Extraction rate

This is the term used for the proportion or percentage of the de-husked and cleaned wheat grain (also known as the wheat berry) that makes it into the flour sack and is expressed as a percentage. Wholemeal/wholewheat flour should be 100% extraction (though see the note below on stone-ground vs. roller-milled flour); British-milled white bread flour will be around 75%, and brown flour will fall somewhere in between, usually 80–85%.

Continental millers use different systems of classification, based on how much ash is left when the flour is incinerated under controlled conditions. The higher the number, the more ash, indicating higher fibre. Just to make things more confusing, each country’s systems differ from each other.