30 DECEMBER 2024 • WORLD AQUACULTURE • WWW.WAS.ORG occur in nature. The use of biodegradable polymers may have a positive impact on the environment and the economy by reducing the demand for petroleum-based polymer manufacture while subsequently reducing plastic pollution (Verma et al. 2024). Figure 1 represents the classification of some materials according to their origin and environmental decomposition. Biodegradable Packaging Materials Sensitive and perishable food products require external packaging materials for effective preservation during transport and storage. Edible food packaging has been investigated as an alternative method to preserve food freshness, in the form of films or coatings. Edible films and coatings used for food packaging include edible biopolymers like lipids, polysaccharides, and proteins combined with other ingredients, such as bioactive materials. They are used to maintain the quality of the food and extend shelf life, considering the specific requirements of the target food product (Athanassiou 2021, Punia Bangar et al. 2021). Cellulose is a natural biopolymer obtained from plants, agricultural residues, shells of marine microorganisms and bacteria. Cellulose is a linear, semi-crystalline polysaccharide. Compared to petroleumbased materials, such as polyethylene and polypropylene, cellulose has higher thermal stability and better filmforming capability. It is used widely in packaging due to its renewability and biodegradability (Jiang and Ngai 2022). Hydroxy propyl methyl cellulose (HPMC) is a derivative of cellulose, and is widely used because of its biodegradability, non-toxicity, biocompatibility and general ability to form uniform matrices. Materials based on HPMC have enhanced gelation, viscosity, solubility, and functional characteristics (such as tensile strength and gas barriers) (Ghadermazi et al. 2019, Ursachi et al. 2024). Plasticizers are chemical compounds with low volatility that are used to enhance the cohesiveness of films. Plasticizers may change the functional properties of the produced materials by improving their extensibility, flexibility and elasticity. It is also possible to change the physicochemical nature of the resultant materials according to the nature of the plasticizer. For example, the addition of a hydrophobic compound in the matrix of a film leads to a decrease in the water vapor permeability (Suderman et al. 2018). Glycerol is a sugar alcohol which can mix easily with water and therefore it is a perfect option as a plasticizer in water-based solutions (Towey et al. 2011). Oleic and linoleic acid are fatty acids, with 18 carbon atoms. Oleic acid is monounsaturated omega-9 and linoleic acid is polyunsaturated omega-6. Both are used in the matrix of biopolymers to impart hydrophobic properties of the produced materials (Balasubramaniam et al. 2020). LEFT: FIGURE 2. The development of HPMC-based films with different plasticizers (glycerol, linoleic acid, and oleic acid). RIGHT: FIGURE 3. The test properties of HPMC-based films. FIGURE 4. Microbiological analysis of packaged gilthead seabream fillets. Sensitive and perishable food products require external packaging materials for effective preservation during transport and storage. Edible food packaging has been investigated as an alternative method to preserve food freshness, in the form of films or coatings. Edible films and coatings used for food packaging include edible biopolymers like lipids, polysaccharides, and proteins combined with other ingredients, such as bioactive materials.
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