Modelling dishes and exploring culinary ‘precisions’: the two issues of molecular gastronomy Herve ´ This* INRA Group of Molecular Gastronomy, Laboratory for Chemistry of Molecular Interactions, Colle `ge de France, 11 place Marcellin Berthelot, 75 005 Paris, France The scientific strategy of molecular gastronomy includes modelling ‘culinary definitions’ and experimental explorations of ‘culinary precisions’. A formalism that describes complex dispersed systems leads to a physical classification of classical sauces, as well as to the invention of an infinite number of new dishes. Soft matter: Colloids: Disperse system: Formalism: Food: Cooking Science explores the world and looks for mechanisms of natural phenomena: geophysicists try to understand the surge of moun- tains, molecular biologists explore the genome, embryologists study the build-up of living organisms, astrophysicists are inter- ested by the structure of the Universe, and chemists unravel the details of chemical processes... Every aspect of our environment is studied by a specific scientific discipline, using the experimen- tal method, introduced by Galileo Galilei (introduced in practice only, as it was theoretically introduced before him by Francis Bacon; Largeault, 1988), and ‘mathematics’, because they are the language of the world (Galilei, 1623). Cooking is such an important part of our world (even the smal- lest flat has a room for it) that it is worth specific scientific studies. The scientific discipline devoted to culinary transform- ations, and to gastronomical phenomena in general has been called Molecular Gastronomy by the late Nicholas Kurti and myself (This & Kurti, 1994). Of course, this discipline is part of food science, but research is focused on (mainly home or res- taurant) culinary transformations and eating phenomena rather than the physical and chemical structure of ingredients. As recipes describe culinary transformations, it is useful to examine recipes, in order to understand the scientific strategy of the discipline. The following one is from a culinary book published in France at the beginning of the 20th century (Anonymous, 1905): Take a dozen pears of middle size, remove the skin and put them immediately in cold water. Then melt 125 g of sugar with some water in a pan at low heat: as soon as the sugar is melted, add the pears, add some lemon juice if you want to keep the pears white; if you prefer them red, do not add lemon juice and cook them pan lined with tin. In this recipe, the words in bold characters give a definition of the dish; it can be observed that this definition here is less than 10% of the recipe. The words in italics add ‘precisions’, a category that includes old wives’ tales, proverbs, and sayings... Depending on the recipe and author, the precision content of recipes can vary considerably; for example, in some recipes from the French cook Jules Gouffe ´ (1867), the precision percentage is nil. The pear recipe indicates the scientific strategy of molecular gas- tronomy: it should model the definitions and explore the precisions. We eat only disperse systems Modelling culinary transformations involves a comparison of food before and after cooking. In this regard, it is important to realize that dishes are disperse systems, i.e. what were formerly called colloids (Hiemnez, 1986; Hunter, 1986; Everett, 1988; Lyklema, 1991). Textbooks on disperse systems (De Gennes, 1997) generally begin by a presentation of simple disperse sys- tems: gas, liquids or solids can be the disperse phase in a continu- ous phase that can be a gas, a liquid or a solid (Table 1). For example, the name ‘emulsion’ was given in the 17th cen- tury by chemists to preparations that are white and thick as milk or cream (Bloch & Von Wartburg, 1975); the word ‘emul- sion’ comes from emulgere, which means ‘to draw milk’, and indeed milk is an emulsion. With foams, which are also disperse systems, emulsions have been thoroughly investigated by famous physicists such as Michael Faraday and Albert Einstein (Everett, 1988; Atkins, 1998; De Gennes et al. 2002). Other important dis- perse systems are gels that were first characterized in 1861 by Thomas Graham, who proposed a classification of different sub- stances according to their ‘diffusive power’: the colloidal sub- stances (from Greek kolla, glue) are slowly diffusing substances which are held in solution by ‘feeble forces’ (Djabourov, 1988). This particular case of gels is important as ‘feeble forces’ are related to soft matter (De Gennes, 1999) and supramolecular chemistry (Lehn, 1995). Among the colloidal materials, Graham grouped together hydrated silicic acid, hydrated alumina, starch, gelatin, albumen, etc. * Corresponding author: Dr Herve ´ This, fax þ33 1 44 27 13 56, email herve.this@college-de-france.fr British Journal of Nutrition (2005), 93, Suppl. 1, S139–S146 DOI: 10.1079/BJN20041352 q The Author 2005 https:/www.cambridge.org/core/terms. https://doi.org/10.1079/BJN20041352 Downloaded from https:/www.cambridge.org/core. 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