RSC - Advancing the Chemical Sciences


Chemistry World

 

Cooked to perfection


Heston Blumenthal, chef-proprietor of the Fat Duck restaurant, uses chemistry to create unusual dishes. Katharine Sanderson talks to him

In Short
  • Heston Blumenthal is chef-proprietor of the Fat Duck at Bray, UK. The triple Michelin starred restaurant is known for its unusual dishes, such as sardines on toast ice cream
  • Blumenthal is interested in the science behind cooking and what affects people's experiences of eating
  • Blumenthal works closely with academics and has built a lab at the restaurant and taken on a food science PhD student               

 

An intense, meaty smell fills the air as you walk into the laboratory. In the corner sits an enormous water bath kitted out with mechanical stirrer and temperature gauge. It all looks very scientific. Until, peering over the edge of the water bath, the contents loom into view: vacuum-packed pigs' heads. Whole. Cooking slowly, at precisely 60C.

This is no ordinary lab. It belongs to Heston Blumenthal, triple Michelin star holder and chef-proprietor at the Fat Duck restaurant in the village of Bray, Berkshire, UK (see Chemistry World, December 2004, p8). Blumenthal is a self-taught chef. One could argue that he's just as much a self-taught chemist. Using rigorous scientific method he has developed some outlandish-sounding recipes based on sound chemical principles.

'Molecular gastronomy' might sound like a gimmicky pseudonym for cookery, and is an accusation that Blumenthal has faced. After talking to him for just a few minutes it becomes clear that this is no gimmick. He is deadly serious about his food and science. 'What I've done in the last 15 or 20 years is to access as much information as I could get hold of that I could actually understand, whether it's from experimental psychology or someone who specialises in hydrocolloids, and then take that information and use it as a learning process,' Blumenthal says.

Flavourful mouthwash

Visitors to the Fat Duck are given a mousse 'poached' at the table in liquid nitrogen. Looking like a tiny meringue, this frozen puffball pops and melts in the mouth. It becomes clear why the word gimmick might spring to mind with dishes like this. But as Chris Young, manager of food research and Blumenthal's on-site scientist, explains the reasons behind this cryogenic culinary invention, any thoughts of gimmicks evaporate as quickly as the mousse in your mouth.

Diners coming for the Fat Duck's expensive eating experience (the tasting menu costs 97.50) often turn up having just brushed their teeth, smoked a cigarette, or drunk strong alcohol. Their mouths aren't properly equipped to appreciate what they are about to eat. So a palate cleanser was invented.

'It's supposed to be a flavourful mouthwash,' says Young. The flavour ingredients of lime, green tea and vodka are all there for a reason. 'Green tea has astringent polyphenols that help get the saliva going,' Young explains. The acidic lime, along with an added malic acid hit, are also mouthwatering, and the vodka is there to disperse fat molecules in the mouth. The spectacle of tableside liquid nitrogen along with the surprising sensation the mousse provides is a clever distraction from a tool to ensure that Blumenthal's creations can be properly experienced.

Part of Blumenthal's infamy comes from his unusual mixing of flavours, for example dishes like sardines on toast ice cream. Ingredients that go well together very often have the same underlying flavour compound, even if on first inspection they seem an unlikely pairing. Neryl acetate, for example, is present in ginger, bergamot, cocoa and mandarin, and these flavours are well known for their complementary properties.

Once a basic flavour compound is identified, surprises can be thrown up: caviar and white chocolate appear on the menu together at the Fat Duck. In their natural state they don't have the same flavour compounds but what they do have in common is a group of precursor amino acid molecules that undergo similar metabolic pathways in fermentation processes. This makes them work well together.

Another example is the combination of fir tree, green peppercorn and mango. These three ingredients all have the same flavour compound - ?,?-pinene.

In principle it might be possible to dream up a wonderful flavour combination just by looking at the chemical spectra of the ingredients and spotting similarities. This methodology could be likened to working out a chemical synthesis in advance. But chemistry and molecular gastronomy part company when it comes to the end result. A natural product synthesis will lead to a natural product. Even if the right conditions, reactions times, temperatures and concentrations are employed in an edible dish, the final result's success is subjective.

'In principle you could say that things are going to work well. But you can't stop there, because there are concentrations of each one, amounts, temperature, texture, colour, they all play really vital roles. You could make something edible on paper, I'm sure, but in terms of actually trying to get that intensity of the flavours, to get the complexities, you still need to cook,' says Blumenthal. 'You can take all the science you want and adapt it into the kitchen - but you still need to eat the food. I think this is a wonderful example of where the two sides both play really important roles. But you're never going to get away from the actual point of cooking.'

