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It is considered an excellent emulsifier for stabilizing oil without any surfactant in water emulsions. The chitosan amphiphilicity plays a significant role of stabilization in acidic conditions. This reduces the interfacial stress and facilitates emulsion formation. The capability to emulsify depends on molecular weight and deacetylation degree (DD); i.e., lower DD (~60%) and higher DD (~80%) are more effective than medium DD (~65–77%) [119]. In view of its emulsification ability, a chitosan–soybean oil emulsion has been used for coating eggs, improving their shelf life [120]; another study has reported that lemon oil–chitosan coating increased the shelf life of strawberries [121].

Also, chitosan is used to interact with cell surfaces of both gram-positive and gram-negative bacteria that are capable of releasing certain proteinaceous components from the cell. This gives chitosan an anti-microbial activity, useful for preservation of processed foods [119]. The existence of amine (–NH₂) and hydroxyl (–OH) groups allow new functional groups to be introduced that can change the characteristics. A modified chitosan showed increased activity against E. coli than native chitosan [122]. Chitosan composites have also been investigated as food coatings and edible films; however, they are frequently mixed with other bio-actives to improve water vapor or oxygen barrier properties. It has also been used for encapsulation and delivery of essential oils, vitamins, flavonoids, plant extracts, probiotics, and polyphenols [119], in the form of microparticle and nanoparticles emulsions. A niche application of chitosan is enzyme immobilization. A report investigated alternate ways to immobilize enzymes using chitin-activated by formaldehyde [123]. A similar work reported immobilization of crude seal gastric proteases, with properties similar to rennin [124]. Enzyme immobilized chitosan investigated as biosensors for glucose [125], choline [126], pathogens [127], and polyphenolics [128]. Wastewater treatment from food industries is another area where chitosan is very effective, as it adsorbs a large variety of water impurities; it is utilized for bioconversion of phenolics, dye, and small ions (Zn²⁺, Cu²⁺) removal [119].