All virgin olive oils are obtained only from the olive, using solely physical means, in conditions which do not alter the oil in any way.
Extra Virgin Olive Oil
To be certified in California, extra virgin olive oils are required to have a free acidity of no more than 0.5 grams per 100 grams (0.5%) using solely mechanical means and it must not be mixed with any other oil. Liquid gold deserves to be free from adulteration and extracted without chemicals or high heat. Extra virgin olive oil accounts for less than 10% of oil in many producing countries. This is the highest quality of olive oil. Extra virgin olive oils will vary in taste, color, and appearance. Their taste and aroma will reflect the fact that they were made from olives and have some positive attributes - they cannot be totally tasteless and that taste is free from defects of flavor and aroma.
Virgin Olive Oil
Virgin olive oil has a free acidity of not more than 2 grams per 100 grams (2.0%) and is obtained only from the olive using solely mechanical means — no chemicals or high heat. There may be minor defects; their quality is lower than extra virgin olive oils.
Refined Olive Oil
Refined olive oil has a free acidity of no more than 0.3 grams per 100 grams (0.3%). This oil is obtained by refining virgin olive oils that have a high acidity level and / or defects which are eliminated after refining with the use of charcoal and other chemical and physical filters. Over 50% of the oil produced in the Mediterranean area is of such poor quality that it must be refined to produce an edible product.
Olive oil is the blend of refined olive oil and virgin olive oil fit for consumption as they are. It has a free acidity of not more than 1 gram per 100 grams (1.0%). The cheap refined oil is mixed with more flavorful virgin oil. Most of the olive oil sold in the world falls into this category. Different blends are made, with more or less virgin oil, to achieve different tastes at different prices.
“Light” or “Extra Light” oils sold in the United States fall in this category, and are most likely made with a large proportion of refined oil. ~ Olive Oil Times
Pomace is the ground flesh and pits left after pressing. Olive—pomace oil is the oil obtained by treating olive pomace with solvents or other physical treatments.It is considered an inferior grade used for industrial purposes.
Extra Virgin Olive Oil & Polyphenols
As we provide tastings, we also discuss polyphenol (antioxidant) levels. We like to share polyphenol information about some common varieties of olives, harvest times and milling techniques. This all adds to making informed choices when selecting a quality EVOO.
It was discovered that diets high in monounsaturated fatty acids (MUFA’s) and low in saturated fatty acids (SUFA’s) could favorably affect blood cholesterol levels and consequently decrease the risk of developing cardiovascular diseases such as coronary heart disease (CHD); even when providing the same amount of total fat. Further studies have revealed that other than its high MUFA content, unprocessed (extra-virgin) olive oil contains non-fat components such as certain phenolic compounds which have been found to have a wide range of beneficial health effects which include favorable effects on cholesterol (both 'good' and 'bad') levels and oxidation, as well as possessing an anti-inflammatory effect and potentially having healthy influences on our blood pressure and blood clotting. http://nutra-smart.net/olive.htm