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Smoking (cooking): the story on HearLore | HearLore
Smoking (cooking)
The smoking of food likely dates back to the Paleolithic era, transforming a survival necessity into a global culinary tradition. Before the invention of refrigeration, this process was a heavy-duty method of preservation, where large quantities of salt were used in the curing process and smoking times could extend over days of exposure. Historically, farms in the West included a smokehouse, a small building where meats could be smoked and stored, generally well separated from other buildings both because of fire danger and smoke emanations. This ancient technique was later combined with pre-curing the food in salt or salty brine, resulting in a remarkably effective preservation process that was adapted and developed by numerous cultures around the world. Until the modern era, the primary goal was to preserve the food, but the advent of modern transportation made it easier to transport food products over long distances, causing the need for the time and material intensive heavy salting and smoking to decline. Smoking became more of a way to flavor than to preserve food, yet the basic steps involved remain essentially the same today as they were hundreds if not thousands of years ago.
The Chemistry of Fire
Hardwoods are made up mostly of three materials: cellulose, hemicellulose, and lignin, which interact to create the complex flavors of smoked food. Cellulose and hemicellulose are the basic structural material of the wood cells, and when burnt, they effectively caramelize, producing carbonyls, which provide most of the color components and sweet, flowery, and fruity aromas. Lignin, a highly complex arrangement of interlocked phenolic molecules, also produces a number of distinctive aromatic elements when burnt, including smoky, spicy, and pungent compounds such as guaiacol, phenol, and syringol, and sweeter scents such as the vanilla-scented vanillin and clove-like isoeugenol. Guaiacol is the phenolic compound most responsible for the smoky taste, while syringol is the primary contributor to smoky aroma. Wood also contains small quantities of proteins, which contribute roasted flavors. Many of the odor compounds in wood smoke, especially the phenolic compounds, are unstable, dissipating after a few weeks or months. A number of wood smoke compounds act as preservatives, as phenol and other phenolic compounds in wood smoke are both antioxidants, which slow rancidification of animal fats, and antimicrobials, which slow bacterial growth. Other antimicrobials in wood smoke include formaldehyde, acetic acid, and other organic acids, which give wood smoke a low pH, about 2.5. Some of these compounds are toxic to people as well, and may have health effects in the quantities found in cooking applications.
The smoking of food likely dates back to the Paleolithic era. This ancient technique transformed a survival necessity into a global culinary tradition before the invention of refrigeration.
What chemical compounds create the smoky taste in food?
Guaiacol is the phenolic compound most responsible for the smoky taste, while syringol is the primary contributor to smoky aroma. Lignin produces distinctive aromatic elements including smoky, spicy, and pungent compounds when burnt.
Which wood is traditional for smoking in Europe?
In Europe, alder is the traditional smoking wood, but oak is more often used now, and beech to a lesser extent. Regional variations highlight how local resources dictate the flavor profile of the final product.
What temperature range is used for cold smoking?
Smokehouse temperatures for cold smoking are typically between 68 and 86 degrees Fahrenheit. In this temperature range, foods take on a smoked flavor but remain relatively moist.
Who invented the Torry Kiln and when?
In 1939 a device called the Torry Kiln was invented at the Torry Research Station in Scotland. The kiln allowed for uniform mass-smoking and is considered the prototype for all modern large-scale commercial smokers.
What health risks are associated with regularly consuming smoked meats?
Regularly consuming smoked meats and fish may increase the risk of several types of cancer. The smoking of food may possibly introduce polycyclic aromatic hydrocarbons, which may lead to an increased risk of some types of cancer.
In Europe, alder is the traditional smoking wood, but oak is more often used now, and beech to a lesser extent. In North America, hickory, mesquite, oak, pecan, alder, maple, and fruit tree woods, such as apple, cherry, and plum, are commonly used for smoking. Other biomass besides wood can also be employed, sometimes with the addition of flavoring ingredients. Chinese tea-smoking uses a mixture of uncooked rice, sugar, and tea, heated at the base of a wok. Some North American ham and bacon makers smoke their products over burning corncobs. Peat is burned to dry and smoke the barley malt used to make Scotch whisky and some beers. In New Zealand, sawdust from the native manuka tea tree is commonly used for hot-smoking fish. In Iceland, dried sheep dung is used to cold-smoke fish, lamb, mutton, and whale. These regional variations highlight how local resources dictate the flavor profile of the final product, from the resinous pines and firs that produce harsh-tasting soot to the delicate fruit woods that impart sweet aromas. The optimal conditions for smoke flavor are low, smoldering temperatures between 200 and 300 degrees Fahrenheit, which is the temperature of the burning wood itself, not of the smoking environment, which uses much lower temperatures.
The Science of Heat
Food can be smoked by cold smoking, warm smoking or hot smoking, but these methods of imparting smoke only affect the food surface, and are unable to preserve food, thus, smoking is paired with other microbial hurdles, such as chilling and packaging, to extend food shelf-life. Cold smoking differs from hot smoking in that it does not cook anything; when cold smoking is finished, the food is still raw. Smokehouse temperatures for cold smoking are typically between 68 and 86 degrees Fahrenheit. In this temperature range, foods take on a smoked flavor, but remain relatively moist. Since cold smoking does not cook foods, meats should be fully cured before cold smoking. Cold smoking can be used as a flavor enhancer for items such as cheese or nuts, along with meats such as chicken breasts, beef, pork chops, salmon, scallops, and steak. The item is often hung in a dry environment first to develop a pellicle; it can then be cold smoked up to several days to ensure it absorbs the smoke flavor. Some cold smoked foods are baked, grilled, steamed, roasted, or sautéed before eating. Cold smoking meats should not be attempted at home, according to the US National Center for Home Food Preservation, as most food scientists cannot recommend cold-smoking methods because of the inherent risks. Cold smoking meats should only be attempted by personnel certified in HACCP to ensure that it is safely prepared.
