Tasting oils at the Department of Agrarian Biotechnology,

Fusty, Musty and Rancid: Tasting Extra-virgins

The title of the two-day seminar was very clear: Methods for evaluating the sensory properties of extra-virgin olive oil, and Professor Erminio Monteleone stressed in his opening remarks that we had not gathered to evaluate particular oils but to understand the methods of evaluating them.

It was tough stuff, tougher than anything I’ve done in the past with olive oil. I’m as capable as the next person of tasting an oil and telling you what I taste in it—I may not know art but I know what I like, right? But describing these flavors, aromas, and textures and then assigning them a position on a graph or chart—that calls for entirely different skills. Sharing the task with a group that included olive oil producers, delegates from the Camera di Commercio di Firenze, and others who were just plain interested in the challenge, added to the interest as everyone weighed in with different questions, different problems, and very different reactions to the oils.

One of the most valuable parts of the course for me was our initial tasting of six defective oils—actually, five defective ones and one that qualified as extra-virgin. Distinguishing between rancidity and fustiness (in Italian that’s called riscaldo) or between fustiness and mustiness (muffa in Italian, meaning moldy, and a lot easier to recognize) often requires concentration. And why should I care? Isn’t it enough for me that an oil is musty, fusty, or rancid? Shouldn’t I just reject it on that basis?

Not really. I kept thinking of something Hemingway, if I recall correctly, said a very long time ago. I could never find the quote again but it had to do with icebergs: The writer’s job is to describe the part of the iceberg that rests above water. But in order to do that correctly, the writer also must know the 90% of the iceberg that is hidden from view. Just so with these extra-virgins (and not).

Interestingly, that fusty flavor (riscaldo) is one that appeals to many people, even though it marks a defective oil. Turns out that for most people, Americans and Italians alike, that’s the taste we remember from the oils we’ve been exposed to over our lifetimes. It goes back to a time when almost all extra-virgin olive oil suffered from that defect, which comes from olives that have been piled up at the mill or elsewhere for too long after harvest. The olives ferment and that fermentation is the flavor olive experts call fusty. So why do some people like it? And like it so much that one French oil producer deliberately and in a controlled way produces a small quantity of fusty oil—because, he told me, that’s the flavor his local market demands. It’s a bit like kids who grow up on orange juice made from frozen concentrate: Give them a taste of freshly squeezed orange juice and their little noses wrinkle. “Eeeuw,” they say, “it’s got bits in it!”

Just so with fusty extra-virgin. People know what they like and like what they know and they’ll go with the frozen juice and fusty oil, time after time. All too often, in rankings of extra-virgin olive oils in national publications, it’s the fusty ones that win top honors.

But how, you may ask, can an olive oil qualify as extra-virgin if it’s fusty? Easily! Extra-virgin refers to the strictly mechanical process by which an oil is produced—and to the fact that it must have “a free acidity, expressed as oleic acid, of not more than 0.8 grams,” and a peroxide level of less than 20. It’s quite conceivable that a fusty oil could comfortably fit these definitions, which are established by the International Olive Council. Beyond that, the IOC says, an oil must demonstrate “perfect” organoleptic characteristics, i.e., perfect flavor and aroma. But perfect, of course, is an entirely relative term, and one taster’s perfect can and often is another’s defective oil.


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