US study: 82% of avocado oil either rancid or adulterated

Avocado oil is a great source of vitamins, minerals and the type of fats associated with reducing the risk of heart disease, stroke and diabetes. New research from food science experts at the University of California, Davis has revealed that the vast majority of avocado oil sold in the US is of poor quality, mislabelled or adulterated with other oils. Findings from the study were published in the journal Food Control.

In the study, UC Davis researchers reported that at least 82% of test samples were either stale before expiration date or mixed with other oils. In three cases, bottles labelled as ‘pure’ or ‘extra virgin’ avocado oil contained near 100% soybean oil, an oil commonly used in processed foods that is less expensive to produce.

“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. 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,” said Selina Wang, Cooperative Extension specialist in the Department of Food Science and Technology, who led the study.

Wang and Hilary Green, a PhD candidate in Wang’s lab, analysed various chemical parameters of 22 domestic and imported avocado oil samples, which included all the brands they could find in local stores and online. Wang and Green received a $25,000 grant from Dipasa USA, part of the Dipasa Group, a sesame-seed and avocado-oil processor and supplier based in Mexico.

“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 supposed to be extracted from fresh fruit using only mechanical means, and refined oil is processed with heat or chemicals to remove any flaws. Of the samples, 15 were oxidised before the expiration date. Oil loses its flavour and health benefits when it oxidises, which happens 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.

Wang is working to develop faster, better and cheaper chemical methods to detect adulteration so bulk buyers can test avocado oil before selling it. Wang 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.

The full report is available: https://doi.org/10.1016/j.foodcont.2020.107328.

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