Flour, Working for Change
An Innovative Mill for Special Grain
Jul
The whole story
Scotland The Bread is the first UK owner of a Zentrofan cyclone mill to make flour from Scottish grain for home and community bakers. We saw it during a visit to heritage grain growers, millers and bakers in Sweden in 2016.
What’s so special about it?
Unlike industrial roller mills which waste about 25% of the grain, or traditional stone mills which have a tendency to heat the flour, the Zentrofan mills whole grains into cool, ultra-fine wholemeal flour.
When grinding makes flour hot, the natural oils in the wheat germ (containing the important vitamin E) are thinned and exposed to air, vitamins oxidise and wholemeal flour begins to turn ‘rancid’. White flour from industrial mills has had the germ removed, so there’s little of any value in it to ‘go off’.
The key to the cool-running Zentrofan is that it mills whole grains into very fine wholemeal flour, conserving all the important minerals (iron, magnesium, zinc, calcium etc), vitamins (especially the B vitamins such as folate) and phenolic compounds that are found in the outer bran layers of the grain. These are the bits that are almost entirely absent in white flour.
Wholemeal flour is usually quite coarse and the pieces of bran, though tasty and full of nutrients, can break up the dough structure and lead to crumbly bread that is difficult to slice (and not to everyone’s taste). With the Zentrofan, this problem is reduced: the wheat grains are milled so finely that the resulting wholemeal flour feels as soft as white flour and is almost as easy to bake with. A real win-win.
How does it work?
A strong fan blows the grain round inside a small chamber made from basalt lava rock. When the particle size of the resulting flour is small enough, the cyclone carries it out into a bin, filtering the air flow through a large bag so that no dust enters the kitchen or bakery. Large particles of grain continue to be whittled down until they are fine and light enough to leave the chamber. Nothing is removed from the grain.
Cyclone milling was invented in the 1930s by Wilhelm Schulte, a German engineer with connections to the founder of biodynamics, Rudolf Steiner. At a time of increasing concern with the damage done to food by intensive processing, the mill attracted people concerned with practical public health through its ability to conserve the vitality of the whole grain in a meal that performs more like white flour than the wholemeal most of us are familiar with.
This is essentially an ‘intermediate’ technology, and as such a useful aid to food sovereignty. The laws of physics prevent the cyclone milling system working efficiently at more than about 20 kg per hour, so the Zentrofan is a tool for decentralised small-scale mills and community bakeries. The technology can’t be ‘scaled up’ and expropriated by giant mills – and in any case fresh milling needs to be done as near to the point of use as possible. Local control and reducing food miles (and carbon emissions) go hand in hand.
What is the flour good for?
Scottish heritage wheat generally has less of the stretchy gluten that has been bred into modern hybrid wheats, so it needs skilful handling – and slow fermentation – to give of its best as bread. Its great advantage is the flavour, sweet and full, that comes mainly from the outer layers of the grain that are completely conserved in flour milled by the Zentrofan. This fine wholemeal flour is very versatile. It can be used for every baking recipe, from bread to cakes and pastries. Check out our baking tips and recipes.
Where is the flour available?
Find our list of stockists and bakeries here. In the fullness of time, we hope to enable community-supported bakeries to acquire their own Zentrofan mills so that everyone can access the tastiest and most nutritious bread made from freshly milled, locally-grown, heritage wheat.
To preserve maximum flavour and nutritional value, flour should, ideally, be used within hours or days of milling. Scotland The Bread sends out freshly-milled flour twice a week by overnight carrier (for orders of more than one 1 kg bag). Any flour not used on the day of arrival can be stored in the freezer to conserve all its vitality. For ultimate freshness, you can buy the grain from us and grind it on your own mill.
Bread for Good Community Benefit Society acknowledges the generous contribution of an Environmental, Conservation and Community Renewable Energy Grant provided by the Naturesave Trust towards the purchase of the Zentrofan mill.
Looks really interesting. And I can see from subsequent posts you are still using the mill which is great.
I am looking at ways of bringing local grains into local communities and this technology looks very promising. I am particularly interested in whether the technology could be used in a decentralised system of flour “vending” which connect producers (farmers) with consumers (either home or small bakers) in areas where they aren’t as lucky to be near you. Your thoughts would be gratefully received.
Thank you for your comment, Jonny. Yes, I think the Zentrofan could be used fora system of fresh flour ‘vending’. Scotland The Bread already supplies one local shop with flour in bulk which is then dispensed with zero packaging. We hope to do this in returnable bins in due course. The ultimate would be for the mill to be set up in a shop or small bakery where it could mill away automatically overnight producing 25-75 kg of fresh flour by morning. This could go straight into the bakery mixing bowl or into home-bakers’ bags, bins or boxes. Different grains (rye, wheat, emmer, spelt etc) or the produce of different local grain growers could be milled on different days of the week. It would be simple to show exactly what today’s flour is, who grew it, in which field and what it’s best for baking etc.
