Extra Virgin Olive Oil (EVOO) is, in essence, the best current olive oil; however, there are good and bad oils among EVOOs if we accept the endless chemical parametres, organoleptic characteristics and, of course, its taste. It is important to understand the labels and what they mean in order to truly know what you are buying. Below is a short guide to this concept.
When we want to analyze the quality of an olive oil from its composition's point of view, we must have in mind 3 parametres: degree of acidity, peroxide index and K-232 and K-270.
Acidity is the result of the degradation of olive's cellular structure which shows the quality of oil. This is the main factor because the oil will be better or worse depending on its acidity. In order for an olive oil to be EVOO, it must have an acidity lower than 0,8, and never higher than 2 to be virgin oil. Those olive oils having an acidity higher than 2 are called lampante oils.
Peroxide index measures the state of the initial oxidation of an oil, it is expressed in milliequivalents of active oxygen per kilogram of fat. Peroxides appear if the olive is badly treated, if you do not protect oil from light and heat or if you do not keep it in suitable containers.
K-232 and K-270 are indicators of the presence of complex oxidation compounds, different from those of peroxides. They appear when no proper conditions are kept. Therefore, the bigger K-270 is, the lower the oxidant capacity of an oil will be.