Unlike many wines, which improve with age, extra virgin olive oil is perishable: like all natural fruit juices, its flavor and aroma begin to deteriorate within a few months of milling, a decline that accelerate when the oil is bottled, and really speeds up when the bottle is opened. To get the freshest oil, and cut out middle-men who often muddy olive oil transparency and quality, buy as close to the mill as possible. If you’re lucky enough to live near a mill — common around the Mediterranean, and more and more so in other areas of the world with a Mediterranean-like climate, like Australia, S. Africa, California, Texas, Georgia — visit it during the harvest to see how olives are picked, crushed, stirred, and spun into olive oil.
Mueller is also author of Extra Virginity: The Sublime and Scandalous World of Olive Oil, which was published a few years after his olive oil exposé in the New Yorker.
In 1997 and 1998, olive oil was the most adulterated agricultural product in the European Union, prompting the E.U.’s anti-fraud office to establish an olive-oil task force. (“Profits were comparable to cocaine trafficking, with none of the risks,” one investigator told me.) The E.U. also began phasing out subsidies for olive-oil producers and bottlers, in an effort to reduce crime, and after a few years it disbanded the task force. Yet fraud remains a major international problem: olive oil is far more valuable than most other vegetable oils, but it is costly and time-consuming to produce-and surprisingly easy to doctor. Adulteration is especially common in Italy, the world’s leading importer, consumer, and exporter of olive oil. (For the past ten years, Spain has produced more oil than Italy, but much of it is shipped to Italy for packaging and is sold, legally, as Italian oil.) “The vast majority of frauds uncovered in the food-and-beverage sector involve this product,” Colonel Leopoldo Maria De Filippi, the commander for the northern half of Italy of the N.A.S. Carabinieri, an anti-adulteration group run under the auspices of the Ministry of Health, told me.