Flour oxidation - green flour


I have made several loaves of bread with what some call green flour. That is, flour fresh from the mill. In this case the mill is a hand operated unit in my kitchen. I've also read of the benefits of using freshly milled flour, both for taste and nutrition. Some authors state that if the flour is not used quickly, the oils will go rancid. Others quote studies that link old flour to sterility (at least in mice)!

I have also read, on the internet and in books by authors I admire, that flour must be oxidized before use to insure proper gluten development. It is written that without proper oxidation a proper loaf cannot be made because the elasticity is compromised.

If the oils in flour go rancid in a couple of days, how does letting flour sit out improve it? It would be oxidized but what about the rancid oil? Does it evaporate? What about folks like myself who have not had problems with gluten development, that I know of, when using fresh milled flour?

Folks on both sides of the question have facts and figures to back them. For now, based on experience, I will continue to use my freshly milled flour. However, if someone can tell me how to oxidize the flour without losing oils or nutrition and without exposing it to critters and airborne nasties, I will try it and unscientifically test the results.

I want to make better bread and learn more. I like the flavor of fresh milled flour and can create light fluffy loaves with it. But if there's an easy way to oxidize the flour and it bakes better bread, I'd like to try it out.

badge posted by: pmiker on June 08, 2012 at 7:19 am in Q & A
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reply by: Mike Nolan on June 08, 2012 at 1:11 pm
Mike Nolan

I don't believe oils in flour will go rancid in a few days, especially if stored away from the heat.

Peter Reinhart recommends either using green (freshly milled) flour RIGHT AWAY, ie, within 24 hours, or letting it age for at least a week. He learned this the hard way at the Brother Juniper bakery years ago when he was trying to track down inconsistent performance in one of his recipes (a struan, as I recall), one for which he used freshly milled whole wheat from a local miller.

I have found I get somewhat more consistent results with flour from my home mill if I let it sit for a week. I have yet to have any of it go rancid on me, though I generally only grind a pound or two of wheat berries at a time, so it seldom sits around for more than a month.

Some of the claims from the health crowd strike me as extreme.

reply by: MangoChutney - Sandra Too on June 08, 2012 at 1:19 pm
MangoChutney - Sandra Too

I cook entirely with freshly-milled flour. It is more convenient for me to mill what I need, when I need it, than to try to plan ahead and guess what I will want a week from now. I don't know the facts about the rate at which oil in flour goes rancid, but I am fairly certain that whole grain keeps better than flour. I have had no complaints about my bread, and am in fact a little proud of it. *smile*

reply by: pmiker on June 08, 2012 at 7:05 pm

PS. One of the respected names who advises against fresh milled flour is an honored employee of KAF and who has even produced a great book. It is his book that specifically advises against the use of fresh milled grain.

Hence my confusion.

reply by: MangoChutney - Sandra Too on June 11, 2012 at 10:28 am
MangoChutney - Sandra Too

Without meaning any disrespect or dishonor to the KAF employee in question, whoever he may be, I don't intend to change what I am doing, because it works for me. Since you are in doubt about what might work best for you, I encourage you to try his way once and see if you prefer the result. Then you can weigh for yourself what the benefits in gluten development are compared to the costs in convenience for your own situation. *smile*

reply by: BibiBaker on January 19, 2014 at 7:23 pm

F.Y.I.: "Freshly milled flour is not good for bread making. The gluten is somewhat weak and inelastic, and the colour may be yellowish. When the flour is aged for several months, the oxygen in the air matures the proteins so they are stronger and more elastic, and it bleaches the colour slightly. Aging flour is costly and haphazard, however, so millers may add small quantities of certain chemicals to accomplish the same results quickly. Bromates, specifically potassium bromate, added to bread flours mature the gluten but do not bleach the flour a great deal. Bromate use is decreasing because of concerns about its safety, and it is not used at all in Canada and Europe. Other additives, such as ascorbic acid (Vitamin C), are used instead. Chlorine is added to cake flour for two reasons: as a maturing agent, and to bleach the flour to pure white."
Professional Baking, Sixth Edition, Wayne Gisslen.

