An antimicrobial agent prepared by N-succinyl chitosan immobilized lysozyme and its application in strawberry preservation

The purpose of this study is to obtain a washable, nontoxic and safe green antibacterial preservation material that can be used for food preservation. Therefore, a water-soluble N-succinyl chitosan (NSC) was prepared by reacting succinic anhydride with chitosan, and lysozyme-N-succinyl chitosan (LSZ-NSC) was prepared using NSC loaded lysozyme (LSZ). The effect of NSC on lysozyme activity and antibacterial activity was studied. Lysozyme activity in LSZ-NSCs increased by 256% compared with the activity of free lysozyme, and bacteriostatic activity also increased, and increased significantly at low concentrations. The structure and stability of NSC and LSC-NSC were analyzed. The active group introduced by NSC was located on the C2-NH2 group of chitosan. During the process of lysozyme loading, the secondary structure of lysozyme changed markedly, which may be one of the reasons for the change in lysozyme activity. Based to the characteristics of NSC and LSZ-NSC, these compounds were used as bacteriostatic materials in strawberry preservation. Both NSC and NSC-LSZ prolonged the shelf life of strawberry, and NSC-LSZ effectively extended the shelf life of strawberry by 3 days. This research provides a safe and feasible green bacteriostatic preservative material for the fresh storage of food.