Rancidity: this consists of a series of reactions of hydrolysis and/or oxidation concerning fatty acids or other lipids present in foods. This rancidity is due to the formation of free radicals (very unstable molecules) and to the absorption of oxygen by fatty acids, especially unsaturated ones, both free and esterified.

Refined olive oil: olive oil obtained from the refining of virgin olive oils. Its free acidity expressed as oleic acid must not exceed 0.5 g per 100 g.

Refining: This is an operation which is carried out in specific establishments. This operation involves the following processes: demucillagination, de-acidification, discoloration, filtration, deodorization and winterization.

Ripening: this is the color change in olives from an intense green to a final color which varies from purple to black according to the cultivar.