El Bulli, in case you hadn't heard, was the hardest Michelin three-star restaurant in the world to get into, receiving a reported two million requests for the about 8,000 seats available in the six months it was open each year. The chances of getting a table were exceedingly slim; now, it's impossible. The restaurant closed yesterday after 47 years in operation, and is scheduled to be turned into the El Bulli Foundation, a non-profit culinary creative think tank that will launch in 2014.

'You just have to live with it; it's part of me, it's part of El Bulli - when you're at the top there are expectations [from diners],' Adria said in May, of the relentless pressure that came with being considered one of the best restaurants in the world, and certainly the most influential. 'The day diners come to El Bulli should be one of the happiest days of their lives. It's a question of proportion, 90 per cent leave thinking it's better than they expected, and that's fantastic.'

ADRIA STARTED WORKING at El Bulli in 1983, when it was a Michelin two-star restaurant serving French food; he was promoted to co-chef de cuisine the following year and, in 1987, took over the kitchen on his own. Three years later, he and business partner Juli Soler bought the restaurant and started serving the experimental, creative cuisine Adria is now known for.

El Bulli received the highest Michelin honour of three stars in 1997, which made journalists and gourmands sit up and take notice, and start making the pilgrimage to the 50-seat restaurant located at an idyllic spot along a long, winding, narrow road in the middle of a country park.

If Adria hasn't changed his mind between when he was interviewed, in May, and now, he'll be doing what he likes to do right after the restaurant closed each season - resting for a while before travelling 'to clear my mind' (he's scheduled to come to Hong Kong towards the end of next month, to host two conferences and three dinners - cooked by his protege Paco Roncero, of the two-star Casino de Madrid - at Tosca, at The Ritz-Carlton). Then Adria and a core team of four will start work on the think tank.

'El Bulli is not closing,' Adria says. 'Sometimes I have to [remember] this myself. We shut it down every year for six months but, this year, shutting down El Bulli has a slightly different meaning. I mustn't say it's closing; I must say it's being transformed. The difference is that rather than six months, I'll have 2?years. But the work is proportion- ate to the time.

'I have lots of projects, including one really big one - the El Bulli Foundation. I'm preparing three books, two documentaries, a Hollywood film - although not as an actor. It's a fiction about El Bulli based on a very good book, The Sorcerer's Apprentices, by Lisa Abend, Time magazine's correspondent in Spain.

'She spent 60 days in our kitchen without any censorship whatsoever, and she writes about what El Bulli is like from the inside. There's a lot of glamour here but there's a lot of work, which is sometimes not properly valued. Especially for the stagiaires - the young people who leave their families because they believe in something. There's passion, risk, creativity - it's what the film tries to portray.'

El Bulli has long relied on stagiaires to do much of the kitchen labour. Each year, Adria receives about 3,000 requests for the 30 to 35 unpaid positions. Every lucky candidate has to pay their own travel expenses and accommodation.

Traditionally, stagiaires are young, although those selected to work at El Bulli must have had work experience at at least one top-level restaurant, says Casanas, 30, who's been employed at El Bulli for 15 years and is part of Adria's 'gang of four', who will stay on to help with the foundation. Selection criteria for stagiaires includes ensuring there's an international mix (the only representative from Asia in the last batch was a Japanese man who worked in the pastry section).

With the start of the foundation, the bar for working in the El Bulli kitchen will be raised even higher: Casanas believes it'll be getting top chefs who have made names for themselves in their own restaurants, and there'll be about 20 at any one time. Established chefs don't normally take six-month sabbaticals from their own restaurants, but the appeal of working at El Bulli will be that their work will gain greater recognition, Casanas says.

'The idea is that whatever we create within this foundation will be shown around the world,' Casanas says. 'There will be a certain amount of diffusion, spreading the ideas that originate within the foundation. Up to now, it's very much been a transmission of ideas from El Bulli to the client - those who eat here. With the foundation, it will be more global, much more internet-based, it will be very immediate. Ferran knows what he wants to do - create new concepts, new techniques. We're not sure how to make it a reality, but we will try. One of the basic ideas behind creating the foundation is that we aren't interested in [making a] profit. All we want is to make enough income or resources so it can finance itself. We'll do that through money that Ferran himself has saved, and through contributions through partners in the industry. Any profit that we might make will be reinvested in the foundation.

