Nisin in Food Packaging
Shalini Singh and Robinka Khajuria
In ancient times, food was eaten fresh, because no particular facilities were available to store it for periods of time. With changing times and requirements, food packaging or food storage became a necessity. Humans developed various ways to protect their food materials from spoilage, owing to contact of foods with different spoiling factors (Sacharow and Griffin 1970; Kelsey 1989). The discovery of microorganisms, including those responsible for food spoilage, along with the beneficial effects of food sterilization to destroy such microbes, further added to an understanding of food characters, and the need to maintain its quality for different durations. Food packaging, one of the final steps in food processing before storage and consumption, thus, became a crucial step to incorporate antimicrobial effects for controlling post-processing contamination (Salim et al. 2017). The prevention of food spoilage addresses deterioration by microbial, biochemical, physical, textural, and chemical agents (Cutter 2002). Natural materials such as tree parts, papyrus, gourds, shells, animal parts, etc. are examples of natural materials used for preventing food spoilage in those times. Also, ancient practices to ferment, dry, smoke, sugar/salt, the addition of beeswax, honey, oil, etc., for various foods further helped in preserving foods. With time, improvements and variations to the early practices were also seen and found to be effective for storing different types of foods (Sacharow and Griffin 1970; Kelsey 1989; Cutter 2002a, b).
Food Packaging Formulations
Food packaging has been drawing a lot of attention worldwide and efforts are continuously being made to innovate and improve food packaging systems. A system that strives to preserve the quality and safety of the product it contains from the time of manufacture to the time it is used by the consumer, and protects the food from damage due to physical, chemical, or biological hazards (Dallyn and Shorten 1988; Hotchkiss 1995), makes for an ideal packaging formulation.
The selection of food packaging materials play a crucial role in the success of food packaging, as it provides a barrier to spoilage agents, and even adds additional functions to the package, which prolongs shelf life, enhances safety, as well as improving the nutritional value of foods (Appendini and Hotchkiss 2002) so that foods reach consumers in a safe and satisfactory condition.
It is thus important that the right package is selected for the right food, through sensible consideration of various influencing factors. Several important aspects to be considered are a slow but sustained delivery of antimicrobials; the evaluation of a microbe for which antimicrobial is to be targeted; additional attributes aimed for the end-use properties of food; compatibility between the antimicrobial agent to be delivered; and the packaging system used, especially with careful consideration of the potential chances of microbial resistance to appear. The most common food packaging materials are glass, wood, metal, plastics, paper, and other flexible packages such as coatings and adhesives (Kelsey 1989). Materials like glass, plastic bottles, pottery items, wood boxes, etc., belong to the rigid category of food packaging materials while plastic films, paper, foils, etc., are flexible packaging materials (Raheem 2012). These materials, singly or in combination with other preservation techniques, offer the necessary prevention of food spoilage (Cutter 2002; Suppakul et al. 2003). With time, both rigid as well as flexible systems have improved (Sacharow and Griffin 1970) Plastic materials are moldable, heat sealable, easy to print, and can be integrated into production processes where the package is formed, filled, and sealed in the same production line (Marsh and Bugusu 2007). At the same time, they exhibit variable permeability to agents like light, gases, etc. Paper and paperboard are sheet materials, basically made of cellulose. They are biodegradable and have good printability and are commonly used in corrugated boxes, milk cartons, folding cartons, bags and sacks, and wrapping paper. The use of rubber and adhesive components, polyester, polypropylene, polyolefins, polyvinyl, polyethylene, vinylidene, vinyl chloride, surlyn, and nylon, etc., has further improved packaging formulations by providing improved strength, permeability, and sealability to the package formulations. Such flexible systems also interact positively with gaseous environments to extend the shelf life of many foods, including meat and poultry (Sacharow and Griffin 1970; Cutter 2002; Stollman et al. 1994). Polymers such as low-density poly ethylene (LDPE) constitute the majority of primary packages for foods and beverages and have been commonly used in active polymer packaging (Rooney 1995a). Besides the synthetically derived packaging materials mentioned above, flexible packaging can encompass the use of edible films, gels, or coatings made from polysaccharides, proteins, lipids, or composites of any or all three. The benefits of using edible films as packaging materials are threefold: These films may resist the migration of outer moisture into the food during storage (Ooraikul 1991); films may serve as gas and solute barriers; and films complement other types of packaging by improving the quality and shelf life of foods (Ooraikul 1991).
