You’re Probably Using Bad Olive Oil

Amy Myrdal Miller, MS, RDN, FAND
Founder & President
Farmer’s Daughter Consulting, LLC

The last time I was home in North Dakota I opened a bottle of extra virgin olive oil in my mom’s cabinet, smelled it, and determined it was awful? How? It smelled terrible. It was rancid; it put off more bad odors than road kill on a hot summer day.

The next day I went to a local grocery store, bought a bottle of Italian extra virgin olive oil, brought it back to the farm, opened it, and knew immediately it too was bad oil. It was fusty, a sensory defect created when olives are allowed to sit in large piles and partially ferment before the oil is made. The vast majority of olive oil made in Europe tends to have this defect due to how they handle olives.

A few days after that I was a bigger town in North Dakota with a grocery store that had a much larger selection of extra virgin olive oils, and I was thrilled to see California extra virgin olive oil on the shelves. I picked up a bottle from a producer I’m familiar with, looked at the harvest date, and bought it, confident I’d have a better flavor and sensory experience with a California extra virgin olive oil. I was right. When I got back to the farm I opened the bottle and noted some grassy aromas, like fresh, green olives. The flavor was fruity and very appealing. This was an oil I wanted to cook with and consume!

So what makes a great extra virgin olive oil and what makes California extra virgin olive oil so great?

Stringent Quality Standards

If an extra virgin olive oil is made in California, it is must meet the California Grade and Standards for Extra Virgin Olive Oil, which took effect September 26, 2014. To qualify for the extra virgin classification, the oil must contain less than 0.5% free acidity (expressed as free oleic acid) and be free of sensory defects.

The international standard for extra virgin olive oil is 0.8% free acidity, so the California standard is more stringent; in fact, major producers in California strive for 0.1% free acidity, which is obtained when the oil is produced within 3-4 hours from harvest and the oil is stored in cold conditions under nitrogen. Nitrogen gas is flushed into large storage tanks as well as bottles and other packaging systems to displace oxygen that would lead to rancidity. Rancidity occurs when oxygen molecules bind to the free fatty acids, which creates the off flavors and aromas associated with rancid oils. The higher the free acidity level, the sooner an oil will become rancid.

High Density Orchards

If the olive oil comes from one of the top two California producers, California Olive Ranch or Corto Olive Co., then the olives come from high density orchards that are mechanically harvested. In Europe olive trees are typically planted 50-75 trees per acre. In high density orchards in California, 750-825 trees are planted per acre (750 with trellising, 825 without trellising).

In Europe, the olives are harvested by hand, using long rakes to shake the olives from the trees onto the ground. In California high density orchards, mechanical harvesters modeled after grape harvesters are used to harvest the olives. Flexible metal “fingers” gently brush the olives off the branches. And instead of having the olives fall to the ground, the olives fall into bins that are quickly transported to olive mills.

Fresh, Fruity Green Olives

A third reason California extra virgin olive oil quality is so high is that the vast majority of olives are green when harvested versus being purple or black. OIives are fruit, and when it comes to getting fruity, appealing flavors and aromas in the oil, you have to start with fresh fruit. Olives that are green will produce grassy, fruity aromas and flavors. Olives that are ripe (purple) or over-ripe (black) will never create fresh, fruity oil.

Olives Ready for Milling

Olive farmer showing off fresh, green olives that were harvested within the past two hours.

Olives Arriving at the MillFresh, green olives being delivered to an olive mill.

International and USDA Extra Virgin Olive Oil Standards Are Ignored

The UC Davis Olive Center published a report in 2010 showing that most imported “extra virgin” olive oils fail international and USDA standards. The researchers found that 69%of imported olive oil samples and 10% of California olive oil samples labeled as extra virgin olive oil failed to meet the International Olive Council/USDA sensory (organoleptic) standards for extra virgin olive oil. If this study were done again today, it’s likely no California extra virgin olive oils would fail due to the new California standards enacted in September 2014.

Why are the international and USDA standards ignored? No one is enforcing them, yet sadly nearly all (97%) olive oil consumed in the U.S. is imported.

Strategies for Finding High Quality Extra Virgin Olive Oil

If you want to experience and enjoy extra virgin olive oil, you’ll first have to accept the fact that you’ll have to pay more for it than what you’ve been paying for the rancid imports. It’s not easy to produce high quality extra virgin olive oil. Expect to pay about $10-15 for a 750ml bottle of high quality extra virgin olive oil.

Second, look for a harvest date on the back of the bottle. If today’s date is within a year or so from the harvest date, buy that bottle. High quality extra virgin olive oil will maintain its quality for about two years from the harvest date, especially if the bottle is made of glass and the glass is dark brown or dark green. Exposure to light affects olive oil quality as much as exposure to air/oxygen and temperature fluctuations.

Storing Extra Virgin Olive Oil at Home

If you paid more for good quality extra virgin olive oil, be sure to take good care of it once you bring it home. Don’t store it on the shelf above your stove where temperature fluctuations will affect the quality. Before opening a bottle, store it in your refrigerator. After opening, store the bottle in a cool, dark place like a pantry.

Some California and Australia producers offer bag-in-box extra virgin olive oil with spouts. These bags have been flushed with nitrogen. The spouts only allow oil to leave the bag; they don’t allow oxygen to enter the bag, which makes them wonderful storage containers. The only challenge is size; most are three liter bags. You’d need to make sure you could use that oil within a year or so of purchase, or else the investment isn’t worth it. Even the best oils go rancid over time.

I hope your kitchen will now only include good quality extra virgin olive oil. In my next blog I’ll address nutrition and health benefits of extra virgin olive oil. There are many, and the topic deserves its own blog. Happy cooking!