Beef stock (also called broth or bouillon), chef Jules Gouffé wrote in Le livre de cuisine (1867), is “the soul of ordinary cooking.” Rather than water, which has no taste, cooks have long used wine or the liquid obtained by simmering meats and vegetables in water. This liquid traditionally is served as a first course, but it is used also to moisten various dishes and as an element in the preparation of sauces. How should it be made?

Cookbooks are filled with admonitions. “The gradual heating of the liquid,” states Le livre de cuisine de Mme. E. Saint-Ange (1927), “is...

Cook books make many curious claims. One by the late Bernard Loiseau asserts that adding ice cubes to a cloudy broth “stuns” the suspended particles, causing them to fall to the floor of the stock pot. One may quibble with this way of stating the matter, but does it contain an element of truth?

Let’s begin by selecting particles close in size to those that actually cloud beef broth. Ground coffee is a good candidate because it consists of particles of various sizes. But because, unadulterated, it would excessively tinge the color of the broth, let’s dilute it by running...

Cook books say that to obtain a hard-boiled egg with a centered yolk, the egg must be cooked in water that has already been brought to a boil. Experience often demonstrates the soundness of this advice, but sometimes one follows it and the yolk ends up being off center. Other times the yolk comes out in the center when the egg has initially been placed in cold water. What good is advice if it isn’t always good?

First things first. Why is the yolk sometimes decentered? Because it has changed position inside the egg. Why has it changed position? Because...

A quiche must not be cooked too long, or it will lose its smooth consistency. It will not be perfectly moist (or chevelotte, as they say in some parts of Lorraine), hence the culinary rule: Cooking must stop when the quiche begins to rise. Rise? Why does it rise? And why is this a sign that the quiche is done?

To answer the question, let us examine another dish that also expands: the quenelle, a cousin of the German Knödel, or dumpling. Whether the quenelle is made of finely minced fish or meat, the flesh has in most cases been...

Échaudés are very old preparations: As early as 1651 Nicolas de Bonnefons mentions small pieces of dough that have been “scalded” in boiling water. There are many recipes, but from the oldest échaudés to potato gnocchi and gnocchi à la parisienne the principle is the same: One begins with a dough composed of starch, egg, and water. In the case of potato gnocchi, extra starch is contributed by the granules found in the potatoes (which are cooked, peeled, and mashed). Other recipes include parmesan cheese and milk. The dough is kneaded with a spatula, then placed on a floured baking...

How can one make a perfect soufflé every time? The question is not only of practical interest to cooks. Measuring the pressure inside a cheese soufflé and the loss of water during cooking will also help food scientists understand the dynamics involved.

Contrary to a widely held belief, this dish is within the reach of beginners. In the case of a cheese soufflé, for example, begin by preparing a béchamel sauce, heating flour and butter, and then adding to this milk and grated cheese. Next, off heat, fold in egg yolks and (very carefully) beaten egg whites. The result is...

As with échaudés, often called gnocchi today, there are many recipes for fish quenelles, but whether they call for salmon or trout or pike they are all variations on a theme: To the finely ground flesh of the fish one adds fat (beef kidneys, butter, or cream) and perhaps egg and panada (either bread soaked in milk or a dough made by combining flour with boiling water). The ingredients are kneaded for a long time—so long, in fact, that Isabella Beeton (author of the famous cookbook published in England in 1860 as Beeton’s Book of Household Management) wrote, “French...

Does the true cheese fondue come from Savoy in France, or the Valais in Switzerland, or the canton of Fribourg? How many types of cheese should be used? One? Two? Four? Connoisseurs passionately disagree. Wars have been started for less. Physical chemistry may not permanently settle such disputes, but it should at least enable lovers of the dish to reach agreement over why, despite its simplicity, the fondue sometimes flops. Athony Blake, director of food sciences and technologies for the Firmenich Group in Geneva, has discovered a surefire way to prevent it from turning into a solid mass lying at...

Many home cooks today are pressed for time. Their haste prevents them from eating good roasts of beef, for example, for they often neglect an indispensable step after cooking: letting the meat rest, with the door of the oven open. Omitting this step means that the meat will be tough and dry. Professional cooks are well aware that letting meat rest is essential if it is to be tender, but they believe this is because, in the process of cooking, the juices want to “escape” the heat of the oven and consequently flow back into the center of the meat....

When you grill a steak, naturally you salt it. But when? Before putting the meat on the grill? During cooking? Just before eating it?

Cooks are naturally inclined to respond on the basis of their own experience, but sometimes this is insufficient. As Oscar Wilde remarked, experience is the sum of all our past errors; as long as errors are not recognized, they remain alternative truths. Therefore it helps to conduct experiments in which the various parameters are controlled—the only way to cut to the heart of things, meat among them.

Some argue that introducing salt beforehand gives it...

It is said that fish must be cooked in white wine but that red wine should be used to marinate and cook tough meats in order to tenderize them. It is also said that parsley must not be used if the marinating process lasts more than two days and that one should not roast marinated meats because roasting dries them out. How far should we credit these familiar dictums?

Japanese physical chemists recently provided partial corroboration. Experiments conducted some twenty years ago in France, at the Institut National de la Recherche Agronomique station in Clermont-Ferrand, showed that beef is tenderized...

The vibrant colors of fruits and vegetables are a sign of their freshness. Alas, no sooner have avocados, salsifies, apples, pears, and mushrooms been sliced or chopped than they turn brown. Can this degradation be avoided? Can fresh-squeezed apple juice make it from the kitchen to the table without turning dark? Cooks have long recommended using lemon, whose juice they believe prevents the appearance of colors associated with overripe, damaged, or rotten organic matter. Is this recommendation sound?

Let’s put it to the test. If we compare avocado slices exposed to the oxygen in the air with slices that have...

Consider this passage from an anonymous work published in 1838 under the title Le cuisinier parisien: “Beans, peas, and lentils, and many other vegetables cook well only in very pure and light water; [water] from rivers and streams is always the best; that from wells is worthless. In places where only well water is to be had, it can be made suitable for cooking vegetables by adding to it a little carbonate of soda, dissolved in water to the point that it no longer whitens the water. It leaves a small deposit; one takes the clear liquid and uses it...

