BACKGROUNDMembrane filtration has the potential for purification of oligosaccharide mixtures. However, single stage performance is limited by the relatively low yield and purity that can be achieved. This paper explores the potential of a three-stage pilot-scale spiral wound membrane filtration cascade for the removal of monosaccharides and disaccharides from a galacto-oligosaccharide mixture. RESULTSTwo three-stage cascaded configurations with GH membranes were tested, one ideal-like configuration (cascade 1) and one adapted configuration (cascade 2). Cascade 1 performed well with regard to oligosaccharide yield (e.g. yield 84%, purity 0.46), while cascade 2 performed better in terms of oligosaccharide purity (e.g. yield 62%, purity 0.58). This might be compared with conventional single stage concentration which resulted in an oligosaccharide yield of 56% with a purity of 0.53. In addition these cascade configurations were explored using different membranes (GE and GK membranes) in each stage. CONCLUSIONThe yield and purity in the cascaded systems were higher than the yield and purity of a single stage system with volume reduction. The yield and purity can be further enhanced by using an inhomogeneous cascade with different membranes in each stage. (c) 2015 Society of Chemical Industry