Bread: Lightness of Being

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Water, flour and heat — it’s probably the world’s most basic recipe, but the chemistry of bread making reveals why certain kinds of grain make lighter bread than others. I’m Jim Metzner, and this is the Pulse of the Planet.

“Take, plant materials, seeds which are very rich in starch and protein, grind those seeds up, and add water.”

Harold McGee is the author of the book Food and Science.

“And by adding water, this made it possible for the proteins in the starch to interact with each other, to form a kind of mass. You could shape it – you could cook it. And that is really what the basis of all breads is. The thing that distinguishes leavened breads from unleavened breads is that, that mixture of, moistened ground up seeds is allowed to sit around long enough that yeasts, microorganisms, can grow in the mass and produce bubbles of carbon dioxide. And the mass is sufficiently thick that those bubbles don’t just escape into the air. They actually stay in the mass and provide a much lighter texture than the original paste would have had. The amazing thing about wheat is that it produces certain proteins which have the property of forming slinky like coils that get all wound up with each other and develop a kind of elasticity, so that when, a yeast cell, in the dough forms some carbon dioxide and it makes a bubble, rather than just letting that bubble escape, these proteins in wheat actually trap it. And thereby make a bread that was much more full of bubbles and therefore, much lighter.”

Pulse of the Planet is presented with support provided by the National Science Foundation.

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Bread: Lightness of Being

Microorganisms and slinky like coils of protein - it's all in the chemistry of bread making.
Air Date:07/05/2002
Scientist:
Transcript:


music

Water, flour and heat -- it's probably the world's most basic recipe, but the chemistry of bread making reveals why certain kinds of grain make lighter bread than others. I'm Jim Metzner, and this is the Pulse of the Planet.

"Take, plant materials, seeds which are very rich in starch and protein, grind those seeds up, and add water."

Harold McGee is the author of the book Food and Science.

"And by adding water, this made it possible for the proteins in the starch to interact with each other, to form a kind of mass. You could shape it - you could cook it. And that is really what the basis of all breads is. The thing that distinguishes leavened breads from unleavened breads is that, that mixture of, moistened ground up seeds is allowed to sit around long enough that yeasts, microorganisms, can grow in the mass and produce bubbles of carbon dioxide. And the mass is sufficiently thick that those bubbles don’t just escape into the air. They actually stay in the mass and provide a much lighter texture than the original paste would have had. The amazing thing about wheat is that it produces certain proteins which have the property of forming slinky like coils that get all wound up with each other and develop a kind of elasticity, so that when, a yeast cell, in the dough forms some carbon dioxide and it makes a bubble, rather than just letting that bubble escape, these proteins in wheat actually trap it. And thereby make a bread that was much more full of bubbles and therefore, much lighter."

Pulse of the Planet is presented with support provided by the National Science Foundation.

music