As seas warm, jellyfish may become more common in food

The summer table smells of lemon and freshly fried fish. The remoulade feels creamy and firm, carrying a faint taste of the sea, as if the salty breeze has been allowed to linger in the bowl. It stays on the fork, even when the sun is hot. A small word on the label explains it all: jellyfish — not as a finished product, but as an ingredient.

Most people in the Western world think of jellyfish as slimy lumps in the water, not as something you would put in your food — even though jellyfish are considered a delicacy in parts of Asia.

In some seasons, they appear in such large numbers — so-called jellyfish blooms — that fishermen haul up nets made up almost entirely of jellyfish, and ecosystems come under pressure as jellyfish feed on fish larvae and small fish. The trend is particularly pronounced as the sea grows warmer and richer in nutrients.

The study is an example of how climate-driven surpluses in nature are not only a problem, but can also become a starting point for new materials and ingredients. The work comes from researchers at the University of Southern Denmark and international partners.

The lead author is Mie Thorborg Pedersen, postdoc and Postdoctoral Villum Fellow, SDU Biotechnology in the Department of Green Technology. Together with colleagues, she is investigating whether a powder made from freeze-dried jellyfish can act as a food-structuring ingredient and form different textures that could be relevant for future food applications.

The study addresses a well-known challenge in food science, says Mie Thorborg Pedersen. Oil and water naturally separate. A dressing or sauce will separate unless something can keep tiny oil droplets evenly distributed in the water.

This is precisely the kind of role the researchers have explored using jellyfish biomaterials. Their experiments show that a powder made from freeze-dried jellyfish can keep small oil droplets distributed in water, creating mayonnaise-like emulsions.

“We are exploring their potential in food innovation and how they can create different textures and open up new ways of formulating foods, rather than just replacing existing stabilisers,” she says. “The same principles could potentially be relevant in other fields, such as cosmetics, and might also contribute to improving ecological balance in fisheries by utilising jellyfish.”

From net to kitchen

For Mie Thorborg Pedersen, the work with jellyfish began with something as concrete as texture. While she was still a student, she carried out a master’s thesis project driven by curiosity about jellyfish and a desire to explore how they might be made more appetising in Western cuisine. She says that it is often not the taste that puts most Western consumers off, but the soft, gelatinous consistency.

Experiences from parts of Asia show that jellyfish can indeed find their way onto the plate. There, they are served and enjoyed as crunchy, elastic, chewy elements in salads, particularly in countries such as China, Japan and Korea. To preserve and obtain this special texture, salts containing aluminium are added.

“Asian-style jellyfish contain high concentrations of aluminium, but that has nothing to do with the natural jellyfish. It is related to the process they have gone through, which creates this chewy-elastic texture that is highly appreciated in many Asian cuisines. But although jellyfish has been eaten this way for thousands of years, this particular texture can be challenging for many consumers in the Western world,” she explains.

“So the idea was: can we make it into a crispy chip?” she says.

From a crispy idea to a functional material

It turned out that if the jellyfish were first placed in alcohol, they could be dried and brought to the level of crispness she was aiming for.

The process, however, required so much alcohol that it was difficult to scale. That prompted a change of direction. Instead of seeing jellyfish as a food in itself, she began to see them as an ingredient. As she worked with the jellyfish material, she noticed how easily it became foamy and slimy.

“That made me wonder what would happen if I tried to make a jellyfish hollandaise sauce,” she says. That observation sparked the idea of testing jellyfish material as a food stabiliser.

The animals consist almost entirely of water, and she began to see that characteristic as a strength rather than a weakness. They can naturally hold large amounts of water with very little solid material, and in food development, that property can be translated into structure formation using only small quantities of raw material.

In the new study, the team collected a common coastal species of jellyfish (Aurelia aurita) off the coast of Fyn, Denmark. The jellyfish were rinsed and ground into a smooth mass, then freeze-dried until only a dry substance remained. The material was ground directly into a powder that retained its natural marine salt content. For part of this dried and ground jellyfish material, the naturally occurring salt content was reduced using a simple process known as dialysis.

In this way, the researchers ended up with two products that differ in salt content — and therefore behave very differently when mixed with oil and water. This is classic food physics applied to an unconventional raw material.

When salt changes the material

The next step was to test the powders in mixtures resembling mayonnaise or hollandaise sauce, in which oil and water must be brought together.

In the laboratory, the researchers stirred the jellyfish powder into water, adjusted the acidity (pH) and added rapeseed oil while stirring vigorously so that the oil was broken up into many small droplets.

