# Edible Packaging: A Technological Update for the Sustainable Future of the Food Industry
## 3 Results
### Categories of Edible Packaging Materials
#### 3.5.1. Polysaccharide-Based Packaging Materials  
Polysaccharide is the most abundant natural macromolecule in nature [5] and it consists of long chains of polymeric carbohydrate bound together by glycosidic bonds which are widely used in the production of edible packaging. Polysaccharides can originate from many different sources, namely, microbial (such as xanthan gum and pullulan), plant (such as cellulose, starch, and pectin), animal (like chitin, chitosan), and marine sources (such as alginate). Films and coatings made from polysaccharides can be oil-free, tasteless, and colorless, have better chemical stability, and have better processing adaptability when compared to protein- and lipid-based packing materials. They can reduce dehydration, surface darkening, and oxidative reactivity, thereby potentially enhancing the shelf life of vegetables, fruit, meat products, or shellfish [5; 26]. Polysaccharide-based film coatings are effective barriers against O\({}_{2}\) and CO\({}_{2}\) at low and medium relative humidities due to their intermolecular structure [26; 40; 41]. Thus, due to their selective permeability, polysaccharide-based materials can be used to improve the shelf life of fresh-cut fruits and vegetables by reducing the respiration rate and gas exchange [40]. However, polysaccharide-based materials provide a low barrier to moisture due to their hydrophilic nature [37]. In addition, packaging materials based on them have a high sorption ability; therefore, when they are consumed, they can adsorb and remove radionuclides, metal ions, and other toxic chemicals from the body [41]. Table 1 groups edible packaging materials based on different polysaccharides.  
Cellulose is a linear-chain homopolysaccharide with anhydrous \(\beta\)1-4 glycosidic bonded glucose rings. It exhibits specific properties such as low cost, low density, durability, high mechanical strength, non-toxicity, biocompatibility, biodegradability, renewability, good film-forming performance, chemical stability, and ease of making chemical derivatives [9]. Nevertheless, cellulose's applicability in the production of edible films is limited because of its inability to dissolve in water and most organic solvents. This is due to its tightly packed hydrogen bonds, high crystallinity, and structural complexity [42]. One way to overcome this limitation is through derivatization by applying an alkali treatment and then acidification by using hydrophilic agents such as methyl chloride, chloroacetic acid, or propylene oxide to produce thermoplastic and hydrophilic cellulose derivatives. Various cellulose  
Figure 3: A compositional overview of edible films and coatings (according to the authors of [4; 32; 33; 34; 35; 36; 37; 38; 39]).  
derivatives that are mostly employed in the creation of edible food packaging include ethers such as methylcellulose, carboxymethylcellulose, hydroxy-propyl methylcellulose, and hydroxypropyl cellulose, as well as esters like cellulose acetate. Methylcellulose and hydroxypropyl cellulose and films are very efficient O\({}_{2}\), CO\({}_{2}\), and lipid barriers, but have a low resistance to water vapor transfer [37]. However, the water vapor barrier characteristics can be increased by including hydrophobic elements such as lipids in the film-forming solution. The FDA has approved cellulose acetate as being generally recognized as safe (GRAS), prompting the food-packaging sector to develop and test new applications for this polymer. Cellulose acetate is mostly used to wrap fresh and baked items [42].