# Effects of Chitosan Coatings on Controlling
## 1 Introduction  
Foods of animal origin--and especially meat--are essential for the human diet because they constitute excellent sources of nutrients, such as proteins of high biological value, essential amino acids, and vitamins. Still, meat is prone to deterioration and bacterial contamination. Edible membranes are thin coatings that can be applied to a wide variety of food products to enhance their quality and shelf life. Chitosan films are predominately used for meat products because they form strong coatings and they positively contribute to their quality [1]. Chitosan is a cationic polysaccharide of N-acetyl-d-glucoseamine and d-glucosamine units and is derived from the partial deacetylation of chitin [2]. It is generally recognized as safe (GRAS) by the United States Food and Drug Administration (FDA) as a food additive and food preservative of natural origin [1]. Chitosan possesses a wide variety of biological activities, i.e., anti-inflammatory, anti-allergic, anti-hypertensive, antidiabetic, hypolipidemic, hypocholesterolemic, anticoagulant, antineoplastic, and neuroprotectiveactivities [3,4]. However, its most distinctive characteristic is related to its antimicrobial properties [2]. Several foodborne pathogens can be transmitted through meat consumption. Among them, _Staphylococcus aureus_ has regularly been implicated in human disease [5]. _S. aureus_ is a Gram-positive and catalase-positive coccus that is commensal in humans and domestic animals [6]. It can grow in a wide range of temperatures (7 \({}^{\circ}\)C to 48 \({}^{\circ}\)C), pH levels (4.2-9.3), and concentrations of sodium chloride (up to 15%) [7]. It is not able to form spores, but it can contaminate food products during food processing [7] and produce enterotoxins under favorable conditions and temperatures [8]. Staphylococcal foodborne diseases are dominant worldwide and can cause a wide variety of symptoms, including nausea, vomiting, diarrhea, and abdominal pain [7]. Although it is a self-limiting disease, it can cause serious symptoms to high-risk groups of people, such as infants, the elderly, the pregnant, and the immunocompromised [8]. The staphylococcal enterotoxins are resistant to heat, freezing, drying, pH, and proteolytic enzymes [9]; once produced, it is hard to remove them from the food product. In addition, methicillin-resistant _Staphylococcus aureus_ (MRSA) is the most prominent example of an antibiotic-resistant human pathogen that can be transmitted between animals and humans via contaminated food--and especially meat. Therefore, to tackle this major threat to human health, more precautionary strategies should be implemented to reduce the occurrence and survival of _S. aureus_--and especially MRSA--in meat and meat products [9]. Meat is often implicated as the causal food commodity of foodborne illness in humans; _S. aureus_ usually ends up in food after slaughter, with food handlers being mainly responsible for meat contamination. In a review of foodborne diseases in the USA from 1998 to 2008, _S. aureus_ was the second most common causative agent of foodborne disease due to meat consumption [5,10]. Thus, the inhibition of _S. aureus_ from growing on food products is of vital importance to prevent the accumulation of staphylococcal enterotoxins and the transfer of microbial resistance to susceptible humans. _Listeria monocytogenes_ is a notorious foodborne pathogen, causing the often-fatal foodborne disease listiosis. It is a Gram-positive, catalase-positive, and facultative anaerobic rod [11]. It is widely distributed in nature, present in soil, water, vegetation, sewage, and animal feces [12]. Moreover, it is commonly isolated from the environment of food processing facilities and from surfaces due to its ability to form strong biofilms. Cross-contamination is considered to be the most important cause of _Listeria_ contamination in food products [10,13]. When healthy people are infected with _L. monocytogenes_, the symptoms are usually mild, as _L. monocytogenes_ causes only febrile gastroenteritis.