“We have tested the two types and found that when we reduce the salts, the powder becomes much better at creating emulsions, meaning stabilising the tiny oil droplets in the water,” says Mie Thorborg Pedersen.

The core of the experiment is to get oil and water to stay together in an emulsion: the oil is divided into tiny droplets in the water, and jellyfish material is preventing the mixture from separating.

In Mie Thorborg Pedersen’s experiments, the jellyfish powder is able to do exactly that. The effect is strongest at low pH – that is, when the mixture is more acidic, a bit like working with vinegar in the kitchen – and these are precisely the conditions found in many dressings and sauces.

In the study, the salt-reduced emulsions remain stable for longer periods without separating — a result that points towards applications such as mayonnaise and remoulade.

When the emulsion breaks down

The salty version behaves differently. The emulsions the researchers make with the salty powder are initially less stable. When left to stand, however, the structure begins to change.

It becomes more elastic, and when the researchers dry the emulsions (remove the water part), they can see under the microscope how the oil droplets are trapped within a coherent network of jellyfish material – visual proof that the structure holds the oil in place.

The result is an oil gel in which the oil behaves as part of a solid structure rather than as a free liquid. In a kitchen, this kind of structure is closer to butter or spreadable fat products and points to a different way of using jellyfish powder than in dressings and sauces.

The powder also carries a complex flavour of the sea. Instead of purifying the jellyfish material down to individual compounds, the researchers have deliberately chosen to work with a coarse powder, in which proteins and sugar-rich substances from the whole animal are maintained.

This approach is somewhat unconventional in food processing, but saves processing steps and reduces waste while providing a complex structuring and flavour profile. For example, simply reducing salt content improved the stability of emulsions, but resulting powder could no longer form an oil gel.

This shows how even small processing steps can change how the material functions – which can be both an advantage and a disadvantage, depending on the intended application. At the same time, a complex flavour profile does not necessarily have to be a drawback; it may offer new flavour combinations that work well in the right context.

Can it become green in practice?

When Mie Thorborg Pedersen talks about future uses, she repeatedly returns to the sea. Jellyfish are part of marine food chains, both as prey for turtles and several fish species, and their dead bodies sink to the seabed, where they become food for microorganisms.

She therefore emphasises that any future harvesting of jellyfish should be targeted at periods and areas in which they appear in such large numbers that they cause problems for fishing and the marine environment rather than being harvested indiscriminately as a new bulk commodity.

She points to examples from other parts of the world where, in some seasons, fishermen catch almost nothing but jellyfish in their nets, and where large swarms can also cause problems for coastal infrastructure.

In those situations, she sees value in removing some of the biomass that upsets the balance, while creating a product that could add new value. Species and geography also matter: some of the jellyfish traditionally eaten in Asia are different species from those that cause problems.

This is where the difficult part begins

Sustainability still requires careful calculations. Jellyfish consist almost entirely of water, and both transport and drying consume energy – and without proper documentation, a green idea can quickly turn into yet another burden. Mie Thorborg Pedersen stresses that her group has not yet carried out life cycle assessments, that is, calculations of the total climate footprint from catch through drying and transport.

In such situations, she sees hope in creating value from a resource that would otherwise be a nuisance – but only if harvesting, processing and ecological effects can be documented as sustainable.

In the laboratory, there are also unanswered questions about the mechanism itself. The salt content clearly changes how the jellyfish powder behaves, but they do not yet know exactly which proteins and sugar chains in the material create these effects. This distinction is crucial if texture is to be controlled more precisely in future ingredients.

When I ask about the process, she says it will be a focus of upcoming projects, in which the team will try to identify the specific proteins and sugar chains responsible for interesting functions.

“We will try to understand what kinds of molecules are actually doing the work. We have some ideas and hypotheses, but this article does not go into that as such,” she says.

“What we have shown, however, is that jellyfish material can be used to create texture in food systems and can be controlled by changing different physicochemical parameters (pH, salts). I have not made a jellyfish hollandaise sauce yet – the idea that originally sparked this research – but the emulsions we are working with are not far off,” she says.

What remains is not a ready-made solution, but a new way of thinking about jellyfish as a food ingredient. Rather than promising sustainability or finished products, the work adds insight into how complex marine biomaterials can be used to control texture in food systems.

Which molecules play the key role – and how the material might be applied in different contexts – are questions the researchers are now beginning to explore.