Shocking number of avocado oils sold in US are rancid or adulterated
Food scientist calls for FDA to establish reasonable standards for avocado oil as her study reveals shockingly high levels of mislabelling and adulteration.
The majority of avocado oil sold in the US is either of low quality, mislabelled or adulterated with other oils, say researchers from the University of California (UC), Davis.
In what is said to be the country’s first extensive study of commercial avocado oil quality and purity, the UC Davis team report that as much as 82 percent of test samples were either stale before their use-by or mixed with other oils.
In three cases, bottles labelled as ‘pure’ or ‘extra virgin’ avocado oil contained almost 100 percent soybean oil, the researchers found.
“I was surprised some of the samples didn’t contain any avocado oil,” said Selina Wang, Cooperative Extension specialist in the Department of Food Science and Technology, who led the study. “Most people who buy avocado oil are interested in the health benefits, as well as the mild, fresh flavour, and are willing to pay more for the product.”
Wang suggested that “no standards” were responsible for such startling results. There is no regulation that can determine whether an avocado oil is of the quality and purity it claims to be, she said.
As avocado oil is relatively new, the Food and Drug Administration (FDA) is to yet to adopt ‘standards of identity’, ie, the basic food standards designed to protect consumers from misleading labels and adulterated goods, according to the researchers.
“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.”
Wang and Hilary Green, a PhD candidate in Wang’s lab, analysed serious chemical parameters of 22 domestic and imported avocado oil samples, which included all the brands they could find in 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,” Wang said.
Test samples included oils of various prices, some labelled ‘extra virgin’ or ‘refined’. Virgin oil is meant be extracted from fresh fruit using only mechanical means, while refined oil is processed with heat or chemicals to remove flaws.
Fifteen of the samples were oxidised before the expiration date. Oil loses its flavour and health benefits when it oxidises, which occurs over time and when exposed to too much light, heat or air. Six samples were mixed with large amounts of other oils, including sunflower, safflower and soybean oil.
The UC Davis team discovered that a mere two brands produced samples that were pure and nonoxidised. Those were Chosen Foods and Marianne’s Avocado Oil, both refined avocado oils made in Mexico. Among the virgin grades, CalPure produced in California was pure and fresher than the other samples in the same grade, according to the researchers.
In terms of products with no current enforceable standards, avocado oil is not alone, say the researchers, who point to honey, spices and ground coffee as key examples.
Wang is now working to develop faster, better and cheaper chemical methods to detect adulteration. She hopes this will provide bulk buyers with a reliable way to test avocado oil before selling it.
She is also evaluating more samples, performing shelf-life studies to see how time and storage affect quality, and encouraging FDA officials to establish reasonable standards for avocado oil.
Wang has a history of exposing lower-grade foodstuffs; 10 years ago she discovered that much of the extra virgin olive oil sold in the US was of much lower quality. Her research sparked a cascade of responses that led California to establish one of the world’s most stringent standards for different grades of olive oil. The FDA is now working with importers and domestic producers to develop standards of identity for olive oil.
“Consumers seeking the health benefits of avocado oil deserve to get what they think they are buying,” Wang contended. “Working together with the industry, we can establish standards and make sure customers are getting high-quality, authentic avocado oil and the companies are competing on a level playing field.”
What to look out for…
- Avocado oil flavours do differ depending on the variety and region, but in general, authentic, fresh virgin avocado oil tastes grassy and buttery. The researchers liken it to mushrooms.
- Virgin avocado oil should be green. Refined avocado should be light yellow and almost clear.
- 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.
- Oil will begin to smell stale once rancid.
- For the freshest oil, buy one that is the closest to the harvest/production time.
- The best-before date is not always a reliable indicator of quality and is different to a use-by date.