A few weeks ago I went to the grocery store to buy a bag of all-purpose flour. I was getting low, as I’ve been baking quite a bit lately. In addition, the sourdough starter that lives in my refrigerator needs to be feed. So, off to the store I went.
When I came back and started unloading the groceries, I realized that I had accidentally picked up a bag of bread flour instead of all-purpose flour. This isn’t a big deal, as the bread flour gets used a lot around here as well. But, this got me thinking, “I need to feed my sourdough starter. Is it ok to use bread flour or cake flour? Or, should I only use all-purpose flour?”
Being a Facebook fan of many baking groups and cooking sites, I decided to ask them for advice. I posted my question to six separate pages. I’ll be honest here, I’m disappointed in the responses. Only 2 of the 6 responded, and one, I’ll quote, said “Use AP Only” with no further explanation. Well, I guess I would like more info than that. So, I decided to do a bit of research on my own.
First, what is All-purpose flour? bread flour? Cake flour? Here goes (and, some of this gets pretty foodie, so I apologize in advance, and feel free to skip to the end if you would rather just get the answer).
All-Purpose flour: made from a blend of high-gluten hard winter wheat and/or low-gluten soft spring wheat (more on the differences between these wheats below*). All-purpose flour is a fine-textured flour milled from the inner part of the wheat kernel and contains neither the germ (the sprouting part) nor the bran (the outer coating). U.S. law requires that all flours not containing wheat germ must have niacin, riboflavin, thiamin and iron added. (Individual millers sometimes also add vitamins A and D.) These flours are labeled “enriched.” All-purpose flour comes in two basic forms – bleached and unbleached – these can be used interchangeably. Flour can be bleached either naturally, as it ages, or chemically. I recommend using unbleached, as bleached flour can give a slightly metallic flavor in simple bread recipes, and I prefer the pretty natural wheaty color of unbleached.
*Wheat differences: The primary difference between high-gluten hard winter wheat and low-gluten soft spring wheat ( and consequently in the flours made from them) is the variation in protein (gluten) content. Hard winter wheat is about 10-13% protein, is harvested in the winter, and is dubbed “hard” flour, because the winter wheat will give baked goods more elasticity. Whereas, soft spring wheat is about 8-10% protein, and therefore, will not impart much elasticity; for this reason, nearly all spring wheat is destined to become cake flour. You can actually feel the difference in proteins with your fingers; the hard wheat flours tend to have a subtle granular feel, while soft wheat flours feel fine but starchy, much like cornstarch.
Bread flour: a high-gluten blend of 99.8 percent hard-wheat flour, a small amount of malted barley flour (to improve yeast activity) and vitamin C or potassium bromate (to increase the gluten’s elasticity and the dough’s gas retention). Bread flour, available bleached and unbleached, is ideal for yeast breads. It has a protein content range of 11.3 – 11.8%. High-protein flours are generally recommended for yeasted products and other baked goods that require a lot of structural support. The higher the protein level in a flour, the greater the potential for the formation of gluten. The sheets that gluten forms in dough are elastic enough to move with the gas released by yeast but also sturdy enough to prevent that gas from escaping, so the dough doesn’t deflate.
Whole-wheat flour: contains the wheat germ, which means that it also has a higher fiber, nutritional and fat content. Because of the higher fat content it will go bad (rancid) faster than All-Purpose Flour, and should be stored in the refrigerator.
Cake or Pastry Flour: a fine-textured, soft wheat flour with a high starch content, and a low-protein content of between 7.8 -8.4%. It makes tender cakes and pastries. Lower-protein flours spread more in chocolate chip cookies and muffins. They’re recommended for chemically leavened baked goods, because baking powder and baking soda are quick leaveners. Quick leaveners lack the endurance of yeast, which can force the naturally resistant gluten sheets to expand; consequently, the gluten can overpower quick leaveners, causing the final baked product to fall flat.
Homemade All-Purpose Flour: If bread flour and cake flour are mixed at a 50-50 rate, the resulting flour will achieve the same thing that commercially made all-purpose flour gives without all the extras they throw in.
Self-Rising Flour: an all-purpose flour to which baking powder and salt have been added. It can be substituted for all-purpose flour in yeast breads by omitting the salt in the bread recipe, and in quick breads by omitting both baking powder and salt.
Gluten: a protein which forms an elastic network that helps contain the gases that make doughs and batters rise as they bake. Read more about gluten in my post on Gluten & the gluten-free diet… what’s up? and Gluten-Free Baking & Baked Goods.
Storage: all flour should be stored in an airtight container. All-purpose and bread flour can be stored up to 6 months at room temperature. Higher temperatures could invite bugs and mold. I store all of my flour in the refrigerator just to be sure no bugs are tempted.
How to measure flour: Most flour on the market today is presifted, requiring only to be stirred, then lightly spooned into a dry measuring cup and leveled with a knife. Don’t scoop the flour with the measuring spoon – this will result in too much flour in your baked goodies, and thus a dry chewy product.
Next, came a little yeast investigating.
Yeast: a living, microscopic, single-cell organism, which, as it grows, converts its food (through fermentation) into alcohol and carbon dioxide. Yeasts feed on sugar, and are killed by heat and salt.
Yeast starter: prior to the evolution of commercially available baking powders and yeasts during the 19th century, yeast starters were the leaveners used in breadmaking. Such starters are a simple mixture of flour, water, sugar and yeast. (At one time, airborne yeast was the only source used, but today commercially packaged baker’s yeast is more common.) Sourdough starter may still be made with airborne yeasts: make a slurry of flour and water and then add a bunch of mashed, organic red grapes or organic red cabbage (wrapped in cheesecloth). You should actually be able to see the yeasts- they are that whitish powdery coating on the outside of the fruit.
Ok, so, that’s what flour is and how it is made. And, now I know about yeast and starters. Everything I wrote above, and everything I read leads me to the conclusion that using white all-purpose flour in your starter means that you can produce pure white bread from the starter, and, that’s it’s perfectly possible, when making bread, to introduce any other kind of flour you desire, just be sure that you don’t add any flour with added salt, as salt will kill the yeast. So, self-rising flour is out. I suggest reading the labels on the flour just in case.
Flour really is fascinating to me – what other ingredient gives so much as it changes form? Bread – the staple of life. Cookies – another staple (hee hee). Cake. Thickens soups and stews. Coats chicken to make dinner. This really was a great exercise in learning. Maybe I’m glad those sites didn’t respond.