Antimicrobial packaging is achieved by adding functional ingredients inside package so that packaging will restrict the microbial growth to prevent the food spoilage . In this teclmique, active functional ingredients to preserve the food spoilage are released at controlled rates. This technology impregnates specific antimicrobials in a specific food packaging film/ package and delivers the active ingredients in a stipulated period to kill pathogens, thereby enhance food quality, and help in extension of shelf-life . Formulation preservative ingredients are added in the food directly, however, antimicrobial films are wrapped over the food. Instant addition of antimicrobials in packaging films results in prompt inhibition of undesirable microorganisms. Due to interactions of food with packaging matrix, effect of degradation in antimicrobial effect was observed as the survival population of pathogenic microorganisms continued to accelerate, as soon as the concentration of antimicrobial got declined [14, 20].
Different antimicrobial ingredients/agents possess different activities against each type of pathogenic microorganism, and these agents are either integrated into the food component or attached to polymeric material (pack) to release active functional ingredients. The antimicrobial agent performs microbial static effects, which retard the target growth of pathogens. Commonly used antimicrobial agents are: antioxidants, bacteriocins, enzymes, organic acids, natural extracts, fungicides, antimicrobial, essential oils (EOs), and antimicrobial polymers .
Control packaging focuses on the controlled release mechanism. Here, the packaging material is used as a controlled delivery medium to bring the active functional ingredients in the vicinity of the package to preserve processed food. This technique regulates the concentration by the controlled release of functional ingredients in the food matrix at a particular targeted level. Slow-release, time- release, and controlled release are three terminologies that are generally used by medication, antioxidants, and vitamin-controlled release . Many parameters (like polymeric material matrix, surface molecular size, intermolecular binding between particles of polymer and within the food and the properties of functional ingredients) play an imperative part in the controlled discharge of an antimicrobial from a package (polymer/biopolymer) matrix .
Lysozyme (LYZ) prevents the evolution of microorganisms more specifically. For example, lactic acid bacteria (LAB) cause of fermentation (malolactic) in PVOH (polyvinyl alcohol) films, and in many cases level of networking of PVOH films affects the rate of release of antimicrobials . Cooksey developed low-density polyethylene (LDPE) films coated with nisin on the natural polymeric matrix for packaging. Coating suppressed the Staphylococcus Aureus and Listeria Monocytogenes growth to a considerable level . Nisin coated LDPE films are utilized to store the microbiota raw milk showing M. Luteus ATCC 10240 inhibition. Structural modification of poly- mers/biopolymers increased the capacity to modulate the controlled release of immobilized functional active compounds. Polyanhydrides are biodegradable polymers gaining popularity in drug delivery and implant coatings .
Milk protein films blended with EOs have presented antioxidant and antimicrobial effects by controlling pathogenic bacteria . Films prepared from ethylene-vinyl alcohol (EVA) linear incoiporated with potassium sorbate inhibited the growth of microorganisms in cheese . Starch-based chitosan incoiporated films have shown increment in mechanical properties and exhibited controlled release of antimicrobial agents . Garlic oil added to edible films made up of chitosan showed antimicrobial activity for most common bacterial strains, i.e., E. coll, Salmonella, Bacillus cereus, Staphylococcus aureus, and L. Monocytogenes .
Antimicrobial agents are blended, immobilized, or coated differently according to the design of the packaging system and requirements of food products. Coating and edible coating on the processed food create barrier layer, which contains antimicrobial agents. Coating material penetrates through the matrix on the surface of food to exhibit the preservation effect. Silver nanoparticles as antimicrobials agents are under trial for new antimicrobial food packaging systems . The optimization of the antimicrobial agent to get released is a critical factor during preservation.
It is concluded that after the application of antimicrobial agents either the agent is released very late or is released faster than the expected cause of food spoilage. In the first instance, if it is released late, then microbes can grow instantly before the activity of the antimicrobial agent or the release of antimicrobial agents. In the second case, if the migration rate of antimicrobial agents through permeable packaging material is faster than the evolution rate of microorganism, then the antimicrobial agent will be consumed and depleted by growing microorganisms, earlier than the required storage of food product . Therefore, the antimicrobial packaging system can retard the growth of microorganisms responsible for food spoilage and thus assure food safety with extended shelf-life.