dimanche 23 juillet 2023

J'ai lu pour vous le livre de chimie des aliments Food Chemistry, publié aux éditions Springer par M. Belitz et M. Grosch.

Dans la série des lectures qui peuvent être utiles aux étudiants, notamment aux étudiants en sciences éléments, comme d'ailleurs en technologie des aliments (en vue de devenir les ingénieurs de l'industrie alimentaire, par exemple), il y a ce livre étonnant, Food Chemistry, en qui en est à sa n-ième édition. 

Ce succès est mérité, car un groupe d'auteurs  parmi les très bons a  colligé une foule d'informations importantes sur la composition moléculaire des ingrédients alimentaires, ainsi que sur quelques transformations qui ont été étudiées par la chimie des aliments. Cela me donne l'occasion de discuter le mot « aliment » : ce n'est pas un ingrédient alimentaire, car le simple fait de cueillir une pomme,  de sortir une carotte du champ, suffit à  provoquer des modifications moléculaires parfois importantes. Je propose de bien distinguer les ingrédients des aliments. Les aliments, c'est ce qu'on mange, et ce que l'on mange fait l'objet de transformations culinaires, d'un travail qui a trois composantes : technique, artistique, sociale. <ul> <li>Technique, parce qu'il faut opérer des transformations : couper les carottes en julienne,  peler les pommes, faire un fond de tarte que l'on cuit...</li> </ul> <ul> <li>Artistique, parce que  la très grande majorité des aliments, ce que l'on mange donc, n'est pas l'ingrédient simplement divisé ou chauffé, mais aussi assaisonné : sel, poivre, cannelle, sucre... Là, il y a une question artistique et non technique. Il n'y a pas de différence technique entre le fait de mettre un peu ou beaucoup de cannelle, mais il y a une différence considérable en termes de résultats ;  parfois, un goût  cannelle s'impose, mais parfois il est à éviter. C'est ainsi que je me souviens de ces premiers chocolats à la lavande produits par des chocolatiers inventifs, il y a de nombreuses années. Au début, la quantité de lavande était trop forte, et le goût était exécrable,  ce qui signifie seulement  que le produit était rejeté en termes de préférence. On aurait pu penser, ou espérer, que l'on s'accoutumerait, mais les artistes chocolatiers ont fait quelque chose de mieux : ils ont réduit les doses de lavande, de sorte que l'on mangeait le chocolat  et l'on s'interrogeait. « Quel est ce gout  étrange, intéressant, que  je perçois quand je mange un bonbon de chocolat ? » Un moment  de réflexion,  puis : « J'y suis, c'est la lavande ! » L'art du chocolatier fut de trouver le dosage exact qui devenait admissible, et même merveilleux. Que l'on y pense un peu, et cette façon de faire est largement présente dans l'art culinaire, puisque nombre de cuisiniers traditionnels disent à titre de paradigme  : « Quand on fait une sauce à l'estragon, il faut que le mangeur aille chercher l'estragon. »</li> </ul> <ul> <li>Pour tout aliment, il y a donc une composante technique, une composante artistique, mais il y a aussi une composante sociale, les aliments étant des produits extrêmement acculturés, et j'en prends pour preuve  les interdits alimentaires, qui récusent certains aliments  sur la base de croyances, de religion ... C'est la culture qui nous permet de manger certains aliments, ou, au contraire, qui nous empêche d'en manger d'autres. C'est la culture  qui pousse l'Alsacien a aimer le munster, mais le Normand à préférer le camembert, le Toulousain à rêver de cassoulet, et le Breton de galettes... Il y a aussi la façon de manger, et il a été  montré quantitativement que le même plat consommé seul était moins bon que quand il était consommé en groupe, preuve que la socialité est essentielle  pour l'espèce humaine, ce que l'on sait bien par ailleurs.

Évidemment, dans le livre de chimie des aliments que je discutais  initialement, les composantes artistiques et sociales ne sont pas présentes : le document se limite à  l'ensemble des transformations  moléculaires,  voire seulement à la liste des compositions  chimiques des ingrédients alimentaires. 

Car il est vrai  que la cuisine est extrêmement peu présente dans ce livre, ce qui est la raison exacte pour laquelle la gastronomie moléculaire fut introduite dans les années 1980. Comme ce que nous mangeons fait l'objet de transgressions culinaires, on ne peut prétendre produire un produit un traité de chimie  des aliments si l'on ne considère pas ces transformations. Le vin ? Bien sûr, on le boit, mais, en cuisine,  il est d'abord cuit, réduit au miroir... Là,  une foule de transformations ont lieu, et un véritable livre de chimie des aliments devrait tenir compte de ces phénomènes. 

