Cooking Science. Condensed Matter
Fundació Alicia’s task (cooking and science) comipled in this original volume, including QR codes that augment this book’s reality. It invites us to look at cooking, gastronomy and nutrition through the scientist’s eyes and see them as a truly cultural activity which brings a wealth of knowledge into play.
Pere Castells - Josep Perell� 2 Cooking Science. Condensed Matter 3 Pere Castells - Josep Perell� 4 Cooking Science. Condensed Matter 5 VICEN� ALTAI� In the Laboratory FERRAN ADRI� 13 Cooking and Science Go Hand in Hand PERE CASTELLS - JOSEP PERELL� 17 Condensed Matter. Cooking Science OLGA SUBIR�S 21 "Condensed Matter. Cooking Science" Project at Arts Santa M�nica 30 TONI MASSAN�S The Theory of the Landscape in the Pot (From the Blind Cow to Beef with Mushrooms) GEORGINA REG�S 33 Preserves Freeze Time: A Way of Keeping Fruit All Year Round JOSEP ROCA - CLAUDI MANS 45 Wine as an Ingredient. Art and Science DAR�O SIREROL 51 Synaesthetic Cuisine. Odour Perception and Cookery XAVIER ESTIVILL - RAQUEL RABIONET - M�NICA GRATAC�S 97 Food Through the Senses AMY ROwAT - DAVID wEITZ 107 On the Origins of the Material Properties of Foods: Cooking and the Science of Soft Matter 115 16 FERRAN ADRI� President of the Advisory Board of Al�cia Cookery and Science Go Hand in Hand With every day that passes, scientific and culinary knowledge are establishing closer ties in order to consolidate a stable relationship. It should be pointed out that not so long ago they were two fields largely unrelated, from the point of view of cookery and science working together. Just a few exceptions from the world of science, albeit notable ones, like for example Nicholas Kurti, had truly devoted themselves to trying to understand, from their discipline, the series of states and processes hidden in every culinary preparation. Curiously, even though it is such an essentially technological activity, from the kitchens no real widespread interest had been shown either in the valuable help that scientific knowledge can provide with regard to culinary construction and reconstruction. But for some time now, the world of cookery has shown increasing interest in learning and gaining greater knowledge of itself, and it has focused on science as yet another element for making advances in cuisine. This line of action has encouraged, among many other factors, a creative revolution in cooking, which has become especially important in recent years, and here Catalan cuisine has played a predominant role in culinary research and innovation, managing to consolidate its international reputation. Obviously, the cookery of this country does not restrict itself to creative cuisine only � traditional cooking also needs the support of scientific knowledge in order to understand and thus better master its processes. Put simply, research and knowledge will help to produce and reproduce in the kitchen, with precision and delicacy, indispensable classics that form an essential part of our heritage. Moreover, the use made of cookery by science in order to explain scientific phenomena is a tool that may become crucial to spreading interest in science among the population. Some scientific phenomena are extraordinarily difficult to explain and cookery has shown itself to be an efficient vehicle Cooking Science. Condensed Matter 17 for making them understood. When, in 2006, I presented a synthesis of my cookery, point number seven said: "As has happened throughout history in the majority of the stages of human evolution, the new technologies act as a support for the progress of cookery." And the last point in the manifesto, number twenty-three, stated: "Knowledge and/or collaboration with experts in the different fields (gastronomic culture, history, industrial design, etc.) is of prime importance for the advancement of cookery. In particular, cooperation with the food industry and science has provided a fundamental boost. The sharing of knowledge among professional chefs has contributed to this development." The degree honoris causa from the University of Barcelona, as proposed by the Chemistry Faculty, that I am so excited to receive; the recent books on science and cookery � for some of which I have had the privilege of writing the foreword; the University of Harvard's proposal of organizing, jointly with Al�cia, a Science and Cookery course. All these things demonstrate the reliability of this approach, increasingly understood as an element of progress. In this context, the Al�cia Foundation has been working for some time now as a research centre devoted to technological innovation in cookery in order to bring about important improvements for our society, and on the educational side to arouse interest in science among the population. Arts Santa M�nica is a fantastic vehicle for establishing dialogue between disciplines in order to invigorate and spread the word about knowledge and culture. I am sure that now, with the exhibition "Condensed Matter. Cooking Science", in its emblematic building in Les Rambles, it will make this encounter more intense for the benefit of everybody. Ferran Adri� 18 Cooking Science. Condensed Matter 19 20 PERE CASTELLS JOSEP PERELL� Department of Gastronomic and Scientific Research. Al�cia Foundation Arts Santa M�nica. Science Ambit Condensed Matter. Cooking Science Who has not felt a certain amount of anxiety when reading in a recipe: "add a pinch of salt", or " just a dash of pepper"? Who has not become exasperated with their own mother or grandmother when not managing to obtain from them the exact formula for the wonderful Christmas cannelloni? Who has not cursed such ambiguous comments like "you'll see that it's cooked if you prick it with the fork ...", when asking how long you have to leave the chicken in the oven? And if, finally, the result did not live up to what you were expecting, who has not justified him or herself with excuses like the peculiarities of the oven or the subtlety of using a different type of water? The lack of quantitative precision in the most diverse or unimaginable facets is what makes us feel vulnerable when faced with the