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Pots & Tubes. New horizons in molecular gastronomy

Dario Bressanini [The Sciences 435]

Pots & tubes. New horizons in molecular gastronomy.
of Hervé This
The Sages of the Gambero Rosso, 2003, pp. 254 (€ 16.00).

filter, heating, cooling slowly or abruptly, stir, bring to boiling, dilute, add ice, place in refrigerator. They are everyday gestures in any chemistry laboratory anywhere in the world. And they are the same steps that anyone does in the kitchen, the most famous chef of the housewife. Not surprisingly, the chemical laboratory speak jokingly of "recipes" when they follow procedures developed to synthesize una molecola. Non deve stupire, perciò, se un chimico-fisico appassionato di gastronomia decide di mettere la scienza al servizio della buona cucina. Hervé This lavora all' Istitut National de la Recherche Agronomique a Parigi e tiene da anni una rubrica di "scienze in cucina" per Pour la Science , edizione francese di Scientific American . Il suo Pentole & Provette sta diventando rapidamente un testo sacro della "gastronomia molecolare", l'insolita disciplina che studia la buona cucina dal punto di vista dei processi chimici, fisici e biologici che avvengono nelle pentole, nelle padelle e nel resto dell'attrezzatura cuisine. It may seem strange that on the Sciences are talking about a book where mayonnaise, soup, souffle and jams are the masters. But it is at least as strange that a text that describes the cooking of meat through lareazione Maillard protein, and blackening of the fruit cut by the action of polyphenol oxidase is one of the essays published by Gambero Rosso. Yet Hervé This tells us that there is no contradiction: what if the food is not the art of physical and chemical processes that occur during the preparation and tasting the food? The book is divided into four sections consisting of easy chapters a couple of pages each. First we will investigate sayings, proverbs and cooking traditions: it is true that to make the broth the meat must be soaked in cold water? And that egg whites do not mount if you change the direction of rotation during the operation? And because it is said that the dumplings are cooked when they float? Sometimes the advice of the tradition are the comfort of scientific inquiry, are sometimes blatantly contradicted by the experiment, and find that to prepare a delicious broth does not affect the initial temperature of the water. So how to put a teaspoon in the neck of an opened bottle of sparkling wine or champagne will not absolutely prevent the loss d'effervescence, despite popular belief states that. The second section explores the physiology of taste, and we learn that the mouth identifies only five flavors: the four "classic" (sweet, salty, bitter, sour), plus the latest addition, the ' umami (Japanese for simply means "taste"), which we could identify roughly in flavor. Flavor to another already known for centuries to oriental cuisine which often uses the characteristics of MSG added to foods, umami taste stimulator. The physiology of taste is actually more complex, This continues, for example There seems to be five different types of "bitter", each with its specific receptors. The third part of the book is dedicated to exploring and modeling of many food processes, from the preparation of jams and jellies to that of the white sauce, where it is suggested, on strictly scientific basis, avoiding the formation of clots, each of shame cook. The wine of course could not escape the scientific curiosity of a French physical-chemical, and several chapters are dedicated. The fourth part, "a food for tomorrow" is perhaps the most challenging. If science is able to investigate the mechanisms of food, why not provare a modificare e migliorare le ricette della tradizione in base alle conoscenze acquisite? O addirittura inventare nuove ricette? Per esempio, la crema Chantilly è una mousse preparata sbattendo la panna con la frusta in un recipiente freddo. Analizzando il processo, This si chiede se si possa creare un "cioccolato Chantilly". E, in un attimo, ecco fatto! Subito preparata una mousse di cioccolato che, contrariamente a quella classica, non ha bisogno di panna fresca o albume montato a neve. Alla fine della lettura del libro rimane solo un piccolo rimpianto: This è francese, e giustamente si addentra nei segreti della gastronomia transalpina, tra foie gras e Champagne, reblochon and quiche lorraine. The Italian cuisine is equally interesting (and tasty) and it would be nice that sooner or later someone will tell the same passion with the chemistry of the thermodynamics of pesto or pizza ...

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The Science of Pizza

Dario Bressanini [Le Scienze 453]

The dough and the leavening are critical to the success of one of Italian dishes more 'famous world: better to rely on chemistry and thermodynamics

