Oleic acid is the main fatty acid in olive oil – 55%-85% of olive oil is made up of triacylglycerols, which are made up of oleic acid.
The higher the oleic acid monounsaturated fat content, the longer the shelf life! Also, the oil will have increased ‘durability’, meaning it can handle higher temperature cooking.
The minimum level of oleic acid an olive oil has to have in order to qualify for extra virgin status is 55%. For Ultra premium, the level is 65%