Antioxidant and antimicrobial activity of xylan–chitooligomer–zinc complex

In this study, a ternary complex based on natural polysaccharides was explored as a novel food preservative. Chitooligomer was obtained by enzyme hydrolysis of chitosan with immobilised neutral protease, and the degree of polymerisation (DP) was mainly from 2 to 5. Chitooligomer–zinc complex (CGZC) was first produced and then co-heated with xylan to prepare xylan–chitooligomer–zinc complex (XCGZC). XCGZC showed higher antioxidant and antibacterial activity than chitooligomer, chitooligomer–zinc and xylan–chitooligomer. The IC50 of XCGZC was 5.37 mg/mL, which was equal to the antioxidant ability of 3.28 mg/mL BHT. The diameter of the inhibition zone for XCGZC against Escherichia coli and Staphylococcus aureus was 17.2 ± 0.4 and 30.3 ± 0.6 mm vs. control of 6.0 mm. Besides, XCGZC had excellent antibacterial activity against Bacillus subtilis, Salmonella typhimurium, Bacillus megaterium. Therefore, XCGZC can be used as a novel promising preservative with antibacterial and antioxidant properties in the food industry.