Keywords

1 Introduction

Biopolymers are chemically derived from a wide array of animal, vegetal and microbial sources. These polymeric biomolecules include lipids, polysaccharides, polynucleotides, and polypeptides, consisting of monomeric units linked by covalent bonds to form larger molecules. The non-toxic biopolymer has been derived from diverse biological sources including plants, bacteria, seafood waste, chicken feathers and other organic matter from the fishing industry [1,2,3,4]. To be animal-specific, the fishing industry is the major contributor to the bio-burden of the aquatic environment, which can be reduced by using fish-derived biopolymer like chitin, chitosan, collagen, glycosaminoglycans, and hyaluronic acids [5]. The circular reinforcement of this fish-derived polymer is an alternative to polyethylene, because it generates low biodegradable waste, similar to plastic in functionality and appearance, and requires less energy consumption to manufacture packaging material. For instance, MarinaTex is a novel, odorless, translucent, and flexible biopolymer with good shelf-life is made from the fish waste, and red algae [6]. Similarly, the seafood waste with crustacean shells is used to prepare recyclable bio-sheets [7].

Fish is considered to be one of the nutritious diets in human food because it is an excellent source of high-quality protein, omega-3-fatty acids, various minerals like phosphorous, magnesium, selenium, iodine etc. [8]. The fish-derived biopolymers are used in the activities of petroleum drilling, deep sea exploration photography, seafood packaging, and other ecological products that can restore the osmotic adaptation in aquatic life and aids in microbial genera to adapt to the harsh environment. The most extensively studied fish-derived biopolymer is chitin and its deacylated derivative chitosan. Chitin is considered the most abundant polysaccharide available in nature. Another biopolymer is collagen, which is extracted from the scales and bones of fishes [9]. It has good tensile strength and majorly applicable in pharmaceutical, biomedical, and food applications. Moreover, when dried solid fish waste is biologically processed with the bacterium, Bacillus subtiltis (KP172548), 1.62 gL−1 PHB (poly 3-hydroxybutyric acid) was produced [10]. Likewise, fermentation experiment of shrimp waste with the bacterium, Salinivibrio sp. M318 yielded 42% (w/w) PHB when fish oil was used as C-source and when the fish matrix was used as N-source, then the yield of PHB is 51.7% (w/w) [11].

1.1 Sources of Fish-Derived Biopolymers

The fish-derived biopolymers exist in several shapes, highly branched with low molecular weight and arranged intrinsically by delicate polysaccharides and proteins as a structural constituent of the skeletal system. Because of their complex polymeric structure bounded by glycosidic linkages, these polymers provide mechanical strength to the tissues and keep them intact [12]. The raw biopolymers belong to plant origin, microbial origin, agricultural wastes, fossil wastes etc. Also, they can be synthesized chemically from the monomer units such as amino acids, fatty acids, lipids, chitin, chitosan, proteins, DNA, RNA etc., that can be scaled readily at low cost, to commercialize processing of the biopolymers [13, 14]. Few of the biopolymers synthesized from microbes include chitosan (polyamides), polylactic acid (PLA), poly 3-hydroxybutyric acid (PHB), polyesters, polyphosphates, hyaluronic acid (HA) connected through linear polysaccharide chains bounded by hydrogen bonds [15]. They provide flexibility, tensile strength, and viscosity to the cells and act as a protective matrix.

The major biopolymer present/produced from fishes and its wastes include collagen (protein-based) such as hyaluronic acid (HA) and glycosaminoglycan (GAG), chitin, and its derivative chitosan (polysaccharide-based), and gelatin s found in various connective tissues of the body like scales, skin, bones, ligaments, tendons and cartilage [16,17,18] (Fig. 1). The collagen is responsible for drug and gene carriers. It is used as burn cover dressings as well in the wound healing process. Many researchers have diverted their studies to the extraction and characterization of collagens obtained from the various fishes like rabbitfish (Chimaera monstruosa), cuckoo ray (Leucoraja naevus), small spotted catshark (Scyliorhinus canicula), Atlantic grenadier (Nezumia aequalis), lantern shark (Etmopterus sp.), Catla, Cirrhinus mrigala. The collagen is extracted from the skin, bones, and fins of fish, which gets denatured at a low temperature (25–30 °C) as compared to mammalian collagen, which has a denaturation temperature difference of 9 °C i.e., (39–40 °C). The skin of the fish usually consists of type I collagen and is around 70% degree of purity depending upon the type of species, found in the various seasons and the fish has a capacity to retain the moisture and exhibits no irritation. Thus, fish collagen is an excellent source and can be used in dermal applications [19].

