*2.3.1.2 Gelatin*

Partial acid or alkali hydrolysis of collagen is used to produce gelatin at high temperature in the presence of water. Due to unique properties of gelatin, it is widely used in cosmetics, food, pharmaceuticals, industry [30]. Edible film obtained from gelatin has impermeability to CO2 and flexibility due to its random arrangement of polypeptide chain in water solution [31]. Also gelatin possesses antioxidant property. Antimicrobial activity of gelatin is studied by Gomez-Guillen et al. [32]. But still, the relation between antimicrobial activity and peptide characteristics of gelatin is not revealed. Edible packaging materials act as carriers for additives, gelatin is one the carriers which carries bioactive components [33]. Gelatin has advantages such as having ability of good film forming, low in price, non-toxicity, biodegradability and gas and oil resistance property but has poor thermal stability, water resistance and mechanical property [34]. Gomez-Guillen et al. [32] stated that formation of an active packaging and extending the functional properties of biodegradable films were only possible due to usage of natural antioxidants and antimicrobial compounds. Gelatin-based edible films have poor water vapour barrier property which can be overcome by adding surfactant, i.e. lecithin, to it [35].
