Types of olive oil are many and are classified by International olive oil council depending upon the process of extraction and blending and the aroma, taste, colour and flavour.
Extra virgin olive oil
These types are extracted from the fruits by physical methods and no chemical method is used.
They are the products of first pressing and about 90% of the olive oil is removed at this stage.To qualify to be called extra virgin, these varieties must not contain more than 0.8% acidity.Extra virgin types must also have good taste, flavour and aroma.
These varieties are used directly at the table to enhance the flavour of soups, salads and stews and also for dipping.
Premium extra virgin is the finest of the types and contains less than 0.2% acidity.
These types appear yellow to deep green in color and have extra superior flavour with fruity taste.
Virgin olive oil
These types are also produced by the mechanical methods and of the first pressing only.
However these varieties contains extra acidity up to 2%. The rise in acidity when compared to extra virgin varieties may be due to the stage of ripeness of the fruits, the time lapse between the harvest and extraction, the variety of cultivar and the geographic region of the product. It must also have good taste and flavour.
Finer types must contain not more than 1.5% of acidity and should have good flavour.
Refined olive oil
The products which do not qualify to be of higher grades like extra virgin, due to higher and extra acidity are processed further by filtration, heat and chemicals to lower the acidity to 0.3% and remove other defects.
Much of the taste and flavour may be lost. However it is to be noted that solvent extraction method is not involved. This is used in restaurants and in cooking.
Pure olive oil
These types are blends of virgin and refined products.
By addition of virgin olive oil (20%), taste and aroma are infused into the refined product without extra fatty acid percentage (less than 1.5%).
This is priced lesser and hence used in cooking and in restaurants.
Pomace olive oil
By further processing the paste, these lowest types are extracted by treatment with heat and solvents. Blending with virgin olive oil may be done.
But this product is denoted as pomace olive oil. Its acidity should not exceed 1.5%. It is used commercially for making various by-products.