Science: Farm it from the sea and put it on your face: Declan Butler meets the entrepreneurs making food, drugs, fertilisers and cosmetics out of seaweed

AVOCADOS taste yummy, feel creamy and are highly nutritious, rich in vitamins, minerals and natural oils. Yet when first put on to Britain's supermarket shelves that is exactly where they stayed. Sales only took off when people learnt that to serve an avocado you simply cut it in half, scoop out the stone and put some vinaigrette in its place. Seaweeds share many of the avocado's gastronomic attributes, but consumers find them considerably more bewildering. This is the dilemma facing British and French entrepreneurs who have begun to farm seaweeds off the Isle of Man and Brittany.

A vast untapped natural resource lies off the coasts of Europe: an underwater reserve of more than 1,500 plant species. Brittany leads Europe's efforts to create products, money and jobs from this resource, and it was this region that hosted the 14th International Seaweed Symposium, held last week in Brest.

Dozens of Breton companies are now producing cosmetics, drugs, animal feed, fertilisers and food from seaweeds, 10 million tons of which grow off the coast of Brittany alone. At the heart of this industry is a small company, Ceva (Centre D'Etude et de Valorisation des Algues), which specialises in the industrial appliance of seaweed science. Serge Mabeau, Ceva's director of new product development, is betting on human foods as the most promising new outlet for seaweeds in Europe.

Four million tons of seaweeds were harvested worldwide last year. Of this, 3.2 million tons were used directly as human food, almost all of this produced and consumed in Asian countries, which cultivate seaweed on a large scale. The West has yet to exploit unprocessed seaweeds for their flavour and nutritive values, although it extracts more than 55,000 tons of thickening and gelling agents from seaweed each year for use in the food and other industries - for example, to maintain the head on beer, to emulsify salad dressings and give texture to ice-cream.

Ceva believes that advanced farming techniques and consumer research are the keys to developing seaweed foods in Europe; this is a view shared by Chris Dawes, a founder of Seaweed Supplies Ltd, who runs the UK's first such farm off the Isle of Man.

Seaweeds need to be farmed properly if they are to be used for food production: monocultures are easier to harvest than mixed wild populations; control of crop age allows quality to be optimised, and farming also opens up the possibility of selective breeding to achieve higher growth rates and improved nutritional properties.

Locating the farm follows the principles (more or less) of conventional agricultural practice. Ceva and Seaweed Supplies tested thousands of pollution-free sites before selecting those which offered the best conditions (light, nutrients, currents and wave action) to grow and harvest their seaweed crops. Attention also has to be given to the choice of 'sea vegetable' to be cultivated. The Japanese mainly grow species of the brown kelp (Undaria and Laminaria), the red seaweed Porphyra (Welsh 'laver'), and the green seaweed Monostroma (similar to sea lettuce). Mr Mabeau says that seaweeds are 'just like vegetables. The choice between an Undaria and a Laminaria is akin to that between a radish and a lettuce: their taste and texture are completely different.'

Seaweed Supplies screened 640 species for taste and texture and finally opted for Alaria, a large brown kelp found in British waters. This year the company is growing four hectares of Alaria at the Isle of Man farm and hopes to produce 200 tons. Ceva has opted for the Japanese kelp Undaria, and is aiming for 600 tons. This choice of a Japanese import has raised some eyebrows (and voices) in seaweed circles; some fear Undaria could spread in European waters and displace native species.

Ceva and Seaweed Supplies both use similar farming techniques, as the species they grow are closely related. Thin threads (around 3mm diameter) are first immersed in a suspension of seaweed spores in the laboratory. The spores settle on to the threads which are then cultured for a few weeks in illuminated tanks until the young seaweed plants are visible to the naked eye. These threads are then inserted between strands of ropes (around 12mm diameter), and transferred to the open sea. In their final position the ropes are suspended horizontally using buoys and weights, a few metres below the sea surface.

The Isle of Man farm seeds the ropes in late autumn and harvests the fully grown plants the following summer; Ceva is able to get two harvests of Undaria per year. Both groups are mechanising and automating many of the cultivation and harvesting procedures, to improve the overall economics of the system.

The harvested seaweed, which usually ends up as dried flakes, pastes or liquids, must have uniform properties of taste, texture and nutrition and meet all of the usual microbial and toxicity requirements. But even at this stage success is not guaranteed; somebody must want to buy the finished products.

One big plus for seaweeds is that they are natural, organically grown products which can be used to flavour, texture and colour foods in place of artificial additives and fats. Euchema, a red seaweed grown in the Philippines, is apparently the secret behind the 'McLean', a low-fat burger introduced recently in the US by McDonald's; the seaweed is used as a fat substitute and results in a juicier burger with less aroma. Ceva, in the French tradition, recently submitted its seaweeds (dried and toasted) to a panel of expert degustateurs who detected aromas and tastes such as 'grilled shellfish', 'leek', 'cress', 'spinach', 'meat' and 'white fish'.

Ceva and Seaweed Supplies have carried out extensive market research and are convinced that a demand for seaweed foods exists. But both have opted to sell their seaweed to food companies for use as ingredients rather than trying to sell them directly to shoppers, even though the plants can be used directly in salads, soups and other dishes. A study by Ceva showed that the French welcome seaweeds as ingredients in terrines, pates, salads, soup, fish dishes and even bread. Seaweed Supplies has also launched a range of aperitif snacks such as Kelp Crunchies. These are made from Alaria and corn and, contrary to all expectations, proved to be rather tasty.

(Photograph omitted)