Many by-products that are harmful to the environment and human health are generated during food processing. However, these wastes are often potential resources with high-added value. For example, crustacean waste contains large amounts of chitin. Chitin is one of the most abundant polysaccharides in natural macromolecules, and is a typical component of crustaceans, mollusks, insect exoskeleton and fungal cell walls. Chitosan is prepared by deacetylation of chitin and a copolymer of D-glucosamine and N-acetyl-D-glucosamine through β-(1 → 4)-glycosidic bonds. Chitosan has better solubility, biocompatibility and degradability compared with chitin. This review introduces the preparation, physicochemical properties, chemical and physical modification methods of chitosan, which could help us understand its biological activities and applications. According to the latest reports, the antibacterial activity, antioxidant, immune and antitumor activities of chitosan and its derivatives are summarized. Simultaneously, the various applications of chitosan and its derivatives are reviewed, including food, chemical, textile, medical and health, and functional materials. Finally, some insights into its future potential are provided, including novel modification methods, directional modification according to structure-activity relationship, activity and application development direction, etc.

在食品加工过程中会产生许多对环境和人类健康有害的副产品。但是，这些废物通常是具有高附加值的潜在资源。例如，甲壳类废物中含有大量的甲壳质。几丁质是天然大分子中最丰富的多糖之一，并且是甲壳类动物，软体动物，昆虫外骨骼和真菌细胞壁的典型成分。壳聚糖是通过几丁质与D-葡萄糖胺和N的共聚物脱乙酰而制得的β-（1→4）-糖苷键形成-乙酰基-D-葡萄糖胺 与几丁质相比，壳聚糖具有更好的溶解性，生物相容性和可降解性。综述了壳聚糖的制备，理化性质，化学和物理修饰方法，可以帮助我们了解壳聚糖的生物学活性和应用。根据最新报道，总结了壳聚糖及其衍生物的抗菌活性，抗氧化剂，免疫和抗肿瘤活性。同时，对壳聚糖及其衍生物的各种应用进行了综述，包括食品，化学，纺织，医疗和健康以及功能材料。最后，提供了有关其未来潜力的一些见解，包括新颖的修饰方法，根据结构-活性关系进行的定向修饰，