Souffléed potatoes look like small, crispy golden balloons. They are said to have been discovered on August 25, 1837, during the dedication of the railroad line linking Paris and Saint Germain-en-Laye. The menu for the official luncheon was to include fried slices of potato, but when the train had trouble climbing the last hill the chef was forced to interrupt the frying; once the guests were finally seated, he immersed the slices once again in very hot oil in order to make them crispy. They puffed up.

Since then cooks have differed over the proper way to make this difficult...

Let’s examine a few more dictums. L.-E. Audot, author of La cuisinière de la campagne et de la ville (1847), says that in order to make fruit preserves “it is indispensable to use an unplated copper pan (earthenware or terracotta ones being liable to burn [the preserves] or impart a bad taste).” Sixty years later, geologist Henri Babinski, in his Gastronomie pratique (1907), advised, “For preserves made from red fruits, it is preferable to use an enameled pan, which does not transmit any sharp taste, as often happens with unplated copper pans.” During the same period, professors at the École...

How can one save a crème anglaise that has curdled? The question is of culinary importance because crème anglaise figures in one form or another in many desserts. One of the differences between crème anglaise and crème patissière, for example, is that although both are composed of milk, egg yolks, sugar, and an aromatic ingredient such as vanilla, crème patissière additionally contains a certain amount of flour, which protects against curdling. Crème anglaise, lacking this protective agent, is more liable to turn.

The Second International Workshop of Molecular Gastronomy, held in April 1995 at the Ettore Majorana Center in Sicily,...

Myths about salt die hard. For example, some cooks recommend adding salt only to water that is already boiling because salty water, they say, takes longer to boil than pure water. This rule is widely believed, but is it justified?

Or consider the question of boiling meat to make stocks. Many cookbooks say that meat should be salted first in order to better extract its juices. Is the promised efficiency real or illusory? On the other hand, salad is not to be salted too far in advance because seasoning it in this way will wilt the leaves. What is one...

A teaspoon placed in the neck of a bottle of opened champagne, it is said, will help preserve its fizz for a certain time. Some even go so far as to claim that the effect occurs only with silver spoons. What reason is there to believe such dictums, which seem to be the product of nothing more than unscientific experimentation? By virtue of what strange physicochemical principle could a teaspoon trap the bubbles of this noble beverage of celebration? As it happens, there is no need for us to inquire into this matter ourselves because the Comité Interprofessionnel du Vin...

The most common everyday experiences give rise to practical questions. Is it true that running, rather than walking, under the rain will keep you drier? Does it really feel cooler to wear white clothes on a sunny day? Does water always drain out from a bathtub in a clockwise direction in the Northern Hemisphere? Testing such questions experimentally is a simple matter, but we are rarely willing to go to the trouble.

Small mysteries of this sort abound in cooking. Take the coffee we drink every morning. It is always boiling hot, and we are never sure how to cool...

To the greek mind, barbarians were people who did not change their diet when they were sick. At the Laboratoire d’Écologie Générale of the Museum in Brunoy, Claude Marcel Hladik and his colleagues demonstrated that under certain circumstances monkeys eat earth, or plants containing alkaloids, in order to preserve a balanced diet—even to treat intestinal disorders. In this they are close relatives of the civilized world.

The reaction of primates to sweet solutions is a striking feature of mammalian evolutionary adaptation: The larger the animal, the more efficiently it detects sugars. Large animals, better equipped to recognize sweet foods,...

Why do we stop eating even though only a small quantity of metabolites has entered the bloodstream? The sensation of a full stomach does not signal satiety: A rat whose belly has been pumped full of air does not cease to eat. Through a series of reflexes, however, the organism is able to anticipate the metabolism of foods. For example, a bit of sugar placed on the tongue triggers the almost immediate release of glucose by the liver.

Around 1960, Stylianos Nicolaïdis and his colleagues at the Collège de France observed that the stimulation of the taste receptors by saccharine...

Jean-anthelme brillat-savarin observed in Meditation 2 of The Physiology of Taste, “Up to the present time there is not a single circumstance in which a given taste has been analyzed with stern exactitude, so that we have been forced to depend on a small number of generalizations, such as sweet, sugary, sour, bitter, and other like ones which express, in the end, no more than the words agreeable or disagreeable, and are enough to make themselves understood and to indicate, more or less, the taste properties of the sapid body which they describe. Men who will come after us will...

In 1994, richard axel and linda buck at the College of Physicians and Surgeons of Columbia University in New York announced the discovery of proteins in the membrane of nasal cells that capture odorant molecules and make olfaction possible. The news caused a great stir, but it failed to satisfy researchers interested in the related problem of taste. Two years later another team of biochemists at Columbia, Gwendolyn Wong, Kimberley Gannon, and Robert Margolskee, published the results of a study of gustducin, a protein found in the papillary cells of the tongue that had been cloned in 1992 but whose...

True gastronomes have two great fears: gout and a diet without salt. To guard against gout they abstain, at least occasionally, from gamey meats; but against a salt-free regime they find themselves powerless and dread the doctor who prescribes it. This fear is doubly well founded. Gary Beauchamp and his colleagues at the Monell Chemical Senses Institute in Philadelphia have shown that the absence of the salt taste is not the sole inconvenience of this regime. Without salt, agreeable tastes forfeit their prominence, and they are unable to prevent disagreeable tastes from asserting themselves.

In earlier chapters I examined the...

One of the holy grails of physiology is finally in our hands. For decades physiologists sought to explain how the cells of the gustatory papillae detect taste molecules. It was supposed that the surface of these cells contains proteins called receptors, to which the taste molecules attach themselves, but these receptors proved to be elusive. Attempts to extract them from papillary cells in solution were unsuccessful because receptors form a weak bond with taste molecules. Compensating for this experimental difficulty is a physiological advantage: If the bond were strong, receptors would be stimulated for long periods of time by a...

