September 27, 2023 - 11:05am
Roller vs Stone Ground
Suppose I have a patent flour - roller ground - that is labeled as say 80% extraction. And suppose I get some stone-ground flour from the same wheat and sift it to 80% extraction. What will be the practical difference between these two? I'm sure the size distribution of the flour particles will be different, and I expect different millers to get different results, even for the same general process. But beyond that, won't there be a clear difference between the roller and stone ground flours?
And is the practical difference between roller and stone ground different between wheat and rye flours?
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Modern roller mills are much better at separating endosperm from the outer layers so generally the flour will be whiter.
I guess it depends on what you call stone-ground. For example, a miller you can do one pass through a stone, send it to the rollers and call it stone-ground. There's no law that say that he can't. But that's not usually happens - typically it's just this pseudo-healthy medieval peasant style single run milling and in that case modern roller mill byvirtue of being much better at separating endosperm from the outer layers will produce much white flour at 80% extraction.
It's also worth noting that gradual reduction milling process was invented long before the roller mills. It was originally realized on stone mills and that flour was just as white as you get from the grocery store today. Roller mills took over because they were much faster and more efficient.
It's also worth noting that gradual reduction milling process was invented long before the roller mills
Right. In fact, I've read that one big difference between polenta and US corn meals is that the Italian millers used several passes to gradually reduce the particle sizes whereas US millers generally did the entire grind in one pass.
TomP
because percentages are relative. But relative to what? Patent flour is 100% endosperm. I suppose the stone ground flour is whole wheat? Then after sifting it to 80% will make it something like high extraction flour with some germ and bran still present. It will be dark in color. I don't think you can easily get white flour this way, or at least not without a lot more sifting. And maybe regrinding. It would be way less than 80%, though. As for the extraction rates, apparently patent flours may be stated in relation to the straight flour not the whole grain. Confused the hell out of me a long time ago when I was looking for information about it. Maybe this post will be helpful?
Tom, it's such a good question!
To begin with, patent 80% roller milled flour will have lower ash content than 80% extraction stone ground and bolted flour. Patent 80% roller milled is about the same as 65% extraction stone ground and bolted flour. Other countries or different periods in history might have different ways of defining extractions.
Overall, stone ground flours have smaller bran particles, many of which you won't be able to remove by sifting unless you use a 100mesh sifter whereas roller milled flours often have very large and medium sized bran particles, because roller milling separates flour into streams which are later reassembled into whole wheat (no germ) and whole grain flours (100% cleaned wheat), or higher extraction flours, or different types of clear flours.
Smaller bran particles make breads taller, they do not interfere as much with gluten development.
Top row. Stone ground flours, or simply white flour with finely ground bran particles, 5% bran, 10%,20%, 30% bran :
Bottom row. Breads with large bran particles 5%bran, 10%, 20%, 30% bran, a.k.a roller milled. Source: Classification of whole wheat flour using a dimensionless number.
A bigger concern would be the fact that roller milled flours from larger mills are of more uniform quality offered as bread, all purpose, cake or pastry flour, etc, whereas stone glound milled flours from different batches of whole grains, let's say wheat, are all unique and perform differently in breads using the same recipe:
Same recipe, different breads baked from different bags of whole wheat flour, for example
A font of knowledge, as usual, Mariana. Seeing such large differences in the baked bread between different bags of flour is new to me - much more than I would have thought.
roller milled flours often have very large and medium sized bran particles, because roller milling separates flour into streams which are later reassembled into whole wheat (no germ) and whole grain flours (100% cleaned wheat)
I learned that years ago when I sifted a commercial "whole wheat" flour. The bran flakes were so large they almost looked like a breakfast cereal. Without them, the bread was easy to handle and rose very well.
This all makes me think that Benny's method of sifting out the bran and using it in a soaker or scald is the best way to approach all stone-ground flours.
Between what Mariana has written and what I have been learning about rye flours, I can see that unless the flours are roller-ground by large commercial mills that one can never count on one's flour being all that similar to another's, not for us home bakers.
Classification of whole wheat flour using a dimensionless number.
Ah, a dimensionless number, it's enough to gladden an old physicist's heart! Though this particular fit shouldn't be taken too seriously because they have nowhere near enough data points for all the parameters to be determined by the curve fitting procedure.
TomP