a) Settling and Degumming

Settling means heating the fat and making it stand for the aqueous phase to separate and be withdrawn. In doing so water, proteinaceous material, phospholipids and carbohydrates are eliminated from the fat. In certain cases, particularly with oils containing substantial amounts of phospholipids (e.g. soybean oil), a primary treatment called degumming is performed by adding 2 to 3% water, agitating the mixture at 50ºC and removing the hydrated phospholipids by means of settling or centrifugation.

In the physical refining process, degummimg is performed by adding phosphoric acid to ensure phospholipid separation instead of water