Residual water from the food industry gives seaweed cultivation a boost


Date:
March 29, 2022
Source:
University of Gothenburg
Summary:
Process water from the food industry is an excellent fertilizer
in land- based seaweed cultivation. Not only does the seaweed
grow faster; its protein content also multiplies. In this way,
process water can go from being a cost to becoming a resource in
the food industry.



FULL STORY ========================================================================== Process water from the food industry is an excellent fertilizer in
land-based seaweed cultivation. Not only does the seaweed grow faster;
its protein content also multiplies. In this way, process water can go
from being a cost to becoming a resource in the food industry.


==========================================================================
Can macroalgae, such as sea lettuce, become a competitive source of
protein in the foods of the future the way soybeans are today? Seaweed naturally has a lower protein content than soybeans, but with fertilizer
that difference decreases.

A scientific article from researchers at the University of Gothenburg
and Chalmers University of Technology shows that process water from
food production can serve as an excellent fertilizer in seaweed
cultivation. The seaweed grew more than 60 per cent faster, and the
protein content quadrupled with the addition of process water.

"The protein content of soybeans is about 40 per cent. By using process
water, we have increased the protein content in the seaweed to more than
30 per cent," says Kristoffer Stedt, a doctoral student at the Department
of Marine Sciences at the University of Gothenburg.

We already know that algae grow better in the vicinity of fish farms in
the sea due to nutrients in fish faeces that spread in the water. Process
water from food industries is often rich in nitrogen and phosphorus in
a similar way.

Different food producers The researchers tested four different types of
seaweed and added process water from several different food producers
-- from the herring industry, salmon farming, shellfish processors,
and a manufacturer of oat milk. A certain amount of process water with a controlled content of nitrogen was added to the seaweed cultivation. After eight days the researchers analysed the results.



==========================================================================
"We included oat milk to achieve cultivation that was completely
vegan. And it turned out that all different types of process water worked
well as fertilizer for the seaweed," says Stedt.

Food production requires large amounts of water, and taking care of the
process water is currently a cost for producers. But this water can be
turned into a valuable resource.

"We think that you could have land-based cultivations of algae, such as
sea lettuce, near a herring factory, for example. Seaweed cultivation
can cleanse large portions of the nutrients from the process water. That
brings us closer to a sustainable approach, and the companies have
another leg to stand on," says Stedt.

No off-taste for the seaweed The researchers were worried that the
seaweed would be tainted by the process water. Not everyone may appreciate herring-flavoured sea lettuce. But test panels did not note any impact
on the taste of the seaweed from the process water.



==========================================================================
In the future, Kristoffer Stedt and his colleagues will focus on scaling
up the experiments with seaweed cultivation. They will use process
water from the herring industry, which showed very promising results,
and focus on the species Ulva fenestrata (sea lettuce).

"We need to conduct tests in larger volumes as a first step in a
controlled environment. But we believe that this may be an alternative
source of protein in future foods. It could also be a completely circular system if we used cultivated seaweed as feed for salmon culture on
land and used the process water to fertilize the seaweed cultivation,"
says Stedt.

Great need for new protein sources An estimated 10 billion people will
live on Earth by 2050, and there is a great demand for sustainably
produced food protein. Between 2000 and 2018, the production of seaweed tripled, reaching 32 million tonnes. Almost 99 per cent is produced in
the Far East.

In the research project CirkAlg, researchers from the University of
Gothenburg and Chalmers University of Technology are collaborating on
processes that can generate a new Swedish marine protein source in a resource-efficient way through both cultivation and processing of seaweed.

"In addition to boosting the seaweed's protein content with process
water, we are looking at several ways to extract the proteins from the
algae for use in other foods in the same way as protein is extracted
from soybeans today.

However, this presents a challenge, because the protein in seaweed
is bound more tightly than in the soybeans," says Ingrid Undeland, a
professor of food science at the Department of Biology and Biological Engineering at Chalmers.

She is also the coordinator for CirkAlg.


========================================================================== Story Source: Materials provided by University_of_Gothenburg. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Kristoffer Stedt, Joa~o P. Trigo, Sophie Steinhagen, Go"ran
M. Nylund,
Bita Forghani, Henrik Pavia, Ingrid Undeland. Cultivation of
seaweeds in food production process waters: Evaluation of growth
and crude protein content. Algal Research, 2022; 63: 102647 DOI:
10.1016/ j.algal.2022.102647 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220329100015.htm

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