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

• Chitosan and glucose were submitted to the Maillard reaction.
• Saccharide concentration, temperature and reaction time were evaluated on the extent of reaction and best conditions were selected.
• A chitosan–glucose derivative with a degree of substitution of 65% was obtained.
• Characterization of the derivative using HPLC–SEC, colloid titration, FT-IR and 1H NMR was performed.

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.