How Sargassum Can Become a Food Ingredient

Seaweed seldom receives a warm welcome when it accumulates along beaches. Across the Caribbean, it has come to represent a source of irritation.

Dense blankets of brown sargassum decay on shorelines, giving off an unpleasant odour, damaging marine ecosystems and deterring visitors. Local governments spend substantial sums removing it, only for fresh quantities to arrive on the coast.

Science, however, is beginning to frame the issue differently. Rather than viewing sargassum solely as rubbish, researchers are considering one straightforward possibility: could this nuisance be used as a resource?

A recent study indicates that it could, with potential consequences extending well beyond coastal areas.

An escalating problem in the Atlantic

Since 2011, enormous volumes of pelagic sargassum have spread throughout the Atlantic. Together, these floating masses form what scientists refer to as the Great Atlantic Sargassum Belt.

It stretches through the Caribbean and the Gulf of Mexico, as well as across parts of West Africa.

Its effects are extensive. Coral reefs are harmed, sea turtles find it difficult to travel through the thick rafts, fishing routes are obstructed and beaches become unsuitable for use. The blooms are so vast that satellites monitor them from space.

For all of this damage, the floating material holds a valuable component. Alginate can account for up to one-fifth of its dry weight, and this compound is already widely used in food.

Alginate: the unseen food ingredient

Many people eat alginate without realising it. Food manufacturers use it to provide texture and maintain stability.

It can thicken sauces, make ice cream creamier and help desserts form gels. It is also responsible for the recognisable burst of bubble tea pearls.

Alginate’s function comes from its composition. It contains two units known as guluronic acid and mannuronic acid, whose arrangement determines the molecule’s behaviour.

With the appropriate balance, alginate can create firm gels or stable emulsions. If that balance changes, these qualities become weaker.

This makes alginate both valuable and delicate, as its performance is determined by the way it is processed.

Sargassum safety still needs addressing

Using sargassum in food without further processing is not straightforward. The seaweed takes up heavy metals from seawater, including arsenic, cadmium and lead, making it unsafe to consume raw.

“It’s generally treated as waste because it smells, affects tourism and can carry contaminants or bacteria,” said Imran Ahmad from the Florida International University (FIU).

To tackle this problem, the researchers improved their extraction approach. It involves acid washing, separation using alcohol and carefully controlled pH stages.

These steps remove many contaminants, resulting in a purer alginate.

The findings are encouraging: the finished material has considerably fewer impurities than the original seaweed.

Refining Sargassum alginate extraction

Conventional alginate extraction is already established. It separates the compound through acid treatment followed by alkaline processing, but the research team sought to take the process further.

They investigated whether physical treatments applied before extraction could alter alginate’s final characteristics.

Their aim was not simply to recover alginate, but to tailor it for particular food applications.

Three techniques were assessed. One used autoclaving, combining heat with pressure; another applied high pressure without heat; and the third used sonication, which relies on sound waves.

Establishing the optimal conditions

Before evaluating these treatments, the researchers optimised the standard extraction method. They examined different temperatures, processing times and chemical concentrations.

Higher temperatures combined with a longer treatment period delivered the strongest results. At 80 °C for five hours, the seaweed released more alginate, with yields reaching about 44 percent.

This stage meant that subsequent comparisons assessed quality rather than quantity.

Heat weakens the structure

Autoclaving delivered the poorest outcome. The combination of intense heat and pressure damaged the alginate chains.

Its molecular weight fell substantially, while viscosity declined and gel strength dropped by more than half. Such changes reduce the material’s usefulness in food applications.

Put simply, heat impaired the structure that gives alginate its value. This approach is therefore poorly suited to products requiring firm gels.

Sound waves offer potential

Sonication achieved a more favourable result. The technique uses sound waves to form tiny bubbles, which collapse and break materials apart.

Much of the alginate structure was retained during treatment. Gel strength stayed high, and molecular size remained in a useful range.

As a result, sonicated alginate could suit foods requiring firmness and stability, including desserts, structured gels and encapsulated nutrients.

Pressure enhances emulsions

High-pressure processing offered a different benefit by producing shorter alginate chains that could move more freely in liquids.

These chains worked effectively in emulsions, helping oil and water combine more efficiently. Of all the samples, the treated alginate achieved the highest emulsification performance.

“Instead of using heat, which can damage nutrients and structure, we apply extremely high pressure,” Ahmad said.

“That high pressure kills harmful microorganisms but preserves the useful compounds we want to extract.”

This means pressure-treated alginate may be useful in items such as dressings, beverages and dairy alternatives.

Core chemistry remains stable

One particularly important result emerged: although the physical properties changed, alginate’s chemical structure stayed stable across the treatments.

The proportion of its two building blocks changed very little. In other words, the methods modify physical behaviour without changing the fundamental chemistry.

That matters for food manufacturing because it supports clean-label objectives while avoiding complicated chemical modification.

A versatile set of options

The research demonstrates that no single technique is universally best. Each method provides its own advantages.

Sonication favours strong gels, while high pressure favours emulsions. Although it was less useful in this case, heat continues to have established uses in other processes.

Food scientists can select an approach according to the intended product. This adaptability makes Sargassum a customisable source of ingredients.

Moving towards practical use

The study creates an opportunity for sargassum to be used on a large scale. It demonstrates that an environmental problem can supply valuable ingredients.

Further research remains necessary. Scientists need to verify safety across locations and seasons, and assess performance in actual food systems rather than laboratory conditions alone.

“Our researchers at the Chaplin School are always looking for ways to solve problems that affect and can help improve the hospitality and tourism industry,” said Michael Cheng, Dean and professor, FIU Chaplin School of Hospitality & Tourism Management.

“We are proud of Dr. Ahmad’s innovative research and look forward to seeing how his work can help solve not only a Florida, but much larger global issue.”

Turning waste into opportunity

Sargassum is likely to remain part of ocean ecosystems for many years. Climate change and nutrient run-off continue to encourage its growth.

The issue is now how to respond. Collecting and throwing it away is expensive and achieves little, whereas using it generates value and cuts waste.

“If we can turn it into something useful, we shift the conversation from disposal to opportunity,” Ahmad said.

Such a change could reshape both coastal economies and supply chains. Material that once ruined beaches may eventually enhance the texture of everyday foods.