Source antioxidants from olive oil waste.

A team of Southern European scientists has developed an economically feasible process for recovering polyphenolic antioxidants from olive oil production waste. Their studies show that the water-soluble olive oil polyphenols might be good candidates as functional food ingredients, potentially influencing the onset of cardiovascular disease, cancer and inflammatory reactions. More human studies are needed, however, before this can be determined.

In the olive mill, olive paste is traditionally washed with water, which removes a large amount of the soluble compounds. Among others, the amphiphilic phenolic compounds, monohydroxyphenols and o-dihydroxyphenols (catechols), are extracted. The esterfied phenols, ligstroside and oleuropein, stay in the oil phase.

Catechols, also present in tea and other vegetable products, are well-known antioxidants. They protect foods from oxidation. They also are challenging biological antioxidants by protecting against oxidative degradation in living cells. For this reason, the substances are of interest not only to food scientists but also health professionals.

The European scientists indicate that the catechols may be industrially isolated from the wash water by using acidification, enzymatic pectin degradation and absorption on sorbent resins. Then the catechols could be desorped. From 10% to 20% of the total phenols can be recovered in the process. The main catechol present is hydroxyl-tyrosol.

The researchers analyzed the biological antioxidant effects of the olive phenols using in vitro, rat and human studies. In vitro, the phenols inhibited LDL oxidation, leukocyte activation, superoxide anion production and the enzyme glutathione-S-transferase. In vivo studies showed a dose-dependent absorption both in rats and in humans, an enhanced total antioxidant activity in plasma and significant interactions with cellular enzymes.

Further information. Claudio Galli, Universiti degli Studi di Milano, Instituto di Scienze Farmacologiche, Via Balzarett 9, 20133 Milano, Italy; phone: [phone]; email: [e-mail]; URL: www.unimi.it.