*3.3.1.1.1 Polyethylene*

Polyethylene (PE) is the most basic plastic in terms of structure, and it is made by additional polymerization of ethylene gas in a high-temperature pressure reactor. Depending on the temperature, pressure, and catalyst of polymerization, a variety of low, medium, and high-density resins is produced. The processing conditions determine the properties of the final outcome [30].

The advancement of PE and its derivatives has revolutionized the market, allowing the plastic to better compete with glass bottles. Polyethylene-based materials are currently preferred for milk and juice bottles, grocery, retail, trash bags, as well as bread and frozen food bags. Polyethylene is a heat-sealable material that can be formed into tough films with good moisture and water vapor barrier. Furthermore, when heat resistance is required for packaging, so polypropylenebased materials opt. Nonetheless, when compared with other plastics, they do not provide in particular a high barrier to fats, oils, or gases [23].

Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) are the two of the most commonly used polyethylenes in the food industry. LDPE is nontoxic, stretchable, and shrinkable. It is a good moisture barrier, but it has low oxygen permeability and is ineffective as an odor barrier. It is widely used for bags as well as coating papers or boards because it is less expensive than most films. Because it is stronger, thicker, less flexible, and brittle, HDPE is a better barrier to gases and moisture than LDPE. HDPE packaging is waterproof and tear and puncture-resistant [30].

#### *3.3.1.1.2 Polypropylene*

Polypropylene (PP) is a low-cost polymer that is catalytically synthesized from propylene. It has good advantages such as good impact resistance, transparency, excellent mechanical property, high melting point, and low density, making it ideal for a wide range of applications. Also, PP has a respectable degradability among polyolefines. Experiments, however, revealed that when used in room-temperature applications, PP has excellent and desirable physical, mechanical, and thermal properties. The PP material has some drawbacks as well, including low-temperature standing, brittleness, and poor aging resistance [31, 32].

Oriented PP is a clear, glossy film with high tensile and puncture resistance. It has a moderate permeability to gases and odors and a higher barrier to water vapor, so humidity changes are unlikely to affect it. It stretches, but not as much as polyethylene While the properties of PP and PE are similar, there are some differences. Lower density, a higher softening point, and greater rigidity and hardness are among these characteristics [33]. It is used in applications that are similar to those of LDPE [34]. It is most commonly found in the packaging of biscuits, snacks, and dried foods [35].

Although these are used primarily for food applications, there are numerous reasons for their success and rapidly increasing market share in packaging technology. Yet, the majority disadvantage of this kind of polymers produced is their poor biodegradability. Gradually, they contributed significantly to a major source of waste accumulation after being used, thus getting involved in environmental hazards. Hence, the incompatibilities with those synthetic materials for packing small volumes of packages necessitate the search for another viable option [36].

#### *3.3.2 Health and environmental impacts*

While food packaging is an important part of the food industry and helps to store foods properly, it can also be a source of concern for food safety. When heated, certain packaging materials, such as certain types of plastic, polythenes, and so on, can release toxins, posing a health risk to consumers. A variety of substances are used in food packaging, including dyes for printing interesting and colorful labels and adhesives to keep packaging closed. To protect consumers effectively, the relevant authority certifies each of these food packaging materials independently, subjecting them to stringent testing standards.

Over the last few decades, the food industry is growing exponentially. On the flip side, the impact of industrial development needs to be analyzed. The materials used in food packaging have a negative impact on the environment. The synthetic polymers, including plastics, and their specific use in the food packaging industry posed a burden on annual solid waste generation. In the current scenario, solid waste management is a noteworthy challenge to a human in concern of the environment, and plastic-based polymers waste is a leading one and remains associated with several ecological issues. The more critical increase in packaging material usage and failure of the natural recycling system, along with the high cost of conventional packaging materials, all prompted to look for alternatives [37]. Natural polymers are the first choice for packaging need to explore and utilize on a large scale. They combine the available packaging materials to be associated with minimal damage, and the latest inventions, including, of course, biodegradability.

#### *3.3.3 Natural polymers*

A lot of emphasis is given in recent times to create new, more productive, eco-friendly content and develop packaging material compatible with food

*Fabricating Natural Biocomposites for Food Packaging DOI: http://dx.doi.org/10.5772/intechopen.100907*

products. The use of natural polymers is a key major packaging material for the future. Biopolymers for packaging applications were developed because they were not only biodegradable but also divisible and displayed additional advantageous properties similar to customized applications. They are exceptionally well suited for the use of advanced packaging technologies such as active, intelligent, and modified atmosphere packaging [38]. While the concept of sustainable packaging is also prevailing, recent investigations are, therefore, focused on procuring materials from bioresources, and their utility in the synthesis of natural polymeric choices to taking over and replacing the chemical-based ones. Biopolymers are made from bio-based resources, though the bio-based resource content varies in practice [39]. Among the polymers derived from natural resources, bioplastic is a leading candidate.

#### *3.3.3.1 Bioplastics*

Nowadays, bioplastics, whose building components are originated from renewable raw materials, have become more popular. These products deal with a high proportion of potentials for enhanced natural recycling. Biomass for bioplastics production can be extracted directly from plants or produced by microorganisms in fermentative processes. Some currently produced and applied biopolymers based on renewable resources include Poly Lactic acid, cellulose, and starch, which are biopolymers that are directly obtained from argo-wastes [40]. Being materials produced from agricultural feedstocks, such sustainable concept, enlighten the approach of turning waste into a wealth of resources. However, "bio-based" does not necessarily imply "biodegradable" or "compostable" [41, 42]. Bio-based products contain renewable raw materials that can be replenished through natural processes. Polymers that can be degraded by microorganisms in the environment over time are examples of biodegradable products [43]. Biodegradable plastics include compostable bioplastics. As a matter of fact, while all compostable bioplastics are biodegradable, not all biodegradable bioplastics are compostable.

Although these materials are environmentally friendly and easy to recycle, they have a number of disadvantages. Physical protection and mechanical strength for transportation and storage are the essential requirements for packaging. The main issue with these innovative materials if used alone for packaging purposes, biopolymers, or bioplastics shows some limitations in terms of functionality: their poor water barrier properties, brittleness, high vapor permeability, and low heat resistance [44–46]. Thus, biopolymers are strengthened with fillers to enhance their mechanical properties, barrier properties, and heat outstanding [44, 45]. Additionally, material product compatibility is an important factor to consider before commercial application. Such products in food packaging provide less evidence for the large-scale commercial claim.

#### *3.3.3.1.1 Bioplastic reinforcement*

As mentioned above, bioplastics alone have some limitations, including low water, heat resistance, and brittleness. Interestingly, some research has been done on the reinforcement of bioplastics through chemical and physical cross-linking treatments to enhance the strength of bioplastics. Quite a lot of potential additives can be used as fillers for bioplastics; these additives are in the micro to nano-sized form. Such fillers can boost the mechanical properties, barrier properties, and heat resistance of bioplastic composites compared with those of virgin bioplastics [44]. Although filler reinforcement can greatly improve the bioplastic performance, the environmental and human health safety concerns posed by these materials during their application should not be forgotten [47, 48].
