**2. Bioplastics and their sources**

Bioplastics which are biodegradable materials made from renewable resources are the new materials of the twenty-first century and are of great importance [9, 10]. Starches from corn, potatoes, wheat, rice, barley, and oats; fibers obtained from pineapple; jute, hemp, banana stems, cassava, newspaper pulp, waste paper, and citrus waste are renewable sources for bioplastics. The use of new techniques for bioplastic production that promotes sustainable solution and reduces plastic waste has been greatly promoted in recent years [11]. Bioplastics can be produced from the inedible parts of food. Food wastes, such as orange peel, pomegranate peel, banana peel, and potato peel, are used in bioplastic production. In recent years, cellulose, hemicellulose, starch, pectin, and these lignocellulosic raw materials are made useful for the bioplastic film production trend [11]. Biobased (biodegradable) packaging materials are a potential alternative to replace petroleum-based (synthetic) polymers. One of the reasons for this situation is the decrease in the demand for petroleum-based products and the movement toward renewable resources to produce plastics and the reduction of the amount of gases released into the atmosphere. Another reason is to reduce the solid waste problem by turning biodegradable materials into compostable organic residues after use [12, 13].

Starch is the most widely used source in the production of biopolymer packaging materials due to its edibility and ease of raw material supply. The main source of starch used for these purposes is usually corn the fact remains that the mechanical properties, such as strain rate and tensile and flexibility strength of films produced from starch are not sufficient. Therefore, starch can be chemically modified or mixed with other substances. Plasticizers, such as glycerol, polyether, and urea, are used to reduce the fracturability of starch [14]. Since starch shows hydrophilic properties, it is not suitable for liquid food products with high moisture content, however, starchbased films have good oxygen barrier properties [15], as well they are used as an alternative to petroleum-derived materials because it is inexpensive and biodegradable [16, 17]. The ability of starch to be hydrolyzed by microorganisms, and used as a carbon source and whether they have the ability to produce α-amylase enzyme is strain specific feature. For this reason, an external source of this enzyme is needed in order for starch to be hydrolyzed by microorganisms and used as a carbon source [18]. **Figure 1** shows bioplastics and their sources.

*Perspective Chapter: Development of Food Packaging Films from Microorganism-Generated… DOI: http://dx.doi.org/10.5772/intechopen.108802*

**Figure 1.** *Bioplastics and their sources.*

Cellulose consists of glucose monomer units linked by glycosidic bonds and is an inexpensive source because it is found in all plants. However, its hydrophilic properties, low solubility, and high crystal structure create difficulties in its use in packaging, and due to the successive hydroxyl side chains, it causes low moisture barrier properties in cellulose-based packages. Also, the packaging material formed due to the high crystalline structure is brittle and has poor flexibility and tensile strength [14, 19]. For these reasons, research now focus on cellulose derivatives for packaging purposes. Cellulose-based biopolymer cellophane films, known as candy wrappers, are highly transparent and colorful. Cellophane treated by lamination, injection, and extrusion molding exhibits good film-forming properties [20]. Because it is insoluble and has excellent dimensional stability, it is also used in packaging products ranging from laminate, flower wrapping, and cheese to coffee and chocolate [19]. Researchers stated that starch/PVA, which is a composite biodegradable film, reinforced with cellulosic fiber is suitable for use in food packaging [21]. Cellulose derivatives are obtained by the reaction of cellulose in the presence of an aqueous solution of sodium hydroxide and an esterifying reagent. Cellulose derivatives, such as hydroxypropyl cellulose, hydroxypropyl methylcellulose, carboxymethylcellulose, and methylcellulose, are used for edible films/coating. Suspensions of these substances have thermogelation properties that form gels when heated and, on the contrary, regain their original consistency when cooled. Such films are poor water barriers and show poor mechanical properties due to the hydrophilic nature of the molecules [22]. The quality of the moisture barrier can be improved by adding hydrophobic compounds, such as fatty acids, to the cellulose matrix [23]. Due to the high production cost, the use of cellulose-based plastic is limited in the market.

