Starch

Starch is the bulk of what a miller keeps when the bag is white flour. USDA’s experimental mill treats the wheat kernel’s interior as endosperm — the starchy part that becomes flour once break and reduction rolls free it from bran ¹. Ash is a bran clue, not a starch assay: minerals concentrate in bran, so leftover ash hints how cleanly that starchy interior was separated ².

It is not Gluten. Gluten is protein that hydrates and is worked. It is not Pectin. Pectin gels fruit. Starch thickens a sauce, sets a crumb, and, once enzymes nick it, becomes food for yeast.

In the mill and the bag #

Wheat flour is mostly this carbohydrate plus protein. How much bran rides along is a milling decision. Higher extraction keeps more kernel and usually more ash; it does not turn starch into gluten.

Feel the dough: a flour that drinks extra Water may be carrying bran or damaged starch from the rolls. Do not invent a percentage from the feel. Adjust water to the flour in front of you.

In the oven #

King Arthur’s steam teaching: early steam gelatinizes starches on the loaf’s surface, which is part of why a steamed crust can look glossy and then shatter ³. That is a crust observation. The crumb’s set is the same family of change happening inside — see Gelatinization and Baking the loaf.

In the rest #

King Arthur’s autolyse account: flour enzymes (they name amylase) start turning starch into sugars yeast can use while flour and water rest ⁴. That is bakery teaching, not a cereal-lab chromatogram. Details: Enzymes.

Watch the difference between a pale, matte crust that never saw steam and a blistered one that did. Taste whether a crumb is moist and set or gummy — gummy is underbaked starch, not a starter personality. Day-old firming is Staling, not a new mill.