The bigger challenge for re-establishing such local networks is the absence of really effective small-scale grain cleaning machines. Either the farmer or the shop/bakery/food hub needs to be able to clean the grain to a high standard before it goes into the Zentrofan.
I wish you success in your venture. If I can be of any more help, please ask.
Andrew Whitley
Chairman, Scotland The Bread, April 16th 2020
Hi Andrew, I just listened to the “miller is missing” cereal podcast episode on Farmerama and am really interested in the mill you have. Do you clean and sift the wheat on site yourselves? I would also be really interested in understanding your set up costs, so how much the mill cost compared to a more conventional stone mill of a similar output. Thanks,
Emma
Thanks, Emma. We don’t have onsite wheat cleaning yet. This is one of the roadblocks on the way to downsizing and re-localising farming and food processing. Grain cleaners for the commodity system process tonnes per hour, with scant regard for the needs of people who might eat the result – because, of course, they are usually cleaning grain for animal feed or, in Scotland regrettably, alcohol production. Our current problem is removing small amounts of fava beans from our wheat. These get in as ‘volunteers’ from the previous crop in the organic rotation and you would have thought that putting the grain twice through big commercial ‘dressers’ would have done a good enough job. But in fact, we need an intermediate-scale technology, somewhere between a laboratory machine (very good but very slow) and the commodity-scale behemoths (fast but careless) to enable us to put only clean whole grains into the Zentrofan mill. Anything much larger than a grain will block the input and slow down or halt milling.
The Zentrofan produces wholemeal flour and we don’t sift it after milling. We figure that there’s not a lot of point working hard to find and grow grain with more nutrients in only to remove them before selling the flour to our customers (because most of the minerals and vitamins are located in the bran layers of the grain).
The cost (in 2016) of the basic mill was about £7k and we have spent quite a bit more rigging up a larger hopper (it comes with a 25kg input) so that we can mill up to 120 kg unattended overnight (as long as no beans block the input!). One thing that is often overlooked in assessing the cost of a mill is the energy input. The Zentrofan produces 15-20 kg per hour but its 1.5 kW motor draws less than 2 amps while running. The considerable extra friction of a conventional stone mill probably indicates a higher energy input per kg of wholemeal milled (the heat of the flour is a bit of a give-away). Big roller mills guzzle energy in de-constructing the wheat grain into its constituent parts to make refined white flour that, under UK law, is deemed so nutritionally depleted that four synthetic nutrients have to be added back (two B vitamins, iron and chalk, i.e. calcium). Putting all these considerations together, we think the Zentrofan cyclone mill is the best way to process grain into fine flour. If people want something lighter than wholemeal, I suggest that they sift the coarse bran out, ferment it separately (generating nutritious compounds and softening the bran) and re-incorporate it into the bread after making the dough with the lighter flour fraction. Zero-waste + maximum digestible fibre and great flavour.
Thanks so much for the info – definitely got me thinking!
Looking at the Zentrofan as a viable option for my milling needs, I appreciate the above information.
If you wouldn’t mind, could you tell me the ability for the Zentrofan to produce a flour that would be suitable for sifting (to a T80-110). Although I want to continue using more whole-gran flour, it would be nice to have the flexibility.
Thanks in advance,
Seth
Hello, Seth. You could certainly sift the wholemeal flour from the Zentrofan to produce a ‘brown’ or ‘85%’ extraction flour, as UK millers would understand T80-110. (For a discussion of the varying terms for flour, from ’00’ to ‘1740’ etc) see page 78 of my book Bread Matters.) The only possible downside is that the Zentrofan reduces both the bran and the endosperm (the white flour) to a very fine particle size, so you might need a fairly fine sieve to remove the 10-15% of bigger bran particles that will result in the flour grade you are aiming for. But it is very doable. Best wishes, Andrew.
Any thought on sprouting the grains dehydrating( to increase digestibility ) then grinding ? I wish this kind of milling was available in the USA !
Yes, Marla. We are hoping to do this with some of our grains next year. There is no doubt that sprouted grains are more digestible and nutritious than unsprouted ones. The only question is, how to manage a proportion of sprouted grain flour in an ordinary loaf. You can’t make bread entirely with sprouted flour because the amylase and the available sugars tend to produce a very sticky loaf. But using a nice acidic sourdough certainly helps.
Thanks Andrew, that is really helpful and I appreciate your time.
I do have a couple of really quick questions that would help me out. Could I direct message you? I am @jonnymoo on twitter.
Ignore my last comment – your answer to Emma was exactly what I was going to ask! Just wanted some cost indications. Don’t know why I thought it should be a closed conversation, how very English of me!
