Iron Oxide Nanoparticle-Loaded Magnetic Cellulose Nanofiber Aerogel with Self-Controlled Release Property for Green Active Food Packaging

Essential oils (EOs) are favored in green active food packaging research because of their excellent antibacterial and antioxidant performance. However, due to their unpleasant odor and high volatility, there is a need to control their concentration and duration after being released to avoid excessive odorant contamination of the targeted products and maintain their antimicrobial efficiency. In this paper, a facile and environmentally friendly strategy using cellulose nanofibers (CNFs), iron oxide (Fe3O4), and thyme EO (TEO) to fabricate TEO–Fe3O4–CNF aerogels with micronano porous structure for controlled release of volatile TEO to extend food shelf life and preserve their organoleptic properties is presented. The chemical deposition method is used to in situ mineralize < c magnetic nanoparticles (NPs) with high antimicrobial activity on CNF surface. An external magnetic field is employed to actuate the fiber movement and to control the aerogel pore structure during the freeze-drying process, which has a significant impact on the storage and release of TEO. Simultaneously, the synergistic interaction between TEO and Fe3O4 nanoparticles having a contact bacteriostatic effect endows the aerogel with excellent antibacterial performance. The results demonstrate the retention of TEO within the CNF network. These aerogels presents smaller and denser porous structure (11.49 nm), outstanding retention (15.48 mg·g–1), and excellent antibacterial capacity (zone of inhibition greater than 25.5 mm, visible antibacterial activity after 48 days), making them antibacterial aerogels with self-controlled releasing property and a relatively stable release–adsorption–release system within an 10 day period. In practical applications, this sustained-release system can be utilized for packaging active foods such as pork and fruit to prolong their shelf life.