Par Hervé This

Les recettes:
[Jumbo Shrimp with Vanilla Bean and Ginger Pears]
[Hot-cold Cald Eggs with Basil and Wheat]

[Le Monde des Chefs] [www.thuries.fr]

I mentioned Michael Faraday in an article several months ago. On that occasion, I promised to share with you my enthusiasm for the greatest physio-chemist of all time. Now, a little history of the sciences before we come back to kitchen.

Michael Faraday was born on Sept. 22, 1791, in London. His father was a blacksmith, but it was a life of illness and poverty. Much later, Faraday said that, some weeks, he only had a loaf of bread to eat. In 1804, the young Michael entered an apprenticeship at a bookshop owned by a French immigrant named Ribeau, on Blanford Street. He learned bookbinding, and how to bind newspapers there (at the time, one didn't buy them, but a child passed them from reader to reader). Young Michael lived with his boss and read all the books that fell into his hands, notably a book of chemistry.

In 1808, a customer who knew of the boy's scientific enthusiasm gave him admission passes to the lectures of Davy, a well-known English who had just discovered potassium. Faraday took some notes, illustrated them, bound them. And in 1812, when he completed his training, he decided not to become a bookbinder: instead, he wrote to Davy to ask him for a position, sending with the letter his 386 pages of notes and illustrations. Intrigued by the work and the intelligence that it revealed, Davy brought Faraday to the Royal Institution (a very British mixture of the Palace of the Discovery, of the National Conservatory of the Arts and Professions and of the College of France) in October 1813.

Faraday bloomed and moved from discovery in discovery: he analyzed the caustic lime of Tuscany, finalized special steels, studied the combination of the ethylene and chlorine, discovered hexachloroéthane and tetrachloroethylene, studied light, liquefied chlorine, discovered benzene, perfected eyeglasses, discovered electromagnetic induction and the laws of the electrolysis... Let's stop ourselves there: there is too much! Today, Faraday is known for his "cage" in the Palace of the Discovery in Paris: when an electric charge is sent into the cage, it doesn't hurt a person who is in the cage. For the same reason, passengers of a car or a plane must not fear the lightning in a storm.

No controversies!

If the scientific Faraday was outstanding (he was nicknamed "the prince of the scientists"), the moral Faraday was admirable: it is because his instruction had been rudimentary that he created in 1826 the Friday Evening Discourses, then the Christmas Readings: one week before Christmas, the orphans and the children of London were invited to attend. Faraday told how his whole life had been guided by six simple principles: to always carry a small notebook to write down ideas, to have collaborations, to maintain correspondences, to verify what one tells you, not to generalize and to avoid the controversies.

It is the last principle of Faraday that will make us come back to kitchen. To the style of cooking, more precisely. Let me confess you first that, following the example of Faraday, I adopted his six principles (that I invite you to transmit around you, to the children especially). The last prescribed to avoid the controversies; not the discussions, but the controversies -- that means the proceedings where self-esteem takes the step on the discussion of the facts. What I want therefore here, is not to attack some men, but false ideas. These false ideas are consigned in two expressions: cooking by concentration, cooking by expansion.

Concentration

One often says that cooking encourages the exchanges between the inside of meats and their environment, and the simple common sense shows that it is true: it is sufficient to look at the dish where a roast was cooked to see that juices came out of meat; it is sufficient to make the soup to see that meat yields something to water. A weighing, in every case, confirms that meat lost something. Yet, the cooking of a roast beef is considered a prototype of cooking by concentration! Concentration of what? Not of juices, since they come out of meat. Observe that I didn't speak of the "juices", because this term is imprecise. 

Meat is constituted of muscular cells, fibers, united in bundles by collagen: the collagen is a protein that assembles in fibrous sheaths. Where is the juice of meat? First, there is some in the fibers. There also is blood in the vessels and a few between the cells. This juice is incompressible: it is for this reason that the mechanics can raise the cars with the hydraulic jacks; while pushing a strength curbed on a small piston that contains a liquid, one displaces the liquid, that transmits the same pressure on a big piston and, there, as strength is equal to the pressure multiplied by the surface, a considerable strength exercises itself and raises the car. 

