A very rich source of poly-phenols filled with biological activities are the olive tree derivatives (olive oil, olive leaves, olive wood and the waste from the mill.
The most biological activities are in oleuropein and hydroxytyrosol and their content in the olive tree by-products, have been researched the most. They also have the most uses in medicine, food and cosmetics.
Oleuropein and hydroxytyrosol possess biological properties, which due to their antioxidant and free radical scavenging ability, are related to the low incidence of cardiovascular disease and some types of cancer. They contribute to the high health benefits of the Mediterranean diet.
Studies have proven that the olive mill water waste contains polyphenols filled with interesting biological activities.
For the recovery of the poly-phenols from the water waste, the solvent ethylacetate, a liquid extraction procedure is used.
Hydroxytyrosol is the main component in olive mill water waste and one litter of the water waste gives 1g of pure and 4g of dry extract of hydroxytyrosol.
To recover oleuropein and hydroxytyrosol, mixtures of water and ethanol, water and methanol have been used. The highest yield of oleuropein is obtained when water and methanol is used as an extraction mixture.
Oleuropein concentration is low in leaves during the harvesting periods.
When you introduce liquid methane extract from leaves, it breaks down the phenolic molecules. An increase in hydroxytyrosol concentration and the complete disappearance of oleuropein were the most noticeable effects. Hydroxytyrosol causes the lowering of oleuropein.
The phenols in olive leaves extracts shows that hydroxytyrosol is the main compound in the extract.
High amounts of hydroxytyrosol are produced from the hydrolysis reaction of oleuropein from olive leaves extracts. Using the system of liquid chromatography, the purity of the produced hydroxytyrosol reached 95%.
The oleuropein is the most important compound in the olives and the reason for their sharp bitterness. It varies with the variety of the olive and decline with the natural development and maturity of the olives.