25.1 Curing, brining and smoking

An old craft

Meat and fish were very likely the first foods people learned to keep. Before they had fire, people probably dried meat; once they had fire, smoke could be added as well. Taking out moisture cut down the harmful bacteria, and that may have been the first step towards what is now called food safety.

Salt came next in importance. In the first century, the Greek geographer and historian Strabo wrote about houses in ancient Greece and Rome where fish was salted. Salt held back microbes and drew out water, so people had protein to eat in an age with no refrigerators. Today the goal is less about survival and more about the cured meats people enjoy, but the need to stop harmful bacteria is the same.

What a cure does to meat

A cure is made from salts, sugars and spices, and today also chemicals such as nitrates and nitrites. Four processes do the work:

• Osmosis. Water, salt and flavor move into the cells of the meat through their walls, while water, albumen and blood move out.
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• Dehydration. As the cure moves in, the meat loses moisture. Salt duck legs with quatre épices for duck confit, and water and blood soon drip into the pan beneath.
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• Denaturing. Acid changes the protein without heat. Fish or shrimp left in an acid dressing turns from see-through to opaque white. Ceviche is fish or shellfish marinated in lemon and lime juice this way. Raw marinated fish should still be cooked to make it safe.
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• Fermentation. Enzymes in the food break proteins down into gases and other compounds. Salt keeps this under control; without it the food would simply rot. As cured meat ages, the enzymes make it more tender, and the acid that builds up helps to preserve it. Kombucha, yogurt, sauerkraut and cured meats are all fermented.
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As the cure works, the meat loses water and grows firmer. With bacon and ham, that is the point at which smoking begins.

Keeping bacteria out with fat

Fat can preserve meat too, because it shuts out oxygen. For confit, duck is cooked in the fat that comes from the duck itself; as it cools, that fat sets around the meat and seals it. Rillettes are boned meat, stewed and then beaten to a paste with a mixer's paddle, mixed with melted fat and covered with more of it; they are eaten on toast. Tuna can be kept in oil in much the same way, and some chefs now keep tomatoes and red onion in fat or oil. Be careful with vegetables in oil: fresh garlic in oil is a potentially hazardous food.

Dry cures and wet cures

Salt pulls water out of meat, and bacteria need water to live. A cure also makes the meat a poor place for bacteria to grow. There are two kinds of cure:

• Dry cure: dry salt and sugar. Do not confuse it with a barbecue rub. A dry cure often buries the meat completely and may work for days, depending on how thick the piece is. In Europe, legs of wild boar are commonly buried in salt for close to two weeks.
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• Wet cure, also called a brine: salts, sugars and spices in water. The brine is often boiled first to draw more flavor from spices such as cloves, cinnamon sticks and allspice.
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Time depends on thickness. A thin slice cures in hours; a whole bone-in ham takes weeks. Check the meat often, so it is cured evenly all through and taken out before it has gone too far to eat.

Many older recipes use more salt than sugar, about 60 parts salt to 40 parts sugar. Many chefs now turn that round and use more sugar than salt, for example in brines for barbecued pork. Country ham is mostly cured with salt; city ham is mostly cured with sugar. Sugar for curing need not be white sugar: molasses, honey, maple syrup and corn syrup all work.

Curing agents

Besides plain salt and sugar, cooks use four curing agents:

• Unrefined salt.
• Saltpeter, which is potassium nitrate.
• Prague Powder I is also called tinted curing mix (TCM), pink powder or pink salt. It is 94% sodium chloride (salt) and 6% sodium nitrite. It is strong: 4 ounces cures 100 pounds of meat. It is dyed pink so that no one mistakes it for ordinary salt. Cooks favor it for bacon, deli meats, sausages and forcemeats; it keeps the meat's red color, and it protects against botulism. It is commonly used in hot smoking, at 185°F to 285°F.
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• Prague Powder II contains nitrate as well as nitrite: by weight it is 90% sodium chloride, with 6% sodium nitrite and 4% nitrate. It is needed for meat that will never be cooked, such as hard salami. It guards against botulism during the long weeks the meat hangs and dries at changing temperatures and humidity, and under controlled conditions it needs as long as six weeks to break down.

Sodium erythorbate and sodium ascorbate are sometimes added to cured meats, but they are not curing agents. Some products are now sold made with no curing agents at all, labeled, for example, as uncured pepperoni.

Getting ready to smoke

Smoke adds flavor, and it can also be part of what makes a food keep longer, as with country hams. A business that wants to make and sell smoked foods may need a variance (special permission) from its local food safety authority.

Read the recipe, because there may be steps between curing and smoking. A ham cured with blackstrap molasses, for example, is soaked in water in the cooler for 8 hours to draw out some of the salt. Next it is patted dry and goes back into the cooler, for some hours or up to a night, until it forms a pellicle: a thin, tacky skin on the surface. Smoke sticks to the pellicle and gets into the meat. Meat that goes into the smoker wet just collects a layer of soot that wipes off with a finger.

The smoke ring

Raw meat is red or pink because of a protein called myoglobin, which turns brown as the meat cooks. If enough nitric oxide from the wood smoke settles on the meat, it binds to the myoglobin that is still red and keeps it that color. That pink layer is the smoke ring. Moisture on the surface helps the gas settle, so cooks spray the meat or set a pan of water in the smoker. Guests like a smoke ring, but some barbecue competitions give it no extra points.

Cured sausages, and why every smoked sausage is cured, are covered with meat. see chapter 11: Fresh, cured and smoked