The increasing interest in the health and nutritional benefits of the Mediterranean diet has resulted in significant development of the olive oil market. The growing popularity of olive oil has been mainly attributed to its high content of oleic acid, which affects the plasma lipid/lipoprotein profiles. It is also rich in antioxidant phenolic compounds, which may help prevent diseases in humans.

Olive oil is usually extracted mechanically by pressure and three-phase centrifugation, which produces large amounts of olive mill wastewater. This waste has a high content of organic substances and thus a high polluting organic load with limited biodegradability, causing major environmental problems for disposal. However, the waste could provide a cheap source of phenolic compounds with strong antioxidant properties.

Olive and husk refined oils are also by-products of olive oil production and are becoming increasingly important in the food industry. However, they are susceptible to oxidation, which produces undesirable flavours and reduces their nutritional quality. Although synthetic antioxidants such as BHT and BHA are widely used in foods, consumer health concerns are promoting a search for natural alternatives. Olives, olive leaves and olive mill wastewater could be potential sources of natural antioxidants for oils.

A study by Fki et al.¹, evaluated various methods for recovering potentially added-value phenolic compounds from olive mill wastewater. The antioxidant and antiradical activities of both extracts and compounds were determined. Their ability to stabilize refined olive and husk oils was investigated and compared with that of BHA and BHT at 50°C. Low cost natural polyphenolic extracts, such as hydroxytyrosol and 3,4-dihydroxyphenyl acetic acid, could be produced from olive mill wastewater for use as alternatives to BHT and BHA.

¹ Fki, I; Allouche, N; Sayadi, S (2005). The use of polyphenolic extract, purified hydroxytyrosol and 3,4-dihydroxyphenyl acetic acid from olive mill wastewater for the stabilization of refined oils: a potential alternative to synthetic antioxidants. Food Chemistry 93 (2) 197–204.

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