In 1995 the physiology of smell took a great step forward with the identification of the proteins that constitute the receptors of nasal olfactory cells. However, the receptors of the papillary cells in the tongue and mouth that are sensitive to taste remained unknown. These gaps are gradually being filled. Alejandro Caicedo and Stephen Roper at the University of Miami have shown that the human gustatory system is capable of distinguishing several sorts of bitter taste.

In 2000, the same biologists who five years earlier had discovered families of olfactory genes found a vast family of receptors for what was...

In seeking to compose a perfectly balanced and flavorful dish, the cook naturally looks to old recipes for ingredients whose combination has been tested and validated over the course of centuries. But traditional ways are not always the best. The various elements assembled from culinary experience must harmoniously stimulate not only the senses of taste and smell but also thermal and mechanical sensors, to say nothing of the chemical sensors for spiciness.

Our chances of success will improve if we have a precise understanding of the underlying molecular mechanisms. We know that sour and bitter tastes are offset by sweet...

The physiology of flavor is riding a wave of fresh discoveries. In recent years physiologists have elucidated the molecular bases of the sensation of spiciness, described the mechanisms in the papillary cells of the mouth responsible for taste perception, and at long last, in April 2000, identified the first receptor for a taste molecule. It was expected that the analytical methods that led to this last discovery would help researchers find other receptors, but a great surprise lay in store: thermal tastes. Variations in the temperature of the tongue alone are enough to cause tastes to be perceived.

When we...

Dr. john harvey kellogg, he of the breakfast cereals, advocated a hygienic regime based on relentless mastication. His ideas echoed an ancient East Asian tradition according to which each mouthful of whole-grain rice was to be chewed 100 times.

Why do we chew in the first place? Everyone knows that mastication breaks up food into smaller pieces—small enough that, having also been lubricated by saliva, they easily descend into the digestive system. Jons Prinz and Peter Lucas at the Odontological Museum in London have identified another function. Without knowing it, we chew until particles of food are bound together...

Less than a decade ago tenderness was thought to be the most important sign of a good piece of meat. After all, the true gourmet detests tough meat. But how does one tell tenderness and toughness apart? It had been forgotten that meat is not butter and that texture is one of its fundamental qualities. Toughness was confused with a lack of juiciness and the need to chew for a while before swallowing. To elucidate the relationship between the physical structure of meats and their texture, Institut National de la Recherche Agronomique biologists in Clermont-Ferrand analyzed the mastication of samples...

Which aromas do we perceive when we eat? For a long time this question could not be answered, for chemical analysis was unable by itself to determine the concentrations of odorant molecules in the vicinity of the receptor cells in the nose. Andrew Taylor, Rob Linforth, and their colleagues at the University of Nottingham, working in association with Firmenich (an international perfume and flavor research group), have been conducting experiments since 1996 with a device that shows how aromatic compounds are released during the mastication of food. The same food, it turns out, smells different to different people.

Odorants—volatile...

Food-minded parents are forever complaining that their children like only starches (pasta, rice, potatoes), the blandest cheeses, and tasteless meats (especially the white meat of chicken). Why do we begin our eating lives liking such dull foods? How can children be set straight about food before it’s too late? It used to be that psychologists and sociologists were likeliest to wonder about the biological motivations that cause parents to despair for their offspring. Today it is the sensory biochemists who have taken the lead in exploring the dietary preferences of children and how these change.

An important experiment that only...

Gastronomy is not a world only of pleasurable aromas and tastes. More than one-quarter of the population in seven countries of the European Union claims to suffer from food allergies or intolerances. Although clinical tests indicate that the actual incidence of such allergies is much lower than commonly believed (about 3.5% of the population), these reactions pose a major public health problem, all the more because the seriousness of the attacks reported is on the rise. In the last ten years the number of cases of anaphylactic shock caused by a food allergy has quintupled, and many of these attackes...

Cases of listeriosis are dramatic, sometimes fatal, and all the more shocking because measures to protect public health have never been more effective. Nonetheless this relative security cannot be counted on to prevent the occurrence of illness, even death, among people in the leading risk groups: pregnant women, the elderly, young children, and those with immunodeficiencies. Because health alerts are issued as a consequence of retrospective epidemiological inquiries that compare strains isolated from the victims with products suspected of contamination, they constitute a response to crisis rather than a means of preventing it. One of the profound challenges facing basic...

The behavior of wheat flour can be understood by analyzing the properties of its two main components: starch granules, which swell up in the presence of water, and proteins, which form a glutenous network as dough is kneaded. How do the forces among proteins contribute to the mechanical properties of the dough? It has long been known that bonds between the sulfur atoms found in wheat proteins play a role in structuring gluten. Other forces have been discovered as well.

Gluten is a viscoelastic network of proteins that becomes elongated by pulling and then partially reverts to its initial form...

French bread—particularly its principal representative, the baguette—is reproached nowadays for having less flavor than it used to and for drying out too quickly. The second criticism is unjust, for it neglects the fact that the baguette was a product meant for city dwellers who could buy what they needed several times a day at their local bakery; the crust was more important than shelf life. Yet many bakers today admit to being more concerned with the mechanical behavior of the dough than the taste and odor of the bread.

The flavor of bread comes from the cooking of...

Behold the egg, whole and raw, in its shell. Where is the yolk? No doubt, the physicists will say, on a vertical axis—for reasons of symmetry. Yet there are other possibilities. The yolk could be in the upper part, in the center, or in the lower part. How can we determine its location? Put a yolk in a tall, narrow glass and cover it with several whites: The yolk rises to the top, which suggests that the same thing occurs in a whole egg.

But could it be that the membranes that surround the yolk and bind it to...

A glass of vinegar is undrinkable, but it becomes palatable if one adds a large amount of sugar to it. Yet the pH—the acidity of the vinegar measured in terms of the concentration of hydrogen atoms—is unchanged. Why is the sensation of acidity weakened? Because the perception of tastes depends on the environment in which taste receptors operate. The same interactions take place in the vicinity of the olfactory receptors. Chantal Castelain and her colleagues at the Institut National de la Recherche Agronomique station in Nantes sought to identify these synergies in order to lay the basis for...