'We're not sure how it's going to work yet; we have a lot of experience because we have the El Bulli Taller [workshop] in Barcelona, which is very much focused on creation. So the foundation is going to be the same thing - a workshop - but much larger. The main difference is that [until yesterday] we had 50 people to serve every night, so we had to produce. With the foundation model, we no longer have to do that, so we can spend all our time creating and developing ideas.'

It's doubtful that many harried home cooks will ever attempt some of the famous El Bulli creations, such as spherical olives (which require sodium alginate and calcium chloride), the golden egg (a quail egg encased in a thin sheet of crisp caramel) and frozen cocktails that rely on liquid nitrogen. But, Casanas says, that isn't necessarily the point.

'Everyone will be free to use the ideas as inspiration, at whatever level they are, whether they're professional chefs or cooking at home. The concepts will start here but they'll evolve globally. We're going to put the tools [online] and anybody can look at them, consult and download, and everybody can apply them whichever way they want.'

It's hard to imagine that Adria and company will exert an even bigger influence on food than they have now: you'd be hard-pressed to find a 'modernist cuisine' restaurant that hasn't adopted some variations of El Bulli creations, such as foam, air (even lighter than foam), microwave cakes and faux caviar.

'The influence of El Bulli is extraordinary,' Adria says. 'There are thousands and thousands of chefs and cooks who have never worked here, who have our 'spirit', which has been taught to them by people who have worked at El Bulli. Of the annual Restaurant magazine list [of the top 50 restaurants in the world], the first eight are children of El Bulli. What is our spirit? Passion, risk and sharing. These are three things which are not usually seen in the world of cooking. The passion was always there, but risk? It's against everything that cooking has been. And cooking was not shared - people kept their recipes secret. This is the most important thing about El Bulli - the thing that really matters is the spirit.'

But there remain barriers to his influence, he admits.

'Today, we can say with all certainty that El Bulli is one of the most influential restaurants in history - in the West. We in Europe tend to think that only the West exists, but the dialogue between China and the West in the world of cooking is just beginning. There are some Chinese cooks who have been influenced by us, but [their number is] very small.

'I'm not interested in Chinese ingredients, I'm interested in the spirit of Chinese ingredients. I've used ingredients from China and I love them, but I wish to understand why they're cooked that way, why people in China eat that way. If I can understand that, one day I should be able to incorporate some of the spirit into my own cuisine, otherwise what I'm doing is just copying a few things.

'Over the next few years I want to visit China and open a dialogue with chefs. I would like China to be part of the El Bulli Foundation.'

Adria, 49, is at the top of his game. He could be forgiven for wanting to retire from the restaurant business entirely and make a good living from easier work, such as lecturing at cooking schools (last year, he taught a course on 'culinary physics' at Harvard University's School of Engineering and Applied Sciences).

'I could have sold everything and given lectures around the world; all my work is well documented, the influence is huge. That would have been the easiest thing to do, the most convenient thing. We did have the possibility of not carrying on, but I realised this was not the way. If I wasn't creating, something would be missing from my life. And that's why we decided to create the foundation.'

Adria remembers much about his past menus. When I tell him I first ate at El Bulli in 2006, he remembers the number of dishes I was served.

'For the past 20 years, we have been creating a language, and for the past three years, we've known how to express ourselves. Everyone who knows El Bulli well has said that the past three years have been spectacular. What changed? The way we express ourselves. In 2006, we served 32 dishes; now we serve 47 to 55. Gradually you learn to express yourself and then suddenly you say, 'Yes, now I've got it.' This is probably why we're transforming El Bulli [into a foundation] - because we finally found our own mode of expression.

'The basis for 2014 is what we have now and how we can improve it. Not the dishes themselves, but the way to explain it.'

The restaurant's final dish, served last night, would have been, according to the chef, the 1,846th created at El Bulli.

'We're the first restaurant in the world to make a catalogue of our recipes for 25 years. We knew that [the number of dishes created over the years] would be somewhere between 1,820 and 1,860. So, why did we choose 1,846? We went to the internet and put in those years to find a date which had some significance; 1846 came up - the birth year of [French master chef] Escoffier. The last dish is a deconstruction of Escoffier's peach melba, which we're going to create as a joint effort by the whole team. It's a dramatic story - it represents respect for history, and it shows El Bulli is not just Ferran Adria, it's a team.

'So we're going to make this last dish for all of us.'