Food preparation is such a routine activity that we often do not question the process. For example, why do we cook as we do? Why do we eat certain foods and avoid other perfectly edible ingredients? To help answer these questions, it is extremely important to study the chemical changes that food undergoes during preparation; even simply cutting a vegetable can lead to enzymatic reactions.
For many years, these molecular transformations were neglected by the food science field. In 1988, the scientific discipline called “molecular gastronomy” was created, and the field is now developing in many countries. Its many applications fall into two categories. First, there are technology applications for restaurants, for homes, or even for the food industry. In particular, molecular gastronomy has led to “molecular cooking”, a way of food preparation that uses “new” tools, ingredients, and methods. According to a British culinary magazine, the three “top chefs” of the world employ elements of molecular cooking. Second, there are educational applications of molecular gastronomy: new insights into the culinary processes have led to new culinary curricula for chefs in many countries such as France, Canada, Italy, and Finland, as well as educational programs in schools.
In this Account, we focus on science, explain why molecular gastronomy had to be created, and consider its tools, concepts, and results. Within the field, conceptual tools have been developed in order to make the necessary studies. The emphasis is on two important parts of recipes: culinary definitions (describing the objective of recipes) and culinary “precisions” (information that includes old wives’ tales, methods, tips, and proverbs, for example). As for any science, the main objective of molecular gastronomy is, of course, the discovery of new phenomena and new mechanisms. This explains why culinary precisions are so important: cooks of the past could see, but not interpret, phenomena that awaited scientific studies. For French cuisine alone, more than 25 000 culinary precisions have been collected since 1980.
The study of the organization of dishes was improved by the introduction of a formalism called “complex disperse systems/nonperiodical organization of space” (CDS/NPOS). CDS describes the colloidal materials from which the parts of a dish are made; NPOS provides an overall description of a dish. This formalism has proven useful for the study of both scientific (examining phenomena to arrive at a mechanism) and technological (using the results of science to improve technique) applications. For example, it can be used to describe the physical structure of dishes (science) but also to examine the characteristics of classical French sauces (technology).
Many questions still remain in the field of molecular gastronomy. For example, one “Holy Grail” of the field is the prediction of physical, biological, chemical, and organoleptic properties of systems from their CDS/NPOS formula. Another issue to be worked out is the relationship between compound migration in food and chemical modifications of those migrating compounds. These questions will likely keep scientists busy in the near future.
The feasibility of note by note cuisine no longer needs to be demonstrated because meals have already been produced using this techniques, but we still have to discuss the nature of the compounds used. The culinary world already uses very pure compounds, such as water, sodium chloride, sucrose and gelatine. The lay person often ignores the fact that these compounds were prepared by industry through various extraction processes, purifications and technological modifications (for example, the anti-aggregation compounds added to sucrose) .
Many other compounds could be prepared in the same way, such as saccharides, amino acids and glycerides, and indeed the food industry already uses some of them. The food additives industry produces pigments, vitamins, preservatives, gelling or thickening agents and so on. Additives are not currently regulated like food ingredients, but could they not be in the future? Or should the regulation of additives be suppressed, and another very different regulation be introduced?
It is difficult to make dishes from pure compounds, and so, to go back to our music analogy, another way is to make dishes in the same way electronic music is composed [37, 38]. That is, to enlarge the list of usable compounds by adding simple mixtures such as those that the industry already makes by fractionation of milk or grain. Gelatine, for example, is not pure, in the sense that it is not made of molecules of only one kind: the extraction method used to make gelatine results in large variation in the molecular weight of the polypeptidic chains . Also starch is not pure, as it is made of two main compounds, amyloses and amylopectins. In passing, let us not forget that, because starch is a simple fraction of grain, most traditional pastry techniques can be kept for making note by note cuisine.
Let us come back to the question of ‘breaking down’ plant or animal tissues to prepare fractions. The industry already extracts polysaccharides, proteins, amino acids, surfactants and other compounds from grain . From milk, the industry recovers amino acids, peptides, proteins and glycerides. Could we not do the same from plant (carrots, apples, turnips…) or animal tissues? Could we not, using the same kind of processes (such as direct or reverse osmosis, cryoconcentration or vacuum distillation), prepare fractions that can be used later for note by note cuisine?
Many technology groups study these questions, and technologists at the Montpellier Institut National de la Recherche Agronomique Centre, for example, have devised techniques based on membrane filtration to recover the total phenolics fraction from grape juice . This fraction is very different depending on the raw material, for example whether the juice is from the Syrah variety, or from Grenache, or Pinot: the diversity of the initial products is not erased by the fractionation process, so that cooks can still play with the ‘ terroir'.
Now we have discussed the issue of ingredients, we have to consider assembling them into dishes. We should not forget that today's food items are material systems of a colloidal nature [41, 42, 43], often with a large proportion of water in them. Many organic compounds are poorly soluble in water, and emulsification is obviously a very important process in note by note cuisine. However it is not the only process; all dispersion techniques will be useful.
During the assembly, the various biological properties of food have to be considered. Of course, the nutritional content is important  but it would be a mistake to forget that food has to stimulate the various sensory receptors involved in vision, odor, taste, trigeminal system and temperature , for instance: this creates many questions. For example, even if the individual absorption spectrum of some pigments are known, the ‘color’ of a mixture of such pigments is difficult to predict theoretically . Also, when one mixes odorant compounds in proportions near the detection threshold, unpredictable odors are obtained. Worst still, we do not know what will happen when you mix only two odorant compounds: do they make a ‘chord’ or a fusion ?
For taste, the question is even more difficult to answer, because taste receptors and their substrates are not known ; it was discovered only recently (less than ten years ago) that the tongue has receptors for fatty acids with long unsaturated chains . This means that other important discoveries could still be made! In the meantime, one can use citric, malic, tartaric, acetic, ascorbic or lactic acids, or saccharides such as glucose, fructose or lactose, as well as the traditional sucrose but experimental tests will be needed to appreciate the result.
For trigeminal effects, some fresh or pungent compounds are known, such as eugenol (from cloves), menthol (one of its enantiomers only), capsaicin (from chilli), piperin (from pepper), ethanol, sodium bicarbonate and many others . But again the knowledge of receptors could lead to new products.
From the texture point of view, technological work can be done, because more studies are needed on the manufacture of colloidal materials. Making simple emulsions is sometimes considered difficult, but more generally one should not assume that the texturization of formulated products is fully solved, even if we now have surimi and analogous systems. Who will succeed in making the consistency of a green apple? Or a pear? Or a strawberry? Not only is there still the question of laboratory prototypes but also of mass production.
As a whole, much remains to be done and many aspects of note by note cuisine remain to be studied by science and by technology. Let us finish this paragraph with an important observation: it would be uninteresting to reproduce already existing food ingredients. As synthesizers can reproduce the sounds of a piano or a violin, note by note cuisine could reproduce wines, carrots or meats … but why? Except for astronauts who have to travel for long periods, there is probably no value in making what already exists, and it is much more exciting to investigate flavors and dishes that were never envisioned using traditional food ingredients .
A simple calculation shows the immensity of what could be discovered. If we assume that the number of traditional food ingredients is about 1,000 and if we assume that a traditional recipe uses 10 ingredients, the number of possibilities is 1,000 to the power of 10 (or 1030). However, if we assume that the number of compounds present in the ingredients is about 1,000, and that the number of compounds that will be used in note by note cuisine is of the order of 100, then the number of possibilities is about 10 3000. And, in this calculation we have not considered that the concentration of each compound can be adapted, which means that a whole new continent of flavor can be discovered.