Chemical and physical properties of olive oil vary depending on climate and soil conditions, type, ripening degree and methods used in olive oil production. The quality of olive oil starts with harvest and continues in many processes from squeezing to bottling. The basic condition of producing a quality olive oil is to harvest at the right time and in the right way. However, no matter how high quality olives need to be well processed. Therefore, the quality controls of olive oil must be carried out at every stage of production.

Quality control of olive oils mainly focuses on analyzes that determine quality and purity. The determinants of quality are free fatty acidity, determination of peroxide, moisture and volatile matter, heavy metals and sensory properties. The determinants of purity are refractive index, fatty acid composition, sterol composition, total sterol amount, triglyceride composition and stigmastadiene amount.

The purity criteria of olive oil include relative density, saponification number, iodine number, transyacid acids, highest difference between true and theoretical ECN42 and waxy substances.

Refined olive oil or olive oil or olive oil is mixed with extra virgin olive oil by abusive people. When refined olive oil is mixed with natural olive oil, specific absorption values, transyacid acids content and stigmastadiene amount of olive oil are affected in ultraviolet light.

Stigmastadiene content analysis is the best method to detect the addition of refined oil to extra virgin olive oil. The amount of stigmastadiene is less than 0,10 ppm in extra virgin olive oil and between 4-50 ppm in refined olive oil. The amount of stigmastadiene in refined pomace oil is around 100-150 ppm.

During refining, stigmastadiene hydrocarbon is formed. Since natural olive oil should never be present, the amount of stigmastadien indicates that vegetable oil is mixed into it. Therefore, for the extra virgin olive oil, the amount of stigmastadiene, acid, peroxide and sensory analysis should be done.

 

Analysis of the amount of stigmastadien in extra virgin olive oil is carried out in authorized laboratories and it is determined whether refined vegetable oils are present.