Guide
Gluten Free Milling, and the Contamination Rule
Milling makes gluten free flours dramatically cheaper, and if the reason is coeliac disease then the mill has to be dedicated rather than cleaned.
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Gluten free flours are among the most expensive things in a supermarket and among the cheapest grains to buy whole. Rice, buckwheat, millet, and sorghum all cost a fraction as much in seed form, and all mill easily.
That gap makes milling more worthwhile for a gluten free household than for anyone else. It also comes with one requirement that is not negotiable, and it needs stating before anything else.
The contamination rule
A mill used for wheat cannot be made safe for coeliac disease by cleaning.
Flour lodges in burr grooves, in stone pores, in chamber seams, and in the fabric of any hopper. Impact mills throw fine dust into every internal surface. Brushing, vacuuming, and running rice through to scour all reduce residue and none of them eliminates it.
For anyone with coeliac disease, or non coeliac gluten sensitivity severe enough to matter, the answer is a dedicated mill that has never processed wheat, rye, barley, or spelt.
For a household choosing gluten free by preference rather than medical necessity, thorough cleaning between uses is a reasonable judgement call and the risk is yours to weigh.
Two further points. Buy the mill new, or from a seller who can confirm what was milled in it, since a used mill's history is not visible. And keep it physically separate from wheat handling if the kitchen processes both, because airborne flour settles.
Check your own national guidance on gluten free thresholds and labelling rather than relying on any website, including this one.
The grains, and what each does
None of these behaves like wheat. Understanding what each contributes is more useful than a substitution ratio.
Rice. The workhorse. Neutral flavour, fine texture, and dramatically cheaper milled at home than bought. Brown rice retains the germ and has more flavour and a shorter shelf life. White rice is milder and stores longer. Mill fine, and expect a slightly gritty result unless your mill goes genuinely fine, since rice is hard.
Sorghum. Mild, slightly sweet, and the closest thing to a neutral base among the gluten free grains. Widely used as the backbone of blends.
Millet. Mild and sweet, mills easily, and goes rancid faster than most. Mill small quantities.
Buckwheat. Unrelated to wheat despite the name. Strong, earthy, distinctive. Excellent in pancakes, crepes, and soba style noodles, and assertive enough that a little goes a long way in a blend.
Oats. Naturally gluten free and frequently contaminated during growing, transport, and processing. If the reason is coeliac disease, certified gluten free oats matter. Oat flour contributes tenderness and a soft crumb.
Corn. Coarse for polenta, fine for cornbread and masa style applications. Some mills struggle with corn, so check the rating.
Quinoa. Distinctive and slightly bitter. Rinse and dry the seed before milling to reduce the saponin coating, or accept the flavour.
Amaranth and teff. Very small seeds, strong flavours, best as a component rather than a base.
Chickpeas and other pulses. Mill into flour with real character and are hard on a mill. Check what your model is rated for and work in small batches.
Building a blend
Gluten free baking is a craft of its own and no amount of freshness substitutes for the structure gluten provides. What a mill gives you is control over the components and a much lower cost per kilogram.
A neutral base, sixty to seventy percent. Rice or sorghum.
A flavour or texture grain, twenty to thirty percent. Buckwheat, millet, oat, or corn.
A starch, ten to twenty percent. Tapioca, potato, or corn starch. These are bought rather than milled and they contribute lightness and chew.
A binder. Psyllium husk or xanthan gum, in small quantities. This is the component that most nearly does gluten's structural job, and omitting it is the usual reason a home gluten free loaf crumbles.
Weigh in grams, work in percentages, and write down what you did. Gluten free blends are less forgiving than wheat and reproducibility matters more.
Start from a published blend ratio and vary one component at a time. Inventing from scratch is a long road.
Milling technique for these grains
Mill finer than you would for wheat. Gluten free flours are noticeably grittier at the same setting, and texture is a bigger part of the eating experience when there is no gluten network to distract from it. Two passes are often worth it.
Sift, and re-mill the coarse fraction. Rice in particular leaves a gritty tail that is worth catching.
Expect more heat. Hard seeds like rice work a mill harder. Let flour cool before use.
Mill small batches of the oily ones. Millet, oats, and amaranth all go rancid faster than wheat.
Check ratings before pulses. Chickpeas and lentils are hard on burrs and can stall impact mills.
Clean between grains even within the gluten free set, since buckwheat and quinoa are assertive enough to flavour a subsequent rice batch.
