The indication Extra Virgin Olive Oil is very important but not enough !
The data from the chemical analysis of the olive oil is the most important thing in order to assess the quality level. Below, we present the basic factors. If you do a research in the market is very rare to notice the following data written on the bottles. Especially, the companies who sell blended or low quality olive oils avoid and never show this data.
For the following values the less the better !
Acidity : It determines the free fatty acids content (mainly of oleic acid) in olive oil. The smaller is the content in acids the better is the olive oil’s quality. According to the applying regulations, the best olive oil quality, to wit extra virgin olive oil shall have acid content between 0.1% and 0.8%. Olive oils with increased acidity are mainly produced by over-ripe fruit or fruit attacked by diseases or by fruit that after its harvest remained in the sacks for several days and without ventilation before its extraction.
Peroxides : The number of peroxides is determined to be the oxidization degree of olive oil in primary stage. Peroxides are chemical compounds mainly created from oxygen’s reaction with olive oil. For excellent well-preserved and fresh olive oil, the number of peroxides should not exceed 10 in primary stage, with maximum admissible limit 20 for extra virgin olive oil. The number of peroxides increases when olive oil is in contact with the air (oxygen).
Κ232 : It expresses the intermediate oxidization percentage of olive oil’s components, when it is examined at 232 mm wavelength. The smaller the index value is the better the quality of the olive oil is. According to the applying regulations, the characterized extra virgin olive oil should have K232 values less or equal to 2.5.
Κ270 : It expresses the percentage of decrease of olive oil’s resistance to oxidization, when it is examined at 270 mm wavelength. The smaller the index value is the better and fresher the olive oil is. High index values refer to old olive oils or mixed with old olive oils. According to the applying regulations, the characterized extra virgin olive oil should have K270 values less or equal to 0.22.
ΔΚ Index : It constitutes an elementary criterion regarding the determination of the olive oil’s quality and cleanness. It results from mathematical relation of K266, K274 and K270 values and it indicates any mixture with other olive oil that is not virgin. For extra virgin olive oil, the index value should be negative (maximum 0.01).