Kitchen stinks

5th August 2005 at 01:00
Ever tried wearing headphones to amplify the crunching while you munch your apple? Or making ice cream in liquid nitrogen? Heston Blumenthal explains the chemistry of cooking to Helen Briggs

Teenagers in blazers and crumpled white shirts cluster around a table loaded with conical flasks. We could be at a school anywhere in the country. But this is no ordinary chemistry lesson. It's a makeshift science lab at the Hind's Head hotel in the Berkshire village of Bray. And the teacher is Heston Blumenthal, the hotel's proprietor and the chef whose mission to prove cooking is a science has earned him the ultimate accolade of three Michelin stars.

At one table in the mock lab - actually the room above the hotel restaurant - kids are sniffing plastic bottles filled with vanilla sticks and cinnamon. At another, a couple of children in the green blazers of St Aloysius' college, Glasgow, are chewing carrot sticks while wearing headphones. They're all here as winners of a national competition run by the Royal Society of Chemistry (RSC), for which the prize was an invitation to a special one-off class to celebrate the launch of Blumenthal's new teaching resource for secondary schools, Kitchen Chemistry.

Over in a corner, equipped with desiccator and vacuum pump, is the author himself, testing the physical properties of a glistening dollop of meringue. It's a long way from his own memories of chemistry lessons, as he cheerfully admits. "My chemistry experience at school was not stimulating," he says. "Potassium permanganate and Bunsen burners, and that was about it.

It never excited me, I think mainly for the reason it was so unrelated to everyday life."

Kitchen Chemistry aims to change all that. The book and CD-Rom, which the RSC will be sending free to all UK secondary schools, contains recipes and experiments designed to make chemistry more accessible. "Kitchen chemistry is a good term," he says. "It doesn't matter whether it's making a cup of tea, a lobster souffle or bacon and egg ice cream; it's all still cooking, and when we cook there is physics and chemistry going on. Just getting to the understanding of that can make life in the kitchen much easier and more enjoyable, which is key. If we can make a subject enjoyable, we're going to want to learn more about it and spend more time doing it."

Having left school with O-level physics and A-level art, Blumenthal had to teach himself science. On Food and Cooking: the science and lore of the kitchen by the American writer Harold McGee inspired him to test theories that have become folklore in the kitchen. For instance, the book says that, contrary to accepted wisdom, browning meat does not seal in the juices. It turns out that many of the conventions of cooking have no real scientific foundation.

"People say you should add salt to beans before you cook them in water, and despite doing several experiments to check this out, such as, 'Is the salt absorbed by the beans?' 'Does the salt raise the boiling point?', all those kinds of things, none actually have any effect whatsoever," says Dr Colin Osborne, the RSC's education manager, schools and colleges. "In Kitchen Chemistry we've created some experiments the students can do to test that."

Carl Dooley, an apprentice at the restaurant, takes me through one of today's experiments, which looks at the psychology of taste. He hands me a plastic bottle to sniff. It smells of vanilla and cinnamon. He passes me another. The sickly aroma of vanilla hits me. Then it's back to the mixture, whose spicy scent of cinnamon tickles my nostrils, smelling much stronger than it did before. The small volatile molecules that give vanilla its scent have saturated the receptors in my nose, so when I sniff the mixture again the smell of the cinnamon is heightened. It's one of the tricks of sensory perception that Blumenthal uses at his other Bray restaurant, The Fat Duck. So what next for the chef-proprietor who serves snail porridge? Can wearing headphones to amplify the sound of crunching make food seem crunchier? Surely not?

"We've been playing around with this for the past year and a half," he says. "I just haven't had the confidence to make the step of actually giving people headphones in the restaurant. Everybody that does it has great fun; it brings a smile to their face, which is really important. But in a dining environment, somebody might not want it."

In a learning context, though, the experiments are certainly memorable. "It was a lot easier to learn because it was a hands-on approach," says 13-year-old Francesca Ruddy of St Aloysius' college. "I didn't really think of the two things (chemistry and food) as being related before I got involved in this." Nicola Cliffe, a chemistry teacher at Stamford school in Lincolnshire, thinks food is a good way into science. "Any resource that is produced that actually will engross the children is fantastic, especially something like this, which is in the forefront of science and food."

No one could doubt Blumenthal's passion. He has a real lab, just across the road, which develops new recipes. He is also co-supervising a PhD student who is studying "hydrocolloid systems with unusual mechanical and thermal properties" (think ice cream, gravies and jellies). But can you really call him a chemist? His co-author, former teacher Ted Lister, says you certainly can.

"He's acting like a scientist. He's asking the question 'Why?' No one knew the answer to a really simple question like, 'Why do you put salt in beans when you cook them?' So he had to go and do some experiments to find out."

Whatever you call it - chemistry, molecular gastronomy or simply cooking - the advantage of this particular school of science is that you can eat the results. I sample green tea and lime mousse "poached" in a bowl of liquid nitrogen. It explodes on my tongue, releasing a tingling blast of lime.

Meanwhile, Dr Peter Barham, a polymer physicist from Bristol University, demonstrates a method for making ice cream that has earned him a place in the Guinness Book of World Records. He mixes cream, egg yolks and vanilla then plunges them into liquid nitrogen, sending plumes of dry ice across the room. "What does it taste like?" someone shouts. "It tastes like, er, ice cream," he replies.

Extra copies of Kitchen Chemistry are available to TES readers at the reduced price of pound;12.95 (RRP pound;19.95) each. Call the RSC sales department on 01206 226050 and quote 'TES'.www.chemsoc.orgkitchenchemistry


Inside Heston Blumenthal's kitchen of science

How to detect flavour (1)

Blindfold the tester and ask them to hold their nose. Feed them a small amount of strawberry jam on a spoon. Ask them what they can feeltaste.

Then tell them to release their nose. Ask them what they can

feeltastesmell now.

When holding their nose, the tester can detect only the sweetness of the jam. When the nose is released, they can identify the flavour. Detecting flavour requires both the tongue and the nose. Much of the sensation of flavour comes from volatile molecules detected by the nose.

How to detect flavour (2)

Blindfold the tester and tell them you are going to give them crisps. Feed them a plain potato crisp at the same time as holding a flavoured one in front of their nose (without telling them). Ask them what flavour they detect.

Most people believe they are eating the flavoured crisp because much of the sensation of flavour comes from the nose.

The science of jellies (1)

Make up some jelly mixture and pour it into two separate bowls. Add some fresh pineapple to one and a similar amount of tinned pineapple to the other. Leave both to set.

The jelly with the fresh pineapple will not set, but the one with tinned pineapple will. Fresh pineapple contains an enzyme that catalyses the breakdown of the setting agent gelatine. Tinned pineapple is heat-treated to kill micro-organisms, and this also stops the enzyme working, therefore the jelly will set.

The science of jellies (2)

Add some halved red chillies to the jelly with the fresh pineapple and leave it to set. The chilli contains a chemical that destroys the enzyme (bromelin), so the jelly will set.

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