Flour is becoming like the telephone - something that used to be so basic and is now so complicated. There are all kinds to be found in the grocery store. All-purpose flour comes in both bleached and unbleached varieties. You can find bread flour, cake flour, self-rising flour, whole wheat flour, white whole wheat flour, instantized flour, and a whole variety of other grain flours - rye, soy, corn, etc. So is it important to choose the right flour?  For anyone who does any baking whatsoever, using the right flour does make a world of difference.

The key to choosing the right flour is something called gluten. Gluten is an elastic protein that is formed when you make a dough by adding moisture to flour, and then beat, knead, or otherwise handle the dough. Gluten provides strength and structure for the final baked good. Different flours have different amounts of the protein that develops into gluten. Higher protein flours are called "hard".

The degree of hardness you need in a flour can be good or bad, depending on what you're baking. For chewy breads that need to rise, you want a lot of gluten. For tender piecrusts or cakes, gluten should be moderated. Gluten protein is only found in measurable quantities in wheat flour, which is why you cannot bake bread wholly from rye, corn, soy or any non-wheat flours.

When you buy wheat flour,the percentage of protein is shown on the label. However, due to rounding, the figure is not precise. The softest flour, cake flour, has 8% protein. All-purpose flour contains anywhere from 9% to 12% protein. The hardest flour is made from durum wheat, which is used for pasta.

Different manufacturers have different levels of protein in the same type of flour. King Arthur's all-purpose flour is 11.7% protein while Gold Medal's is 10.5%. If you use the softer flour in a recipe, you will need to add more moisture to get the same dough texture. The same recipe made with King Arthur's AP flour will taste differently than when made with Gold Medals.

Harder flour also weighs more. One pound of all-purpose flour measures 3 cups of sifted flour, but one pound of cake flour measures 4 ½ - 5 cups. So you cannot evenly substitute one for the other. To substitute one cup of all-purpose flour for one cup of cake flour, put 2 tablespoons of cornstarch in a measuring cup and then top off with all-purpose flour.

Wheat flours are either bleached or unbleached. Flour needs to age before it can be used. Bleaching was developed as a way to speed up the aging process. It also produces a whiter product, which traditionally was considered elite. Unbleached flour is becoming more popular as many people can taste a chemical flavor in bleached flour. Cake flour is always bleached, as the whitest color is important for cake appearances.

Self-rising flour, which has baking powder and salt already added, is another market variation. Self-rising flour is more common in the South, where biscuit making is popular. As tender biscuits need lower protein flour, both self-rising flour and, indeed, all-purpose flour sold in the South by Pillsbury or Gold Medal is softer than the flour sold under the same labels in the North.

However, King Arthur recently came out with a self-rising flour available in New England - it has a protein level of 8.25%. If you have a recipe that calls for self-rising flour, and if you don't have any, it is easy to make your own. For each cup of flour required, put 1 ½ teaspoons of baking powder and ½ teaspoon of salt in a measuring cup. Top off with low protein flour.

Whole-wheat flour includes the germ and bran of the wheat kernel, and is more nutritious and, arguably, more flavorful than white flour. White flour is enriched, i.e. iron, niacin, thiamin, and riboflavin are added to flour to prevent vitamin deficiency illnesses; but this enrichment does not replace all the lost nutrients.

Keeping the germ and bran in flour has two drawbacks. Gluten development is hindered, so any bread made entirely with whole-wheat flour will be dense and heavy. A 3:1 ratio of white flour to whole-wheat flour is recommended to make bread that rises well.

Also, the oil in the germ can go rancid. Whole-wheat flour should be used within three months and preferably stored in the freezer. White flour can be kept in a cool, dry place in an airtight container for up to a year without problems. Should bugs be an issue, put a couple of bay leaves in the container.

A final variation of flour is instantized flour, usually found under the Wondra brand. White flour is chemically treated so it will not clump when liquid is added. It is designed for gravies, crepes, or pancakes, and should not be used for baking.

As a final note, flour is no longer packaged in a way that causes it to clump in the bag, so sifting is generally not necessary. However, it does settle, so if you're measuring flour by volume as opposed to weight, aerate it before putting an amount into a measuring cup.