Purification of caprine oligosaccharides at pilot-scale

Abstract

The purification of caprine milk oligosaccharides (COS) by membrane filtration has been hampered by the low concentration of target COS and high concentration of lactose. In addition, their molecular weight proximity hinders the recovery of a COS fraction with high degree of purity and recovery yield. In this work, the recovery of a high purity COS concentrate was obtained by the optimization of an integrated approach including complete lactose hydrolysis, fermentation of the resulting monosaccharides and nanofiltration. All carbohydrates were quantified using High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC PAD). Defatted goat whey was ultrafiltered with discontinuous diafiltrations to increase the recovery of COS in the whey permeate which was then subsequently concentrated by nanofiltration. COS recovery yields of 75% with negligible amounts of monosaccharides (0.3% of the initial amount of lactose in the whey permeate) were achieved. A final retentate containing 67.6 and 34.4% of acidic and neutral oligosaccharides respectively was obtained from caprine milk.

Keywords: Bioactive oligosaccharides; Fermentation; Microfiltration; Nanofiltration; Ultrafiltration; lactose hydrolysis.

Fig. A.1

Average oligosaccharide retention during nanofiltration (500–700 Da sulfonated polyethersulfone) of fermented goat whey permeate.

Fig. A.2

Effects of diafiltrations on the permeation of oligosaccharides from the ultrafiltration retentate.

Fig. 1

Pilot-scale recovery of COS by an integrated approach based on enzymatic hydrolysis, monosaccharide fermentation and nanofiltration.

Fig. 2

Effects of TMP and feed flow on permeate flux during ultrafiltration of hydrolyzed goat whey (CF < 1.1). Error bars represent the standard deviation of two analytic replicates.

Fig. 3

Effects of concentration factor on permeate flux and density of hydrolyzed goat whey using a 10 kDa membrane.

Fig. 4

Pilot-scale fermentation of hydrolyzed goat whey permeate.

Fig. 5

Effects of TMP on permeate flux and total oligosacccharide retention using a 500–700 Da membrane.

Fig. 6

Effects of TMP on the retention of COS using a 500–700 Da sulfonated polyethersulfone membrane (CF < 1.1). Error bars represent the standard deviation of two analytic replicates.

Fig. 7

Effects of concentration factor on permeate flux and density (a) and on the retention of acidic and neutral oligosaccharides (b) in the retentate using a 500–700 Da sulfonated polyethersulfone membrane.

Fig. 8

Total oligosaccharide and monosaccharide concentration before and after nanofiltration (a) and individual oligosaccharide concentration (6′-SLN, 6′-SL, 3′-SL, LNDFH I, LDFT, 2′-FL and LNFP I (b) in the final retentate (CF 10).