Fisheries: A Rapidly Growing Sector in India
The Fisheries Sector has received recognition as a ‘Sunrise Sector’ in India. This sector assumes huge significance today, as sea food is a powerful source of nutritional food that can ensure food security to a significant segment of population in the country, in addition to encouraging the socio-economic development of the vulnerable communities. India has continued to maintain its position as the second-largest fish producer in the world. In 2019-20, fish production in India was 14.16 million metric tonnes, accounting for 7.56% of the total worldwide production, (FAO, 2022). As per a recent estimate made by National Fisheries Development Board, Fisheries contribute about 1.07% of the total GDP of India.
Being a cheaper and abundant source of animal protein, consumption of fish has proved to be a better option to reduce hunger and nutritional deficiencies. Schemes such as Pradhan Mantri Matsya Sampada Yojana (PMMSY) have been implemented to provide technical and financial support to the fishing community in a sustainable and responsible manner, with a vision to boost fish production in the country.
Fish Waste Generation
With the incredible rise of fish production in the country in the past decade, more opportunities have arisen for dealing with the generation of fish processing waste. Not all the fish produced from water bodies are being utilized to its full potential. Three distinct categories of waste arise from fish production and they are classified as wastes on board, discards and by-products.
According to MPEDA’s latest Report in 2020, there are about 613 Fish Processing Industries in India, with a total daily production capacity of 33,653 MT and around 50-70% of these are being dumped as wastes and they contain skin, head, viscera, bones, scales, etc. that are considered as a wealthy source of valuable ingredients like protein, bioactive peptides, lipid, pigments, enzymes, vitamins, flavours and minerals. In addition to that, due to the lack of adequate disposal facilities, seafood from retail markets near fishing harbours is sometimes dumped nearby the harbour itself. The improper disposal of this proteinaceous organic matter causes a serious environmental threat, as it produces unpleasant odour around the sea-shore, apart from the release of noxious gases such as hydrogen sulphide which can favour the growth of disease-causing vectors and infectious microbial pathogens and have the potential to cause a great economic burden.
In general, these protein rich by-products are converted into low value products, such as fish meal or fertilizers and fish oil or as a raw material for direct feeding in aquaculture and in part it is discarded. With an aim of shifting to a circular bioeconomy, the underutilized marine biomaterial could be exploited as a building block of high value products like gelatin, a potent material in the Food Industry. Thus, it serves as a sustainable strategy to valourize marine resources for better waste management and reducing the pollution concerns to the environment. Indeed, it provides an effective way to overcome problems, such as disease outbreak and religious issues that might arise from the consumption of gelatin obtained from the mammalian sources such as bovine, cattle, pig, etc.
Fish Gelatin: A Waste to Wealth Approach
Fish Gelatin, a versatile biopolymer is widely exploited by the Food Industry for its use in many applications, owing to its desirable functional properties. It is a colourless and tasteless multifunctional hydrocolloid mainly procured from the hydrolysis of collagen, a major protein present in the connective tissues of animals. The proteinaceous nature of gelatin and its ability to enhance the texture, viscosity and stability of liquid and semi-solid systems makes it an ideal food ingredient for use in a diverse set of products that include ice creams, desserts, jellies, low fat spreads, confectioneries, (primarily for providing texture, chewiness and foam stabilization) dairy products (to provide texturization and creaminess) and baked goods (to provide emulsification, gelling and stabilization).
The fish gelatin (g/100 g) possesses a chemical composition of moisture, protein (85-92%), ash and carbohydrates with an extraction yield of 6-19% on dry weight basis. Its structure primarily consists of repeated sequences of Glycine-proline-hydroxyproline. The extraction of gelatin can be achieved by the partial collagen hydrolysis under certain conditions, such as alkali, acid, enzyme and high temperature, which involves three major steps: (i) pre-treatment of raw material (ii) gelatin extraction (iii) purification and drying. It shows a wide variation in amino acid profiling, illustrating that the origin and type of collagen will affect its characteristics.
