Phenolic profile and antioxidant activities of olive mill wastewater

Olive trees play an important role in the Moroccan agro-economy, providing both employment and export revenue. However, the olive oil industry generates large amounts of wastes and wastewaters. The disposal of these polluting by-products is a significant environmental problem that needs an adequate solution. On one hand, the phytotoxic and antimicrobial effects of olive mill wastewaters are mainly due to their phenolic content. The hydrophilic character of the polyphenols results in the major proportion of natural phenols being separated into the water phase during the olive processing. On other hand, the health benefits arising from a diet containing olive oil have been attributed to its richness in phenolic compounds that act as natural antioxidants and are thought to contribute to the prevention of heart diseases and cancers. Olive mill wastewater (OMW) samples have been analysed in terms of their phenolic constituents and antioxidant activities. The total phenolic content, flavonoids, flavanols, and proanthocyanidins were determined. The antioxidant and radical scavenging activity of phenolic extracts and microfiltred samples was evaluated using different tests (iron(II) chelating activity, total antioxidant capacity, DPPH assays and lipid peroxidation test). The obtained results reveal the considerable antioxidant capacity of the OMW, that can be considered as an inexpensive potential source of high added value powerful natural antioxidants comparable to some synthetic antioxidants commonly used in the food industry.