Cooks well know that adding too much flour to a sauce makes it tasteless. The reason is that the flavor of foods does not depend solely on the odorant and taste molecules they contain but also on interactions between these molecules. Molecules with no odor, such as proteins and starch molecules, bind with certain odorant molecules and prevent them from acting on our senses. One would like to know exactly which aromas are masked in this way.

Identifying all the chemical bonds between the various molecules in a food is not enough, for its physical structure plays a role as...

Lumps—the shame and despair of the cook. Cookbooks suggest various ways to avoid them in making béchamel and other sauces that are thickened with flour. Some authorities say to make a roux first, cooking butter and flour and then adding milk (cold according to some, hot according to others); others insist on the opposite method, namely pouring the roux into the milk, which, again depending on the author, should be either cold or hot.

Which method is better? If we are willing to waste a bit of flour, butter, and milk in order to test the four possibilities we...

Foams—low in fat because they are essentially composed of air—first came to prominence with the rise of Nouvelle Cuisine in France in the 1960s and then gained broader popularity as a consequence of the growing interest in lighter foods on both sides of the Atlantic. Today, with the advent of molecular gastronomy and, in particular, the fame of the Spanish chef Ferran Adrià, they are very fashionable among gourmets. In the early days foams were obtained by vigorously beating egg whites, but the variety of eggs combined with ignorance of the optimal conditions for making foams led to...

Hard sausages such as french saucisson are traditionally made by adding sugar, salt, saltpeter, herbs, and spices to a mixture of meats that is then put into a casing and left to dry for several months. This method, which does not rely on any fermentation agents (acidifying and aromatizing microorganisms), can produce both the best and the worst results. Insufficient acidification by bacteria naturally present in the meat carries the risk that pathogenic microorganisms will develop. Moreover, spontaneous flora do not invariably impart a pleasing taste to hard sausage.

In seeking to avoid this Charybdis through the use of controlled...

In recent years the production of Spanish hams has risen to almost 30 million units per year. Some of these, obtained from Iberian pigs by traditional methods in the southwest of Spain (more than a million hams a year), have a taste that is so remarkable that the European Union has granted protection to producers in their place of origin. How is this taste achieved? Jesús Ventanas and his colleagues in the veterinary faculty of the Universidad de Extremadura at Cáceres have examined the various stages involved in the long process of preparing these hams and identified the reasons for...

Both alsace and the southwestern region of France claim to have been the first to invent foie gras, but it is not a new delicacy: The Romans are known to have force-fed geese with figs. The manner in which it is prepared is changing, however. Goose livers traditionally were cooked several hours after the animals had been slaughtered, but a revision of food industry regulations in France has led to a centralization of local slaughterhouses and, with it, the practice of immediate evisceration and cooking. What effect has this had on the quality of the livers?

In the early 1990s,...

Butter and other foods containing fats turn rancid on contact with air as a result of a chain reaction: the autoxidation of fatty acids. Arresting this degradation, which produces disagreeable tastes and odors and creates free radicals, has long been an elusive goal. Eliminating oxygen from foods and to protecting them from light is not enough. Antioxidant compounds are also needed to combat the precursors of autoxidation that are already present.

Some foods naturally contain antioxidant compounds that protect them from turning rancid, such as the tocopherols (vitamin E) found in virgin olive oil and the ascorbic acid (vitamin C)...

What makes sea trout taste so good? Is the pink color of its flesh a sign of quality? How should it be cooked to satisfy gourmets? And how should it be raised to suit processing requirements, particularly in connection with smoking, a technique in which French companies have long specialized?

Although France is among the world leaders in trout production, the study of trout aquaculture is almost thirty years behind the study of beef and other kinds of meat. One of the chief problems is inadequate genetic selection, which causes unwanted variability in the quality of farm-raised fish. Benoît Fauconneau,...

How long should a joint of beef be cooked? The problem is an old one, as we know from Brillat-Savarin’s Physiology of Taste, and raises the question of what laws govern the various methods that have been devised for cooking foods. Putting aside certain exotic cases, such as the preparation of fish with acids in the Tahitian manner, in which filets are marinated in lime juice, the cook should keep in mind that cooking is fundamentally a transformation of foods by heat.

This naturally leads us to ask another question: How is heat most efficiently transmitted for the purposes of...

Do fats impart a distinctive flavor to meats? If so, which one? It was long believed that lipids were capable only of dissolving odorant compounds, many of which are water insoluble. They have also been accused of giving meat a bad taste, turning rancid, or oxidizing during cooking. Nonetheless cooks have long known that the flavor of meat is affected by the fats it contains or the fats that are added to it during cooking. Today chemists can confirm that fats play a decisive role in Maillard reactions, whose products are the chief aromatic components of heated foods.

There are...

Meat is agreeable to eat only when it has been aged for a sufficient period of time. After an animal is slaughtered its meat begins to toughen (for twenty-four hours in the case of beef). This toughness can be reduced by as much as 80% by aging, which lasts for several days (ten in the case of beef). Can this period be shortened, or is it at least possible to determine the minimum amount of time needed to preserve carcass and muscle so that a given cut of meat will be properly tenderized? Ahmed Ouali and his colleagues at the...

Anyone who puts spaghetti in hot water for ten minutes or so and expects a good result is bound to be disappointed. Simple though it is, the cooking of pasta raises a number of questions. The first has to do with salt: Must it be added to the cooking water and, if so, why? Is it really necessary to add oil to the cooking water? How can pasta be prevented from sticking?

At home one can quickly make good pasta from scratch by mixing flour (usually made from wheat, but corn or chestnut flour may also be used), a bit...

A host of unfamiliar vegetables—Japanese artichokes, pepinos, Cape gooseberries, Peruvian parsnips, tuberous chervil, sea kale, skirret—are now available to enliven the diet of those who are tired of carrots, leeks, and potatoes. Jean-Yves Péron and his colleagues at the École Nationale d’Ingénieurs des Travaux de l’Horticulture et du Paysage in Angers are studying forgotten or unknown vegetables with a view to improving their reproduction and cultivation. Not only are food lovers eager to try these novel varieties, but economists also welcome the interest of the Angevin agronomists in promoting diversification because saturation of the market for garden produce...

