About 80% of Store-Bought Avocado Oils Tested Were Oxidized or Impure | Selina Wang | 116

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Most store-bought “extra virgin” olive and avocado oils fail basic purity or freshness tests.

TOPICS DISCUSSED:

• Oxidation Chemistry: Triacylglycerols break down into tasteless peroxides then into aldehydes that produce rancid odors; concentration and matrix determine whether the same compounds smell pleasant or foul.
• Extra-virgin vs. Refined: Mechanical crushing and centrifugation yield EVOO with intact phenolics and pigments; refining removes defects, color, and antioxidants from low-grade fruit.
• Purity Testing: Fatty-acid and sterol profiles distinguish true olive or avocado oil from canola, soybean, or other adulterants.
• 2010 Olive-Oil survey: ~68% of imported samples failed USDA quality standards, largely from oxidation rather than outright substitution.
• Avocado-Oil Findings: ~80% of retail samples were oxidized or impure; some were 100% soybean oil labeled “extra-virgin avocado.”
• Packaging Effects: Clear plastic permits light and oxygen; dark glass, tin, or bag-in-box better preserves freshness once opened.
• Sensory Standards: Olive oil is one of few foods with mandatory trained-panel evaluation of defects such as fusty or rancid notes.

ABOUT THE GUEST: Selina Wang, PhD is a food scientist and chemist at the University of California, Davis. Her lab develops analytical methods for assessing quality, purity, and authenticity of edible oils and other California crops.

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