Bio-derived antimicrobial materials provide a margin of safety and quality in food products such as packaging to maintain food quality, freshness, and safety. The ongoing worldwide COVID-19 pandemic is increasing the urgent demands for preventative measures to curtail the spread of bacteria and viruses. Cellulose nanocrystals (CNCs) and essential oils-based emulsions have attracted extensive interest to be developed as food packaging film. However, a food safe surfactant is needed to improve the CNC surface activity and the stability of emulsions in packaging. In this study, antimicrobial films were developed via incorporating CNCs and cinnamaldehyde-based Pickering emulsions. We use a food-grade cationic surfactant, ethyl lauroyl arginate (LAE), to modify the CNCs and improve the emulsion stability through physical adsorption. It was found that the adsorption of LAE neutralized the surface charge of CNCs derived from the sulfate half ester: the zeta potential shifted from -42.9 mv to 18.3 mv as the LAE concentration went from 0 to 0.12 wt%, and therefore hindered the electrostatic repulsion of CNCs. The CNC/LAE complex and cinnamaldehyde were then mixed to form a stable oil-in-water emulsion with an average droplet size of 1.38 μm. The obtained emulsions were added to polyvinyl alcohol solution for the fabrication of food packaging via casting. The addition of the emulsions into polyvinyl alcohol enhanced the thermal stability of films. Importantly, the addition of 2% emulsions led to significant inhibition of microbial growth of E. coli (88% deactivation) and S. aureus (82% deactivation) on in vitro test. Moreover, there were no significant adverse effects on the mechanical properties, water vapor permeability, and solubility of the films at the addition of 1% and 2% emulsions. The SEM results showed that less than 2% addition of the emulsions enabled a smooth surface structure of films. Lastly, the antimicrobial films have been used to preserve strawberries. Results showed that the films repressed the deterioration rate of strawberries by 52.2% for the film added with 2% emulsions. This work indicates that LAE modified CNCs is an effective approach for the emulsification of cinnamaldehyde, and the CNC-LAE-cinnamaldehyde emulsion demonstrates promise in antimicrobial food packaging to enhance food storage shelf life.

Development of antimicrobial films with cinnamaldehyde stabilized by ethyl lauroyl arginate and cellulose nanocrystals

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.