Dans le livre Food Chemistry que j'évoque,  quasiment rien n'est dit de tout cela. Le livre de chimie des aliments reste donc à faire, mais le livre Food Chemistry, dont le titre est donc  usurpé, a le mérite de fournir un une base de données extrêmement utile à ceux qui voudront un jour produire un véritable livre de chimie des aliments, et non seulement de chimie des ingrédients alimentaires.

samedi 22 juillet 2023

J'ai relu pour vous on le dossier hors-série consacré à Aristote par la revue Pour la science.

La question était de bien nommer les « sciences dures » que sont la physique, la chimie physique, la biologie... 

Sciences quantitatives ? C'était la conclusion à laquelle j'étais arrivé, il y a plusieurs mois, alors que je naviguais de philosophie naturelle (une erreur de français) en philosophie de la nature (le titre du livre de Newton). La terminologie avait été abandonnée, et les Anglo-Saxons utilisent « sciences de la nature » (et non pas « sciences naturelles », encore une erreur de français). 

Finalement, que pensait Aristote, de tout cela ? Aristote ? Quel fut son apport réel aux  sciences quantitatives ? Etait-ce un philosophe ? Un scientifique ? Un proto-scientifique ? 

Ce billet ne sera pas long, mais je vous invite très vivement à vous procurer  ce dossier hors-série de la collection « Les génie la science » consacré à Aristote, aux éditions Pour la Science.  

Il est il est l'oeuvre d'un auteur unique,  dont le nom d'ailleurs est insuffisamment mis en valeur dans l'ouvrage,  ce qui est injuste, puisque c'est son oeuvre. Cela dit, cette oeuvre est érudite, pas pédante, et l'on en sort avec des idées très claires sur l'apport d'Aristote. Évidemment, on n'entre pas dans les détails philosophiques, car le dossier n'a qu'une centaine de pages. C'est bien peu comparé aux immenses traités qui furent consacrés à cet homme représenté un doigt pointé vers le sol à côté de Platon, qui, lui, avait un doigt pointé vers le ciel. Pourtant cette centaine de pages est largement suffisante   pour une initiation, et je ne doute pas que l'Aristote ainsi découvert vous donnera envie d'en savoir plus. N'est-ce pas l'objectif de tout bon livre : donner envie,  au lieu de gaver. 

Je vous invite très vivement à lire ce dossier hors-série consacré à Aristote.

vendredi 21 juillet 2023

Réjouissons-nous : une partie de l'humanité est éclairée !

 
Au Salon de l'agriculture, deux événements, qui donnent des raisons d'espérer :

1. Juré au Concours général agricole, je suis à la même table qu'un charcutier de la Sarthe. Pour lui, le sel nitrité qui est utilisé dans les charcuteries ne pose par l'once d'un problème. Le nitrite est-il un produit chimique ? Peu importe, m'est-il répondu : on en a besoin en charcuterie professionnelle ; pas dans l'industrie, mais chez les artisans. Alors on l'utilise, un point c'est tout. Ses dangers ? Qu'importe : les couteaux aussi sont dangereux, m'est-il répondu. Il suffit de savoir l'utiliser . 

2. L'après-midi, après ma conférence sur la cuisine note à note, un petit homme reste, intéressé, pour des questions. C'est un boucher d'un petit village du Béarn. Il est intéressé par les composés qui ont été montrés (octénol, menthol, pipérine, etc.) : sont-ils "chimiques" ? 

Par ce terme, l'entretien montre qu'il voulait dire "de synthèse". Et la suite de l'entretien conduit à montrer qu'il ne sait pas ce qu'est un composé, de synthèse ou pas, et que cela l'intéresse beaucoup de comprendre. Pour figurer les choses, je prends l'exemple de la synthèse de l'eau, par électrolyse, puis sa recomposition. "Quoi, vous pouvez fabriquer de l'eau ?" Stupéfaction, oui, on peut fabriquer de l'eau, et décomposer l'eau. Tout cela expliqué en termes simples conduit notre homme a conclure  "Vous avez un merveilleux métier". Je lui réponds que lui aussi, a un très beau métier. Que tous les métiers sont beaux quand ils sont pratiqués avec passion par des gens honnêtes. N'est-ce pas ? 

