Simulated moving bed operating conditions for fructo-oligosaccharides separation

Fructo-oligosaccharides (FOS) are produced with low conversion yields and purity. The fermentative broth obtained from the FOS synthesis contains, apart from FOS, small chain saccharides that do not contribute to the overall beneficial prebiotic activity of the mixture and must be removed. In this work, the separation of FOS from mono- and disaccharides by Simulated Moving Bed (SMB) chromatography was studied. Two stationary phases, a Dowex Monosphere 99K/320 and a Dowex 50WX2, both in potassium form, were studied for further implementation in the SMB plant. Resins were characterized regarding retention factor, separation factor, adsorption constants, column efficiency and resolution. Although the Dowex 50WX2 resin exhibited better separation characteristics, its mechanical resistance was not adequate for high flow-rate conditions. Thus, the Dowex Monosphere 99K/320 resin was selected for the SMB experiments. Adsorption-desorption tests showed that sugars are linearly adsorbed into this resin. Finally, FOS were successfully purified from 37.1 to 62.9% (w/w) using the SMB pilot plant, with a yield and productivity of 69.4% (w/w) and 82.1 g.L-1.h-1, respectively.Clarisse Nobre acknowledges to Fundação para a Ciência e a Tecnologia (Portugal) and POPH/FSE for the Post-Doc Grant received (reference SFRH/BPD/87498/2012). The authors acknowledge the financial support from the Strategic funding of UID/BIO/04469/2013 unit and project ref. RECI/BBBEBI/0179/2012 (project number FCOMP-01-0124-FEDER-027462) funded by Fundação para a Ciência e a Tecnologia. The financial support from the F.R.S.-FNRS, the Belgium National Fund for the Scientific Research, (PDR: T.0196.13) is gratefully acknowledged.