A number of innovations such as modified atmosphere packaging (MAP), intelligent and/or active packaging are significantly contributing to the cause (Brennan and Grandison 2012). Variants like controlled atmosphere, vacuum, and modified atmosphere packaging use different gases and flushing systems to alter the head- space within a package (Ooraikul 1991; Genigeorgis 1985; Hintlian and Hotchkiss 1986; Farber 1991; Ooraikul and Stiles 1991; Labuza et al. 1992; Church and Parsons 1995; Garcia et al. 1995).
Modified atmosphere packaging (MAP) involves the addition of a single or a mixture of gases after removal of air from the pack (Blakistone 1999). Active packaging is a type of modified atmosphere packaging, which aims to improvise upon shelf life/improved safety/various improved properties of food by modifying the conditions existing in the food package, usually done with the addition of additives into the packages (Brennan and Grandison 2012; Alvarez 2000; Debeaufort et al. 2000; Quintavalla and Vicini 2002; Vermereinen et al. 2002; Salim et al. 2017; Brody et al. 2001; Appendini and Hotchkiss 2002; Han 2003; Cha and Chinnan 2004; Devlieghere et al. 2004; Dobias et al. 1998, 2000; Brody et al. 2001). These systems are developed on the basis of compatibility of the system with the food properties (Rooney 1995b). Selective permeability, temperature modulation, gas control, alcohol or ethylene scavenging systems, moisture control, controlled release of food colors, flavors, removal of odors, inclusion of antimicrobial agents, etc., are some of the important variants of active packaging systems (Labuza and Breene 1989; Rooney 1995a; De Kruijf et al. 2002). The quality of packaged food during transportation and storage can further be monitored through advanced intelligent packaging systems (Ahvenainen 2003).
Antimicrobial packaging has drawn a lot of attention worldwide, as awareness for minimally processed and chemical-free food products is increasing like never before (Imran et al. 2014; Mauriello et al. 2005). The antimicrobials may be directly coated on food material or incorporated into packaging materials (Hoffman et al. 2001; Kamper and Fennema 1984; Wilson 2007; Quintavalla Vicini 2002). As stated above, a number of factors such as the compatibility of food with antimicrobial agents, food composition, mode of action of antimicrobial substances, diffusion kinetics, polymer use, etc., shall all be considered while choosing the antimicrobial packaging system (Appendini and Hotchkiss 2002). Such compounds, generally in conjunction with other inhibitors or conditions, are used for the control of food spoilage and such use of multiple interventions is sometimes called ‘hurdle technology’ (Leistner 2000; Leistner and Gorris 1995).
At the same time, issues like loss in antimicrobial activity in the case of preservatives such as organic acids or their respective acid anhydrides, spice extracts, chelating agents, metals, enzymes, bacteriocins, etc., might arise when such agents are directly added to food (Teerakarn et al. 2002). The problem can be minimized by a ‘controlled release packaging system’, a form of active packaging utilizes packaging as a delivery vehicle to efficiently bring the actives in specifically controlled rates over prolonged periods to the food product to further improve its quality and safety (Cha and Chinnan 2004; Sung et al. 2013; Lacoste et al. 2005; Han 2000; Guerra et al. 2005; Han and Floras 1997; Davies et al. 1999; Hoffman et al. 2001; Cutter 2002; Quintavalla and Vicini 2002). This enables control of the release of antimicrobials and makes food safer to consume. Sometimes, the antimicrobial packaging films are categorized as those where volatile antimicrobial agents are added to sachets and pads, those where antimicrobial agents are incorporated into polymers, those where polymer surfaces are coated with antimicrobials, those where antimicrobials are immobilized by ionic or covalent linkages to polymers, or those where the use of polymers which are inherently antimicrobial is made (Appendini and Hotch-Kiss 2002; Sung et al. 2013).
The development of edible packaging films, coated with antimicrobials, is a new and attractive biodegradable active packaging concept that aims to improve the environmental friendliness of the packaging (Wong et al. 1994). Viable edible films and coatings produced from whey proteins (Ramos et al. 2012; An et al. 2000; Kamper and Fennema 1984, 1985; Fennema and Kester 1991; Han 2000) is one such example. Foods like meat and meat products have been seen to successfully benefit from edible antimicrobial packaging films Meyer et al. 1959; Siragusa and Dickson 1992, 1993; Baron 1993; Cutter and Siragusa 1996; Fang et al. 1996). The use of antibacterial nanoparticles in packaging films (Sorrentino et al. 2007) is an example of improved packaging film systems. Nanocomposites have been successfully used in vacuum-packaged meat, fish, poultry or cheese and offer improved strength, barrier properties, etc., to the packages (Sorrentino et al. 2007).
