Enzyme membrane reactor coupled with nanofiltration membrane process for difructose anhydride III from inulin conversion

•Operations of UF membrane selection and EMR amplification were obtained.•Experiments of NF membrane selection and DAF III concentration in NF system were carried out.•The system of EMR coupled with NF membrane was founded and processed for batch operations.

Difructosan anhydride III (DFA III) is produced by inulin conversion with inulin fructotransferase (IFTase). The objectives of this study were to investigate enzyme membrane reactor (EMR) coupled with nanofiltration (NF) membrane system for the high concentration of DFA III from inulin conversion. The system could make IFTase recycle to reactor in the EMR performance, while the EMR permeate (mainly DFA III) was concentrated and NF permeate (water) could be recycled to reactor for dissolving inulin in the NF performance. The EMR amplification and optimal operational membranes were also explored. The results showed that the system of EMR coupled with NF membrane contained solution volume of 5 L, the molecular weight cut-off (MWCO) for ultrafiltration and nanofiltration membranes of 5 kDa and 150 Da, and DFA III concentration was enhanced to about 400 g/L. The system could provide a steady operation and be persistent for 8 runs. The research can realize material circulation (enzyme and water) and product concentration, which could also provide theoretical basis for the industrial scale-up production.