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Introduction to Natural Materials for Food Packaging

Manickam Ramesh1, Lakshminarasimhan Rajeshkumar2, Venkateswaran Bhuvaneswari2, and Devarajan Balaji2

1 KIT-Kalaignarkarunanidhi Institute of Technology, Department of Mechanical Engineering, Coimbatore, Tamil Nadu, 641402, India

2 KPR Institute of Engineering and Technology, Department of Mechanical Engineering, Coimbatore, Tamil Nadu, 641407, India

1.1 Introduction

Food packaging material should also maintain the lifetime of the food by dodging adverse conditions such as spoilage microorganisms, mechanical vibration, shocks, gases, moisture, chemical contamination, bad odor, and exposure to oxygen. Fresh and healthy foods are the everlasting demands of the consumers in the global market after the inception of packaged foods [1, 2]. Bio-based polymers have been the first-choice materials for food packaging applications which not only promote sustainable material development but also overcome environmental concerns causing very less ecological threats. To enhance the shelf life of the food material as well as to uphold its quality as it is from the date of manufacture, plastic-based food packaging materials are used [3]. Muizniece-Brasava et al. [4] stated in their study that as per the recent statistics, an 8% annual increase in production of packaging materials from petroleum-based materials has been seen, but on the other hand, only 5% of those materials were potentially recycled. This resulted in almost million ton plastic packaging materials in landfills each year due to accumulation of non-recycled materials, thus affecting the environment which is the current-day problem on planet earth.

One concern about plastic pollution has motivated the growth of degradable, natural, and green product materials [5, 6]. Combining a biodegradable polymer consequent from renewable sources with a natural fiber filler to create a bio-composite represents a self-sustaining as well as a technically feasible alternative to so-called "commodity" plastic products in the food packaging sector. Three critical factors must be considered. To start, we must reduce our reliance on petroleum-based materials while increasing our use of renewable sources to make plastics, thereby reducing the amount of old carbon put into the atmosphere. Second, the use of biopolymers enables the package to be treated similar to an organic biodegradable residue following its use, thereby helping to decrease polymeric trash bound for landfills and incinerators. Eventually, use of natural fabrics as fillers enables the valorization of agricultural residues, thereby reducing the food production cycle's overall impact. Around each other, use of biocomposites composed of biodegradable polymers based on renewable sources and fillers resulting from agricultural fiber garbage as well as other by-products enables more justifiable products by promoting a cradle-to-cradle approach and the life cycle assessment (LCA) [7, 8]. Figure 1.1 shows various materials used in recent days for food packaging.

Figure 1.1 Various food packaging materials.

Source: Sanyang et al. [8]/with permission from Springer Nature.

Green packaging materials made of biodegradable composite are gaining increasing interest in a range of disciplines owing to their distinctive characteristics in comparison to conventional petrochemical-based plastics [9]. Furthermore, they are fully biodegradable and degrade completely including organic material, H2O, and carbon dioxide. These characteristics may enable their use in diverse applications, including smart nano-food wrapping [10-12], biomembranes for water purification, recycling of waste, as well as drug delivery. Thus, the primary function of packaging material is to enhance the quality and safety of food while extending its life span [13]. Due to their ability to prevent the transmission of humidity, oxidant, and flavors among foodstuffs and their surrounding environment, edible films may be a worthwhile alternative to plastics in a variety of applications [14]. As a result, use of edible coatings for preserving the quality of various foods has grown rapidly [15]. Recently, a variety of biodegradable food packaging materials, including sipping beverages, sheets, silverware, overwrap, as well as lamination films, have been manufactured and distributed through grocery stores [16-18].

Owing to its least cost along with easy accessibility for industries, carbohydrate, a normally sustainable energy fructose polymer, is the most frequently utilized fresh material to produce biodegradable plastics [19]. Other studies have been conducted to determine its great potential in aqua-soluble pouches for storing detergents and insecticides, as well as to determine its utility in washable lining, satchels, and other medical equipment. Starch is composed of two molecules: amylose (a sequential chemical compound with very few branch offices) and amylopectin (a branched chain molecule). When starch is processed, the existence of amylose in significant amounts provides strength to the films. Tensile stress in layers is observed to reduce when amylopectin is a predominant component of the starch. Maize or corn flour is the primary source of starch, accounting for approximately 80% of the global market. Rice starches exhibit a range of characteristics depending on the paddy variety [20, 21], resulting in biodegradable films with a range of characteristics. Rice starches are being used in place of synthetic films to generate biologically decomposable films owing to their low cost, abundant availability in nature, and acceptable mechanical characteristics. However, these rice starch films lack adequate barrier properties against nonpolar compounds, restricting their application. This led to development of rice-based starch films with improved characteristics [22, 23].

Among the various widely viable bioplastics, poly(3-hydroxybutyrate) (PHB) is a particularly interesting member of the hydroxyl alkanoates family for packaging applications. PHB is a plastic material that can be transformed industrially using standard polymer transformation equipment. Additionally, it has a good mechanical result in terms of strength and stiffness that is comparable to or greater than that of some commodities (for example, PP), as well as barrier characteristics (comparable to PET). PHB worsens in composting environments and other surroundings such as saltwater [3]. While PHB is an interesting choice for self-sustaining packaging applications, it does have some drawbacks that limit its widespread use in the fresh produce food packaging sector. PHB has a high intrinsic fragility, which upsurges over time as a result of a second crystal growth and physical aging. Additionally, owing to the high crystallinity, PHB has a narrow handling window, which makes it unsuitable for some prevalent food applications, such as blow molding [24, 25].

Edible coatings are very thin films of material (generally or less than 0.3?mm in thickness) which are used to cover food goods to substitute or strengthen the natural layers. They can be devoured as a product or after further expulsion. As a result, the ingredients used in the composition should adhere to applicable food policies and guidelines. Furthermore, the adhesives and films should not have a detrimental effect on the food product's organoleptic properties. Edible packaging may take the form of a surface-level coating on the meals or constant layers among compartments/ingredients of heterogeneous products (for example, grilled cheese, pastry shop fillers, and toppings) [26, 27]. Additionally, the coating can be given to individual pieces of a larger product that are not being independently wrapped for practical reasons, including nuts, kiwis, fruit, veggies, fresh-cut watermelon, and fruits. Edible films as well as layering can be used to counter a variety of barriers associated with food marketing. These features can be specified as restraining the migration of moisture, solute, oil, and gas, enhancing structural stability, retentive volatile flavor compounds, and transporting dietary supplements. Additionally, they enhanced the attractive look by reducing physical damage, trying to conceal scar tissue, and enhancing surface glow. For example, citrus fruits have been encased with hot-melt paraffin wax to retard moisture absorption, eatable connective tissue canisters have been used to offer structural integrity to sausages, and fruits have been encased with sealant to shape the way glow and inhibit actual injury [28, 29].

1.2 Natural Biodegradable Polymers

Biodegradable polymers are considered to be the most likely solution for dodging various environmental hiccups like litter, landfills, and waste pollution which originate due to the use of nonbiodegradable polymers. But owing to the cost of processing and the limited range of selection, the utilization of biodegradable plastics is less than expected in various end applications these days [30]. Hence, it was stated in various researches that blend of one renewable and biodegradable polymer with another during the process of preparation reduces the...