 

Pour conclure, au delà de quelques individus qui troublent le public avec une idéologie douteuse (le gout du pouvoir ? de l'argent ? la peur animale des ignorants ? une névrose), je crois que nous devons nous réjouir  : nos concitoyens sont heureux de comprendre le monde où ils vivent. D'où un devoir d'explication ! 

 

Vive la chimie physique.

jeudi 20 juillet 2023

Why cooking is not a science of nature, and why Pomiane was wrong (he confused sciences, technologies, techniques and art)

 


The microbiologist Edouard de Pomiane (1875-1964) worked at the Pasteur Institute and taught at the Scientific Institute of Food Hygiene (part of the SSHA: Société Scientifique d'Hygiène Alimentaire). He was one of those, along with Benjamin Thompson, Friedrich Accum and Justus Liebig, who proposed using science to revamp culinary practices.




In his Traité élémentaire de chimie [Elementary Treatise on Chemistry], Antoine-Laurent Lavoisier wrote that all acids contain oxygen, which is not true (Lavoisier, 1793). But this error does not diminish the admiration that chemists should have for the father of their discipline, because he pushed back the limits of the unknown much more than any of his contemporaries, transforming an experimental knowledge activity (‘chemistry’) into a modern science (Halleux, ). On another level, at the beginning of the 20th century, the Polish-born French biologist Edouard de Pomiane confused art, science, technique and technology in his various publications on 'gastrotechnie' [gastrotechnics], but it would be unfair if he did not go down in the history of food science as an energetic educator who strove energetically to rationalise culinary


practices, in the tradition of many scientists such as Jean d’Arcet, Etienne-François Geoffroy, Antoine Augustin Parmentier, Benjamin Thompson, count Rumford, Friedrich Accum, Louis Jacques Thenard, Henri Braconnot and others.



From Poland to the Scientific Institute of Food Hygiene


Edouard Pozerski de Pomian, known as Edouard de Pomiane, was born in Paris on 20 April 1875, at 28 rue des Abbesses, at the home of his parents, Polish noblemen who had fled to France because they had taken part in the Polish revolution of 1863. He studied at the Polish School in Paris, then at the Lycée Condorcet, and passed his baccalauréat ès sciences in 1894. He failed the entrance examination for the Ecole Polytechnique and studied science at the Faculty of Paris from 1894 to 1896. After obtaining his bachelor's degree in natural sciences, he worked as a volunteer researcher, then as an assistant preparator in Albert Dastre's physiology laboratory at the Sorbonne (Girard, 2004; Froger, 2004). During this period, he gave lectures at the newly-created Universités Populaires, which organised free evening classes open to all.

This was the start of his research into digestive enzymes and the development of his taste for cooking: "My master Dastre often came to keep me company, discussing culinary techniques with me. We made sauces, we made pastry doughs and we decreed that cooking was a science. These were the beginnings of all my experiments in gastrotechnics, the basic science of the art of cooking" (Pomiane, 1954).

 

Figure 1. Edouard Pozerksi de Pomian, said Edouard de Pomiane (1875-1964).



From 1897 to 1902, he studied medicine at the Faculty of Medicine in Paris, joining the Institut Pasteur in 1901 on his return from an internship in the marine biology laboratory at Roscoff, as a preparator in the physiology department, directed by C. Delezenne. In 1902, he defended his doctoral thesis in medicine: L'action favorante du suc intestinal sur le pouvoir amylolytique du suc pancréatique et de la salive [The favourable action of intestinal juice on the amylolytic power of pancreatic juice and saliva]. Then, in 1908, he wrote his doctoral thesis in natural sciences: Contribution à l'étude physiologique de la papaïne [Contribution to the physiological study of papain]. In 1910, he became an assistant in the laboratory where he worked. His work focused on pancreatic and intestinal juices, blood ferments, immunity and proteolytic ferments. He was also involved in the work of other laboratories at the Institut Pasteur: studies of the intestinal flora of vertebrates with Elie Metchnikoff; research into new theoretical bases for a general concept of antibodies and their action, with M. Nicolle. In 1913, he and his wife wrote two memoirs on immunity to the anticoagulant action of peptone.