Fig. 1
figure 1

Different types of Fish-derived biopolymers used in fishing industries

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Chemically, chitin and chitosan are crystalline in nature and insoluble in common solvents, except the acidic solvent. They have strong inter/intra-molecular units of 2-acetamido-2-deoxy-β-D-glucose bounded by β (1–4) linkages. They are non-allergic in nature, therefore, suitable for controlled drug delivery systems, where they can be used as protein-carrier (amino acids) and enzyme-carriers, and various types of packaging material [20].

1.2 Market Potential of Biopolymers in the Circular Economy

The fishing industry mainly depends on plastics for various activities such as fish luring, fishing nets, ropes, baskets, gloves etc. that further adds the cost of transportation from rural to urban areas. To reduce the financial burden, the proficient set-up of bioplastic plants near the fishing zone can lead to the sustainable development of the packaging industry and restore the environment.

The natural biopolymers obtained from marine sources have a minimum impact on food chain due to its high biocompatibility and rapid disintegration. Moreover, the natural biopolymers help in reducing the land and water pollution.

Also, in terms of employment, the biopolymers are advantageous to get profoundly skilled labour, and create ease of license for commercial fishing assignment with a monetary benefit. According to the global market report by Markets and Markets [21] it is estimated that the biopolymer market will grow to US $27.9 billion by 2025 at the CAGR of 21.7%. The global growth highlights the potential of bioplastic in accordance with environmental concerns. This is a great opportunity to minimize dependence on conventional plastic and enhance the production of biopolymer [22]. The fish-derived biopolymer can provide a restorative solution to marine life, and meet daily human needs of toiletries, paper bags, food packaging material, bottles, textiles and many more [23].

The fish-derived biopolymers are used to make compostable barrier coatings, using equal combination of cellulose pulp from plant sources. This type of sustainable coating can be used in multiple packaging of food and feed in daily lives. The fish residue valorization towards zero-waste sustainable industry can replace the global plastic dependence in the future if it is unanimously implemented under the climate action program [24]. The notable leading market players in utilizing fishery waste and manufacturing bioplastic are NatureWorks, Italy; Braskem, Brazil; BASF, Germany; Biome plastic, UK; Toray Industries, Japan; Plantic Technologies, Australia; Tianan Biologic Materials, China and many more [25]. The successful use of biopolymer in everyday life might bring monetary ramifications but from an ecological point of view, it can balance nature degradation [26]. However, there are certain drawbacks of biopolymers that need to be addressed for universal acceptance, such as, low thermal and tensile strength, high moisture-holding capacity, compatibility, slow production process as compared to synthetic counterparts. To alleviate these disadvantages, a blend of polymers is done to increase their applicability at a larger scale and change the design of the biopolymer for its feasibility in biological degradability.

2 Types of Biopolymer in Fishing Industries

The recent advancement in the biodegradable films in the fishing industry based on their mechanical, barrier and antioxidant properties has gained popularity amongst many industralists [27]. The significant attributes of biopolymers are stability, durability, feasibility and resiliency is further improved by incorporating graphene oxide, protein isolates, fatty acids, essential oils, and other cross-linkers. Natural biopolymers like starch, protein, cellulose, chitin, pectin, chitosan, lignin and collagen is obtained from animal and plant kingdom. Carbohydrate-based biopolymers are low toxic, renewable, biodegradable, and stable in nature; hence, frequently used commercially in pharmaceutical industries, cosmetic industries, fishing industries and so forth [22, 28]. The origin, physical appearance and role of biopolymer are listed in Table 1.

