*2.4.1 Plasticiser*

For improving mechanical property of edible film, plasticisers are added to film solution during formation/manufacturing of film. Plasticiser has small molecular weight and is hydrophilic in nature. These small molecules are situated between their polymeric networks and make them stronger [2]. Commonly used plasticisers in edible packaging are polyols (sorbitol, glycerol), mono-, di- or oligosaccharides (glucose, sucrose), lipid and its derivatives (fatty acids, surfactants). Generally, the selection of plasticisers requires considering plasticiser's compatibility, efficiency, permanence and economics [102].

### *2.4.2 Antimicrobials*

Antimicrobial compounds are additives used to control biological deterioration and to inhibit the growth of microorganisms, including pathogenic microorganisms. Antimicrobial agent can be incorporated directly into the food during manufacturing or may be incorporated into food packaging materials [30]. There are several groups of antimicrobial compounds potentially incorporated into edible films, including chemical agents, natural extracts and probiotics [103]. Janjarasskul and Krochta [2] stated that for controlling growth of microorganisms, both natural and synthetic antimicrobial agents are added in edible film, and this is used as an alternative for it.

#### *2.4.3 Natural extracts*

#### *2.4.3.1 Plant/spice extract*

Different plant/spices, such as seeds, roots, bark, buds, flowers and leaves, are used to create the extracts. The phenolic chemicals, such as catechin, tannin, ferulic acid, caffeic acid, gallic acid and carvacrol, which are found in various portions of plants and spices, are mainly responsible for their antimicrobial properties [103]. Extraction of essential oil from plants (cinnamon, clove, onion, garlic, radish, etc.) comprises phenolic compounds such as phenolic acid and flavonoids which have biological activities such as antimicrobial and antioxidants [104].

#### *2.4.3.2 Enzyme*

The most employed antimicrobial enzyme is lysozyme which is made up of hydrophilic monopeptide chains [30]. Lysozyme is a nutraceutical and is produced from egg white, milk and blood [105]. It is shown to be more effective against Grampositive bacteria. It separates *N*-acetylmuramic acid and *N*-acetylglucosamine bond of the peptidoglycan in the cell wall of bacteria [106]. Gram-negative bacteria have lipid-based outer cover to their cell walls; due to this, lysozyme is less effective on it [15]. By hydrolysing the peptidoglycan, lysozyme causes bacterial death by destroying the cell wall of bacteria [30].

#### *2.4.3.3 Bacteriocins*

Bacteriocins are macromolecules which contain protein and produced from the different varieties of bacteria and have different mode of action, chemical property. Bacteriocins are naturally occurring antimicrobial substances. They are small-molecular-weight peptides produced by microorganisms and effectively inhibit the growth of food spoilage bacteria, mainly Gram-positive bacteria [105]. The most employed antimicrobial bacteria are nisin and pediosin [103]. Antimicrobial efficiency of bacteriocins is influenced by their concentrations and number and species of microorganisms, using condition, interaction or inactivation by food elements and temperature and pH of the product [105].

#### *2.4.3.4 Probiotics*

Live bacteria known as probiotics can improve health when ingested in adequate quantities [107]. After 12 days of storage testing, Bekhit et al. [108] found that the

*Application of Edible Packaging in Dairy and Food Industry DOI: http://dx.doi.org/10.5772/intechopen.107850*

film of hydroxyl propyl methylcellulose (HPMC) contains microencapsulation of *Lactococcuslactis subsp. Lactis* was successful in reducing the growth of *Listeria monocytogenes* by a five-log cycle when compared with control film. According to Beristain-Bauza et al. [109], whey protein isolate films containing *Lactobacillus rhamnosus* cell-free supernatant (12 or 18 mg/ml in film-forming solution) maintain inhibitory action against Gram-positive (*Salmonella typhimurium* and *E. coli*) and Gram-negative (*E. coli*) bacteria (*L. monocytogenes and S. aureus*). Probiotics can be incorporated into the edible polymer matrix to be used in the food packaging industry because of their safety, operative properties and useful qualities.

### *2.4.3.5 Emulsifiers*

Emulsifier has both polarity and non-polarity; due to this, it acts as a surface active agent which has the ability to mix the two immiscible substances such as oil and water, by changing or modifying interfacial energy of these immiscible substances [2]. Emulsifiers are very important because they help to achieve proper and sufficient wetability to product which is essential for proper surface area and adhesion to the wrapping material [53]. Many proteins have emulsifying properties owing to their amphiphilic nature [2].

#### *2.4.3.6 Chemical agents, organic acids and salts*

Organic acids and their salts are mostly used as chemical antimicrobial agents for food products due to their efficacy and cost [110]. They are produced by chemical synthesis or chemical modification of natural acids [111]. The most widely used organic acids in film packaging are acetic acid, lactic acid, sorbic acid and citric acid. Films containing organic acids have been developed as a consequence of numerous scientific studies. For instance, Uranga et al*.* [112] reported that 20% (w/w) citric-acid-contained gelatin/chitosan films decreased *Escherichia coli* in liquid culture. Furthermore, Rocha et al*.* [113] established films made of anchovy protein that are antifungal and contain 1.50% (w/v) sorbic acid or benzoic acid.
