The team writes in the Journal of Applied Phycology that the microalgae are a sustainable and valuable source of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) as well as high quality proteins.
“Growing microalgae biomass, which includes exposure to CO2 production, still has similar or less environmental impacts than aquaculture fish,” says the team.
“The cultivation of microalgae is sustainable in a“ colder ”temperate climate like in Germany, and microalgae can definitely compete with fish as an alternative source of nutrients. .
“With regard to the recommended daily intake of EPA and DHA, microalgae represent a recommended source of nutrients from an ecological point of view.”
Susann Schade, one of the team members of the Institute for Agricultural and Nutritional Sciences at the Martin Luther University Halle-Wittenberg (MLU), adds that so far photobioreactors have usually only been compared with the cultivation of ponds, which are often due to their higher environmental pollution worse performing effects.
“However, little research has been done on the exact extent of the environmental impacts of algae that are produced for human consumption, especially under climatic conditions such as in Germany,” adds Schade.
Global EPA & DHA Demand.
The study gains momentum after scientists raised concerns about fishing and the ability of aquaculture to meet global demand for EPA and DHA.
It has been calculated that based on a daily individual intake of 500 milligrams (mg) EPA + DHA, the annual global gap between EPA + DHA demand and supply is 1.1 million tons, suggesting that fish is only 15% of the worldwide requirement of EPA + DHA makes up these nutrients.
Krill, an alternative source of these omega-3 polyunsaturated fatty acids (PUFAs), currently only accounts for 0.3% of demand, with production potentially increasing to 8–9%.
Some types of microalgae contain high levels of omega-3 PUFAs with concentrations comparable to those in fish oil.
In addition, it has been shown that the quality of proteins from microalgae corresponds to that of proteins from soybeans.
Some types of microalgae have a wide range of high quality nutrients such as vitamins, carotenoids, phycobilins, polysaccharides, and sterols.
MLU researchers began to study different cultivation scenarios of the microalgae species Nannochloropsis sp. And to compare P. tricornutum in comparison to the cultivation of fish.
The scenarios included borosilicate glass and acrylic glass as photobioreactor material (PBR), two different tube diameters and three different cultivation times.
“Among other things, we compared the CO2 footprint of nutrients from microalgae and fish,” explains Dr. Toni Meier, member of the study team and head of the NutriCARD innovation office at MLU.
“We also analyzed by how much both food sources increase acidification and eutrophication in water bodies.
“However, if we compare the environmental impact in terms of the amount of omega-3 fatty acids produced, fish from aquaculture do far worse,” adds Schade.
Carbon dioxide production.
In these scenarios, carbon dioxide production was also taken into account, taking into account the environmental impact of selected fish species from systematic literature research.
The life cycle assessment was also used to study global warming potential, acidification, eutrophication, cumulative energy demand, water footprint and land use.
As a source of EPA and DHA and protein, microalgae biomass was found to have similar or lower environmental impacts than fish fillet from wild-catch and aquaculture production when carbon dioxide was modeled as an avoided exposure.
The research team also found that microalgae production, which included the full exposure to carbon dioxide production, still had similar or lower environmental impacts than aquaculture fish.
Different types of microalgae can affect results when comparisons are based on nutritional values. The study concludes that the recommended daily intake of 250–500 mg EPA + DHA microalgae would make microalgae a “recommended source of nutrients for reducing marine pollution” for ecosystems. “
“Microalgae should and cannot completely replace fish as a source of food,” adds Dr. Meier added. “But if microalgae could be established as a common food, it would be another excellent eco-friendly source of long-chain omega-3s.”
“Several algae are already used as food supplements in powder or tablet form and as an additive to foods such as pasta or cereals. .
“This would be one way of reducing the current gap in the global supply of omega-3 fatty acids. At the same time, this would relieve the world’s oceans considerably. “
Source: Journal of Applied Phycology
Published online before printing: doi.org/10.1007/s10811-020-02181-6.
“Different types of microalgae for food – Part 2: Comparative life cycle assessment of microalgae and fish for eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and protein.”
Authors: S. Schade, GI Stangl & T. Meier