EVOO

Extra virgin olive oil refers to the most stringently-graded among virgin olive oils. In the international organoleptic evaluation method (IOC method, Rev. 11 as of 2024 revision), fruity, bitter, and pungent (a pricking sensation) are positioned as three positive attributes of the oil; bitterness is described as a primary taste perceived at the circumvallate papillae, characteristic of oils pressed from green or greenish olives. Pungency is characteristic of oils produced early in the harvest year and is recorded as a pricking tactile sensation felt especially in the throat.

However, bitterness and pungency are optional labelling terms (robust if the trained-panel median exceeds 6.0, medium if above 3.0 and at most 6.0, delicate if 3.0 or below) and are not mandatory requirements for the extra virgin grade itself. The IOC method grades oils by defect median = 0.0 and fruity-attribute median > 0.0, which aligns with EU sales standards (defect median Md = 0.0, fruitiness median Mf > 0.0). Mild oils with bitterness and pungency medians of 2.0 or less can equally be certified as extra virgin.

In a study analysing 100 extra virgin olive oils from 8 countries, 19 phenolic compounds were quantified; total phenol content ranged approximately from 52 to 315 mg GAE/kg, with oleocanthal and oleacein the most abundant at mean 77.9 mg/kg and 41.8 mg/kg respectively. In the same study, bitterness intensity showed the strongest correlation with total phenol content (r = 0.72) and also correlated with 3,4-DHPEA-EA (oleuropein aglycone, a secoiridoid) (r = 0.57); however, the paper attributes the coefficient to 3,4-DHPEA-EA in the abstract while the discussion section refers to it as 「オレウロペイン」 (in translation: "oleuropein"), leaving ambiguity—whether the correlation was to glycoside or aglycone remains unresolved within the paper itself.

Which phenolic compound is the primary driver of bitterness remains disputed across studies. A study examining 20 extra virgin oils of varying bitterness intensity reported that both oleuropein aglycone and ligstroside aglycone (in both dialdehyde and aldehyde forms) jointly contribute to bitterness, while a separate study found results strongly supporting dependence on oleuropein aglycone (3,4-DHPEA-EA). Attempts have been made to predict bitterness from chemical indicators alone; one study found that bitterness intensity could be adequately predicted from the spectrophotometric absorbance at 225 nm (K225) and total phenol content, but the functional forms of reported models differ across studies, and no single calibration equation has yet been established.