In molte famiglie resiste ancora la tradizione di preparare la pizza in casa impastando acqua, farina e lievito. Una conoscenza dei processi chimici e fisici che avvengono durante la preparazione dell'impasto può aiutare noi pizzaioli casalinghi a preparare una pizza migliore. Esistono vari tipi di farine, ottenute macinando i più svariati cereali, ma quella utilizzata per preparare la pizza è la farina di frumento che contiene circa il 70% di amido, un carboidrato, e tra l'8% e il 13% di proteine. La farina di frumento si distingue da molte altre per presenza di due proteine, la glutenina e la gliadina, che a contatto con l'acqua formano un complesso proteico called gluten that gives dough quell'elasticità and plasticity key to turn it into pizzas, focaccia bread and a thousand different forms. Another key ingredient and
'yeast, whose aim is to produce carbon dioxide, used to inflate the dough. Yeasts are unicellular organisms that belong to the kingdom of fungi. These organisms, commonly used for making bread and alcoholic beverages in contact with water, through the fermentation process, transform the sugars into carbon dioxide and alcohol. When the yeast dissolve in water you have to be careful to use warm water but at a temperature not exceeding 45-50 degrees, not to kill it before it has done its job, otherwise it will fail to leaven the dough.
In trade there are also packages of instant yeast pizza, with a leavening agent already mixed with flour. In this case it is not living organisms but a mixture of two or more components, usually an alkaline substance, sodium bicarbonate and an acidic substance, such as potassium acid tartrate (the so-called cream of tartar) or gluconate delta lactone, which immediately react in the presence of water producing CO 2 . In this case they will fail dough aromas that are typical of yeasts and give it a distinctive flavor.
Once formed the gluten, you knead. During the dough the gluten molecules begin to form long chains. S'impasta longer, more gluten chains stretch into line with each other, creating links between them and forming a complex three-dimensional network that gives elasticity to the dough. If the grid is sufficiently dense, also helped partially hydrated starch, will be able to retain the form of bubbles of carbon dioxide formed during fermentation. is for this reason that the phase of the dough is very important for the success of a good pizza: un impasto frettoloso non permette al glutine di formare il reticolo, e rimane solo una massa informe appiccicosa difficile da stendere sulla teglia. Dopo l'impasto il lievito agisce al meglio lasciando la pasta a riposo a circa 35 gradi.
Anche la percentuale di acqua aggiunta alla farina è importante al fine di far ottenere alla pasta della pizza la consistenza desiderata. Può capitare di aver sbagliato ad aggiungere l'acqua, di avere manipolato la pasta per troppo tempo, o di averla lasciata lievitare troppo poco. In questo caso la pasta è troppo elastica e non ne vuole sapere di essere stesa sulla teglia. Si può risolvere il problema "allentando" un poco il reticolo gluten by increasing the temperature. Between 60 and 80 degrees the starch begins to gel and the proteins start to denature, ie to change their structure. Put the pan for a few minutes with the dough "recalcitrant" in the oven (started at 60 degrees to avoid drying out the pulp). After treatment the dough less elastic and will stretch without any problems.
Then, like a script, add mozzarella, tomato sauce, a drizzle of olive oil and a pinch of salt. Bake and let the thermodynamic take its course.

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Caffeine, our "drug" morning

Dario Bressanini [Le Scienze 455]

Consumed by millions of people every morning, coffee is part of the same group of natural substances of nicotine and cocaine. But, fortunately, is much less harmful

What is the substance, a relative of morphine, which take millions of Italians every morning to start your day? No, no joke: it is the caffeine. Its full chemical name is 1,3,7-TRIMETILXANTINA and belongs to the large group of natural substances called alkaloids. This group includes other well-known substances, and toxic substances such as nicotine and cocaine. Most alkaloids have a physiological effect, and since ancient times were used extracts from plants containing alkaloids for medicinal purposes, or as poisons. It was the coniina alkaloid extract of hemlock, for example, to kill Socrates. Even caffeine is toxic, but only in large quantities: the lethal dose is estimated to be about ten grams, or the equivalent of 100 to 200 cups of coffee '. Caffeine is a stimulant of the central nervous system. But the body does not accumulate, and thrown them away fast enough. Nerve cells mixed with caffeine, adenosine, due to similar chemical structure. When adenosine binds to a receptor in a cell nervous cause drowsiness. Caffeine, "cheats" the cell by binding to adenosine receptors, but without causing drowsiness.

The "discovery" of coffee is lost in the mists of time. According to legend, the shrub grows wild in Ethiopia. A shepherd discovered it by observing the effects that his sheep did not sleep more after the fruits of cibate quell'arbusto. The coffee arrives in Venice at the beginning of the seventeenth century, and from there spread throughout Europe. Caffeine was first extracted from coffee beans in 1819. The same substance, isolated from tea leaves in 1827, was named theine. Only after they realized that the chemical protein and caffeine were, in fact, same molecule. Many will be surprised to know that caffeine is a white crystalline powder, bitter, and is not responsible for the aroma and taste of coffee, which are derived from an amazing mixture of substances present in the grain complex, other varieties' a variety '. it is only after the roasting of green beans at temperatures above 200 degrees, that coffee 'buy aroma and color we're used to. The roasting drastically alters the chemical composition of beans: protein and sugars that are contained react in the Maillard reaction, forming hundreds of volatile compounds that give coffee roasted to the color and the characteristic aroma. But then, 'cause decaffeinated coffee has a different taste? Due to the process of extraction of caffeine from the beans with various solvents are still green. Organic solvents such as ethyl acetate or dichloromethane, unfortunately also extracted part of substances responsible for the aroma of coffee '. The modern decaffeination processes, based on water or CO 2 , are more careful not to remove the substances responsible for the aroma from the beans. Caffeine is not removed completely, but it is still up 0.1 percent. During the preparation of espresso, a small amount of hot water at high pressure is rapidly in contact with the ground coffee, extracting the aromatic substances. The rapidity of the process makes a cup of espresso contains less caffeine than a prepared with the coffee pot (about 80 milligrams versus 150). In addition, unlike other methods of preparation, espresso contains fats that create tiny droplets of essential oils that attach to the tongue and palate and espresso give the typical feeling of creaminess'. that's why the taste of espresso persists longer in the mouth, and is more effective to remove the milk of water, the greater affinity with fat.