Tuesday, March 25, 2008
Anatomy of a Wheat Berry, and About Gluten
Basically, wheat germ is the baby plant, endosperm is the plant food, and bran is the outer covering. White flour is the endosperm alone, and has a relatively long shelf life. Whole grain flour is the whole deal ground up, and has a shorter shelf life because the oils in the germ will go rancid.
It's funny; before I knew this, I had sometimes made bread with white flour, and added bran and germ to make it more nutritious. I had really just reassembled whole grain flour!
Left whole, the grain can last a long time. I just soaked some >8-yr-old grain two nights ago, and it is already sending out spider-like root fingers. I wonder how long the grain will keep?
Gluten is a protein in the endosperm. If you add water to it and knead it, the gluten will form stretchy, rubber-band-like strands. This is of course the friend of the yeast bread, and doom for tender baked things like biscuits, cookies, and cakes. The gluten acts like a bunch of balloons, which fill up with the gas produced by the yeast, allowing the bread to rise. Or, it acts like a tangle of rubber bands, making cookies, biscuits, and cakes tough and chewy. A good "bite" is essential for a bagel; it is bad news for chocolate cake.
Different brans and kinds of wheat flour have differing amounts of gluten. Off hand, the extremes seem to be King Arthur Flour's "Sir Lancelot" on the high side, and White Lily® Flour on the low side. Sir Lancelot: great for bagels; White Lily: great for biscuits. An All-Purpose flour will be somewhere in the middle, and work reasonably well for most things.
Gluten absorbs water. A higher gluten flour will require more water than a lower gluten flour to achieve the same dough texture. I think this is the main thing that affects bread recipes, not the humidity in the air, or the season, etc.
I always use King Arthur Flour for bread, because they test and maintain a consistent gluten level in their flours. Once I find the right amount of water for a bread recipe, it never changes, all year, and I live in the south. Our humidity is all over the place.
Whole-grain bread may be heavy because the bran cuts up the gluten strands, reducing their rise. Bleah. I say mix the whole wheat flour with a good white bread flour; get some benefit of the whole grain while still making bread that's worth eating.
Musing: Hard wheats are higher in gluten, and tend to grow better in the more Northern states. Soft wheats are lower in gluten, and grow better in the South. Bagels are very popular in New York; biscuits are very Southern. Accident? YOU decide.