To make a good quality extra virgin olive oil, care must be applied starting with the growing process all the way through storage and bottling.

Every aspect of olive production ultimately affects the oil itself: the growing region (climate, altitude, soil character), methods of growing, harvesting and transporting the fruit, as well as extraction and storage methods. The care that is taken in each of these steps not only affects the taste and quality of the olive oil but its cost, yield, and shelf life.

The quality and taste of extra virgin olive oil is affected by many factors, including:

Olive Variety: Different olive varieties produce oils of varying intensity, from very mild to very bitter and pungent, with infinite variations in flavor and aroma, yield, antioxidant content, shelf life, and color.

Olive Maturity: is critical in determining the taste and quality of olive oil. Riper fruit yields more oil than green fruit. Its oil contains fewer antioxidants, and its taste will be milder. Oil made from green fruit has a longer shelf life.

Harvesting Time: The harvest time of an olive can be more important than its variety. For instance, green (early harvest) Nablus olives and green Jerusalem olives may yield similar oils, whereas early harvest Nablus olives and late harvest Jerusalem olives may yield oils quite different from each other.

Method of Harvesting: Hand picked, good quality olives that are brought immediately to the mill to be crushed produce higher quality oil than mechanically harvested, damaged fruit or fruit that is left sitting around before milling.

Method of Extraction: It is possible to increase the yield from any type of olives by heating, by adding water, and by other measures (e.g. the use of chemicals) during the milling process, but this results in reduced oil quality.

Method of Storage: Exposure to oxygen, light (inc. halogen and store lights), and heat is detrimental to the quality of the oil. Hence, stainless steel containers and dark glass bottles are preferable to other storing methods. The oil should be kept away from the heat.

Top factors in producing quality olive oil

1. Caring of olive fruits

The delicate nature of a ripe fruit requires that it be protected from pressure, temperature, and abrasion.                      Breakdown of the fruit begins the fermentation process and the development of defective oils.

2. Control Diseases and Pests

Any pest that directly attacks the fruit must be controlled to prevent fruit decay.

3. Harvest and Transport Fruit With Care and Separate Ground Fruit

Do not compromise the integrity of the fruit. Limit the depth of containers to reduce pressure on the fruit. Ground fruit is second-class fruit and should be separated from tree fruit.

4. Classify, Separate, and Process Different Classes of Fruit Separately

It is well known that different fruit qualities will produce different qualities of oil. As stated above, olive fruit should be separated by ground and tree fruit as well as by variety, fruit condition, ripeness, or other sanitary condition. Give priority to the best fruit.

5. Do Not Store the Fruit

Prolonged storage or slow working of the fruit is contrary to the production of quality oil. Oxidation and fermentation occurs in the stored fruit, which can lead to defects and off flavors in the oil.

6. Process the Olives Quickly and at a Moderate Temperature

Quality oil comes from fruit that is processed at temperatures below 30 °C. This is important for protection of the aromas and for the reduction of oxidation.

7. Store the Oil with Care

Good storage is extremely important and will permit the proper aging and conservation of desirable flavor components. It is fundamental to store oil in clean stainless steel at temperatures below 65°F. Dark glass bottles are preferable to clear bottles.

8. Keep Everything Clean

The failure to maintain cleanliness is a major factor in reducing oil quality since olive oil can so easily become contaminated. Odors from the fermentation of waste products can get into oils in the processing plant. Clean machinery, floors, and walls will prevent rancid odors that can also contaminate the oil. Cleanliness is especially important in the olive washing machines where the wash water needs to be kept clean at all times.