An Innovative Mill for Special Grain

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.


Nature Save TrustBread 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.

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