Table 1 Sources and applications of significant biopolymers
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2.1 Chitin

Chitin is crystalline in nature; it is a microfibrillar polymer of glucose and extracted from the exoskeleton of insects, invertebrates, some fish cells, and wall of fungi. It is stable in alkaline solution and dissolves in acidic solutions only. A significant natural source of chitin is shrimp and crab, which are abundant in the seafood processing industry. The chitin biopolymer is mainly used in biomedical engineering to prepare biomaterial that can repair and restore damaged tissue. Globally, the annual production rate of chitin from crustaceans and fish scale waste is estimated to be 10 billion tons. In coastal areas, the material form of chitin is a major source of beach pollution which is hard, inelastic and nitrogenous polysaccharides [36].

2.2 Chitosan

Chitosan is differing from chitin only by the acetyl content of the polymer. It is a modified natural biopolymer that is hard, non-toxic and cellulose-like fibre. A significant production material of chitosan is shrimp waste and other sources of chitosan are crustaceans, insects, fungi and some algae. Their excellent properties include biocompatibility, bioactivity, biodegradability, penetrability, anti-microbial activity, chelation, drug carrier for controlled release, film, and absorptive limit. It promotes bone tissue building, fat absorbent action decalcification of dental enamel, healing of ulcers and injuries and osteogenesis. It inhibits bacterial plaque formation [37]. Commercially, chitosan offers a wide range of applications such as in cosmetic preparation, biomedical, paper industry, food industry, textile industry, pharmaceutical, biotechnology, and biochemistry. It is also used to prevent food spoilage from microbe contamination, preparation of biofilms for food packaging, purify the water, and delay blanching of fruit juices [38]. Commercially, chitosan offers a wide range of applications in diverse industries including biomedical, cosmetic, paper, food, textile and biotechnological industry.

2.3 Collagen

Mammalian cells are rich in collagen protein, which is usually synthesized by fibroblast that originates from pluripotential adventitial cells or reticulum. A collagen molecule is a triple helical structure with a length of 300 nm and a width of 1.5 nm, respectively. The molecular weight of collagen, based on amino acid sequence is 300000 Daltons [39]. Collagen is rod-shaped molecule and accounting for about 20–30% of total body proteins and primary structural materials [40]. The collagen matrix is used in the treatment of severe burns and collagen sponges used in dressing for acute injuries, nucleic acid and protein transporters to assist bone repairs. In addition, collagen hydrogel is used as genetic material delivery carriers in biomedical applications. For example, thermostable collagen nanoparticles utilized as an anti-cancerous agent such as camptothecin and hydrocortisone bearer for parenteral administration and other therapeutic compounds [27]. Collagen has wide range of applications because of their diverse physicochemical properties such as high biocompatibility, low anti-genecity, non-toxicity and high biodegradability [41].

2.4 Gelatin

Gelatin is water-soluble, a sterile biopolymer that does not contains preservative and have a three-year expiration date at room temperature. Structurally, it is a heterogeneous polypeptide, forming a complex mixture of α-chains, β-chains and γ-chains. Gelatin is synthetic colloids produced from the degradation of bovine collagen by incomplete hydrolysis of collagen removed from fish, pig skin and cow bones so forth. It is an important biopolymer that is colourless, translucent, flavourless food ingredients. It is extensively used in preservation of meat and fish-based products due to its good foaming, emulsifying and wetting properties [42]. Therefore, gelatin is widely used in food packaging industries owing to its exclusive functional and technical characteristics.

