Many U.S. consumers, including distributors and marketers, fail to realize how perishable olive oil is. Olives and olive oil begin degrading from the time of the olive harvest as heat, light, and oxygen speed up the enzymatic breakdown of the olives and the oil, creating rancidity. Thus the shelf life and quality of olive oil depends on various factors throughout the production and distribution chain. The olive variety, method of harvest, condition of harvested olive, time from harvesting to milling, type of milling/extraction system, and length and type of olive oil storage all affect both the olive oil’s quality and its shelf life.
Because olive oil is so perishable, its quality is further determined by the methods used in the bottling, handling, and distribution stages. For example, millers and bottlers may top off olive oil storage tanks as well as individual bottles with nitrogen to slow oxidization. Metal tins or tinted glass bottles also aid in shielding the oil from oxygen and light.
The shelf life and freshness of an olive oil are typically signaled to consumers through a “best before” date on the label, although this is not mandatory for U.S. olive oil labels. From a producer’s perspective, an ideal shelf-life designation adequately reflects the freshness of the oil when bottled, but also is long enough to cover the time the oil spends in transit and sitting on a retail shelf. Until recently, shelf life for olive oil was generally accepted as approximately two years.
However, some industry representatives now note that whether any extra virgin olive oil will remain fresh and continue to meet the extra virgin standard for two years depends on a number of factors, particularly the olive variety used, the quality of the oil at bottling, and storage and handling conditions throughout production and distribution. Some in the industry favor shorter time frames for “best before” dates to ensure that the consumer buys a quality product, or advocate including a harvest date on the label to give the consumer more information about freshness.d Some producers are conducting research on appropriate “best before” dates for specific oils, but most agree that more needs to be done.
Most in the industry agree on the need for a “best before” date, even though this is difficult to mandate and there is disagreement about how to calculate it. Bottlers tend to favor a requirement for a “best before” date based on the bottling date, because they do not produce the oil and may not be able to vouch for a harvest date. Some large bottlers would also like to see the rest of the distribution chain be more responsible in handling their olive oil products and take responsibility for olive oil that has degraded throughout the distribution chain and on retail shelves.