Evaluation of table olive by-product as a source of natural antioxidants

The main by-product from the table olive canning industry is the stone with some residual olive flesh. The purpose of this study was to evaluate the composition phenolic compounds (hydroxytyrosol, tyrosol and oleuropein) and tocopherol and the antioxidant activity in different fractions (flesh, stone and seed) from the table olive by-product and the whole by-product. The highest amounts of phenolic compounds (1710.0 +/- 33.8 mg kg-1) as well as the highest antioxidant activity (8226.9 +/- 9.9 hydroxytyrosol equivalents mg kg-1) were obtained in the seed. The highest amounts of hydroxytyrosol (854.8 +/- 66.0 mg kg-1) and tyrosol (423.6 +/- 56.9 mg kg-1) were found in the whole by-product from the pepper stuffed olives, while the stone without seed had the maximum oleuropein content (750.2 +/- 85.3 mg kg-1). a-Tocopherol values were between 79.8 +/- 20.8 mg kg-1 in the seed of the olive stone and 6.2 +/- 1.2 mg kg-1 in the whole by-product from the anchovy-stuffed olives. In light of the results obtained, it would seem possible to use table olive by-product as a source of natural antioxidants in foods, cosmetics or pharmaceutical products, thus contributing to diminishing the environmental impact of table olive by-product and to its revalorisation.