## 3 Impact of Cold Plasma on Packaging Properties
### Biodegradability  
Biodegradable materials are degraded by the enzymatic action of living microorganisms such as bacteria, yeast, and fungi. Biodegradation is investigated in various environments such as soil burial, landfill and compost simulations, and microorganisms [79; 109; 119]. The impact of cold plasma treatment in the biodegradation of polymers has been reported in the literature as summarized in Table 2. [PERSON], [PERSON] [79] investigated the degradation of corn starch/poly(\(\epsilon\)-caprolactone) films following soil burial method and the extent of degradation was reported in terms of an alteration of TS and EAB. It was observed that the rate of degradation was higher for air plasma treated films as compared to untreated film and it increased with increase plasma treatment time. In another study, [PERSON], [PERSON] [46] reported that the biodegradability of the plasma-treated zein-PLA composite film was higher than that of untreated films. The higher degradation of the plasma-treated film was attributed to the increase in the surface area of the porous structure that enhanced the accessibility to the microbes present in the compost into the film resulting in the higher degradation. A similar result was reported for plasma-treated defatted soybean meal film, where the plasma treatment increased the surface area of the film by increasing the roughness of the film, facilitating microorganisms in the compost in faster degradation [109]. In another study, [PERSON], [PERSON] [93] investigated the biodegradation of PLA sachets for a period of 0 to 35 days and reported that at the end of 28 days, the extent of degradation of plasma-treated PLA sachets was higher than in untreated sachets. At the end of the 35 day period, the treated PLA sachets were completely degraded whereas the untreated sachets remained as shown in Figure 7[93]. Overall, it was observed that plasma treatment modifies the film surface and enhances the rate of microbial degradation. Safety Concerns Relating to the Application of Cold Plasma for the Modification of Food Packaging Films  
The application of plasma in food processing/packaging generates reactive species that come in direct or indirect contact with food surfaces. The interaction between plasma  
Figure 7: Effect of cold plasma treatment on biodegradability of PLA film when composted at 90% RH and 37 \({}^{\circ}\)C for 35 days. On each day, untreated and treated samples are kept in upper and lower positions, respectively. Reprinted with permission from Ref. [93], Wiley Online Library, 2022.  
reactive species and the matrices of food or biopolymers is complicated and limited studies have been carried out investigating the potentially detrimental effects to human or animal health [52; 120]. [PERSON], [PERSON] [121] reported that He gas-plasma treatment of di-ionized water for 30 min generated ROS (reactive oxygen species) and RNS (reactive nitrogen species) caused significant apoptosis [121]. In another study, [PERSON], [PERSON] [122] assessed the cytotoxic and mutagenic potential of DBD plasma-treated iceberg lettuce in an in vitro CHO-K1 (mammalian cell) model and short-term toxic effects in an in vivo _Galferia mellonella_ larva model. The results showed a low in vitro cytotoxic effect and spontaneous mutations, however reported a strong in vivo toxicity with less than a 10% larva survival when injected with lettuce broth treated for 5 min [122]. Few studies have been found to evaluate the toxicology of plasm-treated food constituents. Some studies have reported that the plasma reactive species induces alterations in food constituents, like modification of amino acids in proteins, oxidation of high molecular weight compounds to organic acids, and peroxidation of lipids resulting in undesirable metabolites like short-chain aldehydes, keto-acids, hydroxyl acids, and short-chain fatty acids [51; 120; 123].