The protein found in sea lettuce, a variety of seaweed, holds great potential as a supplementary source of nutrition alongside meat and other alternative proteins. In addition to protein, seaweed is rich in various essential nutrients and can be cultivated without the need for watering, fertilization, or insecticides.
The protein found in sea lettuce, which is a kind of seaweed, shows great promise as a supplement to meat and other alternative protein options. Seaweed also offers numerous vital nutrients, and it grows without the need for watering, fertilization, or pesticide applications. However, the proteins are typically bound tightly, preventing us from fully benefiting from them. Researchers at Chalmers University of Technology in Sweden have now discovered a method to extract these proteins with three times the efficiency of previous techniques. This advancement could lead to the creation of seaweed-based burgers and protein smoothies.
“The flavor resembles umami with a slight saltiness, even though it has low salt content. It’s an excellent flavor enhancer for seafood dishes, and the potential applications are endless—think protein smoothies or ‘blue burgers’ made from seaweed,” explains João Trigo, a PhD in Food Science at Chalmers, referring to the dark green powder that’s a protein concentrate from sea lettuce, which is scientifically named Ulva fenestrata. Sea lettuce is a type of macroalgae widely known as seaweed; it typically grows on rocks in calm waters or floats freely on the surface, often resembling regular lettuce leaves.
The so-called protein shift—transitioning from red meat to more sustainable and healthier protein options—is crucial for reducing the climate impacts associated with food production and ensuring that everyone has access to a nutritious diet. Many alternative protein sources, particularly those derived from peas, soy, and mushrooms, are already prevalent in grocery stores. However, vegetarian protein sourced from the ocean remains largely untapped.
The CirkAlg project, spearheaded by Chalmers University of Technology, is exploring ways to develop processes that can create a new “blue-green” food industry in Sweden by utilizing seaweed as a viable protein source. A recent scientific study from the project details a novel extraction method that allows for three times more protein to be obtained from sea lettuce compared to previous techniques.
“This method marks a significant advancement, as it makes it more cost-effective to extract these proteins, akin to how pea and soy proteins are currently obtained,” says João Trigo.
Rich in essential nutrients
Beyond essential proteins, sea lettuce is packed with other nutrients highly beneficial for human health, including vitamin B12 and omega-3 fatty acids similar to those found in fatty fish like salmon. Individuals who do not consume animal products risk vitamin B12 deficiency, which is crucial for producing red blood cells, among other functions. Cultivating sea lettuce offers several advantages compared to traditional terrestrial protein sources—it does not require watering, fertilization, or pesticide treatments. Sea lettuce is also resilient, thriving under a variety of conditions, including differences in salinity and nitrogen availability.
“To meet sustainability and nutritional demands, we will need a wider variety of protein sources in our diets than are presently available. Algae should be considered a valuable addition to many existing products. We require all these solutions, and so far, the opportunities from marine-protein sources have been largely overlooked,” states Ingrid Undeland, Professor of Food Science at Chalmers and coordinator of the CirkAlg project.
Along with the newly developed extraction technique, Chalmers’ researchers are collaborating with the University of Gothenburg to boost the protein content of sea lettuce by cultivating it using process water from the seafood industry. This method notably increases protein levels while recycling nutrients back into the food supply. Numerous successful cultivation trials have been carried out at the Tjärnö Marine Laboratory (part of the University of Gothenburg) in northern Bohuslän, as part of the CirkAlg project, which utilizes industrial water leftovers.
“In the future, we also aim to utilize non-protein parts of the algae for food, materials, or medical applications. Our goal is to ensure that no molecules are wasted, promoting both sustainability and commercial opportunities,” adds Ingrid Undeland.
Insights into the extraction process
Sea lettuce contains not only water-soluble proteins but also fat-soluble membrane proteins, making extraction more complex compared to soy and pea proteins. The new process starts by breaking open the cell membranes of the sea lettuce to access the fat-soluble proteins. Initially, proteins are extracted using water with a high pH, and in the subsequent step, acidity is introduced to precipitate proteins into aggregates, which can then be separated from the water to serve as a protein-rich ingredient. It has been observed that the marine omega-3 fatty acids are concentrated in this protein ingredient, and follow-up research confirmed the presence of vitamin B12 as well, indicating that the new algae protein can help satisfy a broader range of nutritional needs compared to soy protein.
