**1.7 The antiviral properties of active food packaging**

The ongoing global spread of a pandemic caused by the coronavirus, known as SARS-CoV-2, which caused severe acute respiratory syndrome (SARS), currently poses high risks to human health and the world economy. This virus belongs to a family of enveloped viruses with +ssRNA and crown-like spikes on their spherical surfaces. CoV virion is classified as a very pathogenic virus [94]. SARS-CoV-2 is the third virus in the coronavirus family that has globally caused serious ailments in humans [95]. The virus particles are transmitted through human-to-human contact or contact with infected individuals mediated through the eyes, mouth, nose, or through the inhalation of exhaled virus in respiratory droplets [94]. To prevent the transmission of the virus, the use of gloves and medical masks has become essential. For instance, the demand for disposable polymers/biopolymers is expected to increase by 40% in packaging. Safety concerns related to shopping in supermarkets and small markets

#### **Figure 2.**

*Common forms of active food packaging systems with antiviral properties (A) polymer covered with the internal coating containing compounds active against microorganisms responsible for food spoilage and with the external antiviral coating and (B) two-layer film with an internal layer containing substances incorporated into the polymer matrix, active against microorganisms responsible for food spoilage and with an external layer containing substances incorporated into the polymer matrix, active against SARS CoV-2.*

during the COVID-19 pandemic have led to the use of fresh-food products offered in polymer containers by suppliers and consumers, as well as the use of single-use food packaging materials and polymer bags to carry groceries [94, 96–98]. Multilayered active packaging systems are being developed to improve packaging properties, such as barrier properties, mechanical properties, antimicrobial effectiveness against bacteria, and yeast and molds responsible for food spoilage. However, adding antiviral materials as a layer containing antiviral agents to a coating carrier or incorporating them into a matrix of active films is a strategic route to develop antiviral packaging systems. Multilayered packaging systems are being developed through coextrusion, lamination, or covering with coatings [95]. This safe packaging should have an internal coating or extruded film layer to protect food products and an external coating or extruded film layer with antiviral compounds to protect customers (**Figure 2**) [94–98]. Additionally, this packaging-coated material or material containing antiviral substance should be active during storage, meaning it should offer sufficient resistance against UV aging or be shielded against ultraviolet light through the shielding properties of additives [94, 96–98].

In order to prepare antiviral coatings or films, many compounds, which are effective against viruses, such as SARS-CoV-2, such as ZnO nanoparticles, Ag nanoparticles, essential oils, and plant extracts, may be used [94–100]. As an example, Mizielińska et al. [94] developed an active coating based on nanoparticles of ZnO, geraniol, and carvacrol. Then PE films were covered with the active coating (coating carrier containing antimicrobial compounds mixture) using unicoater at a temp. of 25°C with a 40 μm diameter roller. The coatings were dried for 10 min at a temp. of 50°C. The authors analyzed the antibacterial and antiviral activity of these coatings. Additionally, the synergistic effect of the layer obtained was analyzed. Testing antiviral activity with human pathogen viruses, such as SARS-CoV-2, requires immense safety measures. Due to these concerns, the authors used phi 6 phage from the *Cystoviridae* family as a surrogate for the study of SARS-CoV-2. This phage was found to be similar (morphology, envelope, capsid size, and genome material) to the known pathogenic virus responsible for the COVID-19 pandemic [101]. The results of the study demonstrated that coatings containing an increased amount of geraniol or carvacrol and a very small amount of nano-ZnO were confirmed to be effective against gram-positive and gram-negative bacteria. It should be mentioned that a synergistic effect between these active agents was noted. To summarize, PE films covered with coatings containing geraniol or carvacrol and a very small amount of ZnO-NPs (as internal layer) may be used as packaging materials to extend the quality and freshness of food products. The same coatings can also be used as the external

**Figure 3.**

*a) an active coating based on nanoparticles of ZnO, geraniol, and carvacrol; b) an active coating based on a mixture of supercritical CO2 extracts of raspberry seeds, pomegranate seeds, and rosemary.*

layers offering antiviral properties, as they showed moderate activity against the phi 6 phage. It was assumed by the authors that these coatings would also be active against SARS-CoV-2 particles. Similar results were obtained by Ordon et al. [96] who indicated that active coatings containing a mixture of supercritical CO2 extracts of raspberry seeds, pomegranate seeds, and rosemary showed bacteriolytic activity against *S. aureus* and *P. syringae* cells and bacteriostatic activity against *E. coli* and *B. subtilis* strains. The authors have also confirmed a synergistic effect in the active additives/compounds in the coatings. These coatings may also be used as internal coatings for packaging-covered films to extend the shelf life of food and to maintain their quality. All active coatings developed by the authors may also be used as external layers with antiviral effectiveness, as these coatings demonstrated significant effects against the phi 6 phage. Summarizing, the coatings obtained by the authors [94, 96] had antibacterial and antiviral properties. Their additional advantage was that they were transparent (**Figure 3**).

The lower activity of the mixture of CO2 extracts of raspberry seeds, pomegranate seeds, and rosemary when incorporated into a PE matrix [98]. The results of these tests demonstrated that the LDPE film containing a mixture of these extracts in a matrix inhibited the growth of *S. aureus* and this was also confirmed to be active against *B. subtilis.* This active film did not inhibit the growth of *E. coli* and *P. syringae* strains, however, the number of their cells decreased significantly. The LDPE active film was also confirmed to be active against phi 6 phage particles, meaning that the active foil sample had antiviral properties. A PE foil covered with active layers containing mixtures of *Styloscolex baicalensis* and *Glycyrrhiza* L*.* extracts as antibacterial compounds were found to have bacteriostatic activity against *S. aureus* cells and bacteriolytic effect on *B. subtilis* [97]. The layers were confirmed to be inactive against *E. coli* and *P. syringae* cells. This means that the coatings could be used as internal layers covering packaging film to preserve food products against gram-positive bacteria. The authors have also indicated that the coatings were highly effective against phage phi 6 phage, used as a SARS-CoV-2 surrogate. This means that the coatings could also be used as external layers to limit the spread of SARS-CoV-2 via human physical contact.
