Health, Shelf Life & Durability

(Health/Shelf Life/Durability) Oleic Acid

(Health/Shelf Life/Durability) Polyphenols

(Durability/Qlty) FFA

(Shelf-Life) Peroxide

Diacylglycerols

Diacylglycerols are productrs of oul formed from triacylglcerols following the cleavage of a fatty acid from the molecule. Cleavage of fatty acids occurs under various conditions, mostly commonly as a result of lipase enzyme reaction on the ester bond of the triacylglcerols.

Good manufacturing practuce of virgin olive oils results in a content of more than 85% of 1,2-diacylglycerols (1,2-DAGs), as a percentage of total diacylglycerols, in freshly processed virgin olive oils. Processing of rotten and/or fermented olives may result in a content of 40% r less of 1,2-diacylglycerols, even if processed adequately. Very often, such olive oils have sensory defects. Thermal treatment of virgin olive oils is considered NOT to influence the content of 1,2-diacylglycerols. This test is therefore considered usedful to determine whether olive oils have been processed following good practices and retain the sensory attributes of freshly obtained extra virgin olive oils even if deodorising practices have been utilised to remove original defects. DAGs may drop between 20 and 30% year.

A reduction of 1,2-diacylglycerols as reported to occure in storage and therefore levels of less than 45% may be considered to be an indicator of low grade olive oil labelled as EVOO. 1,2-diacylglycerols are transformed to the more stable 1,3-isomers (1,3-DAGs) during storage or due to acidic catalysation. The Australian Olive Assosciation Code of Practices sets 40% for the limit of DAGs.

The Polyphenol Test