2.5 Hyaluronic Acid (HA)

HA is a water-soluble, translucent, high molecular weight biopolymer, which is only present in the eyeball and cartilage intracellular matrix of fishes. It is the only glycosaminoglycan member that is non-sulphated by alternating disaccharide units of N-acetyl-D-glucosamine and D-glucuronic linked by β-(1 → 3) and β-(1 → 4) glycosidic bonds [43, 44]. HA is highly used in the biomedical field due to its high biocompatibility in visco-surgery, controlled tissue permeation and hydration in arthritis treatment, and macromolecular carrier in cancer therapy, plastic surgeries and targeted drug-deliveries of intra-ocular surgeries. It has characteristic inflammation property that allows it to hold water molecules in limited space and provides lubricity to the tissues. Therefore, Hyaluronic acid have tremendous potential in regenerative medicine and cosmetology [45].

3 Commercial Applications in Fisheries

The fish gear should be reused for the sustainable use of biopolymers in the fishery industry (Fig. 2). The alternative approach to design fish binders, gill nets, fishing lines, traps etc. which should be transparent, flexible, dissolve in water after few days and possess superior permeability to prevent ghost fishing. The biopolymer fishing gears can halt the vicious circle of death of fishes and other aquatic animals by derelict nets, and boost ecological restoration of waterbodies and aquatic life [46].

Fig. 2
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Applications of fish-derived biopolymers in fisheries

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3.1 Fishing Lines

Most of the fishing lines or ropes are made from synthetic polymers as they are single-stranded, strong, thin, and available in different colors to distinguish from other fishing lines. The synthetic polymer causes more harm to the fishes as they do not degrade and form a lump of fine network at the fishing place, further entangling and injuring the fishes and rest aquatic life. To overcome this situation, the biodegradable fishing lines were designed with natural materials such as polyglycolic acid resin (PGA) filament with high tensile and knot strength. These PGA filaments when mixed with PLA, p-dioxanone, and ε-caprolactone make it more heat resistant and firm. The monofilament of PGA also gave good results with blends of polybutylene succinate (PBS) and polybutylene adipate-co-terephthalate (PES) to yield optimal strength under seawater [47]. These fishing lines if left in the water bodies for more than a fortnight, they will maintain 25% of the original tenacity [48]. The successful brands of eco-friendly fishing lines, in the form of filament, fluorocarbon and braid (hybrid) are Toray, Eagle claw, Fieldmate showed a remarkable four-month biodegradation time.

3.2 Fishing Nets

Globally, the nylon nets are widely used as a fish gear. Despite its wide use, it is abandoned in the sea for a longer duration as it needs physical labor. According to the technical report available online, on average 13,941 gillnets are lost each year. Because of this, there are a negative effect on the benthic environment, navigational problems, marine litter, and plastic pollution.

To reduce this problem, the Norwegian Directorate of Fisheries has initiated a gear disposal and recycling program named Abandoned, Lost or Discarded Fishing Gears (ALDFG) and retrieved 20,450 lost gillnets and other fish gears [49]. Traditionally, the biodegradable fish nets were designed using a blend of 82% polybutylene succinate (PBS) and 18% polybutylene adipate-co-terephthalate (PBAT), which were tested for their catching efficiency for a longer time duration of 6–42 months [46]. As compared to conventional gear made of Nylon polyamide, polyester, polyethylene, and polypropylene; the biodegradable fishing nets started biodegradation into natural materials by the action of microorganisms and lose their ghost fishing capacity after few months of underwater exposure. However, the fishing performance and stiffness of biodegradable nets is lower with respect to nylon nets. Therefore, projects like Innovative Fishing Gear for Oceans (INDIGO), funded by the European Union is undergoing to design 100% biodegradable fishing net with a controlled lifespan [50].

3.3 Fishing Gear and Traps

As per the FAO [51] technical report, it is estimated to discard approximately 6.40,000 tonnes of all fishing gear in the oceans annually in bad weather conditions. The fishing traps are made to catch fish during low tides. It is usually made of steel boundary vessels, with sufficient enclosed space to house targeted fishes for their smooth entry and barricaded exit. Polyhydroxyalkanoate (PHA) is also used as trap apparatus and degrades naturally if continuously submerged for many months [52]. Currently, the biodegradable fishing trap derived from cellulosic derivatives such as polysaccharides, chitin or chitosan are widely used in fishing industry as it readily dissolves in the water in few days and prevent unwanted fish mortality [52].

