Assertion: vegetable oil's fatty acid | /r/HasProperty | ffa
Facets:
Source sentences:
text: The oil is then treated with caustic soda, which reacts with the unwanted free fatty acids (FFA) turning them into soap; the soap is separated from the oil.
text: Any free fatty acids (FFAs) in the base oil are either converted to soap and removed from the process, or they are esterified (yielding more biodiesel) using an acidic catalyst.