On food and cooking the science and lore of the kitchen ( PDFDrive ) 203

contribute much to the raw foam But it is sensitive to heat, which causes it to unfold and coagulate So when the raw foam is cooked, ovalbumin more than doubles the amount of solid protein reinforcement in the bubble walls At the same time, much of the free water in the foam evaporates Heat thus allows the cook to transform a transient semiliquid foam into a permanent solid one How Proteins Destabilize Foams The very same forces that make egg foams also break egg foams Often just as the foam is reaching its optimum texture, it will get grainy, lose volume, and separate into a dry froth and a runny liquid As the proteins bond to each other to support the foam, they embrace each other too tightly, and squeeze out the water they had held between them There are several different kinds of bonds by which the long, unfolding egg proteins are joined to each other in a reinforcing network: bonds between positively and negatively charged parts of molecules, between waterlike parts, between fat-like parts, and between sulfur groups The protein network begins to collapse when too many of these bonds accumulate and the proteins cluster together too tightly Fortunately, there are simple ways for the cook to limit the accumulation of bonds and prevent the collapse of albumen foams Blocking Sulfur Bonds with Copper Bowls… Long before anyone knew about egg proteins or their chemical bonds, cooks had come up with a way of controlling them The French tradition has long specified the use of copper utensils for making egg foams One early trace of this tradition is a 1771 illustration in the French Encyclopédie that shows a boy in a pastry kitchen working with a straw whisk and what the accompanying key ... collapse when too many of these bonds accumulate and the proteins cluster together too tightly Fortunately, there are simple ways for the cook to limit the accumulation of bonds and prevent the collapse of albumen... Bonds with Copper Bowls… Long before anyone knew about egg proteins or their chemical bonds, cooks had come up with a way of controlling them The French tradition has long specified the use of. .. making egg foams One early trace of this tradition is a 1771 illustration in the French Encyclopédie that shows a boy in a pastry kitchen working with a straw whisk and what the accompanying key