great complexity of the physicochemical reactions and processes of cooking. Everyone's extreme sensitivity with regard to the parameters involved makes the process fragile and enormously variable. So, why can't we understand cookery also as a complex laboratory of experience and knowledge more akin to science? The science of cookery grows with the desire to retain and critically analyse the intuitive wisdom of the gas rings. Cookery attracts the curiosity of the scientist and makes him observe the physicochemical processes involved in the preparation of organic and nutritive matter. It obliges him, therefore, to find in it the chemistry, the biology and the physics involved as added value to the mere nutritional, gastronomic fact, and to the pleasure of the senses it triggers off. We merely have to focus on the course of the 19 th century to become aware of the richness of the existing interrelationships between cookery and science. For example, in 1810 Nicholas Appert, the French pastry chef and inventor of the bain-marie as a technique for preserving food published the book L'Art de conserver pendant plusieurs ann�es toutes les substances animales et v�g�tales. The gastronome Jean Anthelme Brillat-Savarin, with the treatise Physiologie du go�t in 1828, investigated the anatomy of the palate of the Cooking Science. Condensed Matter 21 Parisian diner and ref lected on the senses in a first act before continuing with taste, the aromas, coming finally to the chemistry of culinary preparations, all of it seasoned with philosophical ref lections. The book was even republished with an appendix by Honor� de Balzac entitled Trait� des excitants modernes, in reference to alcohol, coffee, tobacco, sugar and tea. Brillat-Savarin's initiative passed the baton on to the Swiss chef Joseph Favre, who edited the journal La Science Culinaire in his desire to enlighten and democratize the secrets of haute cuisine from 1877 onwards. Over and above what we might understand as the strict world of cookery and quite close to the terrain allotted to science, we find the German chemist Friedrich Accum, known for being one of the introducers of the gas lamp. In 1821 he published in London a treatise with a wholly explicit title: Culinary Chemistry, exhibiting the scientific principles of Cookery, with concise instructions for preparing good and wholesome Pickles, Vinegar, Conserves, Fruit Jellies with observations on the chemical constitution and nutritive qualities of different kinds of food. Justus von Liebig, another German chemist known for the introduction of nitrogen in fertilizers or for the disputes with Louis Pasteur over the mechanisms of fermentation, was especially interested in finding ways of cooking meat that would preserve its nutritional qualities. The 1847 publication �ber das Chemische Untersuchung Fleisch (Investigation of the Chemistry of Food) described a particular "meat extract" prepared from soup of lean meat at a low evaporation pressure, "especially valuable for the sick, wounded and undernourished". Or a little later, in 1892, Elaine Kellogg, nurse, dietician, nutritionist and wife of the founder of the pioneering Battle Creek health centre, wrote Science of the Kitchen, which includes scientific principles of cooking, nutrition and advocates vegetarianism with a series of recipes. And we could go on like this until we reached the present day, but we could also go back. Denis Papin, an Anglo-French physicist, presented the "digester" that "softens" bones and speeds up the cooking process to his colleagues at the British Royal Society in 1681, but he did not manage to attract the interest of cooks. The device was nothing more than what today we call a pressure cooker, capable of cooking without coming to the boil. We could find many other examples at different moments in history but, going back in time, we would inevitably arrive at the knife or the mortar, utensils that play astutely with the mechanical forces of friction and pressure to cut and slice or pulverise and emulsify, respectively. Tools are considered the origins of cookery for their capacity to modify matter for the purpose of making it edible in the Palaeolithic, the Chalcolithic and the Bronze Age; in other words, thousands of years before Christ. They Pere Castells - Josep Perell� 22 Science in the Kitchen (1892) by Elaine Kellogg Cooking Science. Condensed Matter 23 OLGA SUBIR�S Architect INGREDIENTS Cookery and science with Pere Castells, chemist and head of research at the Al�cia Foundation, and Josep Perell�, physicist in charge of the science section at Arts Santa M�nica. With the ingredients contributed by the other guests at the table: centres of research, development and innovation, creators of smells, creators of sounds, creators of communication in space, etcetera. "Condensed Matter. Cooking Science" Project at Arts Santa M�nica Olga Subir�s 30 PREPARATION The rules of the game are a transverse conversation in which each picks up the thread from the other, enriching it, questioning it, enhancing it. Content and form are mentioned. The formalization proposals modify the interpretation of the content and vice versa. The relationship between the parts is horizontal and the project, understood as an agent agitateur of diffusion and production, leads the process. PRESENTATION The installation reveals that what is exhibited in ASM is real, it is presentation not representation. It is reality condensed, categorized: landscape, perception, matter and history. Reality transported in the case of the "towed" fragments of landscape. "Plug and play" apparatus and utensils for working the matter, placed on restaurant trolleys that move over the diagram of the states of matter. The projection in real time of the Al�cia Foundation's vegetable garden. Olfactory and sonorous installations that question the visitor. TASTING Walking around to encounter "pre-cookery", the palette of colours of cookery in the 21 st century. Where one can also taste in the literal sense: honeys from Catalan wines, preserves, peta zetas (sherbet fizz). A series of new "letters" ready to form "words" full of potential