Erica Marcus Erica Marcus (face disguised) is Newsday's food writer.

Marcus has covered food for Newsday since 1998.

What is bacon?

In the United States, "bacon" is a pig's belly that has been cured and then smoked. In other countries, the word can refer to any number of pig parts that may or may not have been cured or smoked, but we're going to stick to American bacon here.

Curing is an ancient method of preserving food by treating it with salt. Dry-cured bacon is rubbed with salt, in a manner similar to Italian prosciutto crudo. Most commercial bacon is brine-cured, that is, immersed in (and sometimes injected with) salt water, since a wet cure is much quicker than a dry cure. American bacon is almost always cured with sugar as well as salt, plus other flavorings such as pepper.

The curing process usually involves the addition of sodium nitrate or potassium nitrate, compounds that break down into nitrites that inhibit bacterial growth, increase shelf life, bestow upon bacon a pretty pink color and lend it a distinctive "bacony" flavor. There is some evidence that when heated to high temperatures, nitrites break down into compounds that may be linked to certain forms of cancer. The bacon industry uses the term "uncured" to connote a product that has been cured without the use of chemical nitrites. The leading brand of uncured bacon, Applegate Farms, actually uses nitrites derived from celery powder and sea salt.

After curing, the bacon is smoked, although cheaper bacon may be cured with smoke flavor and then just gently cooked.

Most bacon is sold already sliced. Slab bacon is simply cured, smoked belly that the butcher slices to order. The advantage here is that you can get slices as thick or thin as you want.

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If the pork belly has been cured but not smoked, the result is salt pork. Uncured, unsmoked (that is, in its natural state) pork belly has long been considered a delicacy in China -- one of the highlights of a trip I took there a few years ago was the ding po pork, steamed and braised pork belly, at 28 Hu Bin Rd. in Hangzhou -- and it is currently in vogue here, braised into unctuous submission at various New American restaurants. Most recent sighting: an appetizer of Berkshire pork belly with white beans and barbecued balsamic glaze at Blackstone Steakhouse in Melville.

In Italy, they take pieces of pork belly, season them with salt and spices, and roll them up to cure. That's pancetta.

Canadian bacon isn't what Americans consider bacon at all. It is from the eye of the loin -- think about that circle of meat in the center of a center-cut pork chop -- that has been cured, lightly smoked and/or cooked. In Canada this is called "back bacon."