For 20 years, during the monthly “Seminars of molecular gastronomy”, culinary questions have been investigated experimentally in Paris, France. These experiments are done in public, in front of an audience made of chefs, interested people, students, professors, and they focus on the various phenomena that occur during cooking.
“Is it true that you can remove the excess salt in a sauce by dipping a potato?”
“Is it true that you have to heat sponge cake batter at 55 °C in order to get a better product, as taught in culinary schools?”
“Is it true that oil from the dressing is absorbed when hot cooked potatoes are immersed in the dressing?”
“Is it true that strawberries loose their flavour when washed in water, as said by some starred chefs?”
Such questions seem anecdotal, but they correspond to practices that cooks implement daily, all over the world. Economically, their interest is obvious, because the answers to them can determine the “quality” of dishes, both at home, or in restaurants, or in the food industry (where chefs are working, before engineers apply their recipes). There is also an issue of technology, and efficiency of the culinary activity: imagine that putting the green beans in water with ice, after cooking, does not change the colour of the beans, and you can understand that one should not spend time at preparing a bath with water and ice, and store the beans in it, at the risk of loosing flavour, through the dissolution of compounds from the beans.
But the seminars of molecular gastronomy have many other interests than simply establishing technical facts. The main one, to my taste, is that they sometimes reveal phenomena that were unknown, and indeed this is the first step of scientific research, in a sequence moving from this identification to quantification of the phenomenon, synthesizing data in “laws”, creating a theory thanks to the introduction of new concepts that are quantitatively compatible with the laws, predicting refutable consequences of the theory, and testing experimentally these predictions.
Now, the experimental tests that are performed during the seminars are also the opportunity to discuss protocols, and to teach the participants how to rigorously design experiments, with only one parameter being changed for the comparison of two products. Also, they show frequently that old “culinary technical knowledge” needs revision, or, at least, needs being considered cautiously. The time is not so far when it was taught in the main culinary schools of the world that one “could not” whip again an egg white that was first whipped and stored until being again liquid (it was demonstrated that you can whip, store, whip again, etc. seven times in a row). Or that a bigger foam volume would be obtained by whipping always in the same direction (this does not change the result). Etc.
For some time, these seminars were named “Meetings of the Group for the study of culinary precisions”, but the goal never changed: it is to test “culinary precisions”. What does it mean? Any recipe (oral, written) is giving information in three fields: social, art and technique. Concerning technique, the recipes give a “definition”, i.e., the goal, but they frequently add tips, advises, sayings, old wive tales and other technical information that should help to reach the goal. All kinds of information can be found.
Some precisions seem wrong, and they are wrong (1); some seem wrong and they are true (2); some seem true and they are wrong (3); some seem true and they are true (4); anf for some precisions, we have no idea about the correctness (5).
(1) As we demonstrated, it does not seem true, and indeed is not true, that menstruation prevents women preparing mayonnaise, as it is proposed in France. Indeed,it is strange that this old wives tale is told in France yet not in England (in this country, periods are said to have an influence on meat preservation: women having their periods should not rub meat with salt) or in other countries. It demonstrates how much cooking is rooted in culture, and why comparative molecular gastronomy could be interested in the future.
(2) In 1994, it was examined whether the skin of suckling pigs is more crackling when the head of the pig is cut immediately after being roasted. 150 This advice seemed wrong, but it proved to be true. The culinary precision was found in L’Almanach des gourmands from the French gastronome Alexandre Balthazar Grimod La Reynière: “suckling pigs should have the head cut immediately when the pigs are taken out from the oven, otherwise their skin softens.” The same advice lies in many other culinary books. For example, Carême indicates to make a cut around the neck (“When you are ready to serve, you separate immediately, with the tip of the knife, the skin of the neck, so that the skin says crisp, which make most of the interest of roasted sucking pigs”). These remarks are strange, as in roasted pigs, no fluid seem to exchange between the head and the skin ; it was highly unlikely that the advice was true, but the experiment was performed (public experiment at Saint-Rémy l’Honoré Yvelines, France, July 7, 1993) with 4 suckling pigs of the same parents, reared together in the same farm, weight 7.17.3 kilograms, cooked on a large outside fire from 4.00 PM to 9.00 PM, one head cut for each pair of pigs. Blind tasting for 143 people showed that the skin of pigs with head cut was crispier. The mechanism behind was easily discovered, as it was observed during cooking that a stream of vapor was escaping one pig from a hole made during the preparation. It means that heat is evaporating water from the surface of the meat during cooking, making the crust, and vapor formed inside the meat is not enough to compensate for the loss of surface water. When the pigs are not heated any longer, the crust softens if vapor goes through; cutting the head prevents vapor perfusion, as it escapes through the opening.
