Potato starch
A light, fast-gelatinising starch that softens gluten-free crumb — and which is emphatically not potato flour.
Also called potato flour (INTERNATIONAL) — NOT the same ingredient. Potato flour is dried whole potato and absorbs far more water; substituting one for the other by weight fails badly.
Potato starch is extracted starch with very large granules that swell readily and gelatinise at a relatively low temperature. In gluten-free blends it lightens the crumb and keeps it soft, and it holds moisture well enough to slow the rapid staling gluten-free bread is prone to.
Its limitation is the same as tapioca’s: it is starch, so it contributes no structure and no protein, and a blend that leans on it needs its body from a protein-bearing flour.
The naming problem is worth stating plainly because it causes more failures than any subtlety of formulation. Potato starch and potato flour are different ingredients with different behaviour and similar names, and recipes are inconsistent about which they mean.
What changes if it is left out
Crumb becomes firmer and stales faster. Structure is unaffected.
Follows from its role as a softening starch rather than a structural one.
RecordedFollows from evidence recorded elsewhere on BakeHQ
Related
What it does
Moisture retention
Large granules that swell readily and hold water, keeping the crumb soft for longer.
Compared in
Cornflour vs tapioca vs potato starch vs arrowroot
A subject of the comparison, so it is reachable from the record a reader is more likely to land on first.