Chitosan, the second most abundant natural polymer after cellulose, is obtained by partial deacetylation of the natural polysaccharide chitin [24]. Chitosan is an important waste of the fishing industry. It has many functions, such as antimicrobial effect against bacteria, molds, and yeasts, moisture adsorbing, precipitation, film formation, and enzyme immobilization [25]. It also exhibits good oxygen and carbon dioxide permeability, but a major drawback is that it has poor solubility in neutral solutions. Sun et al. [26] determined that chitosan films combined with apple polyphenols can be used as bioactive packaging material to increase the shelf life of foods. Pectin, which is a heteropolysaccharide found in the cell walls of plants, is frequently used to thicken jams and jellies [27]. In the industry, mostly apple pulp and citrus peels are used as a source. These types of edible films are used for certain food-related functions, such as food packaging materials, anti-browning, flavor enhancer, and antimicrobial functions, their production usually uses casting method or extrusion [28, 29]. Pectins, which are frequently used to produce biodegradable films, can be supported with nano-structured fillers to compete with commercial polymers because they show poor physical and barrier properties. The nanocrystals obtained from cellulose, a natural component, impart rigidity and strength to the films [30].

Whey, which is a by-product of the cheese and casein industry and makes up 90% of the processed milk volume, is used for humans and animals, while some is thrown into the environment. Whey, which is an inexpensive substrate and carbon source for bacterial growth, is also preferred in the production of polyhydroxyalkanoate (PHA) [31]. Wheat bran contains high protein, carbohydrates, and minerals, and they are suitable for use as waste. Various studies have been carried out to evaluate wheat bran waste. One of them is the use by Van-Thuoc et al. [32] as a carbon source for bacterial growth and PHA production. They determined that growing Halomonas boliviensis LC1 resulted in biomass production of 3.19 g/l and PHB production of 1.08 g/l. Soy proteins are generally a by-product of the soybean oil industry. Generally produced by wet casting, soybeans are preferred in edible films and coatings because of their good film-forming properties. Although their water permeability is high, their oxygen permeability is good like other protein films [33–35]. Gelatin is a naturally occurring hydrocolloid polymer derived from animal skin, bones, and related tissues. Gelatin-based bioplastic films are widely used as packaging material in the food industry [36]. Many studies showed that the physical and mechanical properties of biofilms made of gelatin can be improved with biocomposite films, such as gelatin-starch or gelatin-starch-glycerol [37]. Lipids are used as protective coatings against transfer, but besides lipids, wax and other resin materials have several disadvantages as packaging materials, such as a waxy taste and texture, oily surface, and bitterness. Among its advantages in terms of packaging, the lipid component reduces water transmission, while the hydrocolloid component acts as a gas barrier and even contributes to the strength and structural integrity [29, 38].

In the food industry, large amounts of both solid and liquid waste occur due to the production, preparation, and consumption of food. These wastes cause problems while being destroyed, but they are valuable products as biomass and nutritional components [39, 40]. Especially fruit and vegetable industry is an area that generates a lot of waste. Fruits and vegetables are consumed fresh as well as processed into juice and jam, and vegetables into canned products, and as a result of all these processes, wastes such as shell, seed and pulp with high polysaccharide, protein, and lipid content are formed. These wastes are reusable for different processes. For this reason, a "zero waste approach" is being tried to be adopted. The zero-waste approach is based on the use of organic waste generated after processing, in a different field,

