Evaluation of antimicrobial activity and antioxidant potential of chitosan Maillard-based conjugates in vitro

In this study, chitosan was glycosylated with sugars glucose, maltose and starch through the non-enzymatic Maillard browning reaction at 121 °C for 15 min. The effect of sugars molecular weight on pH changes, intermediate and final (melanoidins) products of the Maillard reaction, antioxidant activity and as well as antimicrobial effect (disk diffusion method, well diffusion method, minimum inhibitory concentration, and minimum bactericidal/fungicidal concentration) of the obtained conjugates were evaluated. Glycosylation reaction led to a significant reduction in pH value of all chitosan-sugar systems (p<0.05) and chitosan-glucose conjugate showed the lowest pH value. Intermediate and final products of the Maillard reaction were significantly increased and the trend was pronounced in chitosan-glucose system than other systems. Antimicrobial activity of the conjugates obtained from chitosan and different sugars against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger improved after the Maillard reaction. Based on DPPH radical scavenging (DPPH-RS) activity and reducing power assays, antioxidative capacity of all samples increased after thermal process. It can be concluded from the results of this communication that chitosan conjugates based on the Maillard reaction can be applied as food-born antioxidant and antimicrobial agents to boost shelf-life of many food products as well as to design novel functional foods containing biologically active components.