Simultaneous decoloration and purification of crude oligosaccharides from pumpkin (Cucurbita moschata Duch) by macroporous adsorbent resin

This study investigated an efficient and recyclable approach for purification of crude pumpkin oligosaccharide (POS) by macroporous resins. Five resins with different physical and chemical properties were tested for decoloration of POS. In virtue of its higher decoloration ratio (92.6%) and POS recovery ratio (81.3%), the macroporous resin DM28 was considered to a better selection. Depending on the changes of molecular weight, part of the monosaccharides in crude POS were removed simultaneously after decoloration by DM28. Operating conditions were also determined by the dynamic breakthrough and desorption curves. Moreover, UV/vis spectroscopy and Fourier transform infrared results revealed that most of the colored impurities and proteins can be removed, but the characteristic groups of the POS exhibited no significant difference. Compared with traditional methods, DM28 resin is superior in decoloration efficiency, pigment recovery and oligosaccharide recovery. This research contributes to further exploration on the structure and function of POS.