How to choose olive oil: what to look at on the label

5 min read

When I looked into "Is olive oil really good for you?", the research used extra virgin olive oil (EVOO).

So what should you look at when buying EVOO in a store? There are dozens of bottles labeled "extra virgin" on the shelf, priced from a few dollars to many times that.

Looking into it, the words "extra virgin" on the label don't tell you as much as you'd think. In this article, I narrow it down to five guidelines based on standards and storage research.

"Extra virgin" means different things in different countries

Under the International Olive Council (IOC) trade standard, extra virgin is defined by both chemical values and sensory evaluation by trained tasters. Free acidity must be 0.8% or less, and in tasting there must be no defects (degraded smells or tastes) and some fruitiness [1].

Meanwhile, under Japan's Agricultural Standard (JAS) for edible vegetable oils, olive oil is divided into "olive oil" and "refined olive oil," and there's no "extra virgin" category [2]. The quality criterion is the acid value (2.0 or less for olive oil), and sensory evaluation isn't included.

In other words, on shelves in Japan, "extra virgin" isn't a grade set by a national standard; it's the seller's label. Many products probably do meet the international standard, but you can't confirm that from the label alone. Rules in your own country may differ, but the same lesson applies: the label alone isn't proof.

Guideline 1: choose a container that blocks light

EVOO is sensitive to light. In an Italian study comparing EVOO stored in light and in the dark, oxidation progressed faster under light, and phenolic compounds (a kind of polyphenol) dropped sharply [3].

Another study compared containers. After 10 months of storage under light, multilayer paperboard cartons that block light curbed oxidation and preserved antioxidant compounds better than green glass or UV-filtering glass bottles [4].

In the store, choose tins, dark bottles, or boxed bottles. Avoid clear bottles that sat at the front of a brightly lit shelf.

Guideline 2: choose a recent harvest or production date

The polyphenols in EVOO decline little by little during storage [3]. So for the same product, newer is better.

But best-before dates are often set from the bottling date, which doesn't tell you when the olives were pressed. A harvest date or pressing date on the label is a clue to freshness.

Guideline 3: choose one that states the basis for its quality

Where there's no official "extra virgin" category, what you have to judge quality by is the information the product gives you.

• A statement that it meets the international (IOC) standard, or a stated acidity value
• The region, olive variety, and producer
• Official certification from the country of origin, or third-party testing

None of these guarantee quality, but they give you more to check than a product that says nothing.

Guideline 4: choose a size you'll finish

Once opened, it oxidizes a little more every time it meets air. Even if a big bottle is cheaper per liter, if it takes you a long time to finish it, you'll be using oil that has degraded.

If you use a little every day, start with about 250–500 mL, learn how fast you go through it, and then decide on a size.

Guideline 5: choose by how you'll use it, not price

As I laid out in "Is olive oil really good for you?", the use most in line with the research was replacing what you used to use, such as butter or mayonnaise, with olive oil. More isn't better.

For uses where you enjoy the aroma, like drizzling on salad or bread, an EVOO with a clear flavor suits well. You can also cook with it; what research shows about heating is summarized in the "Is it okay to heat it?" section of the original article.

Storing it at home

• Keep it in a cupboard out of the light. If it's a clear bottle, keep it in a box or bag [3][4]
• Close the cap right after using it
• Once opened, use it up reasonably soon

Summary

If you choose by these guidelines

Here's the one I actually use, plus two types that fit the guidelines above. Whichever you choose, check the container, harvest date, and stated standards on the product page.