As compared to the mammalian gelatin, the higher concentration of serine and threonine compensates for the lower content of imino acids, being proline and hydroxyproline present in fish gelatin. These are present more in warm water fish than the cold-water fish. Despite the absence of the necessary amino acid, tyrosine as well as the non-essential amino acids tryptophan and cysteine, fish gelatin still contains a variety of amino acids that can be completely utilized by nutritional supplementation. Thus, by incorporating the lacking essential amino acid into the fish gelatin either directly or indirectly, it can be transformed into an ideal food ingredient to accomplish the goal of enhancing nutritional value. (Lv et al.2019)
Food Applications
Fish gelatin can be served as an effective protein supplement even though it lacks the amino acid tryptophan. It is also considered to be a dietary component that is easily digestible, which can be included in several dietary supplements such as protein drinks, nutritional snacks and nutritional formulae. Furthermore, owing to the low-calorie value of gelatin, it is widely employed to increase the protein content and lower the amount of carbohydrate in a variety of food products, particularly in the case of those products that are consumed for body building and in diets designed for diabetic patients.
Gelling ability is a key attribute of gelatin which influences its capacity to form a thermo reversible gel, with a melting point that is quite near to body temperature making it a special kind of protein. Owing to the gelation and melt in mouth texture, gelatin is widely employed for the formulation of water-gel desserts, gellies and gummies. The gel strength or bloom value is an important factor that determines the gelling power and the firmness or strength of the resulting gel. This is measured in grams and is required to push a 12.5 mm-diameter plunger to a depth of 4 mm into a gel surface of 6.67% (w/w) concentration matured at 10OC for 16-18 hours. The skin derived from warm water fish such as tilapia, tuna, cephalopods, etc. can be used for the production of gelatin with very good strength, while cold-water fish such as cod and Alaska pollock have very low melting and gelling points. (Alfaro et al. 2014)
Owing to its remarkable surface-active properties, fish gelatin is extensively utilized as an emulsifying and foaming agent by the Food Industry. The presence of hydrophobic zones on its peptide chain and its atmospheric nature makes gelatin a vital emulsifying agent in the manufacture of candies and water in oil emulsion, such as low-fat margarine, salad dressings and whipped creams. A low-fat spread has been prepared using fish gelatin and pectin. The foam formation ability of gelatin indicates the degree of protein – protein interaction in the matrix, which highlights its application in the production of marshmallow like products.
One of the advanced applications of fish gelatin is its usage as an ingredient in the production of surimi. Surimi is cleaned, minced fish meat that is used as a base for products that resemble sea food, like imitation crab. The gelling and whiteness of surimi are some of its most significant qualities. Fish gelatin has been investigated and identified for its use as an additive in surimi to enhance the functional and mechanical characteristics of gels.
Fish gelatin is marked by its film forming ability, which could be used in the packaging and preservation of food products. It possesses excellent carbon dioxide and oxygen barrier properties, yielding translucent and highly extensible films. However, the weak mechanical properties of fish gelatin based biocomposite film remains a hindrance to its application, which can be overcome by the employment of other biopolymers or plasticizer in the film matrix. In order to broaden its usability as an anti-bacterial film from fish gelatin, several antimicrobial agents can be included.
Pharmaceutical Applications
In the pharmaceutical industry, the film forming ability of fish gelatin (hard or soft) makes it a possible application in the manufacture of capsules, which are extensively used orally, owing to its capability to bind the hostile odours and taste of drugs. Even though it possesses a softening feature to seal quickly, the low gelling temperature impart a limitation for the application of fish gelatin, which can be overcome by the employment of crosslinking agents, such as K-carrageenan, sodium alginate, chitosan, pectin, etc. Several researchers have investigated and identified the preference of fish gelatin capsules for filling marine supplements and for the delivery of magnesium peptides and algal extract.
With regard to the coating application of fish gelatin, it is widely applied to encapsulate oil droplets of food grade or vitamins like fish oil, which contain omega-3 and lipophilic drugs, sunflower oil along with Arabic gum. Indeed, tablet coatings were formulated with ingredients such as fish gelatin, (5–25 w/w %) sodium stearoyl lactylate, sodium sulfate, propylene glycol monostearate in water, sodium acetate.
