Mill Time

Understanding milling methods.

What is stone ground flour? How does it compare to whole wheat flour?

"Did you know that most flour sold in the USA as “stone-ground" probably never rubbed up against a piece of stone?

Stone-ground can mean anything from wheat berries first cracked on stone mills and then ground to flour, on rollers to finished flour passed over a stone after it has been ground. "Or it could mean it's just a nice name," says Jeff Gwirtz, technical services director of the International Association of Operative Millers. "It's more a conceptual, warm, touchy crunchy feel."

I checked the common brand I thought was stone ground—in the Western USA; Stone-Buhr is not stone ground. Who knew!?

Stone grinding is slow and expensive. A typical stone mill can grind about 2,000 pounds of flour an hour. The miller must stay beside the mill through the entire process, smelling the air to make sure the stones aren't getting too hot and touching and tasting the flour to make sure it is not too coarse or too fine. A modern roller mill can grind more than 3 million pounds of flour a day, all of it computer-controlled.

But does stone grinding really make any difference? The story going around in the 1970s, when things such as stone-ground flour and bean sprouts first entered the mainstream, was that stone mills are slow so the flour stays cool, while roller mills are fast and heat the flour up. Heat, the story went, kills vitamins. So stone-ground was supposed to be more nutritious.

Roller mills are now a common method of milling. Are they modern? Nope! They’ve been around since the 1500s. They were an iron roller; grooved and smooth. One roller spins at a faster rate than the other, and the grains are caught in the middle, twisted and chopped; this flattens the bran into large flakes, and breaks the endosperm into chunks.

A study by the Center for Food Technological Research Institute in Mysore, India, found that stone-ground flour reached temperatures as high as 194F degrees, and roller-milled flour got only as high as 95F. The researchers found that stone-ground flour lost more essential amino and fatty acids. But “baking bread typically reaches 200 degrees inside, so worrying about the milling temperature seems silly.” McFall says.

While low heat won’t oxidize the wheat germ oils, the enzymes (lipase and lipoxygenase) in the wheat germ can. Thus this product has very short shelf life. Because of the volatile fats in the germ and bran, stone-ground flours spoil more quickly; it’s best to use them within three to six months of their milling.

Whole wheat stainless steel roller mills often recombine the endosperm and the bran. The endosperm is ground fine but the bran particles are kept large for best gluten development. The germ is flattened but not rubbed; it’s valuable oil thus remains safe. This is said to minimize oxidation of the oil in the flour, it is also likely that the higher heat of roller milling destroys lipids enzymes, which helps prevent off flavours and extends shelf life.

When it comes to baking, stone ground whole wheat flour can be substituted for regular whole wheat flour in a recipe. However, it is important to note that stone ground whole wheat flour has a different texture and flavor than regular whole wheat flour, so the final product may not be exactly the same as when using regular whole wheat flour.

Whole wheat and stone ground flour comes in varying granularity. Coarse to fine. Coarse flour particles absorb water more slowly and don’t form gluten as quickly. Yet, the finer the bran particles the fermentation tolerances worsen. The result is bread made with coarse bran will have a higher volume than one with finely ground bran.

Why does whole wheat although high in protein not produce as much gluten as white flour?

- [ ] Bran particles are sharp and are like tiny knives that ‘cut’ the gluten from forming.

- [ ] Most of whole wheats protein(gluten formers) are in the bran and in the germ.

- [ ] Bran is high in pentosan gums which interfere with gluten formation.

- [ ] Wheat germ has a protein fragment called glutathione, that also interferes with gluten formation.

Stoneground grains often have a larger particle size than those ground in roller mills. This means that breads made from them may have a slightly lower glycemic index (healthier for your blood sugar). At the same time, though, studies show that vitamins and minerals may be less bio-available in larger particles.

If you’re reading this in Canada, however, be aware the Canadian law allows up to 5% of the original wheat kernel to be missing in “whole wheat flour” – so all of the germ and a bit of bran is often left out. If you’re Canadian, look for “whole grain whole wheat” – a term that would be redundant in the U.S.A. As laws there, require all of the wheat’s original bran, germ, and endosperm “remain unaltered” for flour to be called “whole wheat flour.”

Of course, if you are grinding your own wheat this post is likely irrelevant and as always the whole grains council recommends you enjoy such flavoursome, fresh grains.

If you have access to a stone ground mill; I’d recommend trying their product. I am lucky enough to have one in my neck of the woods.

Happy baking!

Please keep it kind. T.H.I.N.K. Is it Thoughtful? Is it Helpful? Is it Inspiring? Is it Necessary? Is it Kind?

Susy

This post was gleaned from a culinary textbook: How Baking Works and data from the wholegraincouncil.org.