This work, which was the subject of some sixty publications, was rewarded with the Monthion prize from the Académie des Sciences in 1909, and the Laborde prize from the Société de biologie in 1912. His career came to an end with the outbreak of the First World War: from 1914 to 1918, he was initially a medical officer, then attached to various medical units at the front. In particular, he was assigned to Auto-Chir N°22 (vans equipped by the Institut Pasteur and the Institut Curie with radiographic and microbiological equipment). Returning to the Institut Pasteur in 1919, he studied with F. d'Hérelle the behaviour of a bacteriophage under the influence of temperature changes, and continued his research into ferments and the stages of digestion. He taught bacteriology on a voluntary basis at the Hôpital-Ecole Edith Clavet. From 1921, he was Professor at the Institut Scientifique d'Hygiène Alimentaire.

He published a number of works, gave many lectures and wrote many articles, with or without Docteur de Pomiane's signature, and finally authored a medical manual on food hygiene, which he published under his real name. The term "gastrotechnie" (which will even appeared in the Larousse dictionary, where the word "gastronomie" was absent at the same time) appears in his book Bien manger pour bien vivre. Le code de la bonne chère (Pomiane, 1922).

From 1922 onwards, he taught at the Enseignement supérieur de la cuisine course run by the sous-secrétariat de l'Enseignement technique. From 1923 to 1929, he gave weekly radio talks on Radio-Paris (the first French radio), as well as lectures, in particular popularising the work of Louis Pasteur.

These years saw the publication of many books : La cuisine en six leçons (Pomiane, 1926), Travaux pratiques de cuisine raisonnée (Pomiane, 1928), Cuisine juive (Pomiane, 1929), La cuisine et le raisonnement (Pomiane, 1930), La cuisine pour la femme du monde (Pomiane, 1932), Vingt plats qui donnent la goutte (Pomiane, 1935), 365 menus, 365 recettes (Pomiane, 1938), Le carnet d'Anna (Pomiane, 1938).

In his books, he denounced one of the most common ailments: poorly prepared food. "As a physiologist, I studied cooking as a science: I did gastrotechnics", he wrote in Vingt plats qui donnent la goutte. This latest work is full of humour... like all the others. Was Pomiane influenced by the artists he rubbed shoulders with when he lived with his parents in Montmartre? His home adjoined the Lapin Agile cabaret. He was himself a painter and musician, and married a musician.

Having retired as head of department at the Pasteur Institute in 1940, during the German Occupation he organised guided tours of the Pasteur Institute, as well as lectures at the Scientific Institute of Food Hygiene, with cooking demonstrations, on how to eat despite severe restrictions, making the best use of the rations allocated and the substitute products that could be purchased without a ticket. Because of the gas shortage, he encouraged housewives to cook with as little energy as possible, using economical utensils and appliances such as the "Norwegian pot". His book Cuisine et restrictions (Pomiane, 1940) dates from this period, but he also published numerous works on food hygiene. For example, his Vingt plats qui donnent la goutte [Twenty dishes that give you the gout], written for Laboratoires Midy, was followed during this period by La cuisine au compte goutte [Drip-fed cooking] (Pomiane, 1939), Réflexes et réflexions devant la nappe (Pomiane, 1940), Manger quand même (Pomiane, 1941), Conserves familiales et microbie alimentaire (Pomiane, 1943).

Although he stopped teaching at the Institut scientifique d'hygiène alimentaire in 1943, he continued to publish: La cuisine pour les estomacs délicats (Pomiane, 1949), Radio Cuisine (2 volumes) (Pomiane, 1949), La physique de la cuisine et son art (Pomiane, 1950), La cuisine polonaise vue des bords de la Seine (Pomiane, 1952), La microbie alimentaire (Pomiane, 1957), La cuisine en dix minutes (Pomiane, 1961). He died in Paris on 26 January 1964 in a traffic accident, having published some thirty culinary works, translated into eight languages (Ginsburg, 2002; Girard, 1964; Girard, 1989; Girard, 1989; Barneoud, 1910).



Pomiane's legacy


One of Pomiane's Polish friends, Tadeusz Przypkowski, had an astronomy museum in his castle at Jedrzejow. He doubled it with a gastronomy museum to honour Edouard de Pomiane, and the estate and castle are now nationalised and open to the public. In the same spirit, Pzypkowski created the Pomiane Order of Poland (a very closed gastronomic order, since the founder only inducted 16 members). In France, the Prix Edouard de Pomiane was founded in 1969 by the Guide du Médecin, in memory of the man whom his colleagues had nicknamed the "prince of gastronome doctors" and whom his friends simply called "Poger". In 1990, the prize was renamed the Prix Edouard de Pomiane-Edouard Longue, to associate the uncle and nephew, who upheld the same values.