In short, the entire piece of meat is not compressible, since it is only composed of incompressible bodies. So it is reasonable to note that it is false to say that, at the time of the cooking, juice concentrates at the heart of a roast. It cannot concentrate since there is not any place to welcome it. Observe that I don't criticize the practice of letting meat sit after cooking, before cutting it: it is true that juices distribute themselves, but not because they have been compressed at heart. The real explanation is that the juices of the meat periphery came out of meat, and the remaining juices distribute themselves and make a juicier roast. 

Would there be a concentration of the heat in the roast, then? Probably not, because, in an oven, it is the inside of meat that is the coldest part. Heat penetrates progressively. And the transmission of heat is not immediate, as soon as meat is placed in the oven, but it is slow. The phenomenon is named "transfer of heat by conduction": heat is agitation of molecules -- the more the temperature is raised, more the molecules are agitated. So if one heats the air in the oven, the molecules in fast movement, and they knock the molecules on the surface of the meat, they are agitated, and then they begin to agitate the molecules inside, and so forth. The phenomenon is immediate, but the energy transmits itself slowly. 

Let's come back to the concentration. It has been said that cooking causes a concentration of aromatic molecules on the surface of meat. But some quantitative ideas would be better than of observations. What is clear, it is that the diffusion of aromatic molecules in meat is very, very small. For marinades, where I have some experience, I measure a speed of penetration lower than one centimeter per day. Think then, one half-hour of cooking ... No, the aromatic molecules distribute very little. Besides, it is sufficient to look at a slice of roast for reassurance of this fact: no brunette coloration inside! Some who extol the theory of concentration also pretend that salt can penetrate in meat: let me tell you very quickly that precise measures have been made and salt, in a steak, doesn't enter in meat. So ... no heat concentration, no juice concentration, no aroma concentration. No concentration of anything!

Expansion

Cooking by expansion, on the other hand, is reputed to happen when meat is boiled. One has the impression that meat yields some molecules to the liquid in which it is being cooked, and one also believes that the liquid takes the taste of meat. Yes, but... 

But the movement of juices is analogous to the precedent: besides, one sees that meat shrivels in the boiling. Let's look at the dictionary. The meaning of "expansion" is "dilation of a body endowed of expansiveness." But meat cannot expand; it is made of muscle fiber, which is made to contract. In fact, the phenomenon is not an expansion, but merely a loss of juice. So let's stop calling it expansion, otherwise we would also have to call the supposed concentration of the roast an expansion! You will also notice that the liquid - a soup, for example - doesn't in fact take the taste of meat. Numerous chemical reactions take place; many aromatic compounds are formed. It is simple common sense: taste raw meat and a soup. They are not the same. 

And, finally, one says that the types of cooking are three: by concentration, by expansion, and mixed. Evidently, since the first two types are offending, the third is as only a mixture of mistakes.

A revolution waited I cannot resist the pleasure of mentioning Antoine Laurent of Lavoisier, the father of the modern chemistry, who wrote in the introduction of his chemistry treatise that "all physical science is necessarily founded on three things: the set of the facts that constitutes the science, the ideas that are behind them, the words that express them ... As these are the words that hold the ideas, and that transmit them, it results some that one cannot perfect the languages without perfecting the science, nor the science without the language." 

In other words, if we want to perfect the culinary art, or only the culinary technique, let's use the words for what they mean and let's banish the badly suited words, whose sense is warped, for fear that they warp the ideas that we have on the natural phenomena that we observe in kitchen. We know all that the seized steak doesn't keep juices (it is sufficient to look at the pool of juice under the cooked meat): why continue to pretend that the cooking creates an impervious crust, who would keep juices? Do we know all that the roast loses juice; why pretend that juice concentrates at heart? 

Faraday said: to "verify what one tells you, not to generalize hastily"; Lavoisier never told to conclude beyond what the experiences present." Lavoisier was guillotined by the revolutionaries of 1789, whereas he had himself created a revolution in science. I believe that he/it is time that we make the one of the kitchen. Let's put to the dish the theoretical ideas, let's observe, let's exchange the observations, the hypotheses, let's measure, let's weigh, let's size up the ideas to the ell of our measures, and we will have some odds to transmit to our successors a better included kitchen. 

It only is not about cooking, a technique founded on healthy ideas; it is about research to explore the one thousand astonishing phenomena in the kitchen. 

It is one of the objectives of the scientific discipline that we named "molecular gastronomy."