Turning Fish Waste into Valuable Products
The Circular Economy of Fish Waste
Reading time : 1 minute,
Discovery Chepe Id-482-ECO
Published in
10-11-2024
During fisheries, non-target species with little commercial value are caught: fish caught in excess of the catch quota (they exceed the permitted fishing limit) and damaged fish that
do not merit being kept on board because they do not meet the quality parameters required by the market.
These practices represent a significant underutilization of marine resources, and since the
discards are generally dead organisms or those with great physical damage, when they are returned to the sea
they also cause significant environmental problems, such as alterations in marine food chains.
On the other hand, during the processing of fishery foods a large amount of waste is produced,
which, today, generates serious environmental problems. If, on the contrary, it is desired to take advantage of them,
they will require adequate management, especially because they are very perishable.
Almost 70 million tons of processed fish are produced annually in the world. This
activity generates waste that amounts to 65% of the original product and, to a large extent, could
be transformed into usable by-products.
The use of fish waste such as heads, bones, viscera, gills, dark muscle,
fins and skin is receiving increasing attention, because these can be an important source of
minerals, proteins and fat for use in various products.2
The main efforts have focused
on managing these wastes efficiently, including useful applications with added value.
How Fish Waste is Creating a More Sustainable Future
Fishmeal and Oils
Fishmeal and oils are products obtained from the waste of both fish and species that are usually discarded as a result of fishing.
Fishmeal is a product obtained through a process that eliminates its water and oil content; the latter is an important secondary product, and both are used in the formulation of
balanced feeds for animal nutrition, whether for aquaculture species, birds, ruminants, pigs and
other domestic animals. Fish flours have clear advantages over other flours, such as those of plant and animal origin, due to their higher protein content (65 to 75%), which is higher than that of soybeans (45%, on average) and even higher than flours made from meat and bone (50 to 55%).4, 5
Oils can be extracted from the whole fish, from the skin or from the liver and are rich in polyunsaturated fatty acids, especially DHA (docosahexanoic acid) and omega-3 compounds that have shown different bioactivities of medical interest, such as prevention of arteriosclerosis, reduction of blood pressure and protection against cardiac arrhythmias.
Collagens and Gelatins
The skin, bones, scales, fins and swim bladder of fish are very good sources of collagen and
gelatin, which have important technological and industrial applications. Collagen is a fibrous protein that
constitutes more than 30% of the total organic matter content; it is the main structural protein
found in the skin and bones of animals, which is used in the pharmaceutical industry for
the microencapsulation of vitamins and drugs, the coating of pills and the production of ointments. In
the cosmetics industry, it is used as a treatment for rough skin resulting from the loss of elasticity
due to aging, for strengthening nails and for hair nutrition; in the food industry, it is added as a supplement for the prevention and treatment of osteoarticular problems.5, 6
Gelatin is the product of collagen degradation. Gelatins are considered functional substances and have numerous applications in the food industry. Its technological properties as
clarifiers, emulsion stabilizers and gelling agents are used to produce edible films,
useful for protecting food from water loss and exposure to light and oxygen, making them an ecological alternative to the use of plastic containers. Gelatin can also
be used to microencapsulate components of food interest (colorants, flavorings, antioxidants)
and components with a possible bioactive role (antihypertensives).
Protein Hydrolysates
Protein hydrolysates (HP) consist of breaking down proteins to form peptides (molecules
formed by amino acids) of different sizes. This makes proteins or peptides,
being smaller in size, easily absorbed by the organism that consumes them. The proteins
that can be used to obtain HP are found in the head, muscle and viscera of the
fish. These parts usually become perishable waste that generates an environmental problem, so using the proteins present in fish is attractive since the nutritional value of the proteins is preserved, in addition to obtaining a highly marketable product with added value and functional or biological properties.
HPs have been found useful in the formulation of milk substitutes and dairy products, as a
supplement in the formulation of cereal-based products and dehydrated soups, and have also been
included in the formulation of extruded starch-based products. As food additives, their potential utility as antioxidants has
been demonstrated.
Hydrolysis can be carried out either chemically (using acids) or using enzymes; however, the first treatment affects the nutritional quality of the resulting peptides, and the enzymatic route is the most advantageous, because there is greater control and selectivity in the process; in addition, this treatment does
not require the addition of acids or toxic substances that are harmful to health or the environment, thus generating a product of greater nutritional value.
Methods based on the use of enzymes that hydrolyze peptide bonds called
proteases, proteinases, peptidases or proteolytic enzymes are considered a promising
development in the production of fish protein hydrolysates, because these enzymes do not represent a risk to
health or the environment as is the case with chemical hydrolysis.
New enzymes have been sought that are cheaper than those sold commercially.
Digestive enzymes have been studied due to their excellent hydrolytic capacity.
Digestive Proteases
Proteases (formed by long chains of amino acids) are a group of enzymes capable of breaking
the long chain of molecules that make up proteins, producing shorter fragments called
peptides (molecules formed by amino acids). In order to offer a variety of proteases,
particularly those with unique properties such as their resistance to salinity, organic solvents and
detergents, as well as their wide pH and temperature ranges, new sources of
proteolytic enzymes have been studied, including fish proteases, especially isolated from the viscera of various
species.
These proteases have shown greater catalytic activity (increase in the rate of a chemical
reaction) over a wide range of pH and temperature conditions, at relatively low concentrations. Therefore, studies describing the enzymes isolated from these animals constitute the first step
to evaluate their potential for technological application.
Conclusion
Nowadays, it is possible to use a large amount of waste generated by the fishing industry to obtain
products that are applicable to various technologies focused on the food, pharmaceutical and
textile industries, generating extra income, in addition to reducing the environmental burden and ecological
damage caused. It is important to highlight that in the future it will be necessary to develop new products
and promote collaboration between fishermen, fishing industries and processing industries so that
the use of these wastes continues to be possible.
Source of information: Gissel Daniela Rios Herrera, Jorge Manuel Sandoval Gallardo, Jorge Saul Ramirez Perez, Jesus Aaron Salazar Leyva, Crisantema Hernandez Gonzalez, Angel Valdez Ortiz. (2019).
Waste with benefit: Utilization of fishing waste. Science and Development.
https://www.cyd.conacyt.gob.mx/?p=articulo&id=481
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