28/09/2026
We talk a lot about fermentation in sourdough.
How long should it ferment?
How active should the starter be?
When is the dough ready?
But there’s a question that comes before all of that:
What are you actually fermenting?
Before wheat becomes flour, the kernel contains three main parts: bran, germ and endosperm.
And they’re not nutritionally or functionally interchangeable.
The bran carries much of the grain’s fibre, minerals, B vitamins and bioactive compounds.
The germ is small, but particularly rich in lipids, vitamin E, B vitamins, minerals and other bioactive compounds.
And the endosperm — the largest part of the kernel — is predominantly starch and storage proteins, including the proteins that form the gluten network.
Then comes milling.
As more of the bran and germ are removed, the composition of the flour changes. This is where extraction rate becomes important.
So flour isn’t simply “white” or “whole grain.”
What you retain can influence fibre, minerals, vitamins, lipids, flavour, water absorption, dough behaviour and fermentation behaviour.
And that leads to one of the most important ideas in this carousel:
Fermentation can transform what is already present in your flour.
But it can’t put back what milling removed.
So before you ask:
“How long should I ferment?”
Ask:
“What am I fermenting?”
Because great sourdough doesn’t start with your starter.
It starts with understanding your flour.
Swipe through to see what’s actually happening inside the wheat kernel — and why your choice of flour matters long before fermentation begins.
And if you want to go deeper into protein, milling, extraction rate, ash content and flour selection, my Flour Mastery Course is currently available for $9 for a limited time.
💬 Comment “FLOUR” and I’ll send you the link.