Mushrooms are fragile and hard to keep. Consumers will put up with wild mushrooms that are a bit bruised, but they want ordinary button mushrooms to be nice and white, with a short stem, small cap, and gills that are covered by a continuous veil, for they know that mushrooms can rapidly change character. A few days is all it takes for mushrooms to darken, for their stems to lengthen, for their ink-black gills to be exposed, and, worse still, for their taste and texture to be denatured.

How can mushroom producers keep their products fresh for longer periods of...

The black diamond! An immense amount of ink has been spilled in singing its praises. No food writer fails to mention its appearance on a menu, and no chef neglects to feature it when he aims for stars. For centuries the merits of the various black truffles that grow in Western Europe have been debated. The black truffle of Périgord is recognized have a quite different taste from the one found in Burgundy, and naturally the truffles found in France are claimed by the French to be far superior to those of Spain and Italy. Can science provide an objective...

Some classic recipes appear paradoxical. To make a salmis de canard, for example, one removes the breasts and thighs of the duck and roasts them. The cook then makes a sauce by cooking the scraps and bones of the duck in water together with vegetables and aromatic herbs. Isn’t the second step redundant? No, because in the final dish the odorant and taste molecules contributed by the duck are retained for different lengths of time by the meat and the sauce before being released. As a result, the flavor of the dish lingers in the mouth longer.

The problem of...

Many of the fries served today in restaurants in France come out of a vacuum-sealed bag. Home cooks still prefer to use fresh potatoes because they soak up less oil. Will traditional practice give way to the new technique of packaging sliced potatoes raw under a controlled atmosphere, developed in 1997 by Patrick Varoquaux and his colleagues at the Institut National de la Recherche Agronomique (inra) station in Montfavet?

In cafeterias and restaurants at least there is no avoiding the convenience of precut and processed potatoes because the large volumes consumed take extensive advance preparation. Another complication is that potatoes...

Why do mashed potatoes made with milk stick less than ones made with water? By showing that proteins modify the thickening and gelatinization of starch, Jacques Lefebvre and Jean-Louis Doublier at the Institut National de la Recherche Agronomique station in Nantes have at last provided an explanation of this venerable piece of culinary knowledge and useful indications for the use of flour in sauces.

Flour and potatoes have in common the fact that they contain a great deal of starch, in the form of granules that contain two sorts of molecules: amylose, which is composed of a linear chain of...

In parts of the far east algae have been used as vegetables in soups and salads since ancient times. In France they serve mainly as a source of iodine and fertilizer and as gelatinizing or texturing additives. Although eleven species of algae were recently accepted as vegetables by the French health authorities, their chemical composition and metabolism are poorly understood. Analysis of the fibers they contain nonetheless has illuminated the sources of their nutritional value.

The modern vogue for fibers began in the early 1970s when the British physician Denis Burkitt discovered a correlation between certain digestive, metabolic, and cardiovascular...

To protect their camemberts and other raw milk cheeses against legislation that would prohibit the use of raw milk in fabrication, countries such as France must demonstrate the gastronomic superiority of these cheeses by comparison with ones made from pasteurized milk. To do this they must perform a detailed comparison of the chemical composition, texture, and aroma of the different types, which will take quite a while. In the meantime, the Institut National de la Recherche Agronomique and the Comité Interprofessionnel du Gruyère de Comté, in collaboration with food research institutes elsewhere in Europe, have been analyzing cheese with the...

Le terroir—the land. For several years food producers have been talking of nothing else, often out of a desire to protect or expand their markets. If they are to be believed, there is a special relationship between a region and its products; no version of a product made elsewhere is as good as the original, which for this reason is the only one to merit a protected designation of origin.

Agronomic analysis has demonstrated the effects of climate, soil, and exposure in the case of wine, but cheese proved to be a trickier proposition. Working with producers in the...

Aromas are the stars of the food industry: Many firms produce and sell them to the large food processing conglomerates that make yogurts, soups, sauces, and so on. Nonetheless, foods that are aromatic and little else please only the nose, for they are lacking in taste—hence the interest in taste molecules, still poorly understood. Do these molecules exert the same effect in foods as in water solution, where their properties have long been studied? At the Institut National de la Recherche Agronomique Laboratoire de Recherches sur les Arômes, in Dijon, Christian Salles, Erwan Engel, and Sophie Nicklaus studied this...

How does one make a good yogurt? The question is poorly posed, for some like their yogurt runny and others like it firm. Ideally what one would want to be able to do, then, is to balance the composition of milk and the method of fabrication in a way that will yield a specific texture and taste. Achieving this objective will take some time, but already Anne Tomas and Denis Paquet of the Danone Group, together with Jean-Louis Courthaudon and Denis Lorient of the École Agro-Alimentaire in Dijon, have shown that the texture of yogurt depends on the microstructure of...

Slowly, over centuries, cooks learned to make solid foods from liquid milk. Cheeses are milk “preserves,” made by destabilizing milk and eliminating the water it contains in the form of whey. Yogurt is obtained by heating milk fermented by the bacteria Lactobacillus bulgaricus and Streptococcus thermophilus. These microorganisms transform the principal sugar in milk, lactose, into lactic acid, which in turn acidifies its liquid environment and causes a network to form throughout the liquid, creating a gel.

In recent years fermentation and curdling methods have been improved, and the texture of yogurt is now known to be determined by the...

Try to imagine what the perfect, ideal, Platonic sabayon would be like. A sabayon (the name is derived from the Italian zabaglione) is made by mixing egg yolks and sugar, beating them with a whisk, and adding sweet wine. Heating the mixture while continuing to whisk it, one observes that it becomes foamy, forming a sauce that is served with thinly sliced fruits or sipped as a digestive. The danger, then, is that for one reason or another the preparation won’t foam up. Can chemistry and physics be harnessed to guarantee a successful result?

There are many published recipes. Marcelle...

Autumn draws near, and with the coming of cold weather summer’s fruits will soon vanish. How can they best be preserved to last through the winter? Several methods are common, especially canning and freezing. In each case one seeks to prevent the proliferation of germs, which at room temperature occurs rapidly in foods that contain sufficient quantities of water and organic matter to favor the development of microorganisms.

