Fabrication of Composite Membrane via Electrospinning: A Novel Membrane Bioreactor Design for Enzymatic Synthesis of Prebiotic Carbohydrates

Abstract

This study presents the fabrication and performance assessment of a composite membrane produced via electrospinning to optimize separation efficiency in the enzymatic synthesis of galactooligosaccharides (GOS). GOS production, facilitated by β-galactosidase, is often hindered by inhibitory effects from monosaccharides like glucose and galactose. Conventional nanofiltration (NF) systems struggle with saccharide selectivity, leading to substrate and product losses. In this study, an electrospun composite membrane, composed of Nylon 6/6, polyethyleneimine (PEI), and polyvinyl alcohol (PVA), was developed and compared with a commercial NP030 NF membrane having a polyethersulfone structure. The production process (PP-III) using the composite electrospun membrane demonstrated improved lactose retention compared to the process (PP-II) using the commercial membrane. The PP-III method achieved a maximum GOS yield of 37.2 g L⁻¹, close to the performance of the conventional stirred-tank reactor system (PP-I) and 18% higher than the yield from the PP-II. Additionally, the composite membrane exhibited an initial permeate flux of 25 kg m² h⁻¹, approximately three times lower than that of the commercial membrane at 78 kg m² h⁻¹. This lower flux minimized lactose loss, allowing more substrate to remain within the reactor, which led to an increased GOS yield and improved reaction efficiency. The PP-III method supported higher GOS yields at early lactose conversion (15%–35%). At later stages (over 45% conversion), monosaccharide removal enhanced lactose hydrolysis but reduced GOS productivity due to lactose loss. Overall, the composite electrospun membrane offers a promising solution for scalable, cost-effective GOS production, balancing enzyme activity and product yield while reducing substrate waste.