How does Plasma work?
Biological decontamination is concerned with the degradation or removal of biological contaminants. For microbiological decontamination, the concern is the degradation or removal of undesired microorganisms. Microorganisms are defined as cellular or non-cellular entities that are capable of multiplying themselves or transferring genetic material or as biological materials that cause infections, allergies, or toxic effects. These may be bacteria, fungi, spores, viruses, viroids, plant or animal cells, pyrogens, prions, and plasmids. Antimicrobial is the effect of a material, mixture, or chemical when it is capable of destroying microorganisms, inhibiting their development, or inhibiting their pathogenicity.
Foodstuffs may exhibit a microbial load of up to 109 CFU/ g (colony-forming units). However, potentially dangerous microorganisms only include Phytopathogens (e.g. Pseudomonads) for plants, and animal and human pathogens (e.g. EHEC, salmonella, and listeria) for animals and humans.
Physical plasmas provide a "cocktail" of potentially antimicrobial agents such as ions, charged particles, radicals (ROS/RNS), molecules, magnetic and electrical fields, and (V)UV radiation. See Figure 1. Furthermore, temperatures higher than 60 °C may also damage microorganisms.
In most cases, foodstuffs contain a high percentage of water (e.g. fruit, vegetables, drinks) which, in combination with the chemical components of the plasma cocktail, result in acidification which actually assists and accelerates the antimicrobial effects of the plasma. Radicals such as reactive oxygen and nitrogen species (ROS/RNS) are likewise known for their microbicidal effects.
Plasma can be applied directly, semi-directly (at a distance of a few mm), or indirectly onto the particular product; this depends heavily on the product's temperature resistance. By direct contact, short-lived species and (V)UV radiation, in particular, can enhance the antimicrobial effects.
This is only a small number of the hypotheses for antimicrobial applications of physical plasmas currently being researched. Beyond this, the individual properties of the products such as surface structure, ingredients, or type and extent of microbial contamination is not considered. Read more here.