A recent study from UC Davis Olive Center and the Australian Oils Research Laboratory has people questioning the purity claims made on the olive oil they purchase. The study found that nearly two-thirds of extra-virgin olive oils found in California grocery stores weren't what they were claiming to be – and most of them were pricey import brands.
Our very own Roger Legg, Senior Nutrition Chemist at RL Food Testing Laboratories, explains, “There are two common criteria for classifying different grades or purity of olive oil: fatty acid percentage, u.v. absorbance at two wavelengths 232 and 270 nm and a calculated delta K value. Based on these results from laboratory testing a company can make a claim about the purity.”