‘Healthy’ fish waste offers cost and sustainability benefits to feed formulators

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

As part of the Intensification of Green Aquaculture in Europe (GAIN) project, Wesley Malcorps, doctoral researcher at Stirling, discovered that a large part of the species commonly farmed (Atlantic salmon, European sea bass, gilthead seabream , common carp and turbot) were regularly wasted in industrial operations and domestic processing.

While the most strategic application requires economic analysis to determine market acceptability, he asserted that fish by-products could be exploited 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 the use in processed foods, such as fish sausages, sauces and cakes.

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

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

“Organs can be used in animal feed, just like skin, because of its high protein content and low ash content. With their high level of valuable omega-3 fatty acids, feeding livestock as a by-product would also contribute to nutrition in 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 waste in known food products have an impact on taste and texture? “It depends on what you consider to be ‘waste'”, Malcorps told FoodNavigator. “The buds are considered waste in Europe, but are used in soups in Asia to add flavor. fish as possible (beyond the fillet) and maintaining food quality, so that most of the by-products can be used for human consumption. Let this. ”

Fish waste “full of goodness”

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

A global scarcity and increase in the value of these nutrients therefore creates incentives to use by-products more efficiently: an estimated one-third of all EPA / DHA from wild and farmed fish in the world is released. .

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 impact. environment of aquaculture.

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

Substituting marine ingredients for plant-based ingredients in aquaculture feed, he explained, risks both compromising the health and welfare of the farm animal and can also affect micro levels. and macro nutrients in the final product consumed. Therefore, it is important to take into account a broader approach to the food system, as unintended consequences of changes in the type of food used can occur throughout the value chain. A reassessment of the potential for increasing the supply of marine ingredients from underused by-products has received much less attention, according to the researcher.

Packaging solutions

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

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

The study was overseen by Professor Dave Little, also from the Institute of Aquaculture, who said: “The use of whole fish is a key part of the sustainable intensification of seafood. There are problems to be solved in terms of technology and infrastructure, which would require capital investments to be solved, but our analysis indicates that the separation of by-products could add nutritional value and efficiency.

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

Reference

“Nutritional characterization of by-products from the transformation of European aquaculture to facilitate their strategic use”

Borders in sustainable food systems

https://doi.org/10.3389/fsufs.2021.720595


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