme 435

Oli goglycerol fatty acid esters (OGEs) are an important kind of polyglycerol fatty acid esters (PGEs) which have been widely used as emulsifiers in food, medicine and cosmetic industries. The aim of this study was to investigate the preparation of OGEs by the esterification of olig oglycerol with linoleic acid in a solvent- free system using Lipozyme 435 as the catalyst. The effects of substrate molar ratio, reaction time, reaction temperature, enzyme dosage, and water addition on the efficiency of esterification (EE) were studied. Single factor experiments and response surface methodology (RSM) were employed to optimize the reaction parameters. The optimum conditions were obtained as follows: reaction time 4.52 h, reaction temperature 90 °C, enzyme dosage 2 wt% (based on the total substrate mass), the molar ratio of oligoglycerol to linoleic acid 1.59:1 and no water addition. Under these conditions, the experimental EE (95.82±0.22%) fitted well with that predicted by RSM (96.15%). Similar results were obtained when the process was scaled up to a production of 500 g in a pilot bubble column reactor (BCR). The enzyme maintained 98.2% of the relative activity after 10 batches of reaction in the BCR. Electro spray ionization mass spectrum was employed to rapidly analyze the esterification products, and most species of OGEs have been identified.