**1. Introduction**

Recent reports from the World Health Organization (WHO) have pointed out the high incidence of foodborne diseases as a public health problem [1]. The globalization of food supply has presented new challenges for food safety and has contributed to the internationalization of the public health problem of foodborne diseases [1]. Foodborne pathogens are usually eliminated by thermal treatment during food processing [2]. These methods can inactivate pathogenic microorganisms but could also reduce nutrients or modify organoleptic and sensory properties. To overcome these disadvantages, nonthermal treatments, such as high pressure, ultraviolet or pulsed light, or irradiation, have been developed. However, they are not as effective as thermal ones, have a high application cost [3], and are not always accepted by consumers [4].

In the last few years, many research groups have been paying attention to antimicrobial food packaging, a nonthermal treatment that involves the development of active antimicrobial films and coatings to act as protective barriers against pathogens present in food products. Polymer films and coatings can be used as carriers for a wide range of food additives, including various antimicrobials that could reduce the risk of pathogen growth on food surfaces and thus prolong product shelf life. In this context, there is increasing demand for natural, healthier additives. Chlorophyllins (water-soluble sodium magnesium chlorophyllin, E-140, and water-soluble sodium copper chlorophyllin, E-141) are semisynthetic porphyrins obtained from chlorophyll and used as colorants in dietary supplements and in cosmetics [2].

When these molecules are exposed to visible light in air, they generate singlet oxygen and radical oxygen substances, which have antimicrobial activity [2,5]. The cationic 5,10,15,20 tetrakis(1-methylpyridinium-4-yl) porphyrin tetra-iodide as photosensitizer has been reported to provide effective photoinactivation of *Pseudomonas syringae* pv. *actinidiae* in kiwifruit leaves under sunlight irradiation without damaging the plant [5]. Other authors have shown that chlorophyllin-based photosensitization reduced mesophilic bacteria and inoculated strains of food pathogens on cherry tomatoes without producing harmful effects on the nutritional quality of the tomatoes or their antioxidant activity [6].

These molecules are not toxic, and they do not present any effect in dark conditions. There are few studies about the use of porphyrins in antimicrobial applications. Porphyrin films with nylon or cellulose have been developed for industrial, household, and medical applications [7,8]. Antimicrobial activity of phthalocyanine-dyed paper has also been tested against *E. coli* and *A. baylyi* by illuminating for 1 h under lights of various intensities.

However, the application of polymer films or coatings carrying these antimicrobial compounds to avoid microbial contamination and improve the shelf life of food products has scarcely been reported. Previous studies with chlorophyllin-based films and coatings have shown their effectiveness in preventing microbial contamination of cooked frankfurters inoculated with *S. aureus* and *L. monocytogenes* [2]. The antimicrobial activity of chlorophyllins has been found to be dependent on the choice of light source: quartz lamps, near-infrared lamps, halogen lamps, slide projector lamps, special photodynamic lamps, or special light-emitting diode lights [9].

The aim of this work was the development of antimicrobial photosensitizer coatings based on synthetic and biological polymer matrices with various degrees of hydrophilicity, such as gelatin (G), polyvinyl alcohol (PVOH), polyethylene (PE) and (hydroxypropyl) methyl cellulose (HPMC), incorporated with two chlorophyllins and exposed to the radiation of halogen lamps and LED lamps as activation sources. These films were applied on bologna slices to test their antimicrobial effectiveness.
