Assessing circular food systems: Fish oil substitute produced from food waste

Imagine that you buy three bags of food at the grocery store and throw away one of them before you get home. Seems crazy right? But the truth is that about one-third of the food produced today is wasted, meaning that a considerable amount of food is produced in vain. Overproduction, cosmetic standards, inefficient logistics and overconsumption are some examples that cause wastage of still edible food along the food supply chain. This waste leads to considerable environmental impact, economic losses and critical social consequences.

Recovering valuable resources and circulating them back to the food supply chain instead of wasting them could lead to important benefits compared to the current system. In fact, using already available resources and reduce waste is considered essential to maintain future food security, enable the transition towards a circular economy and support sustainable development. So, how should we use these resources then? One solution could be to produce a fish oil substitute via microalgae using food waste as feedstock.

Food from waste

Today, aquaculture is one of the fastest growing food-producing sectors globally, and each year we produce about 1-million-ton fish oil rich in the essential fatty acid DHA (found in Omega-3). Since Omega-3 must be obtained through diet, it is often added to food and feed production (often in the form of fish oil) to enhance nutrition levels in dairy, meat and fish consumed by humans. In the beginning, aquaculture was considered a solution to decreased biodiversity and diminished ecosystems, as a result of overfishing. However, the fish oil industry required to support traditional aquaculture is highly dependent on fossil energy and marine raw materials, which leads to depletion of natural resources and ecosystems as the global demand for fish increases. Instead of solving the problem of overfishing, aquaculture has created new ones. At the same time, about 1.3 billion tons of food is wasted globally every year.

In aquatic ecosystems, the essential fatty acid DHA is produced by microalgae and accumulated in fish via the food web. Therefore, one promising solution is to gain DHA directly from microalgae. Research shows that heterotrophic microalgae can be cultivated in bioreactors using volatile fatty acids (VFA) derived from food waste as primary carbon feedstock.

Feeding algae VFA to produce an algae oil rich in DHA could provide multiple benefits in comparison to traditional fish oil, especially since biogas can still be produced alongside. This means that we can produce multiple valuable products from food waste, which would further reduce pressure on natural resources. Producing a fish oil substitute using already available recourses could also support circular food systems and improve global food security. However, assessing and evaluating the environmental implications of new technologies is crucial to ensure that the suggested solutions also support future sustainability.

Environmental impact and loss of biodiversity

This study aimed to evaluate the future potential of DHA produced from algae with a primary carbon feedstock from food waste, by assessing and comparing its environmental impact to that of DHA from Peruvian anchovy oil. The studied systems were modelled as two parallel scenarios to assess large-scale production of DHA: a conceptual Algae scenario and a conventional Fish scenario.

Simplified scenario illustration, created using

A life cycle assessment (LCA) approach was used to obtain a holistic quantification of the impact caused by the Algae scenario and the Fish scenario, from the extraction of raw materials via production to finished product. Using LCA indicators at both midpoint and endpoint along the cause-effect chain can provide a vital dimension of total impact to policymakers, the research community and industry. Moreover, including endpoint impact such as damage to ecosystem quality is especially important in systems dependent on biotic resources, such as fish oil production. By definition, biodiversity refers to the variability among all living organisms and maintaining biodiversity is essential for life on Earth. As natural systems and species are dependent on each other, damaged ecosystem quality or loss of even a small number of species could lead to irreversible consequences. Therefore, the endpoint indicator Ecosystem damage was included in this study as a complement to the midpoint indicators global warming, acidification, eutrophication, and land use.

Algae oil VS Fish oil

The main findings were that DHA produced from the Algae scenario inferred lower impact with respect to global warming, acidification and land use compared to the Fish scenario. Moreover, algae oil also resulted in lower climate impact when compared to rapeseed oil and linseed oil, two common plant-based Omega-3 sources. And even though established LCA methods cannot fully account for the total impact on biodiversity, the result showed that DHA from algae inferred lower Ecosystem damage compared to fish oil even when future energy development, improved efficiency, increased energy demand and impact on biotic resources were simulated.

This study showed that DHA produced by microalgae using VFA from food waste can reduce dependency on marine raw materials while also enabling increased resource efficiency by recovering nutrients in food waste for value addition. By using agricultural and food industry by-products to produce DHA, overfishing could be counteracted which in turn would benefit maintained ecosystem quality. Algae oil holds a promising potential for increased sustainability within aquaculture, provided that continued development and optimization of this emerging technology are enabled through active decision-making and purposeful investments. So, recovering valuable fatty acids from food waste and reusing them to produce a fish oil substitute could indeed be a way to increase circularity and sustainability both within aquaculture and the future food system.

Read more

Want to learn more about this project? Then we invite you to read the full article:

L. Bartek, I. Strid, K. Henryson, S. Junne, S. Rasi, M. Eriksson (2021). Life cycle assessment of fish oil substitute produced by microalgae using food waste. Sustainable Production and Consumption, vol 27, pp 2002-2021. doi:

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