Ah, a perfect wedge of Bleu Mont Dairy bandaged Cheddar, fresh-cut and fabulous. Ideally, every cheese you buy is in such pristine condition. But then there’s real life. Remember that cheese that tasted a little stale, a little cardboardy? Maybe a little bit like the plastic it was wrapped in? Pat Polowsky, a graduate student in food science at the University of Vermont, helped me understand how easily cheese goes rancid at retail. And what can be done about it.

In a presentation at the recent American Cheese Society conference in Denver, Polowsky and a colleague, Dean Sommer of the Wisconsin Center for Dairy Research, took aim at good cheese gone bad. Oxidation, a pervasive problem at retail, is usually the culprit.

Polowsky, who publishes the Cheese Science Toolkit, also works part-time at Dedalus, a Burlington cheese shop. So he understands the issues from the inside. He gave me a little more insight in a conversation after the conference. The images below are from the Wisconsin Center for Dairy Research.

I knew bottled beer and olive oil could be light-struck, but I didn’t know cheese could be. Tell me more.

It’s a big problem, and it’s hard to avoid. With cheese, you have the perfect vehicle for light oxidation because there’s so much fat. Especially at retail, where cheese is exposed directly to bright lights, all you need is oxygen and fat and you can start getting off flavors and bleaching color.

What does oxidation taste or smell like to you?

It varies, but an oxidized cheese can taste like cardboard or like plastic. One common aroma that I pick up is a waxy crayon smell. Some people say “metallic.”

Are some cheese types more sensitive to light damage?

Probably. The more moisture, the better the kinetics. Just anecdotally, Parmesan may get pretty badly oxidized, but it won’t work its way in as quickly as in a high-moisture cheese. Dryer cheeses can still go bad, but maybe you have more time.

With annatto-colored Cheddars, light can shift that orange to pink. It’s widely accepted that it’s the annatto breaking down in the presence of light.

So if you owned a cheese shop, how would you display the cheese?

That’s the million-dollar question. I like how cheese is displayed now. You cut the whole wheel into a working piece and then plastic-wrap it so people can see the face. As a consumer, that’s what I want to see even if I know that, within hours to days, off flavors can develop. But I know enough to say, “Cut me a fresh piece.”

Here’s my hierarchy (best to worst) in how to store cheese:

•    Vacuum-pack it in opaque plastic. The vacuum removes oxygen, and no light gets through, but you can’t see the cheese. Some Cheddars are packaged this way. Some of the packages have a little window, but it’s tough for artisan cheesemakers to use packaging that’s this complicated.

•    Vacuum-pack it in clear plastic to remove the oxygen. At least you can see the product now. But there’s a catch. A lot of retailers think they can hold the cheese a lot longer because it’s vacuum-packed. We don’t want that to be a trend.

•    Wrap it in paper. At least the light’s being blocked.

•    My least-preferred method is plastic wrap. Then you have light and oxygen so there’s nothing stopping the oxidation. Plus cheese goes moldy so quickly in plastic wrap. Cheese sweats and condensation forms between the plastic and the cheese. At least with paper there’s a little more room.

How do you store cheese at your house?

Any cheese that I expect to store for long, I vacuum-pack. Cheddar, mozzarella, Gouda…those are fine in vacuum packaging. But blue cheese, white-mold cheese, washed-rind cheese—any cheese that has actively growing microbes on the rind—vacuum packing destroys it.

What can merchants do to minimize oxidation?

it takes hours, not days or weeks, for oxidation to happen, so one thing merchants can do is pre-cut more often. If you can pre-cut every day instead of every two days, those extra hours can save a lot of cheese. Also, this conflicts with retailing practice but rectangular blocks are better than wedges. The tips of a wedge are so thin that the whole cross-section can oxidize in an hour. And turn off the lights. Chain stores can’t do that, but other places can turn down the lights in the cheese case or take out one of the bulbs, or put butcher paper over the cheeses at night.

If you don’t own a vacuum sealer, what’s second best?

Cheese paper, to let any excess moisture out. Then eat it quick.

If you’ve purchased a cheese with that oxidation smell, what do you do?

If I taste oxidation, I cut a cross-section. Sometimes you can see the bleached-out layer. Cut that off. But the off flavor may have gone deeper than that. Scraping can work in mild cases. But in some national chains, the pieces have been there for months. Those cheeses may be a lost cause.

NEW! Cheese Class: New and Notable from Europe

Monday, October 9
Silverado Cooking School
Napa, CA
5:30 p.m. to 7:30 p.m.
Reservations

An evening devoted to great cheeses that didn’t exist a decade ago. Meet the best new wheels from Spain, Italy, France, Switzerland and beyond.