The Laurel's Kitchen Bread Book_ A Guide to Whole-Grain Breadmaking - Laurel Robertson [19]
Gluten content, starch damage, coarseness of grind—these are variables only when you are talking about whole-grain flours. White flour mills have laboratories that test the flour for gluten content, enzyme activity, baking quality, and other variables, and they make adjustments either by blending the flour or by treating it in various ways so that it is just the same from bag to bag. Whole wheat flour that comes from the giant white-flour mills may be blended in the same way, but most whole wheat flour is made from one kind (usually one crop) of grain, ground up, period. No blending, no stabilizers, no enzymes, no conditioners. You will see over the years that your flours, like fine wines, vary with the kind of grain, the climate that summer, the storage conditions, and many other things. You will notice differences not only in the amount of water the flour will absorb and in the flour’s flavor, but in other baking qualities, as well.
Why knead?
When wheat flour is made into dough and kneaded, certain proteins combine to form gluten, which provides the resilient structure that expands and holds the gas released by the yeast, giving you a high, light loaf.
When the dough is first mixed, the proteins are in big knotted clumps, a little like a tangle of new wool. Kneading breaks up the clumps and straightens out the strands, finally working the proteins into a thin, strong, resilient fabric: the gluten “sheet.”
The sheet is of course not flat but three-dimensional, something like a cellulose sponge. The gluten forms the stretchy wall around the thousands of cells where the gas bubbles reside. A sponge is full of holes, but in dough, the cells are sealed by the elastic gluten sheet: the gas generated inside them cannot escape.
Besides developing the gluten, mixing and kneading incorporate air, and therefore oxygen. The tiny trapped air bubbles provide the balloons that the yeast will fill with carbon dioxide, raising the dough. Oxygen helps bond proteins into gluten, “improving” the dough—making it stiffer and stronger.
How much kneading is enough?
With experience and observation, you can learn to see and feel when a dough is stretchy and elastic, its gluten fully developed. Before that, the dough is underkneaded and will tear easily. When the dough is underkneaded, the gluten is not strong enough to keep in the gas and the bread won’t rise as high as it could.
Too much kneading makes the gluten disintegrate; the dough gets wet and sticky again and can never regain its strength. Don’t worry: there’s not much chance that you would overknead by hand: you’d have to knead vigorously for more than half an hour to do it, providing the dough was made with good flour. (With a food processor, though, overdeveloping the dough is a real possibility. See this page)
The 300 strokes or 10 minutes we suggest will not always be just right, but it is a good guideline for one loaf and with reasonably efficient kneading should bring the dough close to perfection.
What if the dough stays a rough and sticky mess?
If you have given the dough a righteous ten minutes and it shows no sign of smoothing out and becoming stretchy, you have got some flour that is old, or just too low in gluten to make yeasted bread. Bad luck! Please try again when you can get better flour. Meantime, it might be helpful to refer to.
Once it’s risen, why do I have to deflate the dough and let it rise again?
The dough stops rising when the yeast’s metabolism slows down. Because yeast can’t move around in the dough, it eventually uses up the nourishment in its immediate vicinity. Deflating the dough moves the yeast to fresh pastures, putting it in contact with a new supply of food and oxygen. And, in fact, the dough has been fermenting, and alcohol has been produced by the yeast as it grows. If the dough is not deflated so that the alcohol can evaporate, it will harm the yeast and damage the dough.
The dough changes with fermentation and it is these changes that make good bread. The yeast, for one thing, takes time to attain