Extra virgin olive oil is one of the main elements in the Mediterranean diet, with many of the nutrients contained in foods that have beneficial effects on health, deviating from the content of antioxidants, vitamins and minerals. The chemical parameters that help assess the quality of extra virgin olive oil, such as biophenols, the number of peroxides and acidity, are also fundamental indicators for expressing the palate's pleasantness of the oil and its nutritional value. Biophenols, in extra virgin olive oil, are one of the fundamental parameters for determining the quality of the oil. An average quality extra virgin olive oil contains 450 mg / kg. Biophenols play a fundamental role in our diet; numerous studies attest to the active function of phenols as antioxidant substances (they protect cells from damage caused by free radicals), antitumor, antithrombin (inhibits the coagulation of bad cholesterol) and anti-inflammatory. Furthermore, the biophenols influence the organoleptic characteristics of the oils, determining the fruity aroma and the spicy or bitter taste characteristic of extra virgin olive oil. The peroxides are also determined by laboratory analyzes and indicate an oxidative alteration, synonymous with degradation and aging. According to the law, the limit relating to the number of peroxides in an extra virgin olive oil is 20, the important thing is to know that the value is judged good if it is below 12. By law the acidity limit for an extra virgin olive oil olive oil is 0.8%, but in a quality extra virgin olive oil the values are decidedly lower (0.1-0.3%). A low degree of acidity in extra virgin olive oil is a necessary condition to certify the high quality level.