Natural Antimicrobials for Food Packaging
Though a number of preservatives are now available for food preservation, the growing preference of consumers for natural foods containing fewer synthetic additives has made the use of natural or food-grade antimicrobials in food popular (Sohaib et al. 2016; Pekcan et al. 2006; Davidson 1997).
Naturally occurring antimicrobials include compounds from microorganisms, plants, and animals.
Examples include organic acids or their respective acid anhydrides, spice extracts, chelating agents, metals, enzymes, bacteriocins, etc., which are quite popular in food preservation (Dainelli et al. 2008; Han and Floras 2000; Davies et al. 1999; Hoffman et al. 2001; Cutter 2002; Quintavalla and Vicini 2002).
Some of the active packaging systems include 02 or C02 scavengers, ethylene and moisture absorption systems, CO, or ethanol emitting systems, and antimicrobials antioxidants releasing or containing systems. Eugenol, cinnamaldehyde, pectins, carageenan, starch derivatives, alginic acid, cellulose, collagen, chitosan, gelatin, antioxidants, fragrances (vanillin, clove, orange or citric extract, proteins (conalbumin, casein, whey protein, gelatin/collagen, fibrinogen, soy protein, wheat gluten, corn zein, or egg albumen), polysaccharides, lipid (fats, waxes, or oils) and seaweed extracts, grape seed extracts, spice extracts (thymol, p-cymene, cinnamaldehyde), enzymes (peroxidase, lysozyme), natural essential oils of plants such as, rose-mary, lemongrass, etc., can all be incorporated in antimicrobial edible films, where apart from acting as antimicrobial agents, they also provide selective desirable qualities to foods ((De Kruijf et al. 2002; Han 2002; Krochta et al. 1994; Jung 2000; Gennadios et al. 1997; Han 2000; Cutter 2002; Ozdemir and Floras 2004; Appendini and Hotchkiss 2002; Klangmuang and Sothornvit 2016; O’Callaghan and Kerry 2014; Takala et al. 2013; Wang et al. 2017; Mulla et al. 2017; Kuorwel et al. 2013; Kapetanakou et al. 2014; Siripatrawan and Vitchayakitti 2016; Dotto et al.
2014; Dutta et al. 2009; El-Saharty and Bary 2002; Siripatrawan and Noipha 2012; Yoshida et al. 2010; Ouattara et al. 2000; Aider 2010; Cruz-Romero et al. 2013; Soysal et al. 2015; Guo et al. 2014; Siripatrawan and Noipha 2012).
Organic acids like lactic acid, diacetic acid, have been used to reduce pathogens on beef, cheese, and processed meats (FDA 2000) and their activity was found to be better in an immobilized state (Siragusa and Dickson 1992, 1993). Other organic acids such as propionic, benzoic, sorbic, and lauric are also promising agents (Han 2000; Cutter 2002; Cruz-Romero et al. 2013; Branen et al. 2001; Perez et al. 2014; Rodriguez-Martinez et al. 2016; Hauser and Wunderlich 2011; Silveira et al. 2007; Dobias et al. 2000; Zhou et al. 2007; Sohaib et al. 2016).
Materials like ascorbic acid, photo-sensitive dyes, iron powder, are packed to scavenge oxygen and thereby prevent the growth of aerobic bacteria and molds (Floras et al. 1997). Lysozyme was found to inhibit bacteria in meat and that it inflicted wine malolactic fermentation (FDA 2000; Buonocore et al. 2003). Similarly, potassium sorbate’s antibacterial and antimycotic effect has been studied on cheeses (Szente and Szejtli 2004). Milk protein-based film containing pimento and oregano was found to improve the shelf life of beef during storage at 4o C, where, oregano was most effective against Pseudomonas sp and E. coli 0157: H7 (Oussalah et al. 2004). Baron and Sumner (1993) found potassium sorbate and lactic acid to inhibit
S. typhimurium and E. coli 0157:H7 on poultry. Juhl et al. (1994) proposed a number of agents like antioxidants, fragrances, colorants, antimycotic agents, or biocides to be used in thermoplastic polymer.