Using cis-vaccenic acid to differentiate avocado oil from seed oils

Abstract: Recent research has shown that oils commonly used to economically adulterate avocado oil are seed oils such as high oleic sunflower oil, high oleic safflower oil, soybean oils, and canola oil. As industry voluntary standards continue to be developed and adopted for avocado oil, it is necessary to ensure that methods can detect seed oil adulterations. Currently, depending on the blend percentages, it can be difficult to detect the presence of seed oils in avocado oil, particularly for high oleic sunflower and high oleic safflower oil. Cis-vaccenic acid, C18:1 (n-7), is an oleic fatty acid isomer that has traditionally only been used to report the total C18:1 concentration, which is calculated as the sum of C18:1 (n-7) and C18:1 (n-9). This study focused on quantifying the amount of C18:1 (n-7) in avocado oil and other potential adulterant oils. The concentrations of cis-vaccenic acid in avocado oil range from 5.5 % to 7.5 %, significantly higher than the concentrations in other seed oils and thus making this compound a good marker to detect economic adulteration. This work demonstrates that quantifying cis-vaccenic acid separately from the total C18:1 content allows detection of adulterations of 25% for high oleic safflower oil or sunflower oils, whereas the current fatty acid profile standards are unable to detect concentrations as high as 50% for high oleic sunflower and 75% for high oleic safflower oil.