Preparation of ferulic acid-grafted chitosan using recombinant bacterial laccase and its application in mango...

To improve the antioxidant and antibacterial properties of chitosan, recombinant bacterial laccase from Bacillus vallismortis fmb-103 (fmb-rL103) was used to catalyze ferulic acid grafting. The grafted chitosan was characterized using UV-vis and FT-IR techniques. DPPH free radical scavenging results indicated that the antioxidant properties of the grafted chitosan (FA-g-CS) were significantly improved. Meanwhile, the antibacterial properties against E. coli, S. aureus, B. subtilis, and M. guilliermondii were also improved. Furthermore, FA-g-CS was applied to mango preservation as a coating, which improved the sensory qualities of mango Mangifera indica L. The disease incidence of mangoes coated with FA-grafted medium and high molecular weight chitosan were 0 and 5%, respectively. The respiratory peak was delayed more than 4 days, and the titratable acidity and ascorbic acid concentration were all enhanced. POD and CAT activities in FA-g-CS coated mangoes were higher than those coated with chitosan samples with a lower H₂O₂ concentration.