Two ways of imparting flavor to food.
“THINGS OUGHT TO TASTE LIKE WHAT THEY ARE,” the gastronome Curnonsky used to say. His aphorism has been adopted as a slogan by those who seek to promote authenticity in cooking, but does it really make sense? Isn’t the role of the cook to transform foods with the purpose of recreating traditional dishes and inventing new ones?
If the true aim of cooking is to produce specific flavors, the question arises how to incorporate them in various dishes. There are two ways: by adding flavors or by organizing chemical reactions in such a way that flavors are formed in the foods themselves. One technique that has been widely used by the food processing industry involves both natural extracts and synthetic molecular solutions. The use of these so-called aromatic preparations in cooking is straightforward (one simply adds a few drops to the food), but devising them takes the same kind of technical artistry possessed by the “noses” of the perfume industry, laboratory chemists who concoct novel solutions of various odorant molecules in order to approximate or reconstitute familiar scents such as strawberry, ginger, and rosemary.
Cooks are understandably reluctant to allow themselves to be supplanted by such technicians, all the more because the use of natural ingredients (real thyme and real rosemary in a ratatouille, for example) often gives a richer, and certainly more varied aromatic result than artificial thyme or rosemary flavoring (which usually do not contain as many aromatic molecules as natural ingredients).
Must we therefore dismiss such aromatic engineering altogether? This would mean foregoing the opportunity to enlarge the palette of flavors. Why not reinforce the green note of olive oil with hexanal, or add i-octen-3-ol to a meat dish in order to give it an aroma of mushroom or mossy undergrowth (although here one needs to be careful about proportions because in excessive concentrations the same molecule smells a bit moldy)? Why not use beta-ion-one to give desserts the surprising violet aroma that flowers have such a hard time releasing?
Cooks would be also able to create taste, rather than flavor, by using monosodium glutamate and other molecules that impart the taste called umami, which is naturally contributed by onions and tomatoes. They would be able to use licorice or glycyrrhizic acid, which communicate specific tastes that are neither salt, sugar, sour, nor bitter—nor umami.
Advanced Uses of Fire
Need we worry that in this case culinary progress would be limited to chemical aromatization, which is only a modern version of adding fines herbes and spices to foods? Certainly not: Cooks well know that cooking transforms the taste of their creations. Fire is their inseparable ally, and chemistry can help them make the most of it.
For example, one can easily change the flavor of caramel by varying the type of sugar. Caramels can be made from glucose, fructose, or, more generally, from sugars other than sucrose (ordinary cane sugar). An experiment that anyone can perform will show that these caramels may already be present in foods. It is based on an apparently paradoxical observation made by cooks who, in the course of making a béarnaise sauce, for example, reduce a combination of chopped shallots and white wine until the liquid is completely evaporated: Certain white wines leave no residue in the pan. Why? Because they lack glucose, glycerol, and many other things. The practical lesson is this: If your wine is insufficiently rich in such aromatic molecules, add some glucose to it before reducing à sec and you will obtain a glucose caramel that improves the flavor of the sauce.
The Paradox of Reductions
There is something puzzling about even a reduction that has been fortified in this way, however. Why should one want to evaporate most of the aromatic molecules that are present in wines? The same question arises in the case of stocks, which are made by concentrating beef broths through heating. If this concentration has the effect of eliminating the aromatic molecules, why are stocks nonetheless fragrant and flavorful?
Anthony Blake and François Benzi at the Firmenich Group in Geneva used chromatography to compare a stock that had been reduced by three-quarters and then restored to its initial volume by the addition of water with the same stock that had not been topped off. Although the concentration of certain aromatic compounds was reduced by boiling, other compounds were created by heating-induced reactions between the components of the stock. It remains to identify these reactions in order to improve the making of stocks, if possible.
On Chemistry in Cooking
The possibilities of chemistry are unlimited. Our kitchen shelves hold a great many nearly pure ingredients: sodium chloride, sucrose, triglycerides (in oil), ethanol, acetic acid, and so on. And the shelves of our libraries contain a great many chemical treatises that perfectly describe the reactions of these molecules. The challenge facing cooks and chemists today is to apply this knowledge in order to create new flavors.
Take Maillard reactions between amino acids and certain sugars, which produce the tasty brown compounds in the crust of roast beef and bread as well as the aromas of coffee and chocolate. Chemists know that these reactions differ according to the acidity of the reactional environment. Why not soak chicken breasts in vinegar or bicarbonate of soda before putting them under the broiler? To obtain the right degree of acidity once the reaction has occurred, the vinegar could be neutralized with bicarbonate of soda or vice versa.