Olio nuovo. You've probably seen this term tossed around before. Defined as "new oil," it should, by default, be new because it was just milled. This fresh-milled oil is very celebrated in the olive oil world. While olio nuovo gets a special spotlight, what often isn’t discussed is that two to three months after harvest it is no longer considered olio nuovo, and soon won't be suitable for consumption. Whaaaa???
So let's back up. What's the difference between olio nuovo and other extra virgins?
When extra virgin is produced it must either get filtered to remove sediment (read here why we prefer filtering), or racked for two months so that the sediment settles at the bottom (of the tank or container).
Why the need to get rid of this sediment? Because the sediment consists of particles that will much more rapidly oxidize the olive oil -- that is, make it go rancid.
Olio nuovo, on the other hand, has neither been filtered nor racked, and therefore it retains much more of this oxidizing sediment. The appeal of this is that olio nuovo, in theory, comes straight from the mill and therefore, with all its extra particles, *temporarily* has more personality.
But -- big BUT -- with all that extra action, it goes bad rapidly, and that's why olio nuovo is not meant to be sold or consumed beyond a few months after harvest, when it gets replaced by the filtered or racked oils that will have a longer shelf life (the former -- filtered -- has the longest, most stable shelf life).
To be clear: filtered, new-harvest olive oil is also "new" and can be bottled and sold right after harvest just like olio nuovo. But the difference is that the filtered new-harvest oil doesn't have all the particles and sediment in it, and thus we don't define it as olio nuovo.
Bottom line, if you're buying or consuming Northern Hemisphere "olio nuovo" past March, it's likely on its way to rancidity, if not already there. You'll notice that it will no doubt smell like crayons or old nuts, and leave a gross greasy film in your mouth. Good news: you can shop still-fresh, filtered oil here, wink wink.