A recent study conducted by the agricultural department at the University of Foggia in Puglia, Italy, discovered that antioxidant levels in olive oil decreased by 40 percent after six months of storage.
Interestingly, there was no decrease in those levels during the first three months of storage.
This information can be difficult to apply for the average consumer since most olive oil containers do not provide a production date.
If you are able to find a container of olive oil that specifies such a date, purchase whatever is most recent.
If you can’t, here are a few tips:
- To ensure faster replacement times, buy olive oil in small containers
- If you buy olive oil in very large containers from a reputable source (such as the producers listed in the California Olive Oil Council’s page, which are guaranteed to make olive oil exclusively from olives), transfer a small amount — meant for short-term use — into a dark-tinted glass bottle or stainless steel tin. Store the rest in the freezer. Olive oil that will not be used for long periods of time keeps much better in the freezer than the refrigerator
- Time is just one factor that reduces antioxidants. Light, heat, and air have the same effect. Store your olive oil in cool-temperature locations (NOT directly above your stovetop!), away from light, and be sure to tightly cap the container immediately after use (i.e.: do not leave a bottle of olive oil unopened for long periods of time)
While this is certainly an interesting statistic, please don’t think that olive oil with reduced antioxidants is worthless.
Yes, the retention of these compounds is wonderful, but aside from that, olive oil is a great source of heart-healthy monounsaturated fats.
PS: In the same way that eating grapes provides very similar health benefits to drinking red wine, the same goes with olives and olive oil.