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Most avocado oil sold in U.S. is either rancid or contains other oils, study finds

The tests on 22 oils revealed that more than 80 percent of the products had significant quality problems. Fifteen were oxidized — or had gone rancid — before their expiration date.

avocado oil
Some of the samples tested in the study contained almost no avocado oil.
Photo by Mariana Medvedeva on Unsplash

Most avocado oil sold in the United States — including that labeled “pure” or “extra virgin” — is either stale before its expiration date or mixed with other oils, according to a study published recently in the journal Food Control.

In fact, some of the samples tested in the study contained almost no avocado oil.

“Most people who buy avocado oil are interested in the health benefits, as well as the mild, fresh flavor, and are willing to pay more for the product,” says Selina Wang, one of the study’s authors and a food scientist at the University of California, Davis, in a released statement. “But because there are no standards to determine if an avocado oil is of the quality and purity advertised, no one is regulating false or misleading labels.”

“These findings highlight the urgent need for standards to protect consumers and establish a level playing field to support the continuing growth of the avocado oil industry,” she adds.

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The Food and Drug Administration (FDA) has not yet established “standards of identity” for avocado oil because the product is a relatively new one, according to information released by UC-Davis. But avocado oil is not the only product without enforceable standards.

“Honey, spices and ground coffee are other common examples,” the UC-Davis statement notes. “Foods that fetch a higher price are especially ripe for manipulating, especially when adulterations can be too subtle to detect outside a lab.”

A broad sample of products

For the study, Wang and her co-author, doctoral student Hilary Green, tested 22 commercially available samples of domestic and imported avocado oils — all the brands they could find in their local stores and online.

“In addition to testing commercial brands, we also bought avocados and extracted our own oil in the lab, so we would know, chemically, what pure avocado oil looks like,” says Wang.

The samples that were tested had a wide range of prices. Some were labeled “extra virgin” oil, which means the oil was extracted from fresh avocados using only a mechanical process, according to Wang and Green. Others were labeled “refined,” which indicates the oil used heat or chemical solvents during processing.

Five of the products originated in California, while 12 were manufactured in Mexico and one in Brazil. The other four had unclear origins — either Spain, Mexico or the United States.

Key findings

The tests revealed that more than 80 percent of the products had significant quality problems. Fifteen were oxidized — or had gone rancid — before their expiration date. That included five oils labeled as “extra virgin” and six labeled as “refined.”

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“This likely resulted from improper or prolonged storage, using damaged or rotten [avocado] fruits, or extreme and harsh processing conditions,” Wang and Green write.

In addition, six of the samples, including two “extra virgin” ones, were found to be adulterated with other oils, including sunflower, safflower and soybean oil. Indeed, three of the samples contained almost 100 percent soybean oil.

Only two of the products were both non-oxidized and contained pure avocado oil. Both came from Mexico.

‘An urgent need for standards’

A decade ago, Wang was part of a research team that found much of the extra virgin olive oil sold in the United States was actually oxidized or made with cheaper, poorer quality oils. That led California to establish stricter labeling standards for the different grades of olive oils that it produces.

But as the National Consumers League noted in 2015, California supplies “only about 2 percent of America’s total olive oil needs.” If American consumers are going to get “what they pay for when it comes to olive oil,” then the Food and Drug Administration must establish federal standards similar to those enacted by California.

There is “an urgent need” for such standards in the avocado oil industry, too, says Wang.

“Oils that are of poor quality or blended with cheaper edible oil can be traded and sold at lower prices than high quality or authentic products leaving bulk buyers, food service professionals and consumers unprotected,” she and Green write in their paper.

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Tips for consumers

While we wait for the FDA to act, here are Wang’s recommendations for consumers when buying avocado oil:

  • The flavor of virgin avocado oil can differ by varieties and region. In general, authentic, fresh, virgin avocado oil tastes grassy, buttery and a little bit like mushrooms.
  • Virgin avocado oil should be green in color, whereas refined avocado oil is light yellow and almost clear due to pigments removed during refining.
  • Even good oil becomes rancid with time. It’s important to purchase a reasonable size that can be finished before the oil oxidizes. Store the oil away from light and heat. A cool, dark cabinet is a good choice, rather than next to the stove.
  • How do you know if the oil is rancid? It starts to smell stale, sort of like play dough.
  • When possible, choose an oil that’s closest to the harvest/production time to ensure maximum freshness. The “best before date” is not always a reliable indicator of quality.

FMI:  You’ll find an abstract of the study on Food Control’s website, but the full study is behind a paywall. This study was funded in part with a grant from Dipasa USA, a Mexico-based processor and supplier of avocado oil.