My column of Jan. 15 discussed two reasons for domed cakes: (1) the baking of large cakes that set on the edges before the center finishes baking and (2) thick batters with viscosities that inhibit convection of heat to their centers.
Since then, I have received some advice from home bakers on how to prevent cake domes:
1. Cut strips of paper toweling 2 inches wide, wet them and plaster them around the outside of the cake mold just before baking. The strips remain wet and cool long enough to slow down cooking of the outer layers while permitting convection of the oven's heat to the interior of the cake.
2. Do the same, but with wet terrycloth towels. These have the added advantage of reusability.
3. Buy "Magic-Cake Strips" from kitchen specialty stores and cake supply shops. These strips of cloth, cut to fit around cake pans, are moistened before applying to the cake pan.
4. A professional cake maker suggested that for cakes 12 inches or more in diameter, fill a small, metal juice can with stones and grease the can on the outside. Then fill the cake pan with batter to the customary level. The cake will bake as if it were in a tube pan -- flat. To decorate, extricate the can, cover the hole in the cake with a circle cut from a plastic lid and ice over that.
Q. The bread flour available in supermarkets contains malted barley flour and potassium bromate. What is the purpose of each? I would like to try adding malted barley flour to an unbleached pastry flour. Where might I find these ingredients? Would an unbleached pastry flour make a lighter sweet yeast bread?
A. Malted barley flour is added to standardize flour's amylase activity -- that is, the amount and activity of starch-splitting enzymes usually found in wheat. Without amylase, breads have pale crusts. They also have little of the toasty flavor that makes breads and pastries so enticing.
Potassium bromate is an additive that strengthens the dough's gluten. It is blended with flour at a concentration of fewer than 50 parts per million (that is, less than 0.005 percent by weight), and it remains inert until the yeast begins producing acid. At this time -- about halfway through fermentation -- the bromate begins to oxidize parts of the proteins that formed gluten during mixing. Because of this oxidation, the dough becomes more resilient to mishandling and the breads acquire more volume.
Malted barley comes in two forms: liquid and powder. Each form in turn comes in two subforms: diastatic and nondiastatic. Diastatic means that the enzymes are still active and, when added to a dough, cause the splitting of starch molecules into smaller fragments. Among these fragments is the monosaccharide (simple sugar) maltose, which yeast does not assimilate easily but which reacts speedily with proteins to produce a brown crust and baked flavor. In nondiastatic malt, the enzymes have been denatured by heat and cannot cause the splitting of starch molecules.
If you use bread flour, which contains malted barley powder, there is no need to purchase malt. If, however, you prefer to use another flour that does not contain malted barley, the breads and pastries you make from it will have better color and flavor with added malted barley. Liquid and powdered malted barley can be purchased from health-food stores or from stores specializing in wine- and beer-making supplies.
Do not expect pastry flour to perform better than bread flour in a sweet bread. Bread flour is superior because its high protein content produces a stronger dough more able to retain carbon dioxide and rise. Pastry flour's big contribution is the tenderness it lends to a product when substituted for part (1 out of 5) of the bread flour.
Q. What type of oil should one use on a nonstick waffle iron? My waffles are sticking!
A. For the best results, you should use a saturated fat such as clarified butter. This is made by melting butter in a cup measure, skimming off the foam, and then carefully ladling off the yellow, butter-oil layer.
Otherwise, use a vegetable shortening. Its fats have been hydrogenated enough to prevent them from polymerizing and interlinking to form a sticky, plastic-like gunk. However, vegetable oils with molecules that are highly unsaturated (high in double bonds) polymerize readily.