Whole-grain flour keeps all of the kernel and the most nutrition, but its germ oil spoils it within 1-2 weeks, while sifted white flour discards the bran and germ and keeps for months. Because bran and germ together are only about 17% of a wheat kernel, a village that needs 68 kg of grain a day loses at most 12 kg of that to the sieve, and the bran can still be fed to animals.
Part of Community Grain Mill
The choice between leaving the whole kernel in the flour and sifting out the bran and germ: what is lost, how long each keeps, and how a village balances the two.
The Germ Is Both The Nutrition And The Rot
Whole-grain flour carries the germ’s oils, which oxidize in the warm, ground-up flour far faster than in the whole kernel. That is why the carrier says to mill only what will be eaten within 1-2 weeks, and why the wiki gives whole-grain flour 1-2 weeks and white flour months (Grinding and Milling). The longer 2-4 weeks, or up to 2 months in a cool cellar, in the carrier’s own flour-grades section is the best case; do not plan on it in a warm store.
What The Sieve Takes: Arithmetic From A Textbook Split
A wheat kernel is roughly 83% starchy endosperm, 14% bran and 3% germ by weight (textbook milling figures, recalled, not measured here). So bran plus germ is about 14 + 3 = 17% and the endosperm is about 83%. The best white flour a sieve can make is therefore under 83% of the grain, because some endosperm clings to the bran and some bran dust passes the cloth; stone-milled and bolted flour typically runs lower, nearer 70-80% (also recalled).
For the carrier’s village of 100 people eating 1.5 lb of grain each a day, the grain is 150 lb or 68 kg:
- Whole-grain flour: 68 kg a day, nothing removed.
- Sifted flour at the ceiling: 68 x 0.83 = 56 kg of white flour, and 68 - 56 = 12 kg of bran and germ for animals.
- At 70% extraction: 68 x 0.70 = 48 kg of flour and 20 kg of bran and germ.
Fewer kilograms of flour reach the table when the village sifts, so a village that bolts all its flour needs more grain: for the same 56 kg of white flour at 70% extraction it must mill 56 / 0.70 = 80 kg of grain, 12 kg more than a whole-grain village.
Method: Setting A Village Policy
Step 1: Decide the default. Most of the village’s flour should be whole grain or lightly sifted brown, milled a week or two at a time, because it carries the most nutrition from the grain grown.
Step 2: Sift only what is needed white. Bake fine bread and pastry from white flour; do not sift everything.
Step 3: Store white flour for the long gap. Use white flour for the months when the mill cannot run.
Step 4: Use the bran. Feed it to hens and pigs or stir it back into porridge, so the sifting loses nutrition from the table but not from the farm.
Common Mistakes
- Sifting all the flour. It loses 12-20 kg a day for 100 people and the nutrition that goes with it.
- Storing whole-grain flour like white. Whole-grain flour in a warm bin turns rancid in weeks.
- Calling bran waste. The carrier says plainly to feed it to chickens and pigs.
Rancid and dusty flour
Do not eat flour that smells sharp, paint-like or bitter, or that is moldy; throw it out. Flour dust is explosive in a cloud, so sift and store away from flame, and sweep up spills.
What’s Next
- Learn next: Bolting Cloth and Sifting Systems - how the sifting is done
- Combine with: Toll Milling and Community Scheduling - milling little and often