Although the "de Pomiane" spirit was perpetuated, the gastro-technical idea under the name ‘gastrotechnie’ did not survive its founder. Why did this happen? I propose to examine this disappearance by analysing an article entitled Gastrotechnie. La cuisine est un laboratoire [Gastrotechnics. The kitchen is a laboratory], which Pomiane published in 1948 in the magazine Atomes (Pomiane, 1949). This article begins with:

"The study of the phenomena of digestion constitutes a special chapter in a treatise on human physiology. It sets out successively :

1. the chemical composition of foods ;

2. the nature of the digestive ferments and the secretion of the juices that contain them

3. the digestion of food by the various secretions from the saliva, stomach, pancreas, liver and intestine

4. absorption of digested food by the intestinal mucosa

5. assimilation by the organism.

Presented in this way, the study appears to be completely comprehensive. In reality, it is not. Food is considered to be a substance, passing directly from the market where it was bought to the table where it is to be eaten. However, before being eaten, food remains in a laboratory, sometimes for a very long time, where it undergoes numerous manipulations and sometimes profound transformations. This laboratory is the kitchen.

In the kitchen, foods are transformed to such an extent that some of them, which are indigestible, become digestible after cooking, while others, which are perfect foods, become almost toxic substances.

However, in books on physiology, there is no mention of the transformations undergone by foods in the kitchen. These transformations are profound: physical, chemical and biological. Studying them is essential to understanding human nutrition.

For all these data developed in an experimental physiology laboratory, we have proposed the name of gastrotechnics".

In La physique de la cuisine et son art, Pomiane completes this description, explaining that cooking can be simplified and rationalised, so that it can be "considered a scientific technique", that "gastrotechnics is a science" and, further on, that it is an "applied science "1.

These quotations, and that from one of his first books ("cooking is a science") show that Pomiane confuses sciences of nature, technology, technique, and art. In passing, let’s add that the word laboratory is used for sausage makers or pastry chefs, not being restricted to science.
But let us show why cooking has nothing to do with science, why cooking is not a science of nature. Indeed sciences of nature have been defined as the exploration of the mechanisms of phenomena. Galileo Galilei wrote: "Science brings to light, through the relationships of empirical causality, a constant proportionality, the law, and this insofar as it gives these empirical relationships a quantitative and geometric expression") (Galilei, 1623). Now, technology is something different, as the word is defined (etymology and dictionaries) as the exploration of techniques in view of improvemnt them. And finally technique (cooking, in this case) aims at producing dishes.

This explains why "scientific technique" is a misnomer. So is the idea that cooking is a science, since cooking is a production of food, not a search for knowledge. The idea put forward by Pomiane that gastrotechnics (today we would say "culinary technology") is an "applied science" is also wrong: throughout his life, Louis Pasteur made it clear that the expression "applied science" is an oxymoron. For example, "Remember that there are no applied sciences but only applications of science" (Pasteur, 1872). Or: "An essentially false idea has been mixed up in the many discussions raised by the creation of a vocational secondary education; it is that there are applied sciences. There are no applied sciences. The very union of these words is shocking. But there are applications of science, which is quite different. Then, alongside the applications of science, there is the trade, represented by the more or less skilled worker. Teaching a trade has a name in every language. In ours, it is called apprenticeship, which nothing in the world can replace" (Pasteur, 1863). Or even: "No, a thousand times no, there is no category of sciences to which we can give the name of applied sciences. There is science and the applications of science, linked together like fruit to the tree that bore it" (Pasteur, 1871).

In the same book, Pomiane defines gastronomy as the art of preparing food ("Gastronomy is the art of eating well. Gastrotechnics is the scientific basis of this art"), but this is a very personal definition with no legitimity, since the word "gastronomie", introduced in 1800 by Joseph Berchoux (1765-1833), was given its general meaning by the lawyer Jean-Anthelme Brillat-Savarin (1755-1826) in the following form: "the reasoned knowledge of everything related to man as he eats" (Brillat-Savarin, 1825).

All in all, the word "gastrotechnics" was "badly constructed", said even Pomiane. One wonders whether this defect was the cause of its extinction? For sure, when the scientific discipline today called "molecular and physical gastronomy" was introduced, by This and Kurti, they had in mind to avoid the mistakes made by Pomiane and others : it was defined as a science of nature, not as a technology nor a technique. And since that time, it is clear that expressions such as ‘scientific cooking’ have no meaning.



