NATURE|Vol 464|18 March 2010 OPINION

Q&A: Hervé This on flavour and perception French chemist Hervé This is a pioneer of the field of molecular , the science of . From perfecting the boiled egg to making custards with meat proteins, he has advised top chefs worldwide. He tells Nature why he is moving on to ‘note-by-note’ using compounds to build taste and smells, and why turkey is best cooked in the dishwasher.

Why do some taste better create intense sensations such as strawberry than others? or coffee water. The home cook could in The principles of cuisine are love, art and principle do the same. technique: perfect technique without love and companionship is lost. A poor Another professional technique is to cook sandwich shared with good friends will taste for long periods at low temperatures MAÏTEC MAÏTEC/S. D. better than dinner in a three-star Michelin in a vacuum-sealed bag. How might a home restaurant shared by an arguing couple. emulate this 'sous-vide’ method? Primates generally avoid bitter tastes such Use the dishwasher! For the next holiday as beer. But the sensory punishment of , I recommend that you prepare two drinking bitter beer is more than offset by the turkeys. Cook one in the dishwasher, in a social reward of being in a group. plastic bag, for several cycles of your machine. In this way, you can get low temperatures. Does every ingredient have a unique taste? Butterfly the other turkey and cook it on There is no such thing as unique taste. It is a the grill, creating the maximum expanse of phantasm. The taste of chicken, for example, delicious crispy skin. Then serve the moist, does not exist as a pure concept. Chicken has flavourful meat from the dishwasher turkey many different tastes, depending on the type with the grilled skin. A good accompaniment of chicken and on the way you cook it. them to chefs doing note-by-note cooking, would be foie gras, also cooked in the the farmer could make a profit while dishwasher at low temperature. Should dishes be put together from supporting sustainable agriculture and scratch, molecule by molecule? working within the traditional AOC system. What have you found by studying the Meat, fish, fruits and are cooking process of meat? organized mixtures of compounds. Cooking The taste of your famous Chantilly Our experiments have clearly shown that traditionally means mixing mixtures, and chocolate mousse is more intense than most meat cannot absorb liquids, be they is not precise. This is why I proposed the the ingredients alone. Why is this? acidic or basic, hot or cold. This finding concept of note-by-note cooking — using The importance of microstructure on flavour has shocked many. But we have recently specific compounds to build consistency, is an area of active and exciting research. In discovered that certain kinds of meat — those taste and odour. It is difficult, but a huge an emulsion of oil in water, such as a dressing, with low amounts of collagenic tissue, such unexplored continent is ahead of us. large oil droplets enhance the perception of as beef fillet — can absorb liquids through oil and small droplets enhance the perception capillary action. This reconciles the results of Are from different regions the of odorant molecules that dissolve in the various past scientific studies. same chemically? water phase. The molecular mechanism is Geography can alter the flavour of a food still unclear, but the effect is well established. Are any foods poor candidates for produced with exactly the same methods. My Also, the more surface area you have, the molecular-gastronomy research? friend and colleague Jean-Baptiste Coulon, at more odorant molecules are released. The I try not to work on cheese, wine, the French National Institute for Agricultural same holds for foams. So, if your preparation or sausages — the microbiology is too Research in Clermont-Ferrand, has shown contains many small air bubbles, this complicated. Onions and carrots are better that the flavour of reblochon cheese differs increases the flavour of the chocolate. subjects, but progress is slow. After two PhD depending on the cow’s grazing location, and projects studying the creation of carrot stock, that molecular differences are responsible. How might chefs retain the odorant we are only beginning to understand the Here in France, the Appellation d’Origine molecules that are released in cooking molecular diffusion processes involved. ■ Contrôlée (AOC) system [which certifies a vapours? Interview by Michael White, associate editor at food’s geographical origin] is right and there The already recaptures and Nature. is a measurable difference between locations reincorporates ‘essential oils’ that are lost — a real terroir. during cooking processes. As a result, jams Hervé This’s latest book is The Science of the Oven and orange juice, for example, are now (Columbia University Press, 2009). For Q&As with How would local food producers much better. After decades of my promoting molecular chefs Harold McGee and Ferran Adrià, see contribute to note-by-note cooking? it, chefs have recently taken up using go.nature.com/3cs5Yg and go.nature.com/FzrNmn. Take, for example, this bottle of powder rotary evaporators — a device available in Correction made from the phenolic acids from syrah chemistry-supply stores and usually used The brief review of William Langewiesche’s book grapes. A farmer growing grapes for wine for distillation — to extract these often- Fly By Wire (Nature 463, 882; 2010) incorrectly production alone will probably lose money. lost essences. Using a technology that was spelled the first name of Captain Sullenberger as But if you make these phenolics and sell never designed for cooking, chefs can “Chelsey”. It should have read “Chesley”.

355 © 2010 Macmillan Publishers Limited. All rights reserved