Removal of glycerol from enzymatically produced 2-α-D-glucosyl-glycerol by discontinuous diafiltration

2-alpha-D-Glucosyl-glycerol (2-GG) is a natural glycoside that acts as a biological extremolyte. 2-GG is a promising ingredient for cosmetic products. Industrially, 2-GG is synthesised from sucrose in the presence of a high excess of glycerol using the enzyme sucrose phosphorylase. For commercial applications, the surplus glycerol must be removed and an efficient purification strategy is therefore demanded. Here, we demonstrate nanofiltration for the separation of glycerol from 2-GG. Based on membrane screening performed at varied pressure and temperature, we identified a 150-300 Da cut-off polyamide membrane for the selective removal of glycerol at high permeate throughput. An enzymatically produced 2-GG solution was purified with multicycle discontinuous diafiltration on the litre scale. The process was operated at constant permeate flux (13 kg m(-2)h(-1)) and at a temperature of 30 degrees C. A complete removal of glycerol was achieved after six diafiltration cycles. This was in accordance with the simulation results of a mass balance model. The purity of the product solution increased to 80%, which is comparable with commercially products containing functional carbohydrates. The achieved product recovery was around 85%.