Science in the kitchen?


In his publications, Pomiane cites few predecessors, which is partly justified because he was the first to use the word "gastrotechnics". But was the activity he led his own creation?

The science of food was not born with him, since as early as the 2nd century AD, the anonymous author of the London Papyrus used a balance to determine whether fermented meat was lighter than fresh meat, due to an "emanation".

Much later, in France, Denis Papin developed his ‘digester’ for extracting gelatin from bones (Darcet, 1830 ; Dere, 1990), and many doctors, pharmacists and chemists became concerned with food. Antoine Augustin Parmentier (1737-1813) was interested in flour, potatoes and wine; Antoine Laurent de Lavoisier (1743-1794) sought to determine the quantity of meat that should be used to produce "suitable" stock (he wrote himself that this work was of technological nature) (Lavoisier, 1783).

Alongside this work on food science, a number of scientists took a particular interest in culinary processes. In 1794, Benjamin Thompson (1753-1814), Count Rumford, published a 400-page essay entitled On the Constuction of Kitchen Fireplaces and Kitchen Ustensils together with Remarks and Observations relating to the various Processes of Cookery and Proposals for improving that most useful Art. Born in America, an English soldier, statesman, physicist, inventor and social reformer, Rumford was accused of espionage in 1788, fled America and arrived in London, where he took British nationality, and later became advisor to the Elector of Bavaria and head of his military services. Sent to London as Minister Plenipotentiary in 1798, King George III refused to consider one of his subjects as a foreign minister. Rumford then drew up plans for the Royal Institution of Great Britain, which he founded in 1799 with Sir Joseph Bank, who was then president of the Royal Society.

A little later, Fredrick Accum published Culinary Chemistry, Exhibiting The Scientific Principles of Cookery, With Concise Instructions for Preparing Good and Wholesome Pickles, Vinegar, Preserves, Fruit Jellies, Marmalades, And Various Other Alimentary Substances Employed In Domestic Economy, With Observations On the Chemical Constitution And Nutritive Qualities of Different Kinds of Food, With Copper Plates (Accum, 1821). Friedrich Christian Accum was born in Buckeburg, Westphalia, in 1769. He arrived in London in 1793, and soon joined forces with the publisher Ackermann to introduce the idea of gas for lighting English cities. In 1810, when the London Chartered Gaslight and Coke Company was founded, Accum was one of its engineers. He was a member of the Royal Irish Academy, the Linnaean Society and the Royal Academy of Sciences in Berlin.

In his work published in 1821, Accum wrote: "The art of preparing good, healthy food is certainly a branch of chemistry; the kitchen is a chemical laboratory, all the processes used to make food substances fit for consumption are chemical processes, and much material and labour would be saved if those who practise this art knew certain simple chemical facts, which always give certain results".

We should not fail to compare this quotation with that of Brillat-Savarin: "This misfortune befell you because you neglected the theory, the importance of which you did not fully appreciate. You are a little obstinate, and I find it difficult to make you understand that the phenomena that occur in your laboratory are nothing other than the execution of the eternal laws of nature; and that certain things that you do without paying attention, and only because you have seen others do them, are no less derived from the highest abstractions of science".

Accum gave out recipes. For example: "How do you make ketchup? Crush a gallon of ripe tomatoes; add a pound of salt, squeeze out the juice and add a quarter of a pound of anchovies to each quarter of juice, together with two ounces of shallots and an ounce of crushed black pepper ; Bring the mixture to a simmer for a quarter of an hour, then strain it and add a quarter of a pound of mace, the same amount of all spices, ginger and nutmeg, and half a drachma of cochineal; leave to simmer for twenty minutes, then pour it through a cloth and bottle it."

Such a recipe would not have been disowned by Pomiane, who gave, among a thousand others, this one: "Sauce meurette. Casserole. Red wine with herbs and spices: onions, shallots, thyme, bay leaves, pepper, nutmeg, etc. Boil for 45 minutes. Add several knobs of butter mixed with its volume of flour (beurre manié). Leave all the butter to melt over a very low heat. The flour turns into starch and binds the sauce. Cognac or not".

While Rumford and Accum did not claim to be the first to introduce science into cooking, Justus von Liebig (1803-1873) was more pretentious (and wrong) (Brock, 1997). Liebig himself said that he had learnt French from the wife of one of the Duke of Hesse-Darmstadt's cooks, and that he had then become fascinated by culinary operations: "From there, I retained a taste for cooking, and, in my spare time, I occupied myself with culinary mysteries" (Liebig, 1865).

