Fabrication of essential oil lignin nanocomplexes for antimicrobial packaging applications by antisolvent precipitation

Abstract: Developments in active antimicrobial food packaging to prevent foodborne disease and improve the shelf life of food products has become increasingly popular. A greater awareness has developed in this regard due to the COVID-19 pandemic. Implementing technologies to develop active packaging solutions come with a unique set of challenges such as toxicity, cost, recyclability, and antimicrobial efficacy. Creating a safe and effective biobased alternative to traditional active packaging solutions may remedy such challenges. Herein, we developed a method to fabricate a completely biobased antimicrobial suspension of submicron particles comprised of an essential oil component, isoeugenol, and lignin. These lignin nanocomplexes (LNCs) were determined to have double the antimicrobial activity against Salmonella Typhimurium and Listeria innocua compared to isoeugenol alone. The gain in antimicrobial activity was determined to be due to the decreased vapor pressure, improved stability, sustained release, and greater active surface area of isoeugenol. We also proposed that this colloidal system is the result of the unique case of “trapped species in a droplet” emulsion system, where lignin acts as a ripening inhibitor to isoeugenol droplets. This allows for enhanced stability and bioavailability at a high oil/polymer ratio, without the need of traditional surfactants.