### *Perspective Chapter: Development of Food Packaging Films from Microorganism-Generated… DOI: http://dx.doi.org/10.5772/intechopen.108802*

such as chemistry, medicine, cosmetics, or as a raw material again in food production by subjecting it to various processes. Especially fruit and vegetable industry wastes contain plenty of pectin and different essential oils. These organic substances in the structure of waste are used not only to enhance the mechanical and barrier feature of packaging materials but also for the production of biodegradable films [41–44]. In recent years, the production of biodegradable packaging materials obtained from fruit and vegetable wastes has gained importance. Biodegradable films obtained from these are unfortunately not at a level to compete with commercial polymers in terms of mechanical and barrier properties. However, it is possible to develop these properties with nanotechnology applications [45]. Considering the mechanical and barrier properties of commercial polymers, although they are suitable for use as packaging materials, interest in natural polymers is increasing because they are not sustainable and biodegradable. However, films obtained from natural polymers show poor barrier and mechanical properties. In this respect, biodegradable polymers are not yet competitive with commercial polymers. For this reason, developed biopolymers are obtained by supporting many biopolymers with organic or inorganic additives [46, 47]. By integrating nanoparticles into biopolymers, the negative mechanical and barrier properties of biodegradable films can be eliminated, and new materials with completely different properties can be developed. Polymer/clay composites improve the barrier properties of thin films [48, 49]. It is stated in the literature that bio-nanocomposites and nanoparticles have an inhibitory effect on the growth of some bacteria [50], act as a carrier of antimicrobial substances [51], and directly form an antimicrobial film [52]. Antimicrobial bio-nanocomposite films are formed by using fillers, such as chitosan [53], nano-silver [54], zinc oxide [55], and titanium dioxide. The use of food industry wastes in the production of biodegradable films has recently been one of the topics of interest in terms of the environmentalist approach. The components contained in the waste can add different properties to the packaging material, such as elasticity, strength, biodegradability, transparency, and antimicrobial activity.

Orange peels are some waste rich in pectin content, and when the films obtained by using the powder form of this waste were dried, seen that the films obtained from orange peel powder, had values close to the tensile strength of commercial polymers, such as low-density polyethylene, high-density polyethylene, polytetrafluorethylene, polypropylene, and polystyrene (16–32 MPa), were obtained [56]. Another industrial output evaluated for use in bioplastic production is soybean waste. Soybean is a raw material that is processed in large quantities and produces excessive waste. Therefore, it is obtained economically at a lower cost than other bioplastic-produced materials [57]. In a study on the evaluation of food industry waste, a film was obtained by mixing lemon peels and potato pulp at different rates. The amount of potato pulp released during the production of potato chips is between 12% and 20% of the total production. Potato pulp is rich in starch, cellulose, hemicellulose, and fermentable sugar content, and is a potential waste for biopolymer film production [58]. Lemon, on the other hand, is a product that is usually consumed fresh or processed into fruit juice, and its peel is very rich in flavonoids, pectin, and essential oils.

In addition, the antioxidant and antimicrobial properties of lemon pulp are also mentioned in the literature [59]. Pomegranate is a raw material that is generally processed into products, such as pomegranate juice or jam, after processing, approximately 55% of pulp is produced. In addition to its antioxidant and

antibacterial properties, it has a pulp rich in pectin, tannin, and moisture [60]. Studies are carried out to obtain a film from pomegranate peels [41, 42]. After the banana processing process, up to 30% of the fruit is exposed. Banana peel is a waste not only rich in moisture, protein, pectin, and potassium but also rich in dietary fiber (cellulose), antioxidant, and phenolic compounds [61]. In a study conducted by adding pectin and cellulose nanocrystals obtained from banana peels to the film formulation, it was desired to improve physical and barrier properties. This study shows that nanofillers can improve the mechanical and barrier properties of biodegradable films [62]. Pectins, which are frequently used to produce biodegradable films, can be supported with nanostructured fillers to compete with commercial polymers because they show poor physical and barrier properties. The nanocrystals obtained from cellulose, a natural component, impart rigidity and strength to the films. In the production of biodegradable films, not only fruit and vegetable wastes but also the shells of nuts are used. It has been stated in the literature that shells containing a high percentage of starch are a suitable material for the production of bio-thermoplastics [63]. The same is true for walnut shells. In biodegradable films, walnut shells act as absorbent [64] and reinforcing material [65]. In a study in which starch obtained from cashew shells was used as a film matrix, cellulose obtained from walnut shells was also used as a filler. This study proved that the cellulose obtained from walnut shells shows very good barrier properties against oxygen [66].
