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Surfactant-free Pickering emulsion has been considered as a promising carrier to load oil-soluble active agents for preparation of active edible films to keep food quality and safety. Herein, dialdehyde cellulose nanocrystals (DCNC) were obtained by the periodate oxidation. Then, the DCNC-stabilized Pickering emulsion loaded with dihydromyricetin was prepared and incorporated into gelatin matrix to fabricate gelatin-based active edible films. Interestingly, DCNC was used to cross-link gelatin, besides stabilizing Pickering emulsion, to effectively improve the physicochemical properties of gelatin-based films. The results indicate that the Pickering emulsion stabilized by DCNC3 (DCNC3-DP) is quite stable during storage and centrifugation. And DCNC3-DP was homogeneously dispersed in gelatin films. Significantly, the gelatin-based active edible films incorporated with DCNC3-DP have strong UV barrier ability, high transparency, good water resistance, favorable mechanical property, and effective antioxidant activity. Overall, the as-prepared gelatin-based active edible films have advantages in the application of food and drug packaging.

It is of great significance to use safe raw materials, and spontaneously form covalent crosslinking during the fabrication process to obtain active edible films with excellent performance. Herein, l-cysteine as the source of thiol group was firstly conjugated onto gelatin backbone via 1-ethyl-3-(30-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry. Afterwards, the thiol groups in gelatin-l-cysteine (G-Cys) conjugates were oxidized in air to form disulfide bonds, meanwhile the antibacterial polypeptide e-polylysine (e-PL) was incorporated into gelatin matrix to fabricate gelatin/e-polylysine active edible films. The results show that the amount of conjugated l-Cys in G-Cys conjugates ranges from 43.5 to 159.4 mg/g. The disulfide bond crosslinking generated by the oxidation of thiol groups resulted in compact and dense microstructure, which in turn could decrease the moisture content, total soluble matter, water vapor permeability and swelling behavior of gelatin-based edible films, means enhanced water resistance. Moreover, the fabricated gelatin-based edible films showed good mechanical properties, excellent UV light barrier property and effective antioxidant activity. In addition, the incorporated antibacterial polypeptide e-PL endowed gelatin-based edible films with robust antibacterial activity. Overall, the disulfide bond crosslinked gelatin-based edible films incorporated with e-PL could find potential application in the food and drug packaging fields.

The utilization of petroleum-derived synthetic materials causes severe ecological problems, such as environmental pollution and soil degradation. Hence, using naturally derived and renewable materials to fabricate novel biodegradable films for safe and effective food packaging has been a subject of interest over the years. Here, the novel antimicrobial and controlled biodegradable gelatin-based edible films were developed using nisin as the antimicrobial agent, amino-functionalized montmorillonite as the nanoparticle filler, and dialdehyde xanthan gum as the crosslinking agent. The results indicate that the ultraviolet barrier ability, water resistance, and mechanical properties of gelatin-based edible films are obviously improved on account of the crosslinking effect. Moreover, the resulting films demonstrate antimicrobial activity against Staphylococcus aureus owning to the addition of nisin. Furthermore, the crosslinking can slow down the erosion of the edible films by fungi due to the improved hydrophobicity and compact structure. Particularly, the edible films can be completely biodegraded in soil within 30 days. Meanwhile, the rate of soil biodegradation can be well controlled by adjusting the crosslinking degree. Overall, this novel gelatin-based edible films have potential applications in food packaging.