Having begun his remarkable career in chemistry by analysing the elemental composition of various animal and plant fractions (mass of carbon, oxygen, hydrogen, nitrogen in these fractions, identification of mineral salts, etc.), Liebig then sought to apply these results to understanding plant growth, respiration and, more generally, animal and plant physiology (Brock, 1993). For example, his analyses of meat led him to assume that the essential nutrients in meat were not in the muscle fibres, but in the fluids, which were lost during roasting or broth-making (which is wrong). Having studied mineral salts and found them in large numbers in meat broth, which was prized for its nutritional virtues, he concluded that gelatine was not used to form flesh, and that meat should be eaten with its juices, because inorganic compounds were essential nutrients for the formation of flesh. His theory became known as the "mineral theory".

An article published in 1847 (Liebig, 1847; This and Bram, 2003) was very influential: the Lancet presented the Chemische Briefe as giving "the true principles of cookery". However, there were sceptics. Half a century before Liebig, Rumford had demonstrated that meats cooked at a lower temperature were juicier than those roasted directly. This did not prevent Pomiane from writing incorrectly (Dujon, 1961): "He [Liebig] was the first to apply science to the phenomena of organic life".



Minor errors, corrected by scientific progress


In his 1948 article, Pomiane developed his idea of cooking: culinary technique would be based on "four types of cooking" and "three ways of combining" sauces. Unfortunately, this classification is too restrictive.

First, let's look at the question of types of cooking. Pomiane writes:

"Gastrotechnology has grouped all the methods of cooking food into four cooking techniques: 1° Cooking in water; 2° Cooking in fat or frying; 3° Cooking either over an open fire or in an atmosphere of dry heat: grilling and roasting; 4° Steaming or steaming".

It is strange that Pomiane, being a student of Metchnikoff, who introduced the technique, he did not consider high-pressure cooking (Galazka and Ledward, 1995), which was, admittedly, developed for sterilisation purposes, not cooking. He also failed to include in his list chemical processes such as the use of ethanol, salt and sugar, and the use of radiation sources other than infrared, which are included in the third type. To Pomiane's credit, radar had just been developed and its culinary applications had remained a secret.

How can Pomiane's classification be corrected? In 1997, a better classification of cooking methods based on the type of heat transmission was proposed (This, 1997): by conduction (contact with a solid, liquid or gas, by heating the food to a temperature above or below 100°C), by radiation (whatever the wavelength), by physical means (pressure, etc.) or chemical means (ethanol, etc.). The composition of the 12 or so types of single cooking leads to a total of 12x12 'double' cooking methods, i.e. 144, many of which have never been tested and deserve to be.

On the other hand, the "three modes of sauce binding" mentioned by Pomiane are binding by flour, by emulsion and by egg yolk. We now know that sauce bindings are more complex: using the formalism for describing complex dispersed systems introduced in 2003 (This, 2003), a classification of classic French sauces has been carried out. This formalism is based on the use of four letters (G for gas, O for oil, W for water, S for solid) and connectors (/ for "dispersed in", + for "mixed with", @ for "included in", and σ for "superimposed on"). Using these symbols, formulae are constructed to describe the physical structure of food preparations. For example, the formula O/W refers to oil-in-water emulsions, S1/S2 to solid suspensions, etc. The 451 sauces described in the Répertoire général de cuisine (Gringoire and Saulnier, 1901) can be broken down into 14 physico-chemical types, but the addition of three important cookery works (Guide culinaire (Escoffier et al., 1921), L'art des sauces (Académie des gastronomes et Académie culinaire de France, 1991) and L'Art de la grande cuisine française au XIXe siècle, by Antonin Carême (Carême, 1847)) brings the number of physico-chemical types of classic French sauces to 23: W, O, W/S, O/W, S/W, (O+S)/W, (W/S)/W, O + (W/S), (G+O)/W, (G+O+S)/W, (O+(W/S))/W, (S+(W/S))/W, ((W+S)/O)/S, (O+S+(W/S))/W, ((W/S)+(W@S))/W, (O + (W/S)/W)/S, ((O+(W/S))/W)/S, (O / W) + ((G + O) / W), (O + (W / S) + (W @ S)) / W, (S + (W / S + (W @ S)) / W, (((W / S) + (W @ S)) / W) / S, (O + S + (W / S) + (W @ S)) / W, (O + S + ((G + O) / W)) / W.1 Here again, tradition does not close the list of possibilities, because sauces as simple as "foamed veloutés" (formula (G+O+W1/S)/W2) are absent, for reasons that have nothing to do with their physical stability; it is simply that the empirical development of cooking did not find them.