for being turned into "poems". Cooking Science. Condensed Matter 31 Pere Castells - Josep Perell� 44 GEORGINA REG�S Preserves Freeze Time: A Way of Keeping Fruit All Year Round Fruit is a gift of nature. It fills our landscape and gives us certain kinds of fruit at the beginning of each season, always different, that enable us to vividly experience the changes taking place throughout the year. As if one sort led to another, our subconscious awaits the first strawberries of spring, or the cherries, apricots and peaches in summer; the quinces, grapes, apples and pears in autumn, and the winter with its citrus fruit that begins with tangerines, to be followed by three kinds of orange: the sweet, the bitter and the blood. It is they that bring the cycle full circle, as if in silence and stillness they were preparing the most wonderful profusion of fruit that will be back with us next spring. This natural order that provides us with every sort of fruit and which often leaves a surplus is unquestionably the origin of preserves: the centuriesold need to be able to have available all that could not be eaten during the always intense and short-lived harvests throughout the year. Hence the earliest natural ways of preserving foodstuffs entailed using the cold where there was ice and snow, or the heat, exposing the fruit to the sunlight to dry it and rid it of all the water. Salt and vinegar are also ancient forms of preservation that date back to Antiquity. The Romans were most fond of preserving fruit and flowers in honey, and it is typical of Mediterranean culture to keep other foodstuffs in oil or vinegar. The tradition of making jams and marmalades is the province of the countrywomen who each year have filled their pantries with all the fruit that it was impossible to eat at the time. Strangely, however, kings, alchemists, scientists and saints have allowed themselves to be intoxicated with the taste, the aroma and the colour of preserves. It is said that Joan of Arc always ate quince jelly before an attack as it gave her courage. Catherine de' Medici was a lover of preserves; when she was married to Henri II she moved to France with a court that included cooks and pastry chefs so that there would never be any shortage Cooking Science. Condensed Matter 45 of jam and marmalade. It is also believed that preserves were introduced to Scotland by Queen Mary, when she left France and returned there, and that the physicist Marie Curie also experimented with jam-making during her free time. For Nostradamus preserves were a source of beauty and happiness, and before predicting the end of the world, in 1552, he wrote a "Treatise on Jam and Jelly Making" in which he says "... to do cherry jelly that is so clear and vermillion like a fine ruby, and of goodness, taste and virtue excellent, and will be fit to present to a king for its supreme excellence." Preserves went from being a necessity for survival to being virtually a luxury item, but it was the pastry chef Fran�ois Appert who took the first step in the process of sterilization, placing the food in hermetically sealed receptacles and heating them in a bain-marie. Although his method of trapping time inside a jar was already being used in private houses, Appert deserves the plaudits for spreading the procedure and adapting it to different products that, as has been said many times, make it possible to "bottle the seasons of the year". Years later, Pasteur's research conferred a scientific basis on the discoveries that Appert had made empirically. Preserves are memories of childhood. At least the first discoveries of fruit and aromas are. Picking fruit from the trees in the garden or wild berries in the woods, or those moments of discovering the mystery of the transformation of fruit, the delicacy of the flavours, the smells, the aromas, made more intense by the sugar and spices, the pleasure of tasting a jam and the satisfaction of witnessing a fascinating, seductive transformation. Since earliest times, it is the women who have been handed down the recipes for preserves from their mothers; they in turn had learned them from their grandmothers and their grandmothers from their great-grandmothers. A transmission of the experience and the word, seldom written down, that has passed traditionally from one generation to another for years without anyone stopping to think about the background of the science hidden in it. Now, like all aspects of gastronomy, preserves have moreover a component of innovation based on scientific and technological research that I personally have discovered through the technical teachings of Pere Castells. They have enabled me to understand the reason for a process and an elaboration in which I had immersed myself guided only by my intuition and following traditional methods. This knowledge is based on the magic triangle of preserves, resting on the three basic elements: sugar, pectin and acidity, which when they are balanced turn the central product, be it Georgina Reg�s 46 a fruit, a vegetable, a flower, a spice or an aromatic herb, into a technically perfect product. The knowledge of this technique makes it possible to adjust and improve the recipes and enter the always magical and slightly mysterious world of preserves. Equally magical are all the transformation processes that advance on a path, perhaps rather irrationally, but profoundly sensory and knowledgeable, which helps us feel happier. It is the path of the creation of the little things. Georgina Reg�s discovered preserves thanks to a lemon tree that was in the garden of a house in Torrent (El Baix Empord�), where she went to live in 1975. There were so many lemons on it that her English friend Wendy gave her the recipe for marmalade in order to take advantage of them. Starting from this recipe she later set up a marmalade-making workshop, and more recently, in 2004 she opened the Museum of Preserves in Torrent. It is a story that seems never ending. Cooking Science. Condensed Matter 47 Periodic table of preserves Lli lime 36 1 Ll lemon 37 3 4 Pa passion fruit 28 In 1869 Dmitri Mendeleev published his book Principles of Chemistry, which proposed the theory of the periodic table of elements. This table grouped the elements according to variations in their chemical properties. In 2007, the centennial of the death of this illustrious Russian chemist, Pere Castells, together with the Museum of Jam, decided to pay tribute to the scientist, and follow his example by grouping together jams with similar qualities in a periodic table. In 2010 we have updated this table with the new jams made at the Museum. 