Plasma, often referred to as the fourth state of matter, is an ionized gas composed of free electrons, ions, photons, and reactive atoms, formed when energy is applied to a gas or mixture of gases. Industrial processes have used cold plasma (plasma with a low degree of ionization) for surface modifications of materials.  According to Campden BRI, a United Kingdom-based research association, "cold plasma is not yet realized for the food industry but this technology offers potential applications that could have significant benefits."

Indeed, the past decade of research on cold plasma has begun to show its potential use for the food industry. Cold plasma can perform surface functionalization (addition of functional groups on a polymer surface), etching (removal of unwanted materials from surfaces), and deposition (surface coatings). Based on these capabilities, applications of cold plasma for the food industry can include enhanced printing, enhanced barrier properties, and surface sterilization of packaging polymers. Used on food packaging, plasma’s well-known surface modification abilities can enhance gas and water barrier properties of materials to deliver optimal product shelf life.

For surface sterilization, cold plasma is also capable of damaging target pathogens and immobilizing antimicrobial compounds onto packaging films. One-second cold plasma treatments of PET and polystyrene foils can achieve a 2-log reduction of Aspergillus niger and Bacillus subtilis, according to studies by the Fraunhofer Institute. Active packaging could benefit from immobilization of lysozyme, nicin, sodium benzoate, glucose oxidase, or antimicrobial peptides using plasma. A joint study by the University of Delaware and DuPont showed coating of a chitosan/silver film by corona treatment provided effective antimicrobial activity against Escherichia coli (E. coli) and Listeria monocytogenes.

The most recent and interesting trend is in-package decontamination of foods using cold plasma treatment. Research on plasma generation in sealed polymer packaging serving as a dielectric barrier has demonstrated effectiveness in reducing microbial contamination for produce, fish, and meat and for eliminating pathogens like Bacillus subtilis and E. coli. Nanoguard Technologies claims to have developed a high-voltage atmospheric cold plasma (HVACP) technology for commercial treatment of grains. Plasma research is still at an early stage for the food industry, especially for sterilization purposes. Its long treatment time (up to minutes) currently poses a significant challenge for mass implementation. Even for better-established surface modification of polymers, it has seen limited commercial progress in food packaging due to cost and throughput considerations. Nonetheless, cold plasma has shown unique capabilities at an early stage compared to other processing alternatives. It has the potential to be an effective, safe, chemical-free, and solvent-free sterilization technique.

Assessment of compound migration following plasma treatment and efficacy of antimicrobials embedded onto packaging is necessary before realizing the technology’s industrial food applications. Although cold plasma’s food applications exist mostly at the lab stage at this point, these initial studies suggest several early inroads for potentially valuable innovations in the food industry. Those with a stake in the food packaging space should keep this technology in mind for long-term opportunities.

Joice Pranata is a Research Associate on the Food and Nutrition Intelligence team at Lux Research, which provides strategic advice and on-going intelligence for emerging technologies. For more information, visit Lux Research.