UC Davis Study: 82% of Avocado Oils Tested Were Rancid or Mixed With Other Oils

This article summarizes research first published on ucdavis.edu. Read the original post from UC Davis here.

What UC Davis found

Avocado oil has earned its place in the pantry for good reason: it is rich in the vitamins, minerals and heart-healthy fats people are looking for, and it has a clean, mild flavor that works for everything from searing to salad dressing. As demand has grown, though, so has the opportunity for shortcuts. In June 2020, food scientists at the University of California, Davis published the country’s first in-depth look at the quality and purity of avocado oil on store shelves, and the results were sobering.

Led by Selina Wang of the UC Davis Department of Food Science and Technology, with Ph.D. candidate Hilary Green, the team analyzed 22 domestic and imported avocado oils — every brand they could find locally and online, across price points, in both extra virgin and refined grades. To know what genuine avocado oil looks like chemically, they also pressed their own oil from fresh avocados in the lab as a benchmark.

At least 82 percent of the samples failed. Fifteen had already oxidized — gone rancid — before their printed expiration date. Six were cut with significant amounts of other oils such as sunflower, safflower or soybean. In three cases, bottles labeled “pure” or “extra virgin” avocado oil turned out to be almost entirely soybean oil.

Only two brands passed on both counts

Of all the oils tested, just two brands produced samples that were both pure and fresh: Chosen Foods and Marianne’s, both refined avocado oils made in Mexico. Among the virgin oils, CalPure from California tested pure and fresher than the other virgin samples.

We share this not to take a victory lap, but because it is exactly what our testing program is built to guarantee. Every lot of oil we source arrives with a Certificate of Analysis, is verified again in our own laboratory, is re-tested after refining, and is periodically checked by independent third-party labs. The UC Davis study was an outside, unannounced check on that system — and the oil held up.

Why this keeps happening

The study points to a structural gap rather than a few bad actors. Because avocado oil is relatively new to the market, the U.S. Food and Drug Administration has not yet adopted a “standard of identity” for it — the kind of baseline definition that already exists for hundreds of foods, from chocolate to mayonnaise. Without one, there is no enforceable rule for what can be labeled avocado oil, what “extra virgin” must mean, or how fresh a bottle has to be. Honey, spices and ground coffee face the same problem: premium products with no standard are the easiest to adulterate, and the adulteration is often invisible without a lab.

Wang’s earlier work on olive oil followed the same arc. Her finding that most “extra virgin” olive oil sold in the U.S. did not meet the grade helped push California to adopt some of the strictest olive oil standards in the world. Her lab is now developing faster, cheaper tests for avocado oil adulteration, running shelf-life studies, and encouraging the FDA to set reasonable standards for the category — an effort we support.

How to shop smarter for avocado oil

Drawing on the researchers’ guidance, a few practical checks:

• Know the color. Virgin avocado oil should be green; refined avocado oil is light yellow and nearly clear because the pigments are removed during refining.
• Trust your nose. Fresh virgin oil tastes grassy and buttery with a hint of mushroom. Rancid oil smells stale — many people compare it to play dough.
• Buy what you will use. Even good oil oxidizes with time. Choose a bottle size you can finish, and store it away from light and heat — a cool, dark cabinet rather than the shelf beside the stove.
• Look past the best-by date. The researchers found it is not always a reliable indicator of quality. Where possible, choose oil closest to its harvest or production date.
• Ask how it is verified. A brand that tests every lot — and can tell you how — is giving you more than a label.

Our commitment

Chosen Foods started with a single bottle of avocado oil and a simple promise: 100% pure, every time. The UC Davis findings are a reminder of why that promise requires constant verification rather than good intentions. You can read about each step of our testing standard — from inbound Certificates of Analysis to independent third-party labs — on our Purity page.

Source: Nelson, D. “Study Finds 82 Percent of Avocado Oil Rancid or Mixed With Other Oils.” UC Davis, June 15, 2020. First published on ucdavis.edu. The underlying research by Green and Wang was published in the journal Food Control.