Are all olive oils beneficial to the health? Where do they help? What role does the color play? How to store the oil? Prokopis Magiatis, the associate professor of the Department of Pharmacognosy and Natural Products Chemistry at Athens University, provides us with information based on his scientific knowledge.
What does extra virgin olive oil mean and what is the nutritional difference between it and the plain olive oil?
Virgin olive oil is what is obtained by exclusively physical (mechanical) methods from the olive fruit without chemical refining. Particularly, extra virgin olive oil belongs to the upper olive oil category, which is distinguished by its low acidity, the low number of peroxides and oxidation markers and the absence of gustatory defects. The basic difference from the plain olive oil consisting essentially of refined olive oil with a small addition of virgin olive oil is that the plain oil does not contain almost at all the phenols, which are beneficial to health.
How is it possible to prove scientifically that olive oil is beneficial to health?
The only way is to conduct special chemical analyzes, which can accurately measure the levels of beneficial phenols. The certification is strictly scientific and our research team has developed a laboratory method (NMR), with the help of which all the beneficial phenols may be measured just within 30 seconds.
However, this requires the delivery of the sample to the university. Can a consumer do it at home?
Yes, we have developed a special test, the Aristoteleo method by which it is possible, without chemical knowledge, with a simple color scale and a special reagent (kit) to measure the level of oleocanthal and oleosin, which are the most important phenols. Our discovery was awarded as the best invention of the year by the Hellenic Federation of Enterprises at the latest innovation contest.
How exactly does the olive oil affect our health?
It is officially recognized that olive oil protects against the oxidation of LDL cholesterol and falls within the category of phenolic compounds, known by the generic term as hydroxytyrosol derivatives. Due to these substances, olive oil protects the cardiovascular system. However numerous beneficial properties have not yet been officially recognized, but there are already many experimental data with very strong evidence. For example, it has been found that oleocanthal in healthy people inhibits platelet aggregation and blood clots, while in animals it can inhibit the development of Alzheimer’s disease and rheumatoid arthritis. Also, it has been recently found that through a specific mechanism it can rapidly kill cancer cells without harming the normal ones. Oleosin has similar but weaker properties. It is the strongest antioxidant of the oil.
How has your study contributed into this field?
Our study has contributed in several different ways. First of all, the methods developed by us help measure quickly and reliably the levels of phenols in olive oil. Thus, we have analyzed thousands of olive oil samples from Greece and from many foreign countries and we are able to know when olive oil is really rich and when it is not, and which factors act positively to the increase of phenols. Also, in this way we can choose the right oils that are used in various clinical or experimental studies in universities all over the world. In addition, we have developed methods that isolate pure chemicals from the olive oil and, thus, we or our partners abroad have the opportunity to study precisely their pharmacological activity in cells or in animals, and soon in humans.
How can a consumer distinguish the quality of the olive oil? Does its color play the role? Is there anything on the label to help him?
One can distinguish the quality from its taste, but this requires training and experience. If the olive oil has spicy taste in the throat and pleasant bitterness on the tip of the tongue, it means that it contains the beneficial phenols and particularly oleocanthal and oleosin. The color of the olive oil does not tell us something very important. For some period of time, olive oil can be green if produced of green olives. Usually green olive oil is rich in phenols, but this is not always the case because the production conditions at the mill play a very important role. The only way to be sure is to check the analysis certificates attesting first whether the oil is extra virgin and, secondly, if it meets the specifications to be characterized as a health protective product.
What should we pay attention in the bulk oil?
The bulk oil is actually completely uncontrollable and normally consumers should have stopped its release by themselves.
How should we use it in cooking in order to maintain its beneficial ingredients unchanged?
Because the beneficial phenolic compounds in olive oil are sensitive to high temperatures, it is always preferable to consume it raw or add it at the end of cooking. As for frying, surely the high temperature causes significant breakdown of the beneficial ingredients. Nevertheless, it is always preferable to fry with olive oil than any seed oil.
What is the best maintenance and storage method?
As we have demonstrated with experimental data, the ideal way to store the olive oil is in a refrigerator or even better in a freezer as we would do for any fruit juice. Soon we expect to have individual doses of frozen olive oil, which retains all its freshness.
Why is it common to use dark bottles for its storage?
Certain components of olive oil such as chlorophyll are sensitive to light. Thus, when exposed to light, they result in deterioration in the quality and faster rancidity. For this reason we place it into dark colored bottles.