The research, published in the journal Food Chemistry, suggests that antioxidant rich solutions could be extracted from olive oil mill waste, and could then be used to enrich antioxidant levels of foods and oils.
“Phenolic extracts from olive oil mill waste can be used as alternatives to synthetic antioxidants in order to increase the stability of foods,” wrote the researchers, led by Evangelos Lazos at the Technological Educational Institution of Athens, Greece.
Treatment and disposal of olive oil mill waste is one of the most serious environmental problems in Mediterranean countries, as many of its constituents are not easily degradable.
But olive oil mill waste could be used as an excellent source of natural antioxidants.
Olive oil industries have developed new techniques that separate virgin olive oil by recycling the vegetation water of processed olives. The technique greatly decreases the volume of plant waste and disposal problems, and releases a by-product with between 10 and 100 times more of the antioxidant than in the olive oil itself.
The new study investigated the antioxidant levels of olive oil mill waste, and tested the effects of different solvent extraction techniques on antioxidant levels.
Hydroxytyrosol was the major phenolic compound detected in the extract, whilst flavonoids such as luteolin, hesperidin, catechin, cyanidin glycosides and various phenolic acids were also identified.
Methanol and ethanol were found to have significantly higher radical scavenging activity than any of the other solvents tested.
When added to sunflower oil to test the potential for use as a functional antioxidant ingredient, a combination of ethanol extracted olive oil mill waste and ascorbyl palmitate gave the greatest protection.
Ethanol was found to be the most appropriate solvent for extraction of phenolic compounds from the waste.
Researchers reported that the optimum solvent extraction conditions were 180 min using ethanol, at a solvent to sample ratio 5:1 v/w, and at pH 2.
The study concluded that olive oil mill waste is a “low-cost, renewable and abundant source of phenolic antioxidants” that could be used as functional ingredients.
The new process could be used to add antioxidants to oils with lower antioxidant content, and potentially adding oxidative stability to functional foods – preventing off flavour formation in omega-3 enriched foods.
“Phenolic extracts from olive oil mill waste can be used as alternatives to synthetic antioxidants in order to increase the stability of foods by preventing lipid peroxidation, and protect living systems from oxidative damage by scavenging oxygen radicals,” stated the researchers.
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2010.08.041
“Phenolic and antioxidant potential of oliveoil mill wastes”
Authors: T.I. Lafka, A.E. Lazou, V.J. Sinanoglou, E.S. Lazos