Using 3-monochloropropanediol esters and glycidyl esters to discriminate adulteration of cold-pressed avocado oils and their refined variants

The adulteration of cold-pressed avocado oil (AVO), a high-value commodity, poses significant economic and health concerns. This study aimed to develop a method for identifying adulteration of cold-pressed AVO with refined oil and its utilization to evaluate commercial AVO (cAVO) samples. Avocados from the United States and New Zealand at different stages of maturity were subjected to oven-drying and microwave-drying to produce authentic in-house AVOs. Various parameters, including glycidyl ester (GE) and 3-monochloropropanediol ester (3-MCPDE) contents, fatty acid composition, phytosterol content, acid value, and pigment contents, were measured. In-house AVOs exhibited trace amounts of 3-MCPDE formation, and a threshold of 0.25 mg kg^–1 for GEs and 3-MCPDEs was established to differentiate samples adulterated with refined oil. However, no clear correlation between 3-MCPDE concentrations and adulteration ratios was observed. Determination of chlorophyll and carotenoid contents enabled the identification of partial or complete adulteration. The acid value and phytosterol content did not provide sufficient distinctions for detecting adulteration. GE and 3-MCPDE contents could effectively be used to discriminate cold-pressed AVO blended with refined oil, providing a reliable method for detecting misrepresentation of cAVO products.

Practical Applications: Measuring GEs and 3-MCPDEs is crucial for identifying refined oil adulteration of cold-pressed oils. The systematic discrimination methods and criteria developed in this study can be applied to different types of high-value pressed oils in the future. Addressing this issue is essential for maintaining the authenticity and quality of cold-pressed oils in the industry.