The Architecture of Smoke
The main characteristics of the offset smoker are that the cooking chamber is usually cylindrical in shape, with a shorter, smaller diameter cylinder attached to the bottom of one end for a firebox. To cook the meat, a small fire is lit in the firebox, where airflow is tightly controlled. The heat and smoke from the fire are drawn through a connecting pipe or opening into the cooking chamber. The heat and smoke cook and flavor the meat before escaping through an exhaust vent at the opposite end of the cooking chamber. Most manufacturers' models are based on this simple but effective design, and this is what most people picture when they think of a BBQ smoker. Even large capacity commercial units use this same basic design of a separate, smaller fire box and a larger cooking chamber. A reverse flow offset smoker is a variation of the traditional offset design. In this configuration, a solid baffle plate or duct forces the heat and smoke to travel beneath the food before rising and reversing direction to exit through a chimney positioned on the same side as the firebox. This setup promotes more consistent temperatures across the cooking chamber and enhances smoke distribution, which can result in more even cooking. Reverse flow smokers are popular among pitmasters seeking stable heat and reduced hot spots.
The Modern Machine
In 1939 a device called the Torry Kiln was invented at the Torry Research Station in Scotland. The kiln allowed for uniform mass-smoking and is considered the prototype for all modern large-scale commercial smokers. Commercial smokehouses, mostly made from stainless steel, have independent systems for smoke generation and cooking. Smoke generators use friction, an electric coil or a small flame to ignite sawdust on demand. Heat from steam coils or gas flames is balanced with live steam or water sprays to control the temperature and humidity. Elaborate air handling systems reduce hot or cold spots, to reduce variation in the finished product. Racks on wheels or rails are used to hold the product and facilitate movement. The upright drum smoker, also referred to as an ugly drum smoker or UDS, is exactly what its name suggests: an upright steel drum that has been modified for the purpose of pseudo-indirect hot smoking. These smokers have been built using many different sizes of steel drums, such as 30, 44, and 55 gallons, but the most popular size is the common 55-gallon drum. This design is similar to smoking with indirect heat due to the distance between the coals and the cooking racks, which is typically 12 to 18 inches. The temperature is controlled by limiting the air intake at the bottom of the drum, and allowing a similar amount of exhaust out of vents in the lid. UDSs use their fuel very efficiently, and are flexible in their ability to produce proper smoking conditions with or without the use of a water pan or drip pan.
The Health Debate
Regularly consuming smoked meats and fish may increase the risk of several types of cancer. The smoking of food may possibly introduce polycyclic aromatic hydrocarbons, which may lead to an increased risk of some types of cancer, however, this association is debated. Smoke is both an antimicrobial and antioxidant, but it is insufficient for preserving food because it does not penetrate far into meat or fish; therefore, if the food is to be preserved, smoking is typically combined with salt-curing or drying. Smoking is especially useful for oily fish, as its antioxidant properties inhibit surface fat rancidification and delay oxygen from reaching the interior fat and degrading it. Some heavily salted, long-smoked fish can keep without refrigeration for weeks or months. Artificial smoke flavoring, such as liquid smoke, can be purchased to mimic smoking's flavor, but such products have no preservative qualities. The temperature range for hot smoking is usually between 225 and 275 degrees Fahrenheit. Foods smoked in this temperature range are usually fully cooked, but still moist and flavorful. At smoker temperatures hotter than 300 degrees Fahrenheit, foods can shrink excessively, buckle, or even split. Smoking at high temperatures also reduces yield, as both moisture and fat are cooked away.
The Global Table
Some of the more common smoked foods and beverages include Lapsang souchong tea leaves, which are smoked and dried over pine or cedar fires. Malt beverages include the malt used to make whisky and Rauchbier, a smoked beer. Grodziskie is another smoked beer, and in the traditional preparation, yerba mate leaves are smoked. Fruit and vegetables include capsicums, such as chipotles which are smoked, ripe jalapeños, and paprika. Prunes, dried plums, can be smoked while drying, and Wumei are smoked plum fruits. Iburi-gakko are a smoked daikon pickle from Akita Prefecture, Japan. Meat, fish, and cheese include beef, pastrami which is pickled, spiced and smoked beef brisket, pork, bacon, ham, bakkwa, turkey, chicken, sausage, salami, and jerky. Fish varieties include eel, popular in eastern and northern Europe, traditional Grimsby smoked fish, haddock and Arbroath smokies, buckling, kippers and bloater, salmon, mackerel, and bivalves including oysters and mussels. Egg, eggs and fish eggs, and cheese varieties such as Adyghe Qwaye, Gouda, Gruyère, and Oscypek are also common. Competitive BBQ smoking is becoming increasingly popular, especially in the southern United States, where BBQ enthusiasts come together over a weekend to cook various cuts of meat such as a whole hog or a beef brisket. Organisations such as Kansas City Barbeque Society run competitions all over America.