Anyone who has tried to preserve fruit in syrup is familiar with the need to steer a safe course between the Charybdis of fruit that swells to the point of falling apart...

During the winter, the specter of a jam that fails to set haunts cooks who make orange marmalade. Sometimes, instead of forming the expected semisolid mass, the juice remains juice. How can this culinary debacle be avoided? Jean-François Thibault, Catherine Renard, Monique Axelos, and Marie-Christine Ralet at the Institut National de la Recherche Agronomique station in Nantes have found an answer to this question, although the purpose of their research was mainly commercial. They showed that the technique of extrusion cooking, used especially in fabricating cocktail crackers, makes it possible to extract large quantities of pectin, which is to say...

Why does chocolate become covered with an ugly white film after a few days? Michel Ollivon and Gérard Keller of the Centre National de la Recherche Scientifique (crns), in collaboration with Christophe Loisel and Guy Lecq of the Danone Group, have recently explained how certain constituents of this partially liquid mixture migrate and crystallize on its surface, causing it to change color.

Chocolate is a dispersion of sugar crystals and cocoa powder in cocoa butter. Once crystallized, the cocoa butter serves as a binding agent for the solid particles, just as cement binds the sand and gravel in concrete. Nonetheless,...

Seneca mentioned caramel as early as 65 bc, but for more than 2000 years the details of the chemical reactions that give heated sugar its inimitable flavor were unknown. Exploiting recent results in the chemistry of sugars and using modern analysis techniques, Jacques Defaye and José Manuel Garcia Fernandez at the Centre National de la Recherche Scientifique laboratory in Grenoble recently elucidated the structure and mechanisms responsible for the formation of the odorant and taste molecules that make up caramel.

Along with the Maillard reaction, which generates the aroma of roast beef, coffee beans, beers, and bread crust, caramelization is...

Left out in the kitchen, at room temperature, bread goes stale. Frozen, it seems to change more slowly, but at what temperature must it be kept in order to stay in the same state as when it comes out of the oven? 7°c (45°f)? 0°c (32°f)? −10°c (14°f)? Physical chemists at the École Nationale Supérieure de Biologie Appliquée à la Nutrition et à l’Alimentation (ensbana) in Dijon have sought to answer this question using their knowledge of polymers, which are very long molecules formed by the linking of subunits called monomers. This seemed to be a natural approach, for foods...

The world of wine and vine so little doubts the existence of differences in the overall natural environment—the terroir, as it is called—of wine-growing regions that it has made them the basis for awarding protected designations of origin. Is this justified? Agronomists are accustomed to examining how the particular features of a given viticultural site—its climate, soils, and parent rock—affect the growth of its vines. Éric Lebon and his colleagues at the Institut National de la Recherche Agronomique (inra) station in Colmar have studied defined sections of the Alsatian landscape and shown that its openness is...

Biochemists are very interested in the methods used for making wines, but they have rarely explored the physiology involved in tasting them. Recent results suggest that this situation may be changing. In wines made from the Sauvignon Blanc grape an odorant molecule has been found whose effect is registered only when the enzymes in saliva have separated it from its precursor. A few moments are needed, then, for the aroma to be perceived.

In 1995, Philippe Darriet and Denis Dubourdieu at the Institut d’Œnologie de Bordeaux discovered a molecule that gives Sauvignon wines a boxwood or broom note. Significantly, this...

How does wine age? Gourmets have long complained of the lack of scientific interest in the role of tannins in the development of red wines. Tannins are astringent substances that are abundant in young wines and that change as the wine ages, giving it an adobe color, smooth taste, and powerful aroma. Over time, tannins are said to soften up. With the aid of modern analysis techniques, Joseph Vercauteren and Laurence Balas at the University of Bordeaux revived a topic of research that had largely been abandoned since the work of Yves Glories in 1976 and elucidated several chemical transformations...

In 1991, Patrick Étiévant and Bruno Martin at the Institut National de la Recherche Agronomique (inra) station in Dijon began to analyze a wine known as vin jaune (yellow wine) that is produced only in the French Jura. The specific flavor of this wine results from the practice of maturing it in barrels for several years under a thick veil of yeast of the species Saccharomyces cerevisiae. A similar wine is made in Alsace, Burgundy, and in the town of Gaillac, in the Tarn, where it goes by the name vin de fleur or vin de voile. Its only near...

The cold of winter causes tartrate crystals to precipitate in bottles of wine in the cellar. These crystals do not harm the quality of a product that holds both symbolic and economic importance for France, but they do hamper its exportation to demanding or poorly informed clients. How can reductions in market value—or, worse still, returns—be avoided? Jean-Louis Escudier, Jean-Louis Baelle, and Bernard Saint-Pierre at the Institut National de la Recherche Agronomique (inra) station in Pech Rouge and Michel Moutounet at the Institut Supérieur de la Vigne et du Vin in Montpellier have developed a method for balancing...

Is the presence of sulfur always a defect in wine? In the 1960s the undue interest of some growers in preserving their wines as long as possible gave sulfur a bad reputation. Sulfur dioxide added in excessive quantities during the fumigation of casks and the sulfiting of harvested grapes causes painful headaches, it is true. But recent biochemical studies show that the use of sulfur is not to be rejected altogether. Chemists at the Faculté d’Œnologie de Bordeaux have discovered that sulfur is capable of both the best and the worst: Although some sulfur molecules are the source of indisputable...

Disciples of the grape are seldom without a glass. But which one? Generations of gourmets have debated the optimum form and size of a wine glass. In France, the Institut National des Appellations d’Origine (inao) has mandated use of a glass recognized by the International Standards Organization (iso) whose bowl is about twice as high as it is wide. Is it really the best? Because German tasters recommended a rounder glass, Ulrich Fischer, of the Oenology Department at the University of Neustadt, and his colleague Britta Loewe-Stanienda decided to explore the intensity of perceptions of aromas in glasses of various...

