Crowned as the founder of Molecular Gastronomy (The science of culinary practice or cooking techniques), Hervé This has put together "Kitchen Mysteries", a comprehensive little guide to help us dispel some common cooking myths and answer such questions as Why Does Soup Cool Down When We Blow on It? and How to keep Milk from Boiling Over? There are times, when reading it, where you may regret not paying better attention in High School Chemistry. But outside of that the book is chock full of useful tidbits that will hopefully make you a better cook.  Or at the very least you will learn just how long you should let tea steep and how to keep your broccoli from going green to grey in the cooking process. In the excerpt listed below on Vegetables, he reminds us that vegetables should be eaten fresh to be good, but if you insist on cooking them their are certain rules of thumb to remember.  Cook them slowly, remember you are essentially tenderizing them and the worse thing you can do to fresh veggies is overcook them.  Continue reading below as Herve breaks down for you the actual physical process of what happens to these vegetables when you are cooking them. 

Vegetables

Color and Freshness

A Matter of Water

Vegetables, the jewels of the kitchen! Did they not give their names to the great Roman families? Fabius, in honor of faba, or fève, the broad bean; Lentulus, in honor of the lentil; Piso, in honor of the pea; Cicero, in honor of the chickpea.

Vegetables must be eaten fresh to be good. The soil in which they were cultivated, the climate that brought them to life will sing in one’s mouth . . . if they are not mangled in the cooking process. Cooking them is a delicate operation. How long must they cook to become sufficiently tender? Must they be tossed into cold or hot water? Must the cooking water be salted? How to retain their bright colors, which seem to be the mark of their freshness?

Before I launch into an examination of this last question, let me recall that a very fresh vegetable is generally tender, and cooking is not of great value to it. On the other hand, for certain older or even dried vegetables, like lentils, rehydration is essential.

In these two cases, the cooking methods are very different, since the object in the first is to retain the emollient moisture of the vegetable and in the second to reintroduce moisture that has been lost. 

How Long Must Vegetables Be Cooked?

Do not hope for a global response to such a question. Fresh asparagus will cook for less time than asparagus kept for a day or two after picking. And regardless of freshness, asparagus will not take as long to cook as potatoes. Still, as is so often the case, an analysis of the problem can guide us in our culinary transformation operations.

The objective is to tenderize the vegetables, the cells of which, unlike animal cells, are each protected by a hard, fibrous wall. Weakened by cooking (the cellulose is not altered chemically, but the pectins and the hemicellulose are), these walls become porous, and as their proteins are denatured, they lose their ability to regulate the movement of water from the interior of the cell to the exterior, and vice versa. Water can pass through the walls, while larger molecules are blocked.

We know that when we put vegetables into unsalted water, they swell because the water enters the vegetable cells as a result of osmosis. On the other hand, if the cooking water has too much salt, the vegetables harden (especially carrots), because the water does not enter the cells to reduce the salt concentration in them—the contrary!

Excerpted from Kitchen Mysteries: Revealing the Science of Cooking by Hervé This and translated by Jody Gladding. Translation Copyright © 2007 Columbia University Press; Copyright © 1993 Editions Belin. Used by arrangement with Columbia University Press. All rights reserved.

About Kitchen Mysteries

An international celebrity and founder of molecular gastronomy, or the scientific investigation of culinary practice, Hervé This is known for his ground-breaking research into the chemistry and physics behind everyday cooking. In Kitchen Mysteries, Hervé This offers a second helping of his world-renowned insight into the science of cooking, answering such fundamental questions as what causes vegetables to change color when cooked and how to keep a soufflé  from falling. By sharing the empirical principles chefs have valued for generations, Hervé This adds another dimension to the suggestions of cookbook authors. He shows how to adapt recipes to available ingredients and how to modify proposed methods to the utensils at hand. His revelations make difficult recipes easier to attempt and allow for even more creativity and experimentation. Promising to answer your most compelling kitchen questions, Hervé This continues to make the complex science of food digestible to the cook.

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