11 Aj grapefruit 5 12 Gs red currant jelly 32 19 Ta 20 Cs black currant 11 21 Fb wild berries 30 22 Mo mulberries 45 23 Al apricot 1 24 Po apples 54 25 Ci cherries 15 26 Ra grapes 58 27 Si water melon 63 Seville orange 65 37 Tr orange 64 38 Kw kiwi 34 39 Mb wild strawberries 38 40 Mi cranberries 44 41 Pr peach 55 42 Pe pears 51 43 Cia strawberrytree 16 44 Ar must syrup 6 45 Me melon 43 55 Mn tangerine 41 56 Py pineapple 52 57 Ma strawberries 39 72 Mg pome-granate 40 73 Pn plum 56 74 Ne nectarines 46 75 Np medlars 47 76 Cq khaki 8 77 Pl banana 53 Cl clementines 17 87 88 Man mango 42 89 Ge raspberries 31 104 105 Se 106 Gij jujube 113 107 108 109 azarole 73 1 Acidic citrus fruits 2 Acidic fruits from other groups 5 Seasonal and others 3 Transitional fruits 58 Ol olives 72 59 Gal basil 74 60 Kd karkad� 76 61 Cf coffee 7 62 Cny chestnut 12 4 Herbs and vegetables 6 Rare marmalades 90 Ku kumquat 99 91 Om barley+pomegranate 88 92 Cy cinnamon 104 93 Dl dandelion 90 94 Rk rambutan+acacia +karkad� 94 48 Preserve number 19 Symbol Name Ta Drawing Seville orange 65 2 Cp spring 22 Number in the Museum's list of preserves 5 Eu eucalyptus 106 6 Ro rose 59 7 Css pumpkin 10 8 A garlic 3 9 Ab egg-plant 2 10 Ce summer 23 Gm mint 78 13 14 Vio violets 69 15 Pg carrot 50 16 Pv pepper 71 17 Ap celery 4 18 Ct autumn 24 28 Li lychees 35 29 Fi figs 27 30 Co quince 19 31 Rm rosemary jelly 79 32 Sa sambucus 62 33 Re beetroot 57 34 Cb sweet-sour onions 13 35 To tomato 67 36 Ch winter 25 46 Gu guava 33 47 Da dates 26 48 Cy quince preserved 20 49 Gf thyme 91 50 Ga acacia 93 51 N 52 Por leeks 100 53 Lle beans 80 54 Cn Christmas 87 black turnip & honey 81 78 Pi papaya 48 79 C 80 Ca shredded pumpkin 9 81 Gca chamomile 92 82 Tg orange flower 83 83 Mon sweet potato 97 84 Gj parsley 84 85 Cso courgette 85 86 Cr layered 21 coconut 18 110 Xi Fs 111 112 Pf 113 Ml 114 Gli wisteria 102 115 Pt 116 Es 117 Pm 118 Sam ratatouille 95 chirimoyer 96 nuts 103 fruit paste 49 lemon verbena 105 potato+fresh almond 110 asparagus 82 peas+mint 89 63 Sf saffron 75 64 Gi ginger 98 65 Ry cantharellus cibarius 60 66 Va vanilla 101 67 Xo chocolate 70 68 Cv cava 111 69 Rg 70 Te tea jelly 66 71 An nori seaweed 77 rhubarb+ raspberry 61 95 Cli 96 Fa fruits+ Brandy 29 97 Ae star anis 109 98 Cht chutney 14 99 Fn fennel 108 100 Arr rice 86 101 Vi 102 Gcl 103 Atr other 114 cauliflower 112 wine 68 marigold 107 Cooking Science. Condensed Matter 49 Design: www.petitcomite.net / illustrations: Salva L�pez & Joan Alf�s SUPERCRITICAL FLUID SOLID PHASE COMPRESSIBLE LIQUID P C CRITICAL PRESSURE LIQUID PHASE CRITICAL POINT P C TRIPLE POINT STEAM PRESSURE GASEOUS PHASE T TEMPERATURE C T C CRITICAL TEMPERATURE Pere Castells - Josep Perell� 60 Phases of matter solid Offers considerable resistance to changing its form, shrinks and contracts a little with changes of temperature and pressure, and usually presents an orderly structure in a reticulum. without the tendency to separate from each other. liquid Composed of molecules that can move freely gas Group of molecules that are loosely linked to one another by the forces of cohesion and always completely and uniformly fill the receptacle containing them. absence of viscosity; so it flows endlessly without any friction. Temperature and pressure conditions which the solid, liquid and gaseous states of matter coexist. two different states of matter which specifies the specific conditions of temperature and pressure starting from which two states of matter become indistinguishable. critical point End point of a curve that separates triple point Conditions of temperature and pressure in superfluid Phase of matter characterized by the total Cooking Science. Condensed Matter 61 phase naMe Liquid Roner: Thermostatic Bath description Device with water in it that regulates the temperature of the products placed in it through an electrical element. applications Used for cooking evenly, at stipulated times and temperatures. Boiled eggs are cooked at 62 and 65�C, meat between 65 and 70�C, fish between 50 and 60 �C, fruit and vegetables between 80 and 90�C. The name Roner comes from a combination of the surnames of chefs Joan Roca and Narc�s Caner. additional inforMation Pere Castells - Josep Perell� 62 Cooking Science. Condensed Matter 63 phase naMe Liquid Viscometer: Soup, Pur� or Sauce Device that measures the resistance of a fluid to movement. description applications Used for classifying and determining if the fluid is a soup, a pur�, a marmalade or a sauce. additional inforMation There is no clear consensus when establishing whether a product is a highly viscous liquid or an amorphous solid also called a soft solid. The viscosity of a fluid does not only change according to the temperature, the mechanical forces can increase or diminish its viscosity by shaking it or beating it. One of the types most used these days is the Brookfield. The device featured in the exhibition is an old model from the UB Physics Faculty that works with forces and resistances of torsion. In 1932, while he was completing his studies at MIT, Dan Brookfield said to his father "I can create a better world". He was referring to the viscometer. In 1934 the first line of viscometers was commercialized. The product was to become the standard all over the world. Pere Castells - Josep Perell� 64 Brookfield Viscometer Cooking Science. Condensed Matter 65 phase naMe Gas - Liquid - Solid The Rotaval: Distilled and Reduced Matter description A device that, at low temperatures and very low pressures, obtains a distillate from a solution. The liquid distilled is the result of a process of evaporation and subsequent condensation. The substance remaining is reduced with a dense