Synthesis, optimization and structural characterization of a chitosan-glucose derivative obtained by the Maillard reaction

Chitosan (Chit) was submitted to the Maillard reaction (MR) by co-heating a solution with glucose (Glc). Different reaction conditions as temperature (40, 60 and 80 °C), Glc concentration (0.5%, 1%, and 2%, w/v), and reaction time (72, 52 and 24 h) were evaluated. Assessment of the reaction extent was monitored by measuring changes in UV absorbance, browning and fluorescence. Under the best conditions, 2% (w/v) of Chit, 2% (w/v) of Glc at 60 °C and 32 h of reaction time, a chitosan–glucose (Chit–Glc) derivative was purified and submitted to structural characterization to confirm its formation. Analysis of its molecular weight (MW) and the degree of substitution (DS) was carried out by HPLC–Size Exclusion Chromatography (SEC) and a colloid titration method, respectively. FT-IR and 1H NMR were also used to analyze the functional groups and evaluate the introduction of Glc into the Chit molecule. According to our objectives, the results obtained in this work allowed to better understand the key parameters influencing the MR with Chit as well as to confirm the successful introduction of Glc into the Chit molecule obtaining a Chit–Glc derivative with a DS of 64.76 ± 4.40% and a MW of 210.37 kDa.The authors B. Gullón and A. Cardelle-Cobas acknowledge the Fundação para a Ciência e Tecnologia (FCT) for financial support provided by postdoctoral fellowships (refs. SFRH/BPD/79942/2011 and SFRH/BDP/90069/2012/, respectively). A.I. Ruiz-Matute thanks her JAE Doc contract from CSIC. This work was supported by National Funds from FCT through project PEst-OE/EQB/LA0016/2013 and under R+D program of the Spanish Ministry of Innovation and Science, project AGL2008/00941/ALI.Peer Reviewe