ANTIOXIDATIVE ACTIVITY OF 3,4-DIHYDROXYPHENYLACETIC ACID AND ALPHA-TOCOPHEROL ON THE TRIGLYCERIDE MATRIX OF OLIVE OIL - EFFECT OF ACIDITY

Minor constituents of virgin olive oil are important for the remarkabl e stability of the oil in autoxidation, but the exact role and the ext ent to which each antioxidant factor contributes to the total antioxid ant effect has not been thoroughly investigated. In this study the rol e of alpha-tocopherol is explored at various acidity levels and at low concentrations of ortho-diphenols. A substrate of olive dr triacylgly cerols devoid of prooxidant or antioxidant constituents was prepared f rom refined olive oil by column chromatography. To this substrate, sli ghtly oxidized, the additives (oleic acid. 3,4-dihydroxyphenylacetic a cid and cc-tocopherol) were added and the stability was assessed by pe riodical measurements of peroxide values. it was found that free fatty acids reduce mainly the protective activity of the ortho-diphenol. It is also concluded that alpha-tocopherd has a synergistic effect with the ortho-diphenols and contributes significantly to the retardation o f peroxide formation. This is important for oils poor in ortho-dipheno ls.