## 4 Discussion  
The elimination of pathogenic microorganisms from food contact surfaces is of great concern for the food industry. Since many foodborne human pathogens are able to form biofilm on various surfaces, widely used in the food processing environment, the risk of food cross-contamination during production increases. Many pathogenic bacteria are known to adhere to, and subsequently, form biofilm on the food and food contact surfaces, such as stainless steel, plastic, glass, or rubber [8; 11; 12; 26; 27; 31; 32]. In the present study, all the tested species formed biofilm on the glass surface after 72 h at 4 \({}^{\circ}\)C. The strongest biofilm was observed for \(S\). Enteritidis. According to [PERSON] et al. [12], the number of cells in the biofilm formed on the glass surface by \(S\). Enteritidis ranged from \(10^{4}\) log CFU \(\times\) cm\({}^{-2}\) after 2 h to \(10^{7}\) log CFU \(\times\) cm\({}^{-2}\) after 20 h of adhesion at 35 \({}^{\circ}\)C. In our study, the number of \(S\). Enteritidis after 72 h at 4 \({}^{\circ}\)C ranged from 8.74 to 8.86 log CFU \(\times\) cm\({}^{-2}\). Currently, a wide spectrum of conventional chemical methods can be applied for the efficient eradication of pathogens from food contact surfaces. Nonetheless, the toxicity of chemical agent residues and the potential increase of microbial resistance to the applied chemicals encourage researchers to search for new techniques of safe and effective pathogen inactivation. Alternative processes, including the control of quorum sensing, the use of phages, and the application of essential oils (EO), biosanitizers, bacteriocines, blue laser light, ozone, pulsed electric field, high pressure technologies or electrolyzed water, are currently at various stages of development [21; 22; 31; 33]. The important alternative antimicrobial technology is ionizing radiation. The most commonly used forms for decontamination purposes are gamma rays, high energy electrons and X-rays; however, a number of modern methods based on this type of radiation, that is, cold plasma or binary ionization technology (BIT), are still intensively investigated [34; 35; 36; 37; 38]. Radiant catalytic ionization (RCI) is one of these novel techniques and, according to the results of many research studies, appears to be a reasonable alternative to the conventional decontamination procedures. The great advantage of RCI, in contrast to gamma rays, X-rays, and high energy electrons, is the possibility of its application to household refrigeration appliances, industrial cold rooms, and rooms with low indoor temperature, intended for raw or processed food product storage. The antimicrobial efficiency of RCI is attributed to the cell damaging effect of oxidative gases, including ozone and peroxide, generated by the RCI cell [25; 28]. The inhibition of pathogenic microorganisms on various surfaces was confirmed by our previous studies [8; 26; 27]. The reduction rate of the \(L\). _monocytogenes_ number in biofilms formed on different surfaces (rubber, milled rock tiles, polypropylene) varied from 3.92% to 70.10%, whereas in the case of stainless steel AISI 304 and lacquered veneer surfaces, up to 95% of \(L\). _monocytogenes_ and \(S\). Enteritidis were reduced [26]. [PERSON] et al. [39] achieved 4.37 log CFU reduction of the \(L\). _monocytogenes_ number on stainless steel coupons after 15 min of photohydroionization (PHI) treatment. According to [PERSON] et al. [25], the reduction of different microorganisms, including foodborne pathogens, on stainless steel surfaces subjected to 24 h of RCI treatment reached at least 90%. RCI efficacy against _Salmonella_ on food contact surfaces and animal food products was also confirmed [28; 40]. The present research showed the inhibition of \(C\). _jejuni, L. monocytogenes_, and \(S\). Enteritidis strains on a glass surface after RCI treatment. To assess the RCI effect exclusively on bacteria, the absolute reduction rate coefficient (E) was calculated.