Everyone knows that champagne is best drunk chilled. But how long does the bottle need to be left in the refrigerator? Does it matter whether a child comes along and opens the door of the refrigerator in the meantime? Or say you want to bring wine up from the cellar in order to warm it to room temperature before a meal. How far in advance should you do this? The use of a thermocouple, a device that precisely measures temperatures, gives gourmets useful orders of magnitude.

Let’s start with the bottle of champagne. In a simple experiment, the probe of...

When we hear the unmistakable sound of the cork popping off a bottle of champagne, we stop talking and look closely at what happens as it is poured into our glass. If the foam subsides slowly, if the frill of bubbles is delicate and persistent, and if the liquid is effervescent, the wine is considered to be of good quality. Conversely, a rapid fall in the level of the fizz, the absence of a collar, and the presence of large bubbles are taken to be signs of inferior quality, even though the taste of the beverage may otherwise be satisfactory....

Sparkling wines are judged first by the uniformity of their color and by their intensity, clarity, and effervescence. The palate has ample reason to react unfavorably when the eye perceives a bit of tartar or other loose foreign particles. The wines of Champagne nonetheless are measured against a different yardstick. The bubbles that rise up from the bottom of the glass are the most obvious index of quality in the popular mind, together with the accumulation of a fine foam at the top of the glass. The foam should be a few millimeters high, but not more, and the bubbles...

The magnum of champagne is a prince among princes: Connoisseurs ascribe virtues to it that they do not detect in regular or half-bottles of the same wine. Are they correct? And are they correct in supposing that champagne should be stored lying down because the cork remains moist and so better preserves its hermetic properties? Experiments performed recently by Michel Valade, Isabelle Tribaut-Sohier, and Félix Bocquet at the Centre Interprofessionnel des Vins de Champagne (civc) in Épernay led to a new understanding of the role of corks in the aging of sparkling wines.

Champagne is a wine that foams, by...

Scotland, blessed land of whiskey! There it is called scotch, and there are several kinds. Single malts are made from fermented barley at a single distillery; blended whiskeys are mixtures of different kinds of whiskey that may come from different parts of the country. Obviously the single malts are preferred by connoisseurs, who scrutinize them with regard to five crucial qualities: nose, color, body, mouth, and finish.

Does the provenance of a single malt determine its organoleptic qualities? If it does, can types of scotch be associated with particular environments (or terroirs)? To find out, François-Joseph Lapointe and Pierre Legendre...

Traditionally made by adding alcohol to fresh, unfermented grape juice, the cartagène of Languedoc has never enjoyed the reputation of the Pineau des Charentes or other mistelles, as such apéritifs are known in France. Nonetheless, its producers sought to obtain a protected designation of origin, which meant that it had to be more precisely characterized and its method of production codified. At the request of the manufacturers, Jean-Claude Boulet and his colleagues at the Institut National de la Recherche Agronomique (inra) station in Nantes studied liver mousses to which a large amount of starch had been added, in order to...

Foods and beverages contain so many amphiphilic molecules—one part of which are water soluble and another part insoluble—that foams are common in the kitchen: stiffly beaten egg whites, champagne, beer, cream, and so on. In cooking one sometimes tries to minimize contact with antifoaming agents, taking care not to spill any drops of egg yolk into whites that are about to be whisked, for example, because the fatty molecules in the yolk bond with the hydrophobic part of the proteins in the white, removing them from contact with the air and thus stabilizing the water–air interface. Similarly,...

Cooks filter stocks today just as they did in the Middle Ages: They put the bones and vegetable matter in a conical strainer known as a chinois (or China cap) and press it with a pestle or a ladle to squeeze out as much liquid as possible. Naturally the effectiveness of this procedure is limited by the size of the mesh of the chinois. A fine cloth liner helps, but it has to be cleaned after every filtering. Can’t we devise a more modern and efficient method? Looking to chemical laboratories for inspiration would be a useful first step on...

“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...

Butter is a strange solid: When one takes it out of the refrigerator it is sometimes necessary to wait as long as fifteen minutes before it can be spread easily. Would it be possible to make a butter that is spreadable immediately after being removed from the refrigerator?

The question has been around since 1988, when legislation in France granted a butter appellation to products that, like butter, consist of droplets of water in milk fats, on the condition that such products have been separated by physical methods. Thus one could imagine selling butters having various properties, prepared by mixing...

The food industry is forever looking for ways to make its products lighter by reducing lipid content and increasing water or air content, without the taste suffering as a result. Even liver mousse, renowned for its sturdy lipidic constitution, has not been spared. Michel Laroche and his colleagues in the Laboratoire d’Étude des Interactions des Molécules Alimentaires at the Institut National de la Recherche Agronomique (inra) station in Nantes studied liver mousses to which a large amount of starch had been added, in order to determine by how much the fat content of such products can be reduced without affecting...

Fatty foods are accused of blocking our arteries and making us fat. Unsurprisingly, perhaps, one hears calls nowadays for banning fats from the kitchen. Nonetheless, fats are an indispensable part of the cook’s repertoire. Let’s consider the reasons why.

Deep frying, which involves temperatures of 200°c (392°f) or more, gives French fries and fritters their crispiness. Because water cannot withstand such temperatures without boiling, the surface of fried food is dried out without the water inside having time to diffuse outward. The crust that is formed in this way is what produces the sensation of crispiness. If deep-fried foods were...

Mayonnaise is a remarkable sauce: Through the miraculous intervention of the egg yolk, cooks manage to combine oil and water. Let’s try our hand at making a few new varieties that preserve the spirit of traditional recipes while enriching our culinary arsenal.

What happens when one adds oil to a mixture of vinegar, mustard, egg yolk, and salt? To the naked eye the preparation is homogeneous, but a microscope shows that the ingredients are not thoroughly mixed together: Large oil droplets are dispersed in the small amount of water contributed by the vinegar, mustard (which is itself made with vinegar),...

We start with aioli—the real article made in Provence by adding olive oil to crushed garlic, without the benefit of egg yolk. It is an emulsion, which is to say a dispersion of oil droplets in water, supplied in this case by the garlic. Why should this sauce be stable, whereas normally a mixture of oil and water separates? Because garlic contains tensioactive molecules that coat the oil droplets and prevent them from fusing. Aioli is a relative of mayonnaise, in which the protein molecules and phospholipid lecithins of the egg yolk are tensioactive.

