Membrane-assisted enzymatic production of galactosyl-oligosaccharides from lactose in a continuous process

Abstract

Functional foods such as oligosaccharides have attained significant acceptance in Japan and are attracting interest elsewhere.Beneficial physiological properties are attributed to oligosaccharides. Here, we describe the continuous production of oligosaccharides from a low-cost substrate (lactose) in a continuous membrane-assisted reactor (both polymeric and inorganic membranes were tested). Different enzymes, a number of feed concentrations, and different average residence times were investigated. The enzymes were used in their native form. Retention and recycling of the enzyme was successful, while the products together with some unreacted substrate and byproducts were removed as the ultrafiltration permeate. For the ultrafiltration, a steady-state flux of about 20 l/m 2 hr was achieved. A maximum oligosaccharide concentration of over 40 %w/w was reached with an average residence time of 1 hr and a feed lactose concentration of 31 %w/w. Pilot scale experiments based on the laboratory tests are also reported.

Experimental and Modeling Study of Galactosyl-Oligosaccharides Formation in Continuous Recycle Membrane Reactors (CRMR)

“…They can be thought of as low molecular weight, non-viscous, water-soluble, dietary fibre. They are considered to be physiologically functional foods which promote the growth of bifidobacteria in the colon and a wide variety of health benefits has been claimed in connection with this effect [1][2][3]. A serious issue in this enzymatic catalysis is the enzymatic hydrolysis of the newly formed oligosaccharides back to lactose and the monomers.…”

“…GOS can be produced with native enzymes in Continuous Recycle Membrane Reactors (CRMR) or with immobilized enzymes in Plug Flow Bed Reactors (PFBR) [1,[6][7][8][9]. With immobilized enzymes a significant portion of the oligosaccharides appears to be enzymatic hydrolyzed before reaching the bulk solution from where the valuable product could be recovered [6,10].…”

Membrane chromatography reactor system for the continuous synthesis of galactosyl-oligosaccharides

“…ß-Galactosidase (EC 3.2.1.23), commonly known as lactase, catalyses not only the hydrolysis of lactose to the monosaccharides glucose and galactose but also the transgalactosylation reaction to produce galactosyl-oligosaccharides (GOS) [1][2][3][4]. GOS are non-digestible oligosaccharides which are recognized as prebiotics.…”

“…The enzyme was reported to have stronger hydrolytic activity than transferase activity and produced a high proportion of trisaccharide in the synthetic GOS mixtures [1,2,7]. Some techniques have been developed for immobilization of ß-galactosidase including non-covalent adsorption, covalent binding, entrapment and encapsulation [1][2][3][8][9][10][11]. The newly developed synthetic micro porous membrane adsorbers as chromatographic media are an attractive alternative to traditionally used packed bed chromatography, which has several limitations [12].…”

“…In our study, the membrane adsorbers have been investigated as an alternative support for immobilization of enzyme to produce GOS. Some of the advantages of immobilized enzymes via physical adsorption of enzyme on activated support are: the chemically inertness of activated supports, good stability during storage, controlled residence time on the enzyme, the recovery of the enzyme after usage, the possibility of a continuous process in enzyme reactors and the elimination of the enzyme from the final product [3,10]. This present study focuses on developing of a method for immobilization of ß-galactosidase in chromatography membranes, investigating the properties of immobilized enzyme and the possibility of using the immobilized enzyme system for the synthesis of GOS from lactose.…”