Impact, stone, or burr covers which mechanisms handle hard and oily material.
Storage
Shorter than wheat across the board, and worth planning for.
Whole seed keeps well. Rice, sorghum, buckwheat, and millet all store for a year or more sealed and cool, following the same logic as any grain.
Milled gluten free flour keeps poorly. Several of these are oilier than wheat, and rice flour in particular can develop an off flavour within weeks at room temperature.
Refrigerate or freeze milled flour if you are not using it within a fortnight. This matters more here than for wheat.
Blends age at the pace of their shortest lived component. A blend containing millet or oat flour is a short life blend regardless of what else is in it, which is an argument for blending small quantities from separately stored components.
Cost, which is the strongest argument
The gap between whole seed and bought flour is wider here than anywhere else in this hub.
Rice bought as grain and milled at home costs a small fraction of packaged rice flour. The same is true of buckwheat, millet, and sorghum, and more so for the less common flours, which carry a substantial specialty premium.
For a household buying gluten free flour regularly, a mill can pay for itself within months rather than years, which is a genuinely different proposition from the wheat case where payback is measured over a longer period.
Add the ability to blend to your own ratio rather than paying for someone else's, and the case is strong. The milling hub sets out the general economics, and this is the corner where they are most favourable.
Starch, gums, and what a mill cannot give you
Two components of gluten free baking are bought rather than milled, and being clear about that avoids disappointment.
Starches. Tapioca, potato, and corn starch are extracted rather than ground, which puts them out of reach at home in the same way cacao is. They contribute lightness, chew, and browning, and most successful gluten free blends contain ten to twenty percent of them. A mill does not replace them.
Binders. Psyllium husk and xanthan gum are the components that most nearly perform gluten's structural job, holding gas and giving dough elasticity. Psyllium is a milled plant husk and is generally bought pre-ground. Xanthan is a fermentation product. Neither is optional in a bread style bake and both are used in small quantities.
So the honest picture is that a mill gives you cheaper, fresher versions of the bulk of a blend, and the two functional components still come from a packet.
That is still a substantial saving, since the base flours are the majority by weight and the most expensive to buy. And it gives you control over the character of the blend, which is where home gluten free baking actually improves on the shop version.
Store starches and binders sealed and dry. Both are hygroscopic and both clump.
RUN THE NUMBERS
Illustrative guide. Grind fineness and cost vary considerably.
| Grain | Role in a blend | Mills easily | Keeps milled |
|---|---|---|---|
| Rice, white | Neutral base | Hard, mill fine | Reasonably |
| Rice, brown | Base with flavour | Hard, mill fine | Poorly |
| Sorghum | Neutral base | Yes | Reasonably |
| Millet | Base or flavour | Yes | Poorly |
| Buckwheat | Flavour | Yes | Moderately |
| Oats, certified | Tenderness | Yes | Poorly |
| Corn | Flavour, texture | Check rating | Reasonably |
| Quinoa | Flavour | Yes, rinse first | Poorly |
| Chickpea | Flavour, protein | Hard on mills | Moderately |
A working starter blend: sixty percent rice, twenty percent sorghum, twenty percent tapioca starch, plus psyllium as a binder. Adjust one component at a time.
WHAT GOES WRONG
A crumbly loaf that will not hold together. No binder, or not enough. Psyllium or xanthan is doing gluten's job and it is not optional.
Gritty texture. Milled too coarse, particularly with rice. Mill finer, sift, and re-mill the coarse fraction.
Rancid or soapy flavour after a few weeks. Milled flour stored at room temperature. Refrigerate or freeze.
Bitterness in a quinoa blend. Saponin coating. Rinse and dry the seed before milling.
A stalled mill on chickpeas. Not rated for pulses. Check first.
Everything tasting of buckwheat. Mill not cleaned between grains.
Contamination symptoms despite careful cleaning. A shared mill is not a dedicated mill. This is the one on this page that matters.
DO THIS NOW
- If the reason is coeliac disease, buy a mill that has never processed wheat and keep it dedicated.
- Start with rice and sorghum as your base, since both are cheap, neutral, and easy to mill.
- Mill finer than you would for wheat, sift, and re-mill the coarse fraction.
- Refrigerate or freeze any milled gluten free flour you will not use within a fortnight.
Next
For the full range of grains including the wheat family, and what protein and gluten actually do, see grains worth milling.
Rice and pulses are hard on mills and oily seeds clog several designs. Impact, stone, or burr covers what each mechanism handles.