Optimization of oligoglycerol fatty acid esters preparation catalyzed by Lipozyme 435

Y Wang,N Zhang,Y L Teng,A J Li,F L Wan

doi:10.3989/gya.1180142

Abstract

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.

Highlights

Natural fats and oils are attractive feed stocks for the chemical industry as they are renewable and more eco-friendly compared with fossil resources
The effect of reaction temperature on the EE was studied at the range of 60~120 °C for 5 h with an oligoglycerol/linoleic acid molar ratio at 1.5:1 and an enzyme dosage of 3 wt%
The appropriately elevated reaction temperature was very effective in improving the mass transfer by increasing the activity of the enzyme and the diffusion of the substrate

Summary

Introduction

Natural fats and oils are attractive feed stocks for the chemical industry as they are renewable and more eco-friendly compared with fossil resources. This makes it very interesting for them to be manufactured into surfactants. PGEs are amphiphilic molecules which show good properties for emulsification, crystallization adjustment, viscosity modifier, moisturizing, antimicrobial, etc. Their amphiphilic nature makes them suitable to be used for the stabilization of food emulsion (Curschellas et al, 2013) and reverse microemulsion (Ding et al, 2007). Since PGEs have a higher content of hydroxyl groups, their emulsifying properties are considered to be superior to that of monoglycerides (Yamagata et al, 2000)

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