What are the factors K232 and K270 in olive oil?
The chemical analysis of the olive oil, together with the organoleptic tasting, is carried out in order to obtain its classification in one of the existing commercial categories: extra virgin, virgin or lampante.
Just as a doctor can know through an analysis if we have followed a healthy lifestyle, through the chemical analysis of the oil we can determine its quality.
Factors such as the degree of acidity, its peroxide value and/or the K232 and K270 factors of olive oil, allow us to know the final quality of the oil and under which category it should be labelled.
What values indicate the quality of the oils in a chemical analysis?
In the chemical analysis of olive oil, 3 tests come into play:
- Degree of acidity. It measures the percentage of free fatty acids related to oleic acid and determines the quality of the fruit (olive) used. The degree of acidity is often confused with the flavor of the oil. However, they are not related, since acidity can only be determined in a laboratory and not through taste.
- Peroxide index (PI). It determines the degree of rancidity or initial oxidation of olive oil and the deterioration that natural antioxidants may have suffered. Measures the quality of the production of virgin olive oil.
- UV spectrometry. Here the K232 and K270 factors come into play, together with the Delta-K. It measures the absorbance of the oil at different wavelengths and determines the quality of an oil and its conservation status.
For an olive oil to be extra virgin, it must not exceed 0.8% acidity. Following the established values, an extra virgin olive oil will never be higher than 20 in the peroxide index, it does not exceed 2.50 for K232 or 0.22 for K270.
As we previously explained, the peroxide index measures the quality of oil production. When an extra virgin olive oil becomes rancid, it not only acquires bad odors and flavors, but its antioxidants are also destroyed, which are very beneficial for our health.
Oxidation is a natural process that occurs over time. However, it can be accelerated due to certain errors when making olive oil, such as the temperature of the production process or excessive milling time, as well as poor subsequent conservation.
Therefore, the lower the IP, the higher quality the olive oil examined will have.
The factors K232 and K270 are those that are measured in this test. These compounds are the result of the state of conservation of the oil, of modifications suffered by technological processes, of contaminations or adulterations.
In this test, ultraviolet light is transmitted through a mixture of oil and solvent, measuring its absorption capacity. Some compounds generated by oxidation are absorbed at wavelengths of 232 nanometers and others at 270. These are the parameters known as K232 and K270.
Therefore, a higher value of K232 or K270 implies greater oxidation of the oil, so its quality will be worse.
Are these values related?
The three previous tests (degree of acidity, peroxide index and UV spectrometry) are essential to determine the quality of an oil in a chemical analysis. However, the peroxide value and UV spectrometry are related. Although the three tests measure the degree of deterioration of an oil, the degree of acidity does not give rise to confusion.
However, it is important to know that oxidation occurs in two phases: primary and secondary. The values obtained in the peroxide index can mean two things, that we are dealing with a very fresh oil or a very rancid one, since the peroxide values of the oil oscillate depending on the moment of analysis.
Therefore, and to make sure that we are dealing with a virgin olive oil, it is necessary to carry out the UV spectrometry test. If we have a low IP and low K values, there is no doubt: olive oil is a quality virgin oil.