Hydrogels composed of biomaterials are promising drug delivery systems. In this study, we prepared an antibacterial hydrogel by incorporating the antimicrobial peptide nisin into bagasse cellulose nanofibrils, followed by mechanic shearing to obtain hydrogel microparticles as antimicrobial coatings for paper packaging. The concept of combining nisin with a hydrogel network helps to reduce the nisin depletion disadvantage in a nisin alone coating while achieving a prolonged antibacterial efficacy in application. First, antimicrobial hydrogels were constructed by electrostatic attraction between TEMPO-oxidized cellulose nanofibrils (TOCNF) and nisin. The rheological analysis confirmed that the hydrogel with a TOCNF/nisin ratio of 3:1 formed a good gel network accompanied by a high nisin loading efficiency. The obtained hydrogel exhibited controlled release of nisin in response to pH, with a slower rate at pH 7 than that of pH 5 and pH 9. Then, the obtained hydrogel has been processed to microparticles to facilitate its application as coating on paper packaging. Highly stable TOCNFs/nisin hydrogel microparticles were obtained under a water/hydrogel ratio of 4:1 and a mechanical shearing rate of 8000 rpm. The paper with hydrogel microparticles coating displayed an enhanced tensile strength by 14.67% compared to uncoated paper. As a packaging for cheese in storage at 4 °C for 7 days, the hydrogel microparticle coating paper can significantly reduce the growth of Listeria monocytogenes on the surface of cheese and show a sustained inhibition advantage over a nisin alone coating. The utilization of hydrogel microparticles as the coating slurry provides a versatile approach for paper treatment and endows the paper with a sustained release characteristic in actively preventing the bacterial proliferation on food surfaces during storage. The finding from this work is expected to broaden the application of nanocellulose and nisin into the field of food active packaging.

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Bio-based porous materials can reduce energy consumption and environmental impact, and they have a possible application as packaging materials. In this study, a bio-based porous foam was prepared by using a Pickering emulsion as a template. Nisin and waterborne polyurethane (WPU) were used for physical modification of 2,2,6,6-tetramethyl piperidine-1-oxyl-oxidized cellulose nanocrystals (TOCNC). The obtained composite particles were applied as stabilizers for acrylated epoxidized soybean oil (AESO) Pickering emulsion. The stability of the emulsion was characterized by determination of the rheological properties and microscopic morphology of the emulsion. The emulsion stabilized by composite particles showed better stability compared to case when TOCNC were used. The porous foam was obtained by heating a composite-particles-stabilized Pickering emulsion at 90 °C for 2 h. SEM (scanning electron microscopy) images showed that the prepared foam had uniformly distributed pores. In addition, the thermal conductivity of the foam was 0.33 W/m·k, which was a significant decrease compared to the 3.92 W/m·k of the TOCNC foam. The introduction of nisin and WPU can reduce the thermal conductivity of the foam, and the physically modified, TOCNC-stabilized Pickering emulsion provides an effective means to preparing bio-based porous materials.