A solvent extraction free, process for producing refined soybean oil that is
high
in calcium and/or magnesium is described in which mechanically extracted crude
soybean oil is subjected to a two-stage process to separate hydratable and nonhydratable
phospholipids. In the first stage, the crude oil is intimately mixed with water
or with a weakly acidic aqueous solution, e.g., a aqueous solution of citric acid
or a similar organic acid, to form gums of the hydratable phospholipids. After
removing the gums from the oil, e.g., by centrifuging, the oil from the first degumming
is intimately mixed with a weakly basic solution, e.g., an aqueous solution of
sodium hydroxide or sodium metasilicate, to produce soapstock and reduce the magnesium
and calcium in the oil to less than 100 ppm, followed by separation of the soapstock,
e.g., by centrifuging. Free fatty acids are then removed through physical refining.