Finally, we will pass over a series of errors of detail contained in the 1948 article ("Most proteins undergo hardening and coagulation during cooking. This starts at around 56°C. It is complete at 65°C". Or "Cellulose softens during cooking. It does not undergo any chemical transformation." Or also "Solid fats melt at around 50°C. Liquid or melted fats subjected to heat undergo a considerable rise in temperature"); like the many errors that appear in Pomiane's books (the theory that egg whites should be beaten in copper pans with an iron whisk, so that a pile effect occurs), they reveal not the weakness of Pomiane's thinking, but rather the remarkable progress made in food science over the last fifty years.

A remarkable gastronome, an unclassifiable biologist, an outspoken writer and lecturer, a captivating teacher (according to many of those who attended his courses), Pomiane was a driving force in French food education for half a century. Above all, he was an extraordinary populariser, whose books were bestsellers.

If we don't forget that "Man is only as good as his ability to admire" (Renan, 1859) and that "We all scale each other" (Montaigne, 1988), we have celebrated the centenary of the Société scientifique d'hygiène alimentaire by giving Pomiane a very special place.


 













Figure 2. A book by Edouard de Pomiane.



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ANON., s.d., Pozerki de Pomiane, Edouard . Souvenir d'un demi siècle à l'Institut Pasteur, Paris.


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1 « The starting point of this applied science is knowledge of the chemical composition of the very many foods we use. In fact, their number is limited if we adopt the classification used by chemists. »

1 The letters W, G, O and S stand for water, gas, oil and solid phases respectively, and the symbols /, +, @ and σ stand for dispersion, mixing, inclusion and superposition.

J'ai lu pour vous : Trois hommes dans un bâteau, de Jerome K. Jerome.


Il y a peu de livres qui m'ont fait autant rire que Trois hommes dans un bateau ! Plus exactement  il n'y en a pas : un jour, alors que je lisais le livre dans le métro, j'ai même fait pipi de rire dans mon pantalon. Je sais, ces choses ne se disent pas, mais c'est pourtant la vérité. 

On le voit : le ton de ce billet est un peu léger, voire trivial, mais est-ce répréhensible, même au vu de l'objectif élevé qu'est la recherche scientifique ? Avant de répondre à la question, qui est le cœur de ce billet, ajoutons que le livre de Jerome K. Jerome est plein d'intelligence, de malices, d'humour, et, mieux encore, d'humour  anglais. Du meilleur ! Je me garde bien de  raconter l'histoire, car cela serait gâcher le plaisir, et je me contente -vous le voyez- de faire des effets de manche, de l'épithétisme...  

Que faire d'autre ? S'étonner : s'étonner que  nombre d'Anglais (le livre était en anglais mais la traduction que j'ai lue était  remarquable) ne connaissent même pas cet ouvrage. 

 

Mais arrivons au fait :  la présentation d'un livre d'humour est-elle déplacée dans les discussions d'un scientifique ?

Les Jésuites disent qu'il ne faut pas font vivre en tant que chrétien, mais en chrétien. Transposons :  il ne faut pas vivre en tant que physico-chimiste, mais en physico-chimiste !   Cela signifie que si le physico-chimiste est un homme  ou une femme, il ne deviendra pas  meilleur physico-chimiste s'il se coupe un bras ou une jambe, au contraire ; il ne deviendra pas meilleur s'il limite sa vie à des matières « sérieuses ». Les très bons physico-chimistes  que je connais sont des êtres d'une culture immense, culture qui n'est pas strictement scientifique, et qui contribue à leur « créativité ». 

Pensons à Léonard de Vinci, par exemple, qui s'intéressa à tout : aux ramifications les arbres, aux  tourbillons de l'eau derrière les piles de ponts, au samares qui, préfigurant les hélicoptères, emportent loin de l'arbre qui les libèrent les semences qui assureront la reproduction de ce dernier. 

J'ai l'impression que la science est encore plus belle quand elle se nourrit de milles courants, quand elle s'embellit de mille fleurs. Et puis, n'avons-nous pas été créé avec cette capacité de rire... ou de sourire ? Rabelais disait que le rire est le propre de l'homme, ce qui n'est sans doute pas vu les études récente des primatologues... mais le sourire ?