Blumenthal and Young work closely with the academic community and, as his restaurant developed in the late 1990s, Blumenthal sought out more academic help. His quest led him to a polymer physicist, Peter Barham, from Bristol University. Barham was more than happy to be involved and his input has helped Blumenthal develop his old pub kitchen into the scientific setup it is today. 'Blumenthal realised that he didn't understand the processes of cooking,' explains Barham. 'In the early days we helped him by introducing him to what's available in the lab, all sorts of bits of kit that he'd never used in the kitchen.'

Enormous impact

Another of those academics is food scientist Andy Taylor from Nottingham University. Taylor describes working with Blumenthal and Young as 'both exciting and intellectually challenging'. Taylor and Blumenthal are co-supervising a PhD student whose thesis will be entitled Science driven gastronomy. This doesn't mean that Blumenthal wants to become a science academic. He laughs off the suggestion that he should have been a chemist: 'I'd have blown myself up by now probably. I'd be a liability.'

According to Barham, Blumenthal's impact on the world of food is 'enormous'. 'I think we are in the early days of a revolution in cooking,' he says. But now, with the upcoming publication of an RSC book for schools, Blumenthal's influence is extending to science education. The book and CD, Kitchen chemistry, is his latest venture. Launching next month, it will be distributed free to all secondary schools, sixth forms and further education colleges. Aimed at all ages, the resource has explanations ranging from why asparagus should be cooked in fat and not boiled (the important flavour molecules are soluble in water) to the complex chemical processes that happen to collagen in meat when it reaches different temperatures.

'Food is a very good way to get kids into science,' says Barham, who appears in the video clips that accompany the book. And academics are keen to collaborate: 'I have yet to meet a scientist who doesn't find it great fun getting involved with a chef,' he adds.

Purple microgels

Back in the Fat Duck lab, Young produces a dropping funnel and a beaker, each containing different coloured solutions. When the purple liquid hits the solution in the beaker, small spheres of purple jelly form. These microgels are the latest way of getting flavours to people in an unusual medium.

Gellan gum has been used for years in food manufacturing. It has found applications as artificial 'cherries' in pie fillings and in low-calorie jams and jellies, taking advantage of the excellent flavour release the gel offers.

Gellan is an extracellular polysaccharide derived from a yeast-like microbe, Sphingomonas elodea. In the solid state, gellan gum is a double-helix polymer made up of tetrasaccharide repeat units. When a gellan solution (the purple liquid, which can be coloured and flavoured at will) is dropped into a solution of cations, the gellan fibrils' loose ends associate causing the double helices, and subsequently the gel, to form.

The gel's exact consistency depends on pH, ion concentrations, temperature and the length of time they are allowed to gel. These specific conditions and the flavour compounds used in the Fat Duck's gel balls will remain a closely guarded secret until they are ready to star on the menu. But extensive investigation in the Fat Duck lab has ensured the conditions are perfect to form spherical, pea-sized gels that revert to liquid when subjected to a sheer force. In other words, when you bite into the little jellies they become runny in your mouth.

In the future, Blumenthal will continue exploring the psychology of taste - trying to decipher what affects people's experiences of eating. He is working with Edmund Rolls at Oxford University, UK. Rolls is a leading expert on the world of mind and basic emotion. He has looked at cognitive responses to eating in terms of both hunger and pleasure. Blumenthal explains that his unusual chemical combinations might not always be well received, but by joining chemistry, psychology and cooking, he might be able to get around peoples' preconceptions.

'There are a load of theories that we are trying to adapt to the dining room. There's a dish we have with mango, green peppercorn and pine. The reason we took up pine was the terpenes that existed in the mango and the pine. I think it's a wonderful combination.

'But, to some people, it reminds them of household cleaning products. It isn't, it's essential oil of Christmas tree, but there's an association there that needs knocking out. People aren't used to eating it in food. What we did initially in conjunction with Edmund, was give a pre-hit of pine in a pine sherbert. You have this pine flavour five minutes before the dish arrives. It's only one hit but you just fed some information into the memory to soften the potential.' This means that when the dish finally does arrive, the taste isn't unexpected and the diners don't think they've just had a mouthful of toilet cleaner.

Running a busy restaurant doesn't allow much time for scientific tinkering. Blumenthal hopes that the recent appointment of a manager at the restaurant will free up a lot of his time, so he will be more able to dedicate himself to investigating chemical, physical and psychological concepts.

