We look at the truths and myths behind cooking techniques as the molecular gastronomy pioneer Ferran Adria prepares to close El Bulli at the end of this month.
The science of cooking
He is a man that many view as a modern master and in culinary circles, is regarded with the same respect as Auguste Escoffier, Paul Bocuse and Antonin Carême.
In short, this is a chef who will go down as one of the greats. Each year, some eight million people attempt to secure a table at his famed three Michelin-starred restaurant in Spain. With only 8,000 spaces available, most come away disappointed. Young chefs travel from far and wide, often offering their services for free, in the hope of crossing hallowed ground and stepping into his laboratory-style kitchen. The majority are quickly sent packing. This is a place that has, over the years, become known as the epicentre of modern cooking.
Ferran Adrià is his name (one of Time magazine's 100 most important people in the world) and the restaurant is El Bulli. Despite its popularity, come the end of this month, no one will be eating there. Adrià has decided to shut the restaurant's doors, with plans to reopen in 2014 under a different guise. He has spoken of creating a culinary academy, mentioned the term "gastronomy think-tank" and suggested that this venture will be launched in collaboration with charitable organisations and academic institutions.
It seems that he is ready to share some of the wealth of his knowledge.
And what knowledge he has. It was Adrià who inspired the likes of Heston Blumenthal (the man behind the three Michelin-starred restaurant The Fat Duck in the UK) and René Redzepi (whose restaurant Noma in Copenhagen has been voted the world's best).
Whether he likes it or not, Adrià's name is synonymous with the term "molecular gastronomy" - broadly speaking, the application and study of scientific processes in cooking - and it is this that he will be remembered for. Through his often pioneering use of spherification, gelification, foam guns and water baths he and his team of chefs have pushed boundaries, challenged preconceptions, invented techniques and, importantly, confused, amused, entertained and befuddled those who have eaten their food. His work has been imitated all over the globe: warm jelly and light, airy foams have become ubiquitous on restaurant menus and much of this is due to Adrià's influence.
While his achievements are undoubtedly impressive, the relevance of his work to the home cook (those of us whose kitchens are equipped with whisks and cheese graters, rather than gas canisters and test tubes) might not be immediately apparent. However, food is a science and a vague understanding of why certain things happen is certainly helpful.
So often when cooking we follow culinary lore (often passed down through the generations or picked up from a quickly glossed over book) without ever stopping to question why. Why do we brown the diced lamb before adding it to a tagine, or waste time by leaving a crêpe batter to rest for 30 minutes, for example?
The meat myth
Accepted wisdom dictates that we sear meat to seal in the juices. Brace yourself, though, because one of the most oft repeated of all culinary clichés isn't actually true. This idea was made popular by the German chemist Justus von Liebig in the 1850s, who suggested that the crust that forms around a piece of meat when it is cooked over a high heat acts as a watertight seal, thus locking moisture in. Despite its enduring popularity, this theory has long since been disproved and, as Harold McGee points out in his book On Food and Cooking "the continuing sizzle of meat in the pan or oven or on the grill is the sound of moisture continually escaping and vaporising".
Although it doesn't magically contain juices, searing meat still has its benefits. It not only creates a pleasing difference in texture between the interior and exterior of the meat, but often improves its appearance and, most importantly, ensures fullness of flavour, thanks to the Maillard reaction. In simple terms, this is the explanation for a series of chemical reactions that occur when small amounts of sugar or starch are heated with a protein or amino acid. Perhaps all the home cook need know is that doing this won't keep their piece of rib eye or fillet full of moisture, but it will intensify the salty, savoury umami flavour of the meat.
Reasons for resting
From steaks to roasted joints, the need to rest meat before slicing and serving it - often for longer than you'd imagined - is regularly impressed upon us. The reasoning behind this practice is often less clear. Very basically, as meat cooks, the proteins within heat up and contract, which forces moisture towards the centre. By leaving the meat to rest, you allow time for this process to be reversed. The core temperature drops, the proteins relax and moisture is redistributed throughout (from the centre outwards) and reabsorbed. This means that when the meat is carved, less liquid seeps out and as a result the meat is juicier.
But it's not just meat that benefits from being left to stand for some time. Batter does, too. Next time you're tempted to skip this step when making pancakes or Yorkshire puddings bear the following in mind. By leaving your prepared batter to rest, you allow the starch molecules in the flour to absorb the liquid (be it water or milk or a mixture of both) which causes them to swell (just like a dried pulse that is left to soak overnight). Because the starch molecules have increased in size, they stick together to form a moist, stable structure. When you pour the batter into the pan, it is more cohesive and cooks in a uniform manner.
The egg issue
While batter isn't hugely temperamental (take 15 minutes off the resting time and it's more than likely that you'll still be able to knock up a half-decent pancake), egg whites certainly are. This probably goes some way towards explaining why recipes that rely on whites (soufflés, mousses, meringues) are often regarded with fear. Treat them without the care and attention they demand and they will either deflate spectacularly or refuse to be whipped up into a foam in the first place.
When you get it right, whisking can exert a transformative power upon an egg white. It creates a foam from captured air bubbles which, when taken to the stiff peak stage, can stand alone and hold its shape - hence the trick of turning the bowl upside down to prove it.
To achieve this, a clean, dry, grease-free bowl is key to your success. But why? Fat, egg yolk and water are sworn enemies of egg-white foam: they interfere with the bonding of the protein molecules and cause the air bubbles to collapse. This doesn't mean that it will be impossible to whip them up, but it does make it harder to do so and the end result is likely to be less stable. Egg whites are so sensitive, that even the oil from your finger tips can make a difference here. If a drop of yolk happens to fall into the bowl, be sure to use an empty piece of eggshell to fish it out, rather than your hands.
When you're baking a sponge cake, although the instruction to "whisk the sugar and butter together until light and fluffy" can feel like a drag, it's an important step. What you're doing is not only ensuring that the ingredients are well combined, but incorporating air bubbles to produce something similar to a foam, which helps to guarantee a tender, light, end result. This is known as fat-sugar aeration. In On Food and Cooking McGee describes the mixing process as being critical in influencing the final texture of the cake and stresses that you should add the flour by: "gently folding it in, not beating, to avoid popping a large fraction of the bubbles, and to avoid developing gluten" - so be gentle.
Cooks are forever being warned that no matter how great the temptation, you should never open the oven door when the cake is baking, particularly at the start. Well, it's all true. The first stage of the cooking process is the crucial one and will determine how much the cake will rise (as the temperature rises the gases in the air cells begin to expand). A rush of cool air (from opening the oven door) will hinder this process and cause the cake to flop disappointingly. Leave it alone at this stage and, all being well, the cake will expand, the batter will solidify and set (second stage), before the surface is lightly browned (third stage).