Zingerman’s proprietor Ari Weinzweig travels to Europe frequently to select olive oils for his popular Ann Arbor, Mich., shop. We asked him how he separates the best olive oil from the rest. Answers in a moment, but first let’s meet Ari Weinzweig.

Q: It can be intimidating to face all those oils on store shelves. Where’s a consumer to start?

With wine, people take for granted that there are different quality levels and regional styles. Bordeaux is different than Chianti is different than Burgundy, and everybody knows it. I also think people are comfortable with the idea that there are bulk table wines that are perfectly good for everyday drinking but not what you’d serve for your twentieth anniversary. The same is true of olive oil. For greater complexity, look for an estate-grown product.

Q: What else do you want to know?

I look at where it comes from. People talk about country of origin, but I look at regions. The truth is that oil from southern Spain will have no more in common with oil from northern Spain than it will with oil from Italy. Each region has its own style and flavor characteristics. Typically, if I’m doing Tuscan dishes I want to use a Tuscan oil. If I’m doing dishes from Provence, I might pick a Provençal oil with the lighter, more flowery flavors typical of that region.

I also try to find out how the olives have been picked. The best oils are from hand-picked olives. For most mass-market oils, the olives are removed with machines that knock the olives off. Or worse, the farmers allow the olives to become so ripe that they fall to ground. The olive fruit is past its prime at that stage, and bruising can happen.

I also look at when the olives were pressed. When olives are picked earlier, the oil content is lower but the flavor complexity is higher. Those oils are going to be more interesting, with bigger flavors, but also more costly because yields are low. Generally the oils produced early tend to have longer shelf life because they are higher in antioxidants.

Another factor is how quickly the olives go from being picked to pressed. You’d like to get them into the press within 24 hours because the longer the olive is off the tree, the more likely you are to have defects in the oil.

Q: How is the average consumer supposed to find these things out?

Talk to the merchant. Ask if the oil is from the most recent harvest. Typically oils produced in the fall, say from October through December, are going to last a good 12 to 18 months. But at Zingerman’s, we’re always trying to offer current-crop oils. So if you’re buying oil in April 2004, it should be from the fall of 2003.

Q: Any tips on using extra virgin olive oil?

One of the first things I learned was not to skimp on amount or quality. In our part of the world, we view fat as something to use in minimal amounts. In the Mediterranean, because olive oil is so good and good for you, they use as much as they can. Instead of drizzling it on toasted bread, they use a lot. The flavor is what it’s about.

The reason not to skimp on quality is that you really can’t get any complexity out of low-end oil. Going with the smaller-production estate oils gives you a chance to experience olive oil at its best.

Q: What about storing it?

Keeping it in a cool place out of direct sunlight is key. If you keep it in the fridge, it will congeal. There’s nothing wrong with that, but then you’ve got to let it sit out to un-congeal. Don’t put it near the stove; heat and light are enemies of good oil. More peppery oils tend to keep longer, but I just recommend using it often and you won’t have to worry about storage.

Swirl, sniff, spit? Learn the basics of tasting and evaluating olive oil with Weinzweig. [Part 1][Part 2]