3.4 Fishing Lure

The artificial fishing lures are well fabricated by fine plastics of PVC or silicone rubber. Such lures do not get digested in the fish body and thus become aquatic pollutants. They also affect the growth and development of fish by hindering its gastrointestinal tract and can eventually led to the death of the fish. The biodegradable, semitransparent, and the soft lure is made by molding like worms using jelly chitosan, water-soluble gum, cereals starch, soy protein, etc. Further, the addition of marine fats and oils, to the bait attracts the fish and makes the process less time-consuming. The PVOH polymers as hydrogel matrix of soluble capsules, which are prepared by mixing carrageenan and gum, is biodegradable, transparent, and used mostly in recreational fishing activities [53]. The biological lures can control the bait release in an effective way, as an aquatic feed in farmed fisheries.

4 Industrial Applications of Biopolymers

The fish-derived biopolymers can be valorised to produce various useful materials.

4.1 Functional Foods

Several edible marine invertebrates, including cuttlefish and sea cucumber, are promising potential ingredients as functional foods [54]. Many researchers have reported that chitin and chitosan (biopolymer) derived from these edible marine invertebrates exert a broad spectrum of bioactivities, namely antioxidant, antimicrobial, anticoagulatory, anticancer, hypocholesterolemic and wound healing properties [55, 56]. These bioactivities of chitin and its derivative have been mainly attributed to its physical and chemical properties, including molecular weight, functional groups and deacetylation degree [57].

Chitin is used as a health supplement in the form of capsules due to its exceptional lipid metabolism capacity [58]. Kuprina et al. [59] have developed a functional food from a mixture of pollock and salmon belly minced fish meat with the biologically active chitin mineral food supplement “Hizitel”. Azuma and Ifuku [60] suggested that chitin nanofibers (CNFs) and surface-deacetylated chitin nanofibers (SDACNFs) are promising functional food for patients with inflammatory bowel disease or obesity. The authors observed that CNFs substantially ameliorate the clinical symptoms of IBD. SDACNFs reduced the levels of leptin in serum and repressed the rise in body weight.

Chitosan increases the nutritional benefits of the food products, including boosting immune response and glucose-lowering effect while maintaining the organoleptic properties of the product [61,62,63]. Chitosan is a promising source of dietary fibre in organisms that lacks a specific chitinase enzyme in their gastrointestinal tract [64]. Lie et al. [65] reported that the feed supplementation with high molecular weight chitosan decreased fatty deposit in liver, spleen, and muscle of broiler chickens. Qinna et al. [66] suggested a new functional food containing chitosan (1%) and pectin (5%) as an alternative to meat. Anandan et al. [67] found that dietary supplementation with chitosan had a protective effect on lipid oxidation in induced myocardial infarction in rats.

Microcrystalline cellulose (MCC) biopolymer is broadly considered as a functional ingredient in several food products, including dairy, bakery, and confectionary [68]. The colloidal MCC contains 98 g/100 g of insoluble dietary fibre [69]. The experimental animals fed with MCC fortified diet showed a reduced level of cholesterol [70]. MCC fortified food also plays a substantial role in the management of obesity and diabetes mellitus via hypolipidemic and hypoglycemic effect, respectively [71]. Cellulosic nanomaterials (CNMs) biopolymer is extensively utilized in nutraceutical and food industry because to its exceptional physico-chemical properties, namely high mechanical strength, lightweight, and biocompatibility [72]. Bacterial cellulose (BC) biopolymer is widely used as a resource of dietary fibre, and it is approved as a “generally recognized as safe” food by the U.S.FDA [73].

