Parametre identity: The phenolic fraction of olive oil is a total of simple phenols and polyphenols. More than 20 phenols have been isolated from various types of olive oil, the most characteristic being hydroxytyrosol, tyrosol, vanillic acid, caffeic acid, ferulic acid, vanillin, ρ-Coumaric acid, ο–Coumaric acid, oleacein, oleuropein and its various aglycons, ligstroside and its various aglycons, eleocanthal, cinnamic acid, luteolin, protocatechuic acid.
Reason: Phenols exist naturally in olive oil and behave as antioxidants, protecting the olive oil from going rancid when it is attacked by atmospheric oxygen and the rays of the sun.
Points of Information: An olive oil with high phenol content has a high degree of protection and therefore a longer life, while at the same time consumption of such oil protects human cells from oxidative stress. As a final point, to a large extent, the fruity and bitter taste of the olive oil is due to the phenols.
Useful things to know about phenols
The essential points about olive oil phenols can be summarised as follows:
- The phenolic substances in the olive fruit increase as it ripens and reach a maximum when the skin has attained full coloration and the flesh is starting to change colour.
- A proportion of the phenolic substances in olive oil are polar, the others being non-polar. The protection again rancidity is provided by those phenolic substances that are dissolved in the non-polar part of the olive oil, while those dissolved in the polar part offer little protection.
- A large part of the fruity and bitter taste of the olive oil is due to the phenolic fraction as well as to aldehydes and terpenes.
- The olive pulp contains 2-5% phenolic substances. Of that, 1-4g/l passes into the pomace liquid while a quantity of between 70-900mg/l (ppm) is retained in the extracted olive oil, depending on the particular conditions at the time.
- There is a high correlation between the phenols and the flavour characteristics of the oil. A concentration of phenols of between 70 and 150 ppm ensures a pleasant sweet and fruity flavour. If the concentration of phenols is between 250 and 450 ppm, it gives the oil a fruity, peppery and a lightly to significantly bitter flavour.
- Since December 2012, the following health claim may be included on the packaging of olive oils: “Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress in the context of a varied and balanced diet”. This claim can only be made for olive oil with a content of at least 5mg hydroxytyrosol and its derivatives (e.g., eleuropein and tyrosol complex) to 20g olive oil (250mg/l or 250 ppm) until the end of its shelf life. Together with the claim, the consumer must also be informed that the beneficial effects are to be gained with a daily intake of 20g of olive oil. The proportion of phenol content per 100gr of olive oil must also be recorded.