Emma – you sound like you are investigating the same thing as me. Good luck, and I loved the Farmerama cereal postcasts. It would be interesting to know if anyone is looking at similar tech to Zentrofan, it sounds very promising. The Dyson of mills.
haha – I am obviously too blunt. Definitely super interesting but agree with Andrew above about the cleaning. Good luck!
Hey all of you!
As a professional baker (and geek about milling, health, old grains) the Zentrofan really brakes my head.
I learned about it while reading (and browsing) on the implemented ideas of Viktor Schauberger. I probably has no link to his work whatsoever, but one way or another it came up in a similar context. It probably has to do with the vortex it creates while milling.
I tried to read as much as I can on the internet about the Zentrofan, but there is not very much to find. What I did find, is that this mill always finds itself around millers (or bakers) who venture into a more bio-dynamic way. So something gives me the feeling there might be something really valid about it, …and in the last few days I even started to consider buying one for my bakery to test out its qualities because it’s slowly becoming too difficult to contain my curiosity :p
Rationally, you would think this would be the worst way to grind flour. Granted, the air gives a cooling effect, but only a very inattentive of uncaring miller would let their grains heat up more with a classical stone mill, than you would get with the Zentrofan. Even many moderns roller mills take very good care about the temperature.
And the Zentrofan really screams ‘Oxidation’ and ‘Starch Damage’ to me 🙂
Something that is ‘confirmed’ by a random article I found online, which reads:
“Zentrofan milling brings high oxidation effects, but also increases the mechanical stress on the starch grain. Extremely fine wholemeal flours with high water absorption are ground this way. However, the volume yield of the final baked goods is rather modest and the damage to the starch structures can lead to cleavage marks in the bottom area of the spelt bread. Zentrofan flours therefore are better for pastry baking” (source: homebaking.at/en/koenig-ludwig)
So I’m really braking and baking my head on the question what would be the reason to choose for a Zentrofan mill. You also can’t use symbiotic grown grains (when they have pieces of beans in them). And the grains have to be perfectly cleaned (a quality that leads automatically to more large scale cleaned grains in stead of going with the bio dynamic grain of your local small scaled farmer with more imperfections).
Probably not as fine as the Zentrofan, but with well dressed mill stones you can get very fine flour as well. And I wouldn’t really see any reason to go finer as what I can get now. Although if it makes whole wheat bread less strong (or even bitter) tasting, without having to have to sift part of the bran out to make a well balanced tasting bread, then going for the super fine grind of the Zentrofan is a huuuuge plus. Yet, I can’t see how going finer might lead to having a more balanced taste of whole wheat grains.
I’m also open for the idea that the specific cyclonic air treatment the flour receives in the mill, might give a special kind of (energetic?) quality to it. I know this definitely applies to water, but I can’t see how matter with a moisture content of around 12% can receive similar qualities.
Yeah, I would definitely say that this mill is (until) now a real mystery to me. The noise facture (80db) is also a rather big downside. And it’s also not particularly cheaper then a stone mill with a similar capacity in kg/h.
So yeah, If one day anyone of you has the feeling he wants to write an article about the comparison of the practical implementation of the Zentrofan vs a classical stone mill, and about the effects on bread of the milled flour, … I wouldn’t skip it to read it 🙂
Well, anyway, you are all doing a great job with the whole Scotland The Bread project.
The Bread Matters book had a great influence on me a few years ago. Keep up the good work 🙂
Andrew, re: appropriate scale grain cleaning, have you spoken to Alvan Blanch in Malmesbury?
https://www.alvanblanchgroup.com/.
They offer machinery using a range of cleaning techniques.
Hello, Chris. We got our thresher (Aspra Major) from Alvan Blanch in 2015 and it has worked reasonably well. I’ve looked at their range of cleaners but they have nothing of the right (small enough) scale for us. We are currently waiting for a grain cleaner which will do up to 600 kg per hour from Alma Pro in France.
I was at a presentation by a Danish engineering firm at a Nordic Grain conference some years ago, at which the presenter described (with elegant slides) a total of 17 different machines and/or processes for cleaning wheat. If only…
Re: grain cleaning – I grow organic wheat, rye and barley which I clean and sell as flour and whole to home and small scale bakers and local water mills. It is possible to get grain cleaned by our local seed supplier but that is very cumbersome and expensive. I bought many years ago an old on-farm cleaner from a sale (for £25!) which dates from about 1956 and was used to clean a whole harvest very quickly and crudely to get the green and bigger items out before storage or drier. It works by dropping grain through a winnowing wind onto two layers of different sized screens to select the grain size desired and take out over sized stones, unthreshed heads, straw, flower heads etc and undersized weed seeds and broken grains. I was lucky to get a full set of screens with it, but I have also bought perforated steel sheets and made intermediate sizes so my cleaning can be very subtle. I have adapted it to run slowly and to collect everything cleanly into bins without dust in the mill or my lungs and I can do about half a tonne per hour, which is a fine speed for a small operation. Anyone who wants more details is welcome to contact me or visit.