Effect of various compounds on virgin olive oil stability measured by Rancimat.

Phenolic and orthodiphenolic compounds together with carotenoids, tocopherols, pigments, and fatty acids were tested for their antioxidant effect in 79 samples of virgin olive oils cv. Picual and Hojiblanca. A linear regression based on the oleic/linoleic ratio and the contents of phenols and tocopherols showed a good correlation (adjusted-R(2) = 0.91) with the stability measured by Rancimat, later verified with an external text set (adjusted-R(2) = 0.95). A tentative study on the percentage contribution of each chemical variable to stability is discussed. The contribution of phenolic and orthodiphenolic compounds was around 51%, the composition of fatty acids 24%, and in less percentage alpha-tocopherol, carotenoids, and chlorophylls. No effect, or very little, was shown by beta- and gamma-tocopherols.