2.4.1. Content of free fatty acids in FOG
Free fatty acids were determined according to the AOCS official
method Ca 5a-40 (AOCS, 1999). Samples (in triplicate) of the dried
FOG dissolved in hot neutralised ethanol were titrated with
sodium hydroxide using phenolphthalein as indicator. The percentage
of free fatty acids is expressed as the content of oleic acid.