Neutralization is the refining stage in which free fatty acids in degummed crude oil are reacted with an alkali solution to form soapstock, which is then separated, reducing acidity and improving the oil’s flavour stability and shelf life.
In trade practice
Refiners treat degummed oil with a caustic soda solution, then centrifuge out the soapstock. Quality teams verify the outcome by testing free fatty acid content and soap residue before the oil moves to bleaching. A common error is insufficient washing after separation, leaving soap traces that impair bleaching efficiency. The soapstock by-product is typically sold for industrial soap manufacture or further processed for fatty acid recovery.
In a specification
Purchase contracts for refined oil typically require a free fatty acid level expressed as oleic acid, referencing the method in ISO 660, with neutralization confirmed as a completed refining stage in the processing declaration.