4.2 Biodegradable Preservative and Packaging

Seafood is a rich source of functional health-promoting compounds, including vitamins (vitamins D, B and A) and polyunsaturated fatty acid [74]. However, seafood products are highly perishable, and it is most prone to degradation by microbiological, enzymatic, and chemical reactions. Currently, chitin and chitosan biopolymer are used as an alternate biodegradable natural preservative for retaining seafood quality and increasing the shelf-life of seafood-based products [74]. Generally, chitin and chitosan increase the shelf life of marine-based products by improving oxidative stability, reducing lipid oxidation, and inhibiting the growth of microorganisms.

Chitin biopolymer is used as an edible coating in food safety as it principally maintains the sensory characteristics of food material. Moreover, chitin is also used as a support matrix for enzyme immobilization that imparts remarkable operational stability in the food processing industry [74]. Morganti [75] has developed chitin-based biodegradable food packaging material by using chitin nanofibrils. The combination of polylactic acid and nanocellulose biopolymer is also used as a novel promising sustainable eco-friendly food packaging material [76].

Chitosan is widely used as a packaging material component, additive and coating agent for seafood-based products because of its distinctive functional and physicochemical properties [77, 78]. Several researchers have demonstrated that chitosan-based coatings help in maintaining the physico-chemical properties of fish and other seafood-based products[78]. Sathivel et al. [79] documented that an edible coating of 1 or 2% chitosan biopolymer suspended the degree of lipid oxidation in Oncorhynchus gorbuscha during frozen storage. Kumar et al. [80] demonstrated that the chitosan can be used as an encapsulation biomaterial for several sensitive products, including fish oil due to its noticeable emulsification capacity. Benjakul et al. [81] concluded that chitosan can enhance the gelling properties of marine-based products, including fish surmini products. Kok et al. [82] observed that chitosan (1%) constrained the growth of microorganisms in fish ball throughout 21 days of storage. Ye et al. [83] showed that chitosan-coated plastic films inhibited the growth of Listeria monocytogenes on salmon for at least 6 weeks. Mohan et al. [84] revealed that the edible chitosan coating (1 and 2%) improved the textural properties, water holding capacity, drip loss, and inhibited the bacterial growth in Sardinella logiceps during cold storage conditions.

Numerous researchers have repeated that chitosan-based coatings could impede the production of trimethylamine—nitrogen in marine food by inhibiting the growth of microorganisms [85, 86]. Chitosan has been used as an edible coating or film in marine-based products owing to its tremendous film-forming ability. Moreover, it is used as an antimicrobial and antioxidant agent in seafood-based products [87]. Chitosan-based coating is used as a preservative in seafood products due to its remarkable ability to reduce the increase in pH value [88]. Several studies have reported that chitosan-based coatings can increase the quality, sensory attributes (taste, odour, colour, appearance, texture, flavour and elasticity) and shelf life of seafood products [88]. Therefore, chitosan-based biopolymer possesses promising prospects in food preservatives and food packaging industries.

4.3 Wastewater Treatment

Wastewater contains heavy metals, dissolved and particulate matter, solids, micropollutants, nutrients, and microorganisms in a complex matrix [89]. The water is generally contaminated through various industrial processes, agricultural and domestic activities (swimming, boating, and fishing etc.) [90,91,92]. The contaminated wastewater is highly toxic and can adversely affect the organisms [93,94,95]. Therefore, it is of paramount importance to develop effective strategies for treating wastewater [96,97,98]. Additionally, in the current scenario, wastewater treatment is highly critical due to dwindling water supplies, tougher discharge regulations, and rising wastewater disposal costs [99]. The primary aim of wastewater treatment is to remove as many dissolved solids as possible before discharging the residual water (effluent) into the environment. Conventional wastewater treatment encompasses pre-, primary-, and secondary-treatment [100]. However, the conventional methods lack accuracy, cost-effective discharge standards and desired level of purification [101]. Over the last few decades, natural biopolymers including chitosan, chitin and cellulose have garnered tremendous interest in wastewater treatments due to their high efficiency, low-cost, high mechanical stability, abundance, renewability, biodegradability, and high porosity [102, 103]. The different biopolymers used for wastewater treatment are summarized in Table 2.

