How Is Meat Like Ham and Fish Preserved Without Refrigeration?

Meats don’t spoil because they’re “cured,” which is a catch-all term for any process that inhibits bacterial growth, even at room temperature. But hams can be bewildering. How are they cured? Are all hams salted? Smoked? Do you have to soak them? Cook them?

There is no single set of answers to these questions because there are so many different kinds of ham, prepared in so many different ways. Few challenges to humankind seem to have evoked as much resourcefulness as how to eat the hind end of a hog.

In terms of cuts, you can find whole hams, half (shank end or butt end) hams, skin-on or skinless hams, and rolled and tied hams, not to mention bone-in, boneless, and the artlessly oxymoronic “semi-boneless” hams. (“Semi-boned” might be a tad more logical because in butcherese, “boned” actually means boneless!)

And then there are hams named not for the surgical procedures they have endured, but for their styles or places of production. Every region and culture outside of Israel and Islam seems to have its own ways of dealing with a hog’s butt.

Some of the best-known regional hams come from England, France, Germany, Poland, Italy, and Spain. And in the United States there are highly acclaimed hams from Kentucky, Vermont, Georgia, North Carolina, and…yes, Virginia. (I’ve always wanted to write

“Yes, Virginia” in answer to a question.)

Now please don’t write to tell me that I’ve left out “the best hams in the world.” I do not argue politics, religion, or hams.

What classifies these many products under the common heading of “ham” is that they are all hogs’ hind legs, treated, except for “fresh” ham, which is untreated, by one or more of five processes: salting, smoking, drying, spicing, and aging. There are almost as many different hams as there are combinations and permutations of these five procedures, except that salting is the one step common to all and is often called “curing” all by itself.

Salting, smoking, and drying all contribute to killing food-spoiling bacteria. Here’s how they do it.

Salting

Meats have been preserved with salt for thousands of years. Salt preserves food because it kills or deactivates bacteria by osmosis.

A bacterium is essentially a blob of protoplasm inside a cell membrane, like a pillowcase full of Jell-O. The protoplasm contains water with dissolved stuff, proteins, carbohydrates, salts, and a lot of other chemicals that are of vital interest to the bacterium but of no concern to us at the moment.

Now let’s douse an unlucky bacterium in very salty water, so that there is a stronger, saltier environment outside its cell membrane than inside. Whenever there exists such an imbalance on opposite sides of a water-permeable barrier (the cell membrane), Mother Nature, who hates imbalances, tries to restore the balance.

In this case she does it by forcing water out of the less concentrated side (the bacterium’s guts) and into the more concentrated side (the external salt water). The effect is to diminish the imbalance by making the strong solution weaker and the weak solution stronger. The unfortunate consequences for the bacterium are that it loses water, shrivels up, and dies. At the very least, it’s no longer a threat to us because it is discouraged from reproducing. (“Not tonight, Dear; I’m dehydrated.”)

This spontaneous movement of water through a membrane, driven by an imbalance of concentration between the solutions on either side, is called osmosis. It comes into play also in the brining of meats to improve their flavor and cooking properties.

And by the way, a strong solution of sugar in water can have the same effect as strong salt water. That’s why we can use lots of sugar to preserve fruits and berries to make, well, preserves. In principle, you could just as well make your strawberry jam with salt instead of sugar. Just don’t invite me to breakfast.

These days, hams and other pork products may be cured with salt mixed with additional substances, including sugar (“sugar-cured hams”), seasonings, and sodium nitrite. Nitrites do three things: They inhibit the growth of Clostridium botulinum bacteria, the notorious source of botulin poison; they contribute flavor; and they react with myoglobin, the red color in fresh meat, to form a chemical called nitric oxide myoglobin, which turns the meat a bright pink color during the slow heating used in the curing process.

In the stomach, nitrites are converted to nitrosamines, which are cancer-producing chemicals. The FDA therefore places a limit on the amount of residual nitrite that can be present in cured meat products.

Smoking

Curing a ham doesn’t cook it, so it usually has to be dealt with further.

Smoking it over a wood fire also kills germs, partly because it dries out the meat, partly because it’s a sort of low temperature cooking, and partly because the smoke contains evil chemicals. (You don’t want to know.) But it can also give the meat a wonderful range of flavors, depending on the type of wood, the temperature, the length of time, and so on.

Generally, hams that have been smoked, and that’s most of them, need not be cooked any further before eating. Supermarket hams may be either partially or fully cooked. Ask the butcher or check the label, which will say something like “cooked” or “ready to eat” or “cook before serving.”

To answer your question, then: Virginia hams, including the renowned Smithfields, have been thoroughly cured by both salting and smoking, so they don’t need to be refrigerated or cooked. But that doesn’t stop many people from soaking, simmering, roasting, glazing, and generally fussing over them once they get them home.

Drying

Long periods of hanging in dry air can also do the job of dehydrating and killing bacteria. Italian prosciutto and Spanish serrano are cured with dry salt and then dried by hanging, traditionally in wind-blown caves or attics.

Not having been hot-smoked, they are still technically raw and are eaten that way, sliced paper-thin. There’s nothing wrong with eating bacteria-free raw meat.

Spicing and Aging

This is where real individuality comes into the picture. Hams can be coated with salt, pepper, sugar, and various secret concoctions of spices, and then aged for years. If cured and dried, they won’t spoil from bacteria, but with age they may develop coatings of mold that must be scrubbed off before eating. So-called country hams are often in this category. The mold may look awful, but the meat inside can be superb. Again, there’s no harm in eating it.

At the lowliest end of the ham spectrum are those pink, plastic-clad, square or round slices in the deli cases of supermarkets and convenience stores. They can be called ham because they contain cured pork, but all relationship to real hams ends there. (Have you ever seen a perfectly square hog’s leg?)

They are made by pressure-forming meat scraps into geometric loaves to fit between the slices of gummy, convenience store white bread that they so justly deserve. Even though smoked, they spoil easily because of all the water they contain, so they have to be kept in the refrigerator case. Leave them there.

Preserving with Sugar and Salt

Gravlax.

Hams and other meats are usually cured by salting, while fruits are usually preserved with sugar. The reason for the difference, obviously, has to do with flavor. But salt and sugar are equally effective at killing bacteria; they pull water out in the same way: by osmosis.

One classic cured meat, fish, actually, is gravlax or gravad lax, a Scandinavian cured salmon. Whether you spell it lax (Swedish), laks (Danish and Norwegian), lachs (German), or lox (Yiddish), the word means salmon, and gravlax means buried salmon. Medieval Scandinavians were in the habit of burying salmon and herring in holes in the ground to ferment.

Today, the salmon is cured by coating it with sugar and a dash of salt. The French sometimes do it with salt and a dash of sugar. The recipe uses half and half, because that’s the way we like it, but you can vary the ratio of salt to sugar to suit yourself. Just make ½ cup total of the mixture.

Gravlax is a cinch to make, but you have to plan ahead because it takes two or three days. At the end of that time, you’ll have one of the prettiest and most toothsome of appetizers. Serve it thinly sliced with Sweet Mustard Sauce (recipe below) and buttered rye bread.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

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