Just a thought.

reply by: Mike Nolan on January 19, 2014 at 9:07 pm
Mike Nolan

Gisslen is talking primarily about white flour, I suspect, not whole grain flours, and especially not home-milled whole grain (sometime called whole meal) flours.
Based on what folks in Europe have posted here, bleaching with chlorine (eg, cake flour) is no longer permitted in the EU.

reply by: Lynette Bakes on January 28, 2014 at 9:22 pm
Lynette Bakes

Hmm...I've been baking with home-milled whole grains since 1997, and have never had any issues at all with "weak" gluten. To the contrary, my yeast breads rise beautifully, and produce loaves which I am proud to call my own. I grind just what I need for a particular recipe, keeping the remainder of my whole grains...well, whole! I've always felt that being able to be sure that I'm not losing the good nutrition of my whole grains is a major benefit of my mill. The other huge benefit is that my baked goods simply taste better.
So, maybe the "green" flour only refers to white flour, which is stripped of the nutrition in the bran and germ already? I guess I'm confused here...

reply by: Mike Nolan on January 29, 2014 at 11:42 am
Mike Nolan

What Peter Reinhart has written about 'green' flour is that it can lead to inconsistent results, and he was talking about his experiences with a whole grain flour. I find if I use freshly milled flour the same day I grind it I get better results than I do a day or two later, but if I let it sit for a week or two it is fine again.

reply by: mmmpork on January 29, 2014 at 11:58 am

I've also heard that about aging flour, but never for whole wheat. I guess it makes sense for white flour because it doesn't really taste like anything anyways, but whole wheat flour is a whole different ball game. Frankly, I've never had a problem with gluten development using freshly ground sprouted wheat flour. The only time I've let freshly ground flour sit out is when I'm using it to feed my sourdough culture. For some reason, whole grain sourdough cultures tend to prefer old flour.

Also, here's an interesting discussion about this very topic on another forum:

Personally, I use freshly milled sprouted whole grains because the nutrients are much more bioavailable than with unsprouted grains. I also find that sprouted whole grain flours are much lighter than their unsprouted counterparts. The author quoted in this thread mentions usage of chlorine and potassium bromate, both of which inhibit nutrient absorption. Potassium bromate in particular can hinder iodine absorbtion and has been linked to thyroid complications. Most white flour you buy in the store doesn't contain it, but commercial flours for mass produced processed baked goods do contain it. Yet another reason to make your own baked goods and skip the Costco muffins.

reply by: Mike Nolan on January 29, 2014 at 12:22 pm
Mike Nolan

I suspect that unless, like Peter Reinhart, you're making several dozen loaves of bread every day, and expect today's batch to be similar to yesterday's batch, you might not notice much difference. (I only did because I was specifically looking for it, and taking notes, including doing things like measuring the size of baked loaves.)

reply by: pmiker on February 21, 2014 at 7:35 pm

Sorry for the late followup. I mill my grain and then it goes straight into my breadmaking. No wait. I now make a light whole wheat that is sugar free and it has good crumb, nice crust, slightly sweet taste and is soft and great for sandwiches.
So, do they refer to fresh white flour or whole wheat flour? Doesn't matter because no matter how I prepare the flour I make, it works out great and everyone likes the flavor.


reply by: TheSourOaf on May 24, 2015 at 10:56 am

In Jeff Hamelman's book, "Bread," he recounts attending a bread conference in France in which old school baking pros, the best in the world, debated, in French, about the pros and cons of stone-ground vs steel milled flour. The consensus, according to Hamelman (who couldn't follow the details in French), was that steel milled flour seems to have better working properties (texture, elasticity, extensibility), while stone ground flour has better flavor.

Steel milled flour is typically tempered (hit with both dry and wet heat) before the bran and germ are cracked off, after which the endosperm is milled on its own to a very fine, even grind. Whole grain steel milled flour gets some bran and germ, milled separately after the separation, added back in. Stone milled flour, at least in the traditional process, is milled whole (and, ideally, COLD), and some bran and germ may be sifter off AFTER milling, if white flour is desired. Fine bran and germ particles are possible, so truly white flour is not possible in this process, and furthermore milling the whole grain together stains the white endosperm with minerals from the bran, meaning even very finely sifted stone ground flour is still somewhat brown. I suspect stone ground flour always contains some oils from the bran as well.

Here is my theory, and it relates the aging of flour to its milling: freshly milled flour has more flavor, while aged flour has better working properties. Aging of flour obviously is not ideal for whole grain flour, as there is no arguing that oils in the bran go rancid. So, the discussion must be about white flour. Stone ground flour, as I've explained above, retains parts of the bran and germ no matter what, so aging must apply mostly to steel milled flour as well. This flour is processed thusly (steel milled and made white) for its workability advantages, so processors are clearly focusing on that; indeed, the advantages of oxidization that I've heard all relate to gluten and workability, not flavor. So, it seems that aging is part of an agenda to produce easy to work with flour, alongside steel milling and tempering (making white).

