To classify it by taste, olive oil is judged by a panel of trained tasters in a blind taste test. This is also called its organoleptic quality. Label wording[edit]

h refers not to its chemical acidity in the sense of pH but as the percent (measured by weight) of free oleic acid. This is a measure of the hydrolysis of the oil's triglycerides: as the oil degrades, more fatty acids are freed from the glycerides, increasing the level of free acidity and thereby increasing hydrolytic rancidity. Another measure of the oil's chemical degradation is the peroxide value, which measures the degree to which the oil is oxidized (damaged by free radicals, leading to oxidative rancidity.
To classify it by taste, olive oil is judged by a panel of trained tasters in a blind taste test. This is also called its organoleptic quality.
Label wording[edit]
The different names for olive oil indicate the degree of processing the oil has undergone as well as the quality of the oil. Extra-virgin olive oil is the highest grade available, followed by virgin olive oil. The word "virgin" indicates that the olives have been pressed to extract the oil; no heat or chemicals have been used during the extraction process, and the oil is pure and unrefined. Virgin olive oils contain the highest levels of polyphenols, antioxidants that have been linked with better health.[31]
"Made from refined olive oils" means that the taste and composition are chemically controlled, usually to improve lower quality oils.[citation needed] In Australia, Pure, Light and Extra-Light are terms introduced by manufacturers for refined oils to avoid labeling them as such. Standards Australia's code of practice for olive oil now recognises these words as meaning refined oil. Contrary to a common consumer belief, they do not have less calories than Extra-virgin oil as implied by the names.[32]
Cold pressed or Cold extraction means "that the oil was not heated over a certain temperature (usually 80 °F (27 °C)) during processing, thus retaining more nutrients and undergoing less degradation."[33]
First cold pressed means "that the fruit of the olive was crushed exactly one time-i.e., the first press. The cold refers to the temperature range of the fruit at the time it is crushed."[34] In Calabria (Italy) the olives are collected in October. In regions like Tuscany or Liguria, the olives collected in November and ground often at night are too cold to be processed efficiently without heating. The paste is regularly heated above the environmental temperatures, which may be as low as 10-15 °C, to extract the oil efficiently with only physical means. Olives pressed in warm regions like Southern Italy or Northern Africa may be pressed at significantly higher temperatures although not heated. While it is important that the pressing temperatures be as low as possible (generally below 25 °C) there is no international reliable definition of "cold pressed".
Furthermore, there is no "second" press of virgin oil, so the term "first press" means only that the oil was produced in a press vs. other possible methods.
PDO and PGI refers to olive oils with "exceptional properties and quality derived from their place of origin as well as from the way of their production".[35]