How to Store Olive Oil to Preserve Its Polyphenols
When you invest in polyphenol-rich, cold pressed olive oil, you’re making an investment in both the flavor of your food and your health. However, it’s essential to understand how to store olive oil in order to take advantage of these health and flavor benefits. Unlike wine or other products that age over time, olive oils are delicate and, if not properly stored, can have short shelf lives. To ensure that you reap the benefits of a bottle of high-polyphenol olive oil from the first drizzle to the last drop, we’ve created this guide to proper olive oil storage.
What Are Polyphenols and Why Worry About Preserving Them?
Polyphenols are compounds that naturally occur in the olives that are used to make extra virgin olive oil. In olive oil, polyphenols provide flavor, prevent spoilage, and bestow a variety of health benefits, acting as both antioxidants and anti inflammatories. The olive oils that are richest in polyphenols, high-polyphenol olive oils, are those that contain at least 300-400 ppm when lab tested. Frantoio Grove’s 2024 EVOO, for example, tested at 428 ppm, qualifying it as an HP-EVOO.
Though olive oil can go rancid when stored improperly, the polyphenols in olive oil can slow this process by slowing oxidation. Typically, oxidation of food products occurs when food is consumed and digested. It’s a normal metabolic process, but when too much oxidation occurs, as can happen when you consume an unhealthy diet, your cells can experience oxidative stress and produce disease-inducing free-radicals. Many doctors recommend diets rich in high-polyphenol olive oil, a natural antioxidant, in order to counteract the negative effects of oxidative stress.
Oxidation can also occur in olive oil during storage. If not stored correctly, oxidation damages olive oil, nullifying the health benefits of its polyphenols before they even reach your body’s cells. Oxidized EVOOs can even fail to meet standards set by the California Olive Oil Council, disqualifying them from third-party EVOO certification.
Happily, just as the polyphenols in EVOO can prevent excess oxidation in the body’s cells, polyphenols can slow the oxidation during storage. Studies have indicated that olive oils rich in polyphenols like oleuropein are most resistant to oxidative damage during normal marketplace storage. In short, in order to reap the benefits of extra virgin olive oil, it’s equally important to identify and purchase a high-quality HP-EVOO and to know how to properly store it.
How Light, Oxygen Exposure, and Temperature Affect Olive Oil Storage
On the shelf in the grocery store, olive oils are exposed to bright fluorescent lights for hours at a time. In home kitchens, it’s not unusual for olive oils to be stored in direct sunlight, near the stove, in the refrigerator, or in other less-than-ideal conditions, all of which speed the oxidation process. In order to prevent olive oil from going rancid, experts recommend storing it in a dark, cool location and in a vessel that properly seals, preventing excess oxygen exposure.
How Light Damages Olive Oil:
In a 2004 study published in European Food Research and Technology, two batches of extra-virgin olive oil were stored for 12 months, one with exposure to light and the other in the dark. The results, shown in the charts on the right, indicated that after just 2 months of exposure to light, the first olive oil was so damaged that it could no longer qualify as EVOO
Another 2017 study found that the extent of light’s impact on olive oil depends on the olive oil’s composition. For this experiment, scientists placed 14 different EVOOS in 11 different types of bottles. These bottles were placed under 11 hours of light per day for 6 months. Though all the olive oils were damaged, the olive oils highest in the antioxidant oleuropein and its derivatives were found to be the most resistant to oxidation caused by light. Even so, light was found to cause oxidation in olive oils across the board.
How Oxygen Damages Olive Oil:
Since oxidation is the process by which olive oil goes rancid, it’s no surprise that direct exposure to oxygen decreases olive oil’s shelf life. Olive oil must be properly sealed during storage in order to prevent exposure to oxygen. Olive oil producers and distributors like Frantoio Grove must bear this in mind in order to minimize the oil’s exposure to oxygen during production and distribution. Sparging with nitrogen, a process that involves bubbling nitrogen gas through the olive oil, is a common technique used by olive oil producers and winemakers alike as it removes any dissolved oxygen from the liquid oil. It’s also important to store olive oil in a sealed container to minimize its contact with oxygen even after opening the bottle.
How Hot & Cold Temperatures Damage Olive Oil:
Like Goldilocks, olive oils prefer to be not too hot and not too cold. A three-year study of olive oil storage conducted by researchers in Australia found that at higher temperatures, olive oil becomes rancid more quickly, as a result of faster oxidation. Rancid olive oil contains more free-radicals, which rather than preventing disease, can actually cause it. Generally, olive oils should be stored at room temperature, between 57 and 68 degrees Fahrenheit.
In order to avoid overheating olive oil, it may be tempting to store it in the refrigerator. However, storing olive oil in the refrigerator isn’t considered best practice as the low temperature will cause the oil to solidify. Repeated heating and cooling of olive oil won’t help it taste any better or extend its shelf life.
Should You Store Olive Oil in A Glass or Plastic Bottle?
Experts tend to agree that the best storage option for olive oil is an opaque glass bottle. Opaque glass prevents light from reaching and damaging the olive oil during transportation and storage, thereby protecting the EVOO inside. Many olive oils available for purchase by consumers are sold in opaque plastic bottles. Are these oils equally protected from light damage?
While opaque plastic bottles may prevent light from reaching the olive oil, plastic isn’t the best choice for several reasons. Firstly, Frantoio Grove is a regenerative organic certified orchard. This certification speaks to our commitment to protecting the environment and mitigating the impact of climate change wherever possible. It’s well known that plastics are not a sustainable option and that glass is more recyclable than plastic, so for environmentally-conscious consumers, glass is the way to go.
Secondly, recent scientific research has also emphasized the dangers storing food in plastic due to PFAs, the forever chemicals found in plastics that easily make their way into our bodies through our food. Olive oils stored in plastic have also been found to contain phthalates which are detrimental to human health.
How to Extend the Shelf Life of Your Olive Oil
Once you’ve purchased a high-quality EVOO in an opaque glass bottle, how can you keep it fresh? Here are some of our favorite tips:
- Lifestyle experts like Martha Stuart recommend keeping olive oil in a closed container rather than in a cruet. Cruets are pretty on a table, but provide far too much exposure to oxygen.
- Store your olive oil in a dark cupboard, not in the fridge, near a window, or next to the stove.
- Purchasing olive oil in bulk can be a cost-effective decision, but be sure to make a plan for how best to store your olive oil. We offer a 3 liter pouch of Frantoio Grove EVOO that can be decanted into a glass bottle for serving.
- If you really want to use a plastic squeeze bottle, as some professional chefs do, experts recommend decanting small amounts of olive oil into squeeze bottles at a time. Store the rest of the olive oil in an opaque glass vessel or airtight pouch until you’re ready to use it.
How We Pack Our Oil to Preserve Its Polyphenols
At Frantoio Grove, our priority is making sure that the olive oil we sell is of the highest quality. Our high-polyphenol EVOO is award winning and third party certified, boasting notes of peppers, herbs, and grass. In order to make sure olive oil polyphenols make it from each olive on our farm to your table, we take the following precautions:
- Sparging our olive oils with nitrogen before bottling to remove any excess oxygen
- Storing our olive oil in stainless steel tanks during production
- Packaging our olive oils in resealable opaque glass bottles and in phthalate-free 3 liter pouches
Ready to store your high-polyphenol olive oil? Check out our range of olive oil products in our shop today!