To me, this conversation fits in nicely with the difference between older and newer varietals of wheat. Newer varietals have a lot of gluten and are easy to work with. Newer wheats put all their energies into the kernel, rather than the roots and stalks, and are short; they are dubbed "dwarf" varietals. Older varietals have more flavor, but less gluten, than newer varietals; older varietals grow taller (which shades out weeds, eliminating the need for herbicides), and have stronger roots, requiring less water, and less advanced irrigation technologies. These flours taste better but are harder to work with, due to their lower gluten.

So: stone milled tastes better and is healthier but is harder to work with than steel milled. Whole grain tastes better and is healthier but is harder to work with than white. Freshly milled flour tastes better and is healthier but is harder to work with than aged flour. Older varietals taste better and are healthier but are harder to work with than new varietals. Sourdough bread tastes more interesting and is healthier than commercially leavened bread.

In the 1950s machines were invented to churn out bread, and high gluten flours developed in the green revolution of the 1960s made this process easier. The commercial yeast available since the 1910s also standardized this process. Bakers became obsolete, and the skills necessary to work with the more difficult ingredients and techniques above dwindled. Without demand for harder to work with but superior ingredients, millers catered to the skill-less or mechanical bakers, and aging came into fashion.

I don't know the history of aging, but I suspect it was not considered essential until the middle of the 20th century. I'm sure some finely sifted flours were aged for especially particular professional bakers in strong baking cultures, like in France, who may have noted the tradeoffs involved. The understanding of those tradeoffs, however, has mostly been lost, and now we don't really know what we want.

Hamelman's account of highly skilled bakers reaching the consensus of there being a tradeoff between "workability" and "flavor" clued me into this tradeoff permeating all aspects of wheat culture.

reply by: pmiker on May 25, 2015 at 11:09 am

Thank you for the reply. You've obviously done your homework.
The mill I use most likely produces flour that's a bit different from commercial mills, either steel or stone. My mill is a Country Living mill which uses flat, round steel burrs. In theory this works similar to the stone mills. It is slow, crushes the grain into flour and does not heat it. I rarely sift the bran out unless I am doing experiments that call for that. My flour feels very soft to the touch.
Workability? I can't really say. I've been milling for a couple of years now and I use the about the same amount of hydration and same length of kneading. No, I have not done comparison tests. My main goal is to make good bread and to enjoy the making of it. Not to prove any point or show any body up.
Flavor? I have found that in using freshly milled flour I don't need to add a sweetener for whole grain breads. It has it's own sweetness. Some prefer it sweeter but no one has complained of bitterness.
New vs Old wheat? I have both a heritage wheat - turkey hard red wheat and modern wheat. I do not notice handling differences in the amounts I use. The turkey wheat was popular in the 1800's and is not a dwarf wheat.
Most of the information out there is for commercially processed bread. I do not mean just the stuff at the big store. Even artisan breads bought at small bakeries are made in quantities that would boggle the mind of a home baker.
So what I would like to know is what are the home millers and bakers experiencing with their baking. I mill around forty to fifty ounces of grain at one time for a batch of four loaves. I have done more but this fits comfortably into my mixer and oven. I will use the flour within 1/2 hour of milling.

reply by: Mike Nolan on May 25, 2015 at 12:27 pm
Mike Nolan

It's logical that most bread research concentrates on improving commercial breads, that's where much of the funding for that research comes from.
I haven't seen a lot written on 'green flour', it may show up in textbooks on commercial milling. Peter Reinhart mentioned a problem he had with green flour back at Brother Juniper in one of his books, and based on that I started keeping track of how well my own milled flour worked.
I find the first 24 hours is pretty good, then it kind of drops off for 2-3 weeks and after that it works pretty well for 3-4 weeks. I seldom have freshly milled flour last me more than 4-5 weeks, I usually mill about 10 cups of wheat berries at a time, and I just don't make as much whole wheat bread as I used to since our younger son moved out. I did forget about one batch for several months, and it smelled off by then, so I tossed it. Better to throw out some potentially bad flour than make bad bread with it.