Degumming is the first stage of vegetable oil refining, in which phospholipids and related gums are removed from crude oil by treatment with water, acid or enzymes, improving oil stability and enabling lecithin recovery as a by-product.
In trade practice
Water degumming hydrates hydratable phospholipids so they can be centrifuged out; acid degumming, using citric or phosphoric acid, also removes non-hydratable phospholipids and is standard before further refining steps. The separated gums are dried to produce lecithin for food or feed use. Refiners monitor phosphorus content in the degummed oil as a proxy for gum removal efficiency, and incomplete degumming causes problems in subsequent bleaching and deodorisation stages.
In a specification
Refinery intake specifications for crude oil destined for degumming often state a maximum phosphorus content, expressed in parts per million, measured by a defined analytical method.