concentration with its less volatile components. applications Makes it possible to obtain liquid distillates from solids like cocoa, coffee, earth and also alcoholic products. The process of reduction allows us to obtain a concentrate of fruit, sweet wine or others. The name rotaval comes from the fusion of the term `Al�cia' and the word `rotavap' (rotary evaporator), a similar device but used in chemistry laboratories. It was used for the first time in cooking in 2004. additional inforMation Pere Castells - Josep Perell� 66 Cooking Science. Condensed Matter 67 Flask in the rotaval Pere Castells - Josep Perell� 68 Cooking Science. Condensed Matter 69 Creamy mat� with reduction of muscatel Bread with wine and sugar with sweet wine concentrate Pere Castells - Josep Perell� 70 naMe Project Wine as sweet as honey description The exhibition allows us to taste reductions of sweet wines from the 11 denominacions d'origen in Catalonia. Distillation extracts the alcohol so that the resulting reduction becomes a dense and concentrated liquid free of alcohol. 5 4 5 8 4 4 3 4 9 11 10 6 10 7 1 Denominacions d'origen (D.O.) of Catalonia 1. Alella / 2. Catalunya / 3. Conca de Barber� / 4. Costers del Segre / 5. Empord� / 6. Montsant / 7. Pened�s / 8. Pla de Bages / 9. Priorat / 10. Tarragona / 11. Terra Alta Cooking Science. Condensed Matter 71 phase naMe Gas - Liquid Cava with Xantana: Gas Trapped in Liquid description Cava, like champagne and other sparkling wines, keeps the carbon dioxide bubbles generated in the process of fermentation in the liquid, and the gum xantana, due to its effect as an elastic thickener, makes the retention even more obvious. applications Xantana does not change the taste of the product and makes it possible to taste the cava as a bubbly sauce in preparations like oyster in cava sauce, strawberries with pink cava. Xantana comes from the fermentation of the bacteria Xanthomonas campestris and thickens the cava through reaction with the sugar chain. The product is also called "solid cava" even though it is only a thickened liquid. additional inforMation Pere Castells - Josep Perell� 72 Cooking Science. Condensed Matter 73 phase naMe Solid - Gas Lyophilizer: Dehydrated Solids description A device that extracts the water from a product by subjecting it to a strong vacuum at temperatures between -50�C and -80�C. The device sublimates the water from the substance making it pass directly from a solid to a gaseous state. applications Makes it possible to extract the water from fruit, vegetables and in general from any product. Once it has been lyophilized, the food can be transformed into a powder. additional inforMation Lyophilized products are used widely on extreme campaigns and expeditions, like in the high mountains, given that this represents a notable reduction of the load to be transported. Space missions also use these products for the simple fact of not containing water and thus avoiding conservation problems, for example preparations for soups and rice dishes. Pere Castells - Josep Perell� 74 Cooking Science. Condensed Matter 75 Lyophilized pistachio Pere Castells - Josep Perell� 76 Lyophilized pineapple, raspberries and carrot foam Cooking Science. Condensed Matter 77 Lyophilized chocolate foam Pere Castells - Josep Perell� 78 Cooking Science. Condensed Matter 79 phase naMe Solid Knife: The Dawn of Cooking description Cutting instrument that consists of a blade with a sharpened edge, with a handle and at times forming a single piece with the blade. applications The serrated knife tears substances with a high resistance to penetration like bread lengthwise. The non-serrated knife penetrates and slices crosswise making a very clean cut, as in meat and fish. It is said that the Greek wise man Democritus managed to discover atoms, the constituent elements of matter, through just philosophical arguments and by observing how a knife cuts an apple, without using today's electron microscope. The sharper the blade, the more efficient the transmission of the force applied to the handle will be. The pressure on the product can be huge if the edge of the blade is very sharp. The first stone knives are not only the earliest evidence of cooking that we have; they are also the first human technology and therefore evidence of complex cultural behaviour that we know of. additional inforMation Pere Castells - Josep Perell� 80 Flint denticulate Abric Roman� (Capellades, Barcelona) Dating: 43.000 BCE. Homo neanderthalensis AR-4/1214 (75 x 64 x 15 mm) Cooking Science. Condensed Matter 81 Cooking. Maillard reaction Pere Castells - Josep Perell� 82 Foam that can be cut Cooking Science. Condensed Matter 83 phase naMe Solid Mortar: Mechanical Emulsion description Vessel with a hemispherical cavity in which by exerting intense pressure certain substances it is wished to pulverize or reduce to a paste are crushed or ground. applications Reduces to powder grains of wheat, cloves of garlic and others. Reduces to a pulverized paste a solid or liquid. Mixes immiscible liquids like water and oil. By crushing a few cloves of garlic to a paste and slowly adding olive oil to it we get the waters and oils to mix; this is called "aioli", and it is an example of an emulsion like mayonnaise, picada or romesco. The historical origins of the mortar date back to the Bronze Age in Europe, from 1800 BC, and the instrument has evolved towards grinders as far as the modern handblenders and mincers/crushers, which aside from pressure also work with the forces of friction and cutting. additional inforMation Pere Castells - Josep Perell� 84 Elliptical stone mortar with spout on one side Bronze Age. Unknown Origin Museu d'Arqueologia de Catalunya Length: 265 mm / Maximum width: 189 mm / Height: 86 mm Cooking Science. Condensed Matter 85 phase naMe Solid - Liquid Gels: Soft Solids description Colloidal systems of a solid in a liquid that appears in the form of a gelatinous mass and behaves like an elastic solid. applications Gels give texture to the products in confectionery, vegetable conserves (jams, jellies, marmalades, etc.), rendered meat products, ice creams, fresh cheese, coverings