Olive oil harvest date vs best by date

You olive oil may list a harvest date in addition to a best by date.  What's the difference and how should you use these pieces of information?

You've heard it before.  Olive oils and wines are similar in how they can be appreciated for their diverse flavors, geographic origins and varieties, and how they are paired with foods.  But there is one critical difference.  Wines can last for many years and generally are considered to get better with age.  That is not the case with olive oils.  An extra virgin olive oil's flavors will mellow with time. If you are a fan of full-flavored oils, for you, an olive oil was always better yesterday.  

So what do you need to know when choosing an oil?  Consider information that may be on the bottle concerning harvest date and best by date.  

• Harvest date is when the olives were picked from the trees.  
• The olive oil best by date (or best-before, or best-if-used-by, etc.) is a calculation by the producer/bottler of the olive oil as to how long the olive oil will last under good storage conditions measured from the date of bottling. 

A harvest date on a label can be an important piece of information for olive oil companies and consumers. However, the absence of a harvest date does not indicate a lack of quality.  A company may decide not to include a harvest date on the label for a number of legitimate reasons. 

For example, if a product produced in October is still on the shelf in November a year later, a consumer may think the oil is too old and choose something else—even though the oil may have as much as another year of good quality shelf life left. (Indeed, a retailer might be reluctant to purchase new product from that company if oil from the prior harvest is still on the shelf.)

Another reason can be that the producer has packed oils from different harvest dates which can mean different months and/or even years, given that harvest can continue over a few months in a given locale, and occurs at different seasons in different hemispheres. On such olive oils—which are obviously not “estate produced” and include the more economical everyday extra virgin olive oils you find in the supermarket—the inclusion of multiple harvest dates might be complicated and confusing.

Thus while harvest date can be relevant, the “best by date” is always the critical information consumers need to know when buying an olive oil. Here, to protect consumers, producers need to make their best efforts to estimate the shelf life of the oil at the time that it is bottled. This means taking into account variables such as harvest date(s), storage conditions prior to bottling, the physico-chemical properties of the oil, the opacity of the package, and anticipated shipping/storage prior to consumer purchase.

Unfortunately, although methods for estimating shelf life are getting better, they are not perfect. As a general rule, and as provided by the International Olive Council standards, and required by the NAOOA labeling guide, the “best before date (BBD)” should not be more than 2 years from the date of bottling. In many cases, however, the BBD should be less than that.  

Whatever the harvest date, or best before date, it is also important to realize that once you open the bottle of oil, all bets are off, and you should try to consume the bottle within 2-3 months.