(3) It is said that the pan where green beans are cooked should not be covered, as it would keep volatile acids, that would promote pheophytinization of chlorophylls, but tests show that there is no color difference. The idea seemed true, but it is wrong.
(4) It is sometimes said that the soufflés should be made from very firm whipped egg whites, added to a viscous preparation. It was demonstrated that this precision holds, as vapor bubbles formed in the bottom part of soufflés, during cooking, escape less through firm foam. The advice seemed true, and it is true.
(5) Let us now discuss a fifth class, with precisions having a non clear-cut status. For example, it was said by the French chef Pierre Gagnaire that wine sauces are more “brilliant” when shacked than when whipped. Such a declaration, even from a famous chef, should be considered with caution, because in many circumstances experiments showed that cooks were influenced by tradition rather than experiments and facts. In such cases, one has to carefully define the question, because it would be useless to make tests in conditions different from the real ones from which an observation is made. In particular, wine sauces production depends both on authors and on period in the history of cooking. The “wine sauce” discussed by Gagnaire are made from a veal “fond”, wine, and butter. This “fond” is a solution obtained by grilling veal bones until they have a brown (not black) color. Then water, carrot (Daucus carota L.) roots, onions (Allium cepa L.) bulbs and possibly other plant tissues are added. A thermal treatment at a temperature lower than 100°C for some hours (between 2 and 20, depending on authors, but also on each particular sauce) is achieved. Then the fond is filtrated, and its volume is reduced by boiling to one tenth of its initial volume. Red wine is added. The sauce is reduced again, and again red wine is added, before butter is added while the sauce is heated at a temperature lower than 100°C, so that there is no boiling (when details are not given here, it has to be understood that the cooks themselves can change depending on any particular sauce; e.g. the exact quality of the “red wine” is not considered, and any red wine can be used).
In our studies, the sauce was first modeled by distilled water (instead of stock and wine), gelatine (because gelatin is extracted in the first steps of sauce production) and butter (ca 100 mL water, 6 g gelatin, 60 g butter, based on former analyses). The initial mixture of water and gelatin was divided into two parts, and the same quantity of butter was added in each. Then the model sauce was heated and either shacked (the pan is move forth and back on a distance of 5 cm, 23 times in 10 s for 65 s) or whipped using a whisk (4 whipping movement per s). Initial visual tests with 52 people did not detect any difference in visual appearance. However, the observation of the model sauces using optical microscopy (microscope Meiji Techno ML Serie 2000, Model ML2300) showed clear differences that were characterized. These differences can be explained by the fact that the energy given to the sauce is very different when the sauce is shacked or whipped. This energy is used to increase the surface energy of the emulsion, and, hence, the size of the melted butter droplets dispersed in the water phase. At that point, it should be concluded that if there is no difference in “brilliancy”, there is however a difference in flavor, as it was demonstrated on model emulsions that the composition of odorant molecules above an emulsion is different depending on the microstructure of the emulsion, the composition being held constant.
Much remains to be done
After 20 years of monthly seminars, only about 200 culinary precisions were tested, over a total of about 25,000 collected only for French cuisine, and many were refuted. But if this is helpful for culinary education (it is better to teach right information, isn’t it?), one should stress that refutation is not the most interesting: for the improving sciences of natures, the most useful is when preconceived ideas, based on current theories, are refuted. And this is why mysterious phenomena such as graining of whipped egg whites, or curdling of melted chocolate are scientifically more interesting than other more
To finish, let us give some results, from the long list of those that were synthesized recently, adding that the results are only valid in the particular conditions of the experiments, which you can consult in the complete reports
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