of fish conserves and semiconserves, soups, sauces, marzipans and many others. The gelling agents, agar-agar, carragenates come from seaweed; pectins come from fruit and fishtail gelatin is animal in origin. additional inforMation Research with gelling agents Pere Castells - Josep Perell� 86 Cooking Science. Condensed Matter 87 Agar-agar Pere Castells - Josep Perell� 88 Alginate Cooking Science. Condensed Matter 89 Jellified structure Pere Castells - Josep Perell� 90 Cooking Science. Condensed Matter 91 phase naMe Solid - Liquid Spherification: Liquid Trapped in a Solid description Culinary technique defined scientifically as controlled jellification that makes it possible to give external rigidity to a liquid food product with a gelling agent, usually alginate. This external jellification only takes place in the presence of calcium. applications A culinary technique of external jellification has been developed that keeps the substance in a liquid state inside and solid in the external shell, marketed in the form of small spheres called caviar, and in larger ones called ravioli. In 2003 at the restaurant ElBulli the product was applied with alginate in a calcium bath and was called basic spherification. The first ones were done with apple, melon and pea. In 2005, also at ElBulli, the product was applied with calcium in an alginate bath and called inverse spherification. This evolution preserves for a long time the solid part in the external shell and the liquid one inside. The first inverse spherifications were done with liquid of olives and dairy products. The spherical shape acquired is due to the effects of the product's surface tension. additional inforMation Pere Castells - Josep Perell� 92 Cooking Science. Condensed Matter 93 Oil caviar Spherified balls of melon with ham Pere Castells - Josep Perell� 94 Cooking Science. Condensed Matter 95 Sensory experience What sensory images would you ascribe to the colours in the series? It is an entertainment designed to enable readers to let their imaginations fly and try to ascribe, as if it were a synaesthetic process, the possible smells, sounds, textures and tastes to the colours presented. Dar�o Sirerol 104 An interpretation of the colour series: Ivory, lemon yellow, straw, new gold, mahogany yellow, old gold, onion skin, chestnut, tile red, ruby, maroon red, purple red, violet red. The colours have been defined by taking as a reference a subjective perception of the colour of certain natural substances. The colours in this series try to represent how the colour of wine changes inside the bottle over time. It is its ageing process, with the improvement of the quality of the wine, its maintenance and the subsequent decline and deterioration. From left to right, white wine, and from right to left, red wine, until they meet at a central point at which the colours could seem alike at the moment of maximum degradation. It is a presentation that is intended to be general and cannot be extrapolated to all wines. There are some excellent wines that are, for example, the colour "onion skin" when their quality is optimum. Cooking Science. Condensed Matter 105 Pere Castells - Josep Perell� 106 XAVIER ESTIVILL - RAQUEL RABIONET - M�NICA GRATAC�S Food Through the Senses Many people think that gastronomic critics, sommeliers and professional tasters have supernatural or, at least, above-average skills. In actual fact, taste has physiological bases that are the same for everyone, although individual differences in the sensitivity and ability to perceive and discern the quality of food may be either inherited or educated and trained. The tools we use to determine "flavour" and enjoy food are our five senses: sight, hearing, touch, smell and taste. We observe the colour of a wine to discover its youth or maturity. We pass a piece of cheese through our fingertips to feel its texture. We use smell to obtain very complete, detailed information about practically all foodstuffs. The crunchiness of a croissant when we bite it is just as important as the smell and the taste. And yet, there can be no doubt that the most important sensory analysis in food and drink is that which we experience when we place the food or the liquid in our mouths. The perceptions we have at this point are related to taste, smell and touch. When the food is in the mouth, the substances go from a solid to a liquid state, due to their volatility. The airflow between the mouth and the nose allows the smells of the substances to reach the nasal cavity and the sense of smell. The aroma of a food or drink is perceived as we chew. Oral mucous is very rich in tactile nerve endings, which detect smoothness and texture in food. THE FLAVOUR SPECTRUM OF FOOD Whereas in ancient times there were two flavours considered fundamental, sweetness and bitterness, in the middle of the 18th century the naturalist Linnaeus produced a classification of ten tastes: sweet, bitter, salty, acidic, astringent, sour, fat, mucous, moist and dry. In the 19th century four basic tastes were distinguished: sour, salty, sweet and bitter. Recently the existence has been scientifically demonstrated of a fifth basic taste, umami Cooking Science. Condensed Matter 107 (savoury), a Japanese word that means literally "good taste". Umami corresponds to the taste sensation caused by glutamate, one of the 20 amino acids that make up proteins. While the reduction to these five basic tastes is a good reference, it is clear that the sensation of taste is very complex, especially if we consider that a single item of food contains hundreds of different substances that can affect its taste. THE PHYSIOLOGY OF TASTE The erroneous notion of the tongue's taste maps is very widespread (sweet at the tip, bitter at the back, sour and salty at the sides). In fact, the neurons of the taste receptors are distributed all over the tongue and the palate, with no kind of spatial distribution as regards taste sensitivity. The taste cells are located in the taste buds, found chiefly on the tongue. The taste buds are structures formed by a variable number (50-100) of epithelial cells, specialized in the incorporation