Seaweed can be a sustainable protein source

By using circular strategies, it is possible to harness the potential of seaweed to produce protein food in a sustainable way. The findings of the Swedish project

by Matteo Cavallito

 

Developing new circular methods for cultivating and processing seaweed, a notoriously valuable resource that could be used for the production of protein ingredients. That is the goal of the CirkAlg project, an initiative at Chalmers University of Technology in Gothenburg, Sweden, which has been underway for five years now.

After completing the trial, the researchers explained in an article published by the same university, the results show that significant progress has been achieved. That, they claim, could pave the way for the production of a new low-impact nutrient source.

The seaweed potential

Seaweed, or macroalgae, has “a relatively high protein content and can be cultivated with minimal climate impact,” the researchers explain. Unlike terrestrial crops, their cultivation does not require the use of farmland, fertilizers, pesticides or irrigation. In addition, seaweed benefits the environment by absorbing excess nitrogen and phosphorus from water and acting as carbon sinks.

For these reasons, in the long run, macroalgae “could become a viable alternative or complement to products such as red meat.”

These plants, points out Ingrid Undeland, professor of food science at Chalmers who coordinated the project, contain “dietary fibers, essential micronutrients like vitamin B12, minerals, and marine omega-3 fatty acids.” Their taste, “rich in umami and saltiness, also makes it a unique ingredient in the kitchen.” Several hurdles, however, still need to be overcome: some algae proteins, in fact, are difficult to digest, and certain species can accumulate high levels of iodine. Finally, plants can absorb heavy metals that are dangerous to the human body.

Two-step production raises protein levels

To overcome these problems, researchers developed a new two-step production method. The first focused on increasing the protein content of the algae by using a useful yet undervalued resource: process water from various food industries. Byproducts of operations such as peeling, marinating or heat treatment, “these nutrient-rich waters, often discarded or treated at high cost, can be repurposed to support the growth of seaweed,” Undeland explains.

Grown in the process water of the herring industry, in particular, the algae showed particularly high protein levels, comparable, the authors explain, to those of soybeans.

The second phase of the project focused on developing new technologies to extract protein from cultured algae. The new methods allowed vitamin B12 and omega-3 to be concentrated in the extracts, while also improving the digestibility of the proteins themselves. “This breakthrough marks a significant advancement,” explained João Trigo, one of the researchers involved in the project. “The challenges of low yields and difficult digestion have long hindered the development of seaweed as a viable protein source, but we are changing that paradigm.”

A circular method for nutrient recovery

The processes adopted proved effective in several respects. For example, the researchers were able to apply pretreatment methods that reduced iodine concentrations before protein extraction. The scientists also identified particular species of algae that had lower levels of heavy metals. Finally, the algae grown in the herring process water did not change in taste or aroma.

The CirkAlg project, in summary, has once again highlighted the potential of circular solutions for recovering nutrients from waste byproducts and reintroducing them into the human food chain. The results now pave the way for new collaborative projects involving academia and the private sector while a patent application has already been filed for the new extraction technology, the scientists explained.