Below is a link to a recent UC Davis study that found olive oils labeled extra virgin often fail international standards for extra virgin. Bariani was the only oil of the Californian oils studied that failed the IOC/USDA sensory (organoleptic – the human taste panel) standards for extra virgin. The study found that human tasters can still detect sub-par oil more effectively than chemical analysis. Currently the international standards only recommend three chemical tests. This study also includes 5 other chemical tests that are being developed by Australia and Germany to determine quality.
The study purcahsed 14 imported oils and 5 oils from California from supermarket shelves located in Los Angeles, Sacramento, and San Francisco. This is a very good technique because if you ask producers for samples some unscrupulous producers will send high quality samples that they do not sell to stores. A total of 69% of the imported samples failed the human taste panel. The IOC/USDA standard chemical tests only detected 31% of these. The German/Australia chemical tests detected 86% of these. Both the Rachel Ray and Paul Newman brands had two samples that failed the human taste panel.
Other common brands that failed the IOC/USDA sensory (organoleptic) test were Star, Bertolli, Filippo Berio, and Colavita.
So it is very encouraging to get official scientific results to confirm what we have known all along – oil not certified by a human taste panel is usually sub-standard. The whole report is worth reading.