Waste water from olive oil production may be used as a source of valuable bioactive antioxidants - widely believed to have a protective effect on human health - as scientists in southern Europe develop a new technique to recover the antioxidants for use in foods.
Olives and olive oil, in particular extra virgin olive oil, contain a variety of bioactive compounds (phytochemicals) widely believed to be potentially beneficial to health. A European-backed research project in southern Europe claims to have developed a process to recover natural antioxidants from the water used to wash the olive paste during olive oil production.
Alongside in vitro studies, human studies were carried out to test the absorption and potential bioactivity of hydroxytyrosol (HT), which is one of the phenolic compounds transferred from the olives into the waste water. Capsules of the waste water extract, containing 50mg of HT, were prepared and given to human volunteers for several days.
The absorption of HT from the capsules was confirmed by measuring the excretion of HT and metabolites in urines, an effective method to assess the bioavailability of ingested compounds. Scientists, led by Professor Claudio Galli at the Università degli Studi di Milano in Milan, Italy, observed that production of serum thromboxane B2 (an index of pro-blood clotting activity) was markedly decreased after taking the capsules, indicating that HT inhibits the activity of the platelet cycloxygenase system, an activity similar to that of aspirin.
In another part of the project, the waste water extract was added to a very low-fat yoghurt and, again, analyses showed that the HT was absorbed in humans. However, at the dose of HT used in the yoghurt (20mg) there was almost no observed effect on serum thromboxane B2 after 3 days.
The scientists maintain that more work is needed, possibly based on a dose-dependent design and for longer duration, and using different food matrices, to elucidate the biological activity of the extracts, on various biological processes such as inflammation or endothelial function and their potential usefulness in functional foods.