Owing to its excellent biocompatibility as compared to synthetic polymers, fish gelatin is preferred for drug delivery via various channels. Modification using crosslinking agents can further improve its stability and extend its In vivo circulation period. The non-gelling, non-hydrolyzed form of fish gelatin, especially those that are derived from cold-water fish sources was used as a carrier in a pharmaceutical formulation, designed to release the active component quickly. Fish gelatin was additionally used in oral administration to release the active ingredient in the oral cavity following contact with saliva.
Biomedical Applications
The hydrolyzed fish gelatin i.e., protein peptides had the ability to scavenge free radicals, prevent lipid peroxidation, shield DNA from hydroxyl radical damage and function as chelating agents. The occurrence of hydrophobic amino acid at the carboxyl and amino terminals, degree of hydroxylation, presence of free amino acid and dipeptide sequences, etc. were recognized as the factors affecting the exact mechanism of the antioxidant properties. In addition, antimicrobial peptides obtained from the enzymatic hydrolysis of fish gelatin contain positively charged Lys, Arg and His residues, which interact with the negatively charged membrane of bacteria resulting in the destruction of target pathogenic organisms.
Challenges and Future Outlook
The rise in demand for gelatin in the global markets may lead to creation of further interest in the use of fish gelatin rather than mammalian gelatin, the reason for the same being that it has the capability to satisfy consumer needs. On the one hand, the usage of fishery discards in gelatin production could provide an opportunity for exploitation of the available water resources in a sustainable manner that can further help in reducing environmental concerns, while also helping generate an additional source of revenue for the processing industries.
Although, there are significant advances in the derivation of gelatin from various fish body parts, scaling up of the extraction process still poses a problem in the current scenario. Some of the reasons for such problems to persist even today are due to constraints faced by the Fish Gelatin Industry, such as poorer rheological properties, insufficient availability of a particular fish type favoured by the manufacturer, certification issues, variation in gelatin quality and other intrinsic factors like fishy odour and lower yield.
In order to overcome these challenges, it is necessary to make further progress in the technological aspects for increasing the production volume of fish gelatin. The incorporation of different agents like solutes, bonding agents, crosslinking adhesion promoters and hydrocolloid mixtures have proved to be a viable way to enhance the functional properties of fish gelatin. Thus, the current article successfully seeks to establish the fact that fish gelatin could be a supremely viable product, especially with its magnificent properties that could find its use in several applications and also open up new business prospects for the gelatin manufacturers.
References:
1. Alfaro, Alexandre & Balbinot, Evellin & Weber, Cleusa & Tonial, Ivane & Machado, Alessandra. (2014). Fish Gelatin: Characteristics, Functional Properties, Applications and Future Potentials. Food Engineering Reviews. 7. 33-44. 10.1007/s12393-014-9096-5.
2. Al-Nimry S, Dayah AA, Hasan I, Daghmash R. Cosmetic, Biomedical and Pharmaceutical Applications of Fish Gelatin/Hydrolysates. Mar Drugs. 2021 Mar 8;19(3):145. doi: 10.3390/md19030145. PMID: 33800149; PMCID: PMC8000627.
3. FAO. 2022. The state of world fisheries and aquaculture2018. Meeting the sustainable development goals. Rome.
4. Lv, Lin-Chen & Huang, Qing-Yun & Ding, Wen & Xiao, Xing-Hua & Zhang, Hong-Yan & Xiong, Lixia. (2019). Fish gelatin: The novel potential applications. Journal of Functional Foods. 63. 103581. 10.1016/j.jff.2019.103581.
5. Usman, Muhammad & Sahar, Amna & Inam-ur-Raheem, Muhammad & Rahman, Ubaid & Sameen, Aysha. (2021). Gelatin Extraction from Fish Waste and Potential Applications in Food Sector. International Journal of Food Science & Technology. 57. 10.1111/ijfs.15286.
About the Authors:
1. Fathima Asharaf
Fish By-products Lab,
Department of Fish Processing Technology,
Kerala University of Fisheries and Ocean Studies (KUFOS)
Kochi, Kerala, India.
2. Radhika Rajasree S.R.
Fish By-products Lab,
Department of Fish Processing Technology,
Kerala University of Fisheries and Ocean Studies (KUFOS)
Kochi, Kerala, India.
Email ID: radhikarajasree@kufos.ac.in
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