of gustatory stimuli. The gustatory cells have an internal cavity that communicates with the outside through the gustatory pores. On the sides of the pores there are tiny villi, where the taste receptors are, that can bind with certain molecules and which have a useful life of approximately 10 days. The chemical products of the food and drink are dissolved in the saliva and penetrate the pores where they interact with the taste receptors. This sets off a series of reactions in the gustatory cell that will culminate in the release of a nerve impulse towards the brain. This process is called transduction. It is interesting to note that the chemical binding between the molecule and the taste receptor is weak, whereby the sensation of taste is short lived. If this were not the case, we would continue to sense the same taste for a long time and we would not be able to distinguish between different flavours in quick succession when we eat or drink. Unlike smell and sight, in which the signals are transmitted via a nerve (olfactory and optic), in the case of taste there is no specific gustatory nerve. The information travels directly from the mouth to the brain: it first reaches the gustatory cerebral cortex and, from there, the frontal lobes, where conscious thought resides. In this respect, taste is quite different to smell, as the taste signals do not pass through nuclei of the brain that regulate the emotions. Xavier Estivill - Raquel Rabionet - M�nica Gratac�s 108 THE TASTE RECEPTORS According to the type of taste, the process that takes place in the gustatory cell varies. Sweet and bitter substances interact with the taste receptors in the membranes of the gustatory cells. The process of transduction that follows is made up of different stages. The protein receptors for sweet or bitter are attached to special proteins called G proteins (or gustducins), which are located beneath the cellular membrane. These proteins represent the first stage of the process of transmission of the signal and they set off a series of reactions in the cell. These reactions are different according to whether the receptor is joined to a substance with a sweet or bitter taste, although in both cases positive charges are accumulated in the cell that give rise to the release of neurotransmitters. It is the neurotransmitters that will finally stimulate the neurons connected to the gustatory cells, giving rise to nerve impulses. Strangely, sour or salty substances behave differently, as they do not attach themselves to the taste receptors, but they lead directly to the accumulation of positive charges in the cell. In the case of the fifth basic taste, umami (savoury), specific receptors for glutamate behave similarly to the receptors of sweet and salty transduction. In recent years a great deal of research has been done on the genetics of taste. There are two families of taste receptors: T2R, which includes around 30 genes that codify the synthesis of bitter taste receptors, and T1R, with three members that are combined in different ways to form the receptors for sweet and umami. Each gustatory cell presents a variable number from among the 30 different bitter taste receptors and can interact with a wide range of bitter substances. The presence of so many different T2R receptors means that they can be distinguished very well among the different types of bitter substances. A DIFFERENT TASTE FOR EVERYONE The differences in taste among human beings have not only a cultural basis but also a genetic one. This may explain why one person needs five spoonfuls of sugar in their coffee and another only two. Different sweet taste receptors may need more or less sugar for the same level of stimulus. A lot of research has been done on the perception in humans of the bitter taste, probably the one that presents the greatest variability among individuals and which is a typical genetic trait transmitted from parents to children. In order to study it, bitter substances from the thiourea family, 6-n-propylthiouracil (PROP) and phenylthiocarbamide (PTC) are used, Cooking Science. Condensed Matter 109 impregnated on small strips of paper that are placed on the tongue. Largescale research of the population has shown that some people are highly sensitive to the bitter taste (the so-called "supertasters", who are also more sensitive to sweet and spicy sensations) and they therefore have a low taste threshold, while others have low sensitivity (the "non-tasters") and a high taste threshold. There is often an intermediate category in the classification, the "medium-taster". Moreover, sensitivity to bitterness varies widely in the world: non-tasters represent nearly 3% of the population of West Africa, over 40% of Indians and 30% of Europeans. The great variability in receptors for bitterness explains, for example, that a non-taster will like bitter coffee without sugar, certain kinds of beer, vegetables or bitter chocolate with 70% cocoa. THE SENSE OF TASTE AND HUMAN EVOLUTION The sense of taste has been transformed, in the course of the evolution of mammals, into a system capable of determining whether potential foodstuffs are useful or harmful. The preference for sweet food is related to the search for food with a high calorie count; the umami taste, for food rich in proteins; and the liking for salt to the need to ingest a certain amount of mineral salts. In general, all human populations feel an aversion towards sour and very bitter food. High acidity levels may indicate the presence of contaminated food. This possibility, obviously more frequent in the past than now, has remained as a widespread attitude in order to assess whether or not food has been properly preserved. However, these innate behaviour patterns are influenced by a population's eating habits and culture, as, for example the salty, and especially the sour, tastes are obvious from the habit of eating food preserved with salt or vinegar. It is reasonable to suppose that an aversion to bitterness is due to the fact that many of the compounds harmful to health are found in vegetables and taste bitter, and so our body has developed a preventive