“Healthy” Fish Waste Offers Food Formulators Cost and Sustainability Benefits

Researchers from the University of Stirling’s Institute of Aquaculture have found that by-products – such as heads, frames, trimmings, skin and organs – are an underutilized resource that could support the sustainable growth of the European aquaculture sector and increase the food supply.

As part of the GAIN (Green Aquaculture Intensification in Europe) project, Stirling PhD researcher Wesley Malcorps found that many of the commonly farmed species – Atlantic salmon, European seabass, gilthead seabream, common carp and turbot – were regularly wasted in household transformations.

While the most strategic application requires economic analysis to determine market acceptability, he asserted that fish by-products could be capitalized by food manufacturers.

For example, 10% of Norwegian salmon by-products (heads and frames) are considered a high-value export product to Asian countries where they are used in soups. Another route could be use in processed foods, such as fish sausages, sauces and cakes.

“Although fish by-products may not look appetizing, they are full of goodness and can be used for many purposes, including food supply and dietary supplements. Our results show that a significantly higher total meat yield (64-77%) can be achieved if the fish is fully processed, compared to fillet only (30-56%), as is often the case,”revealed Malcorps.

“Heads, frames and trimmings of all species show potential to increase the food supply, in soups or processed foods, such as fish sticks, sauces and fish cakes. They could also be made into food extracts and nutraceuticals – such as protein powders, fish oil and collagen supplements – potentially yielding higher economic value.

“The organs can be used in animal feed, as can the skin, due to its high protein content and low ash content. With their high level of valuable omega-3 fatty acids, feeding livestock by-products would also contribute to the nutrition of the human food chain, and the by-products can also be used in pet food.

Consequences on taste and texture?

Does the use of food scraps in known food products impact taste and texture? “It depends on what you consider ‘waste'”, ​Malcorps told FoodNavigator. “As the heads are considered waste in Europe, they are used in soups in Asia to add flavor. This is about extracting as much flesh as possible from as much of the fish as possible (beyond just filleting) and maintaining food quality, so that most of the by-products can be used for consumption human. allow this.”

Fish waste “full of goodness”

Fish byproducts contain omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), according to research. They are essential micronutrients for human and animal health. Additionally, seafood consumption can improve the intake of other key micronutrients such as vitamins D and B12, iodine, selenium and other minerals, as well as being a good source of bioavailable protein.

A global shortage and increased value of these nutrients therefore creates incentives to use the by-products more efficiently: an estimated one-third of all EPA/DHA from wild and farmed fish worldwide is rejected.

Malcorps claimed that the current 33% of by-products used in fish feed – such as fishmeal, fish oil and protein hydrolyzate – could be increased, which could significantly reduce the environmental impact of aquaculture.

“European aquaculture depends on imported feed from marine and terrestrial systems, such as fishmeal, oil and soy, especially for carnivorous species such as salmon”,he explained. “Replacing plants with marine ingredients only shifts the impact from the sea to the land, and also risks compromising the health and welfare of the farmed animal.

Substituting marine ingredients with plant ingredients in aquaculture feeds, he explained, risks both compromising the health and welfare of the farmed animal and can also affect micro levels. and macro nutrients in the final consumed product. Therefore, it is important to consider a broader food system approach, as unintended consequences of changes in the type of foods used can occur throughout the value chain. According to the researcher, a reassessment of the potential to increase the supply of marine ingredients from underutilized by-product resources has received much less attention.

Packaging Solutions

Finally, the study showed the potential industrial uses of by-products in food packaging. Examples include the manufacture of films and coatings based on fish gelatin and chitosan (a sugar obtained from the hard outer skeleton of shellfish.

“Fish skin offers potential for collagen and gelatin extraction, as an alternative source to cattle or pigs,”Added Malcorps.

The study was overseen by Professor Dave Little, also from the Institute of Aquaculture, who said: “Using whole fish is a key part of sustainable seafood intensification. analysis indicates that the separation of by-products could add value and nutritional efficiency.

“It could increase aquaculture production without using more resources.”


“Nutritional characterization of European aquaculture processing by-products to facilitate strategic use”

Frontiers of sustainable food systems


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