LAUSR

Abstract Chitooligosaccharides (COSs) have continuously attracted considerable attention as numerous biological activities. The highly efficient preparation of COSs, however, is still a challenge. In this paper, a clean two-stage method is developed to hydrolyze chitosan at high concentration into COSs, comprising of pretreatment with hydrogen peroxide (H2O2) and hydrolysis with food-grade cellulase. The pretreatment reduced the viscosity of chitosan solution quickly, making more chitosan dissolving. Chitosan solution at high concentration (9%, w/v) was successfully prepared by fed-batch chitosan during the oxidative pretreatment. Within 6 h, the chitosan was enzymatically hydrolyzed to oligosaccharides with degree of polymerization (DP) of 2–9 and a small amount of monosaccharide, which was analyzed by thin layer chromatography (TLC) and MALDI-TOF MS. In addition, the results from FT-IR and NMR spectra demonstrated the chemical structure of degraded chitosan was not significantly altered. In summary, the two-stage method shows great potential in large-scale production of COSs. Besides, it is expected to couple with membrane bioreactor and immobilized enzyme technology to realize production of COSs with controlled molecular weight.