cooking liquid of poached or steamed fish, since even brief cooking will extract flavor and gelatin into the liquid The traditional cooking liquid for fish is a court bouillon or “quick bouillon” made by briefly cooking water, salt, wine, and aromatics together (p 215) The bony shells of crustaceans don’t contain collagen, so cooking them in water won’t give body to the extract In fact crustacean shells are normally extracted in butter or oil, since their pigments and flavors are more soluble in fat than in water(p 220) Other Protein Thickeners Gelatin is the easiest, most forgiving protein any cook deals with Heat it up with water and its molecules let go of each other and become dispersed among the water molecules; cool it and they rebond to each other; heat it again and they disperse again Nearly all other proteins in animals and plants behave in exactly the opposite way: heat causes them to unfold from their normally compact shape, become entangled, and form strong bonds with each other, so that they coagulate permanently and irreversibly into a firm solid Thus liquid eggs solidify, pliable muscle tissue becomes stiff meat, and milk curdles Of course a solid piece of coagulated protein can’t be a sauce But it’s possible to control protein coagulation so that it can give body to sauces Protein thickening and curdling Two possible outcomes of heating egg proteins, which start out folded in compact shapes (left) If conditions favor their unfolding, they form a loose network of long chains (center) and ...proteins in animals and plants behave in exactly the opposite way: heat causes them to unfold from their normally compact shape, become entangled, and form strong bonds with each other, so that they coagulate... outcomes of heating egg proteins, which start out folded in compact shapes (left) If conditions favor their unfolding, they form a loose network of long chains (center) and ... But it’s possible to control protein coagulation so that it can give body to sauces Protein thickening and curdling Two possible outcomes of heating egg proteins, which start out folded in compact shapes (left)