Table 2 List of different biopolymers used for the treatment of wastewater
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Chitosan biopolymer has widely used an adsorbent for removing several pollutants from wastewater, including heavy metals and dyes, because of its high degree of deacetylation that promotes higher interaction of free amine groups with the pollutants. It is also considered to be an efficient bio-sorbent towards several other contaminants because of its hydroxyl group enriched structure [104]. Chitosan is also an ideal alternative substitute to conventional synthetic materials for the treatment of effluents in agricultural wastewater, such as residual pesticides, herbicides, and fertilizers. Pambi and Musonge [105] suggested that chitosan is a suitable low-cost biodegradable material for treating wastewater from sugar industry by performing a dual role of coagulant and flocculant through its relatively high molecular weight and charge density. Crini et al. [106] reported a novel direct bioflocculation method for treating wastewater from paper and pulp industry by using low-cost chitosan. Ahmad et al. [107] effectively remove the solids from palm oil effluent using flake and powdered chitosan. Altaher [108] successfully remove the turbidity from seawater by dissolving chitosan in hydrochloric acid. Dima et al. [109] reported that reticulate chitosan micro/nanoparticles can efficiently remove the toxic Cr (VI) from seafood processing waste.

Gopi et al. [110] have successfully developed cellulose nanofibers (CNFs) basedbio-aerogels for specificadsorption of methylene blue and rhodamine 6G from wastewater. Albukhari et al. [111] purified nitrophenol and dye-contaminated water using silver nanoparticles@cellulose acetate paper prepared by impregnation method. Zhou et al. [112] used magnetic cellulose powder for purifying dye-polluted water–ethanol combination. Garcia et al. [113] immobilized laccase on chitosan and alginate-based matrix for effective removal of 17α-ethinylestradiol from water. Chitosan-silica nanoparticles have been successfully developed for catalytic degradation of 1,1-dimethylhydrazine from wastewater [114]. Overall, natural biopolymers have demonstrated prodigious potential in wastewater treatment.

5 Conclusion and Future Perspective

The multiple applications of fish-derived biopolymers have widened the scope of the circular economy of the fishing industry. Over the last few years, the nanotechnological advancement of biopolymers has been exploited to purify wastewaters. This treatment is environment friendly as it avoids chemical substances, thus safe for flora and fauna of the aquatic system. The treated wastewater is free from toxic micropollutants, dyes and pesticides and reusable for seafood processing. More specifically, seafood is highly perishable, and the biofilm packaging enhance the shelf-life of the food product without compromising the organoleptic characteristics. The edible coating is thermostable, pH stable, resistant to bacterial growth and a good emulsifier to be considered for food processing and packaging material.

Another promising industrial application is to prepare functional foods by blending fish waste with biopolymers. This can be used as a dietary supplement as it is rich in protein, omega-3-fatty acids, dietary fibres and minerals and GRAS in bakery, confectionary, and nutraceuticals. Because of the biocompatibility, elasticity, translucent and odourless characteristics of chitin, chitosan, collagen, gelatin, and hyaluronic acid are potential candidates for biomaterial. This soluble biopolymer is suitable for fishing gears as it will reduce ghost fishing incidents and reduce the physical activity of collecting submerged fishing nets/lines. The latest technologies involve hybrid polymers that need less time and energy to produce with superior flexibility and strength to lessen the dependence on plastics. As mostly fishing gears and plastic-based and many companies are working together on more sustainable ways to produce completely biodegradable products. However, many challenges like increasing the catching capacity of fishes, using biopolymeric fishing nets; low tensile strength of fishing lines; high water holding capacity of fishing lures which leads to microbial degradation etc. are needed to be addressed.

Therefore, the future study needs in-depth analysis on the structural and functional aspects of biopolymer to be reinforced in the fishing industry as an alternative to polyethylene. Despite all the challenges, the biopolymer prototypes need to be exclusively developed for efficient drug-delivery systems in medical and pharmacological products. In addition, the promotion of biopolymers in the fishing industry community will further reduce the global bioburden.