This scientific methodology and investigation when applied to collagen in meat led him to that vacuum packed, 60C for 40 hours method for cooking pigs' heads. It seems likely that with more time to think about the science behind his food, the more likely Blumenthal is to come up with new questions to find the answers to.

'If I discover something for the first time,' he says, 'I get terrifically excited'. And there speaks a true scientist. But Blumenthal might disagree: 'No matter what your theories might be, it has to have a reason to be on the menu. And 90 per cent of the time the reason is because it tastes fantastic. You can do all sorts of clever things for clever's sake, but it still has to pass that test.'

Pommes neuf with hint of hay
Pommes neuf with a hint of hay
Pommes neuf with a hint of hay
 
Ingredients

Potato such as Maris Piper (ideally with high dry matter content) 125-150g per person

Sweet meadow hay 80g per person

Groundnut oil, quantity depends on fryer

Method

1. Soak the hay overnight. Drain the hay, pat dry, and using a blowtorch, flame until a smoky aroma is produced - be careful not to overdo it!

2. Put hay in a casserole and fill with water, covering it by four centimetres. On a high heat bring to a boil. Reduce the heat and simmer for 15 minutes. Remove and stand for 20 minutes to infuse the flavours.

3. Meanwhile, cut chips into 1.5cm 1.5cm 8cm lengths. Place under running water for five minutes. Place chips in casserole and bring to a simmer. Cook until they are about to fall apart, but just holding together - this is crucial for the final texture; you want to cook them as far as you can before they actually fall apart. To test, squeeze lightly between thumb and forefinger, there should be very little resistance.

4. Remove from heat and lift the chips out carefully with a slotted spoon. Place immediately in a vacuum desiccator chamber and, using a vacuum pump, drop the pressure so the chips' residual heat will boil off the moisture in their surface and cool the chips rapidly through evaporation.

5. Heat the groundnut oil to 140C. Place chips in oil and fry until they form a dry looking crust. Remove before they take on any significant browning colour and blot off excess oil. Place hot chips in the vacuum desiccator and repeat the process above to dry out the crust and cool the chips.

6. At this point the chips can be refrigerated or frozen until needed. To finish, heat the oil to 190C and fry until golden brown. Remove from the fryer, blot off excess oil with a paper towel and season with salt.

Explanation

Chips lose their crunch due primarily to the steam created in the centre of the chip itself. This steam wants to escape and in doing so, softens the crust.

A range of methods were tried to reduce the level of moisture within the centre of the chip, ranging from pre-soaking them at 70C to placing them in a drying cupboard after the first blanching process in order to allow some excess moisture to escape.

There will be variation depending not only on the potato variety but also the condition under which it was grown, harvested and stored. No process will compensate for the wrong potato. The chips can be cut into regular pieces or randomly. Although irregular-shaped chips might not look as striking, they do provide a wider textural contrast.



Green tea sour mousse

IngredientQuantityPercentage
Water2kg69%
Fresh lime juice375g13%
Billington's sugar350g12%
Pectin32g1.1%
Green tea60g2.1%
Egg white50g1.7%
Vodka25g0.9%
Malic acid2.5g0.1%
Method

1. Mix together water and lime juice. Mix the sugar and pectin together dry, then blend into the water and lime juice. Bring this solution to a boil and simmer for five minutes. Let cool completely. Infuse the green tea in the cold solution for two hours and then strain through fine muslin.

2. Take this base mix and combine with the egg white, vodka, and malic acid. Pour into a foam canister and charge the foam with nitrous oxide.

3. To serve, spray a small amount of foam into a soup spoon, knock the foam off the spoon into a Dewar bowl filled with liquid nitrogen. Turn the mousse over in the liquid nitrogen for around 10 to 15 seconds until the entire surface has been frozen. Remove from the liquid nitrogen and pass the cold 'poached' mousse to a guest.

Explanation

This dish was conceived as a palate cleanser to remove any residual tastes from the guest's mouth. The polyphenols in the green tea were selected to be breath cleansing, acidity from the lime juice and the malic acid are mouthwatering, and alcohol from the vodka disperses fat and enhances flavour perception. The low temperature provides a visual and tactile surprise.



Further reading

  • Kitchen Chemistry  T Lister and H Blumenthal, RSC, 2005
  • McGee on food and cooking: an encyclopedia of kitchen science, history and culture  H McGee, Hodder & Stoughton, 2004 
  • The science of cooking  P Barham, Springer-Verlag Berlin and Heidelberg GmbH, 2000           



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