defence system against these risks. The alkaloids, for example, that are contained in around 20% of plant species and which taste bitter, are noted for their toxicity (strychnine or atropine), for their stimulating effects on the nervous system (caffeine and theobromine), or for being drugs (cocaine and mescaline). It is therefore easy to understand how plants with a bitter taste have always been regarded with suspicion and caution in the history of human evolution. Xavier Estivill - Raquel Rabionet - M�nica Gratac�s 110 THE "OTHER" TASTES There are some sensations experienced in the mouth that are not strictly classified as tastes but which are a part of the gustatory experience. For example, tactile sensations provide information about the nature of food: texture, friability, granularity, crunchiness, juiciness, elasticity, viscosity, and so on. Other sensations are related to "chemical sensitivity", like the astringency of tannins, the spiciness of substances like capsaicin (capsicum), piperine (black pepper), allicin (garlic) and zingerone (ginger), which are transmitted to the brain by the trigeminal nerve, following a path different to the taste stimuli. Capsaicin, for example, is the molecule responsible for the spiciness of black pepper and capsicums, which contain varying quantities of it depending on the variety. A brief exposure to capsaicin generates strong effects. From the evolutionary point of view, the spiciness of pepper is this species' defence strategy against predatory mammals. Thus, whilst all mammals may suffer from the effects of capsaicin, birds are insensitive to this molecule and this explains why they can eat capsicums and contribute to the dispersal of the seeds and the propagation of the species. The effects of the mixture of tastes may be mutually reinforcing, as is the case with sourness and bitterness, or mitigating with sweetness and bitterness or sourness. Salt has considerable influence over the other tastes. It can reduce the intensity of the bitterness and improve the sweetness, thus enhancing the other tastes indiscriminately, and this is the reason why its presence is essential in the cuisines of different cultures. Moreover, exposure to a substance with a certain taste produces adaptation, a phenomenon that also occurs with smell and touch, so that over time the intensity of the perceived stimulus diminishes. This adaptation is a defence in order to avoid the over-stimulation that would arise with an excessive stimulus. For years it has been thought that the principal characteristic of the molecules that constitute taste was that they had no smell, but we now know that they are often capable of interacting with smell. This is why the perception of taste and smell act independently in our brain on the level of the frontal cortex, and thus our mind forms an impression of the "taste" that superimposes and mixes the taste, the smell, the touch, the astringency, and so on. One only has to remember that, as has been shown, the intensity of the perception of taste is better if it is combined with the aroma. Finally, the taste is also affected by the temperature of the food or drink. Flavours are best expressed between 30 and 35�C, whereas at temperatures higher than 50� or close to 0� the gustatory stimuli are virtually non-existent. Cooking Science. Condensed Matter 111 TOwARDS THE PERSONALIZATION OF THE ENJOYMENT OF FLAVOURS The new genetic technologies should enable us to identify individual characteristics with regard to all the senses that have to do with "taste". The study of the variability in the perception of these senses, together with the identification of new genetic variants that may be related to them, will make it possible to create individual genetic profiles, based on the analysis of DNA samples from each of us. In this way we might achieve a personalization of food adapted to our personal characteristics. Xavier Estivill was born in Barcelona in 1955. He studied Medicine at the Autonomous University of Barcelona, specializing in Haematology, in 1985. He did his doctorate in Medicine (Autonomous University of Barcelona) and Genetics (University of London) on the genetic causes of cystic fibrosis. He was director of the Cancer Research Institute's Centre for Medical Genetics and of the Hospital Cl�nic's Genetic Service. Since 2001 he has been the Coordinator of the Centre of Genomic Regulation (Barcelona)'s Genes and Disease Programme, and Associate Professor at Pompeu Fabra University. His research work is focused on the study of the variability of the genome in relation to human disease. Raquel Rabionet was born in Barcelona in 1974. She took a degree in Biology at the University of Barcelona, and did her doctorate in Genetics in 2002, after studying the genetic causes of hereditary deafness for five years. She moved to the United States of America, where, at Duke University (Durham, NC) she worked on discovering genetic factors involved in autism. Since 2005 she has been part of the research team of the group researching into the genetic causes of disease in the Centre of Genomic Regulation (Barcelona)'s Genes and Disease Programme. M�nica Gratac�s was born in Barcelona in 1964. She took her degree in Medicine at the Autonomous University of Barcelona, and specialized in Clinical Biochemistry. She did her doctorate on the genetic causes of anxiety disorders and in 2001 she joined, as a collaborating researcher, the group researching into the genetic causes of disease in the Centre of Genomic Regulation (Barcelona)'s Genes and Disease Programme. She currently works as a researcher at this same centre and is focusing on the study of genetic susceptibility to suffering psychiatric illnesses such as emotional disorders, anxiety disorders, obsessive-compulsive disorder, substance abuse and eating disorders. Xavier Estivill - Raquel Rabionet - M�nica Gratac�s 112 Cooking Science. Condensed Matter 113 Pere Castells - Josep Perell� 122 Cooking Science. Condensed Matter 123 Pere Castells - Josep Perell� 124 Cooking Science. Condensed Matter 125 Pere Castells - Josep Perell� 126 Cooking Science. Condensed Matter 127