We’ve already written about how it’s not easy to produce high-quality extra virgin olive oil. It’s necessary to pay attention to a range of elements, from growing healthy olives to processing and producing olive oil. In the House of Istrian Olive Oil, we emphasize and teach our visitors that extra virgin olive oil is the pure juice of the olive fruit, and to preserve it as such for as long as possible, it’s extremely important how we store and keep it.
According to international standards, extra virgin olive oil is oil without any defects. Mistakes in storing and preserving will irreversibly spoil the olive oil, causing it to develop various defects. Extra virgin olive oil is obtained through a mechanical process from the olive fruit, and after processing, it still contains some impurities such as water and small particles from the pulp. These impurities are dispersed in the oil and slowly settle naturally. Over time, processes of decomposition begin in these particles, causing spoilage and the development of unpleasant smell. To prevent this, the oil needs to be filtered.
There are two options for filtering olive oil, and both processes have their advantages and disadvantages. Filtration by decantation is a traditional method still used by many producers of extra virgin olive oil, especially those who produce smaller quantities of oil. The oil is first decanted one month after processing and then again two to three months later. If necessary, it can be decanted again in the spring.
The other filtering method is immediate filtration by passing the oil through cellulose filters made of cotton fibers, which removes water and pulp particles from the oil.
While fresh, unfiltered oils have slightly more aromas and higher phenolic content, such oils are less stable and more prone to spoilage. On the other hand, filtered oils are more stable and resistant to long-term storage.
Once olive oil is filtered, it is placed in containers made of inert materials, preferably stainless steel or dark glass. Stainless steel containers are most commonly used today due to ease of handling and cleaning.
After the containers are filled with oil, it’s important to fill the remaining empty space with inert nitrogen gas to prevent the oil from coming into contact with oxygen.
Plastic bottles are not suitable for storing oil because these materials are porous and release odors. Storing oil in terracotta or stone containers used to be a tradition throughout the Mediterranean, but this method is no longer in use. In such containers, the oil is always in contact with the air, they cannot be cleaned well, causing the oil to quickly develop a rancid odor.
The ideal temperature for storing and preserving oil is between 14-16 degrees Celsius. At higher temperatures, the oil will spoil more quickly, and at lower temperatures, it will begin to solidify and crystallize, making its structure porous. Air enters the pores, accelerating spoilage. This “freezing” process starts at around 10 degrees Celsius.
Maintaining the storage temperature is now achieved by installing air conditioning systems in the storage area, whereas in the past, containers were buried in the ground to maintain a moderate soil temperature year-round.
Olive oil will retain its quality for a long time, especially if liquid nitrogen, which displaces air from the bottle, is added during bottling. This prevents any changes in the oil due to contact with oxygen. According to legal rules, unopened oil has a shelf life of two years. Once opened and in use, it should be consumed within one to two months, and the bottle should be stored away from light at room temperature.
Olive oil, storing in the refrigerator. We often hear the question: Can olive oil be kept in the refrigerator? Absolutely not. Extra virgin olive oil begins to crystallize at temperatures below 10 degrees, which initiates and accelerates the spoilage process.
What if olive oil freezes or crystallizes? Can I thaw it and use it again? Yes. Olive oil won’t spoil so quickly that it can’t be used again. However, if it has been frozen, it is recommended to use it quickly.
Can I store olive oil in plastic containers? Plastic is not recommended for storing olive oil because it releases small particles and is not suitable for long-term storage of the oil. If a plastic container is used for short-term purposes, such as during transportation, it won’t harm the oil.
To preserve the health benefits and polyphenols in extra virgin olive oil, it is crucial to store it properly. Without proper storage, even the best-produced oil will develop defects, making it neither of high quality nor flavorful for consumption.