Let’s try varying the traditional...

In making flans one often seeks, for economic or dietary reasons, to limit the proportion of egg or increase the proportion of water. How far can one go in this direction? Much farther, certainly, than traditional cuisine has yet gone. Let’s begin by analyzing two related cases: making mayonnaise from a single egg yolk and making meringue from a single egg white.

Cookbooks often say that one egg yolk is enough to yield a large bowl of mayonnaise. But in fact the physical chemistry of mayonnaise makes it possible, as we have already seen, to obtain liters of sauce from...

Eggs used to be put in sand, sawdust, or wax in order to be preserved. Asian peoples devised recipes that took advantage of aging, instead of compensating for its effects, in order to create what were variously known as hundred-year-old eggs, centenary eggs, and even thousand-year-old eggs—names that symbolized links with the past as well as longevity. How credible are these recipes from the chemical point of view? A few experiments reveal the unexpected behavior of eggs in acid and basic environments.

The origins of the Chinese art of preserving eggs are lost in the mists of time. Initially,...

Smoked salmon is an expensive delicacy that France has long specialized in producing. Manufacturers buy imported salmon and resell their smoked filets the world over. A team of researchers from the Institut Français de Recherche pour l’Exploration de la Mer and the Centre de Coopération Internationale en Recherche Agronomique pour le Développement perfected the process currently used to accelerate processing without sacrificing flavor. The two principal ingredients of the new method are osmosis and electrostatic smoking.

Smoking, like salting and drying, was originally used to preserve foods. In all three cases the idea was to eliminate water from foods in...

We cook today the way people cooked in the Middle Ages, content to mechanically execute fixed recipes—this at a time when space probes are being sent to Mars. We need to ask ourselves how reflection and rationality can be combined to renew creativity in cooking.

Certain types of cooking are pure in the sense that they involve only a single physical phenomenon. The oldest ones are those in which heat is transmitted through conduction. Since ancient times only the materials that transport the heat have changed.

The first type of pure cooking consists of putting food in direct contact...

Why do the french eat less beef than they did only ten years ago? In part it is because the quality of the meat does not justify its high price. Tender cuts that can be cooked rapidly (various types of steak, for example) are expensive because they constitute only 20–30% of bovine muscle tissue. What can be done with the other cuts that used to be tenderized by long, slow cooking?

The meat processing industry has proposed a solution in the form of restructured products such as ground beef and meats sliced into thin sheets. Both techniques—cutting fresh...

A gouda or a cheddar takes on its full gustatory quality only after several months, and many cheeses, even ones that have been aged for a long time, do not have the powerful flavor that one might want. The aging of cheese has been a lively topic of debate in the gastronomic world for centuries. The milk that is curdled and seeded with lactic bacteria acidifies in the course of maturing: The transformation of the milk sugar lactose into lactic acid prevents contamination by pathogenic microorganisms, and the lactic bacteria release aromatic compounds that contribute to the taste of the...

The words chantilly cream conjure up images of fresh strawberries, ice cream, and airy desserts. Chantilly is a kind of foam, or mousse, made by whipping cream in a chilled bowl. When the whisk is guided in a circular motion, through a vertical plane, its wire loops steadily introduce air bubbles in the cream that are stabilized by the molecules of the casein (a protein) and by the crystallization of the fatty droplets. This crystallization takes place at a low temperature, which is why the cream and the bowl must be chilled beforehand. This cooling process also prevents the cream...

At christmas and on new year’s eve, chocolate is obligatory. But in what form? Chocolate puff pastry, perhaps? Chocoholics know that chocolate contains cocoa butter, and they would like nothing better than to be able to substitute it for ordinary butter in puff pastry. But they also know that the hardness of chocolate stands in their way. A few simple observations about state transitions will make it possible to solve this problem and to adapt the majority of classic recipes for pastry to new uses.

To make puff pastry one first makes a paste by kneading flour with a little...

Emulsions are an inexhaustible source of culinary discoveries. Here we will use them only as a point of departure for investigating more complex physicochemical systems that anyone can use in cooking.

In the preceding chapters we have considered several types of emulsion, foremost among them mayonnaise, the prototype described by all textbooks dealing with the physics of soft matter. Mayonnaise is a dispersion in water of oil droplets stabilized by the proteins of the egg yolk. A great many variations on this theme are possible. We have already looked at two of them: one made without a yolk, the other...

The holidays are here—time to set to work in the kitchen. Should we be satisfied with cooking a turkey with medieval methods now that we are living in the twenty-first century? No, let’s invent new dishes. But how? The cook who looks to chemistry and physics for inspiration will not find it difficult.

Let’s begin by considering a new mode of cooking based on a remark by François Pérégo, a restorer of paintings in Bécherel and a keen student of chemistry who uses egg in treating canvases. He pointed out the effect of ethyl alcohol on egg whites, which...

Grapes are like a lazy student who can do better. In addition to odorant volatile compounds (members mainly of the class of terpenols—linalol, geraniol, nerol, citronellol, alpha-terpineol, linalol oxides, and terpenic polyols—whose very low threshold of olfactory perception plays an important role in giving wines their typicity), grapes also contain, in much greater quantities, terpenic glycosides, molecules composed of terpenols bound to sugars. These molecules are precursors of terpenols, but unfortunately they do not contribute to the flavor of wines.

Claude Bayonove and his colleagues at the Institut National de la Recherche Agronomique Laboratoire des Arômes et Substances...

Recall the boom in popularity that classical music underwent in the late nineteenth century, when anyone who had access to a telephone could appreciate the virtuosity of the great performers. At the time the transmission of visual images seemed a utopian dream, but only a few years after Alexander Graham Bell patented his famous device Paul Nipkow was awarded a patent in Germany for an apparatus that would transmit such images. This time the beneficiaries were the followers of Polymnia, Terpsichore, Erato, Melpomene, and Thalia.

What realms of communication are left to conquer? The transmission of tactile stimuli is now...