Smoking (cooking)
Smoking is the process of flavoring, cooking, or preserving food by exposing it to the smoke from burning or smoldering plant materials, most often wood. Meats and fish are the most common smoked foods, though cheeses, vegetables, and ingredients used to make beverages such as whisky.[1] Rauchbier and lapsang souchong tea are also smoked.
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 fuels 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 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, resulting in a unique and rather strongly smoked flavor.
Historically, farms in the western world included a small building termed the smokehouse where meats could be smoked and stored. This was generally well-separated from other buildings both because of the fire danger and because of the smoke emanations.
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Types
- "Hot smoking" exposes the foods to smoke and heat in a controlled environment. Although foods that have been hot smoked are often reheated or cooked, they are typically safe to eat without further cooking. Hams and ham hocks are fully cooked once they are properly smoked. Hot smoking occurs within the range of 165 °F (74 °C) to 185 °F (85 °C). Within this temperature range, foods are fully cooked, moist, and flavorful. If the smoker is allowed to get hotter than 185 °F (85 °C), the foods will shrink excessively, buckle, or even split. Smoking at high temperatures also reduces yield, as both moisture and fat are "cooked" away.
- "Smoke-roasting" or "Smoke-baking" refers to any process that has the attributes of smoking with either roasting or baking. This smoking method is sometimes referred to as "barbecuing", "pit-roasting", or "pit-baking". It may be done in a smoke-roaster, closed wood-fired masonry oven or barbecue pit, any smoker that can reach above 250 °F (121 °C), or in a conventional oven by placing a pan filled with hardwood chips on the floor of the oven so the chips smolder and produce a smokebath. However, this should only be done in a well-ventilated area to prevent carbon monoxide poisoning.
- "Cold smoking" can be used as a flavor enhancer for items such as pork chops, beef steaks, chicken breasts, salmon and scallops. The item can be cold-smoked for a short period, just long enough to give a touch of flavor. Such foods are ready to be finished to order by such cooking methods as grilling, sautéing, baking, and roasting, or they may be hot smoked to the appropriate doneness for an even deeper smoked flavor. Smokehouse temperatures for cold smoking should be maintained below 100 °F (38 °C). In this temperature range, foods take on a rich, smokey flavor, develop a deep mahogany color, and tend to retain a relatively moist texture. They are not cooked as a result of the smoking process, however.
Wood smoke
Hardwoods are made up mostly of three materials: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are the basic structural material of the wood cells; lignin acts as a kind of cell-bonding glue. Some softwoods—especially pines and firs—hold significant quantities of resin, which produces a harsh-tasting soot when burned. Because of this, these woods are generally not used for smoking.
Cellulose and hemicellulose are aggregate sugar molecules; 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 "smokey" taste, while syringol is the primary contributor to smokey aroma.[2] 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. 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. See Health Effects.
Since different species of tree have different ratios of components, various types of wood do impart a different flavor to food. Another important factor is the temperature at which the wood burns. High-temperature fires see the flavor molecules broken down further into unpleasant or flavorless compounds. The optimal conditions for smoke flavor are low, smoldering temperatures between 570 and 750 °F (299 and 399 °C). This is the temperature of the burning wood itself, not of the smoking environment, which sees much lower temperatures. Woods that are high in lignin content tend to burn hot; to keep them smoldering requires restricted oxygen supplies or a high moisture content. When smoking using wood chips or chunks, the combustion temperature is often lowered by soaking the pieces in water before placing them on a fire.
Types of smokers
There are a few basic types of smoker designs, each with their own advantages and disadvantages.
Charcoal Smokers
Traditional American BBQ is cooked in one of two different types of smoker; the offset charcoal smoker or the Upright Drum Smoker (also called a UDS or Ugly Drum Smoker).
Offset Smokers
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 is 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.
The UDS
The Ugly Drum Smoker (also referred to as an Upright 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. There are many ways to accomplish this, but the basics include the use of a complete steel drum, a basket to hold charcoal near the bottom, and cooking rack (or racks) near the top; all covered by a vented lid of some sort. They have been built using many different sizes of steel drums (30 gallon, 55 gallon, and 85 gallon for example), but the most popular size is the common 55 gallon drum.
This design is similar to smoking with indirect heat due to the distance from the coals and the racks (typically 24"). The temperatures used for smoking are controlled by limiting the amount of air intake at the bottom of the drum, and allowing a similar amount of exhaust out of vents in the lid. UDS's are very efficient with fuel consumption and flexible in their abilities to produce proper smoking conditions, with or without the use of a water pan or drip pan. Most UDS builders/users would say that a water pan defeats the true pit BBQ nature of the Ugly Drum Smoker, as the drippings from the smoked meat should land on the coals, burning up, and imparting a unique flavor that you cannot get with a water pan.
The term "UDS" originated on the BBQ Brethren website (www.bbq-brethren.com). The original UDS Build thread is a very popular and helpful post at that website, with over 6,000 replies and over 1,000,000 views. It does a great job of showcasing many people's builds with plans and pictures, helpful hints and answers for most questions, and food that has been cooked using a UDS.
Propane smoker
A propane smoker is a newer method that is designed to allow the smoking of meat in a somewhat more controlled environment. The primary differences are the source of heat and cause of the smoke. In a propane smoker, the heat is generated by lighting a gas burner. This lies directly under a steel or iron box that contains the wood or charcoal that is used to provide the smoke. The steel box has few vent holes which are on the top of the box only. By starving the heated wood of oxygen, it will smoke instead of burn. Any type of wood, charcoal or mix could be used. This method uses less wood and may be more convenient for some people.
Smoke box method
This is a more traditional method that uses a two box system: The fire box and the food box. The fire box is typically adjacent or under the cooking box, and can be controlled to a finer degree. The heat and smoke from the fire box exhausts into the food box, where it is used to cook and cure the meat.
Commercial smoke house
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.
Preservation
Smoke is an antimicrobial and antioxidant, but smoke alone is insufficient for preserving food in practice. The main problem is that the smoke compounds adhere only to the outer surfaces of the food; smoke does not actually penetrate far into meat or fish. In modern times, almost all smoking is carried out for its flavor. This flavoring can be purchased as a liquid in most supermarkets to mimic the flavor of smoking—not its preservative qualities—without the actual cooking process (see also liquid smoke).
In the past, smoking was a useful preservation tool, in combination with other techniques, most commonly salt-curing or drying. For some long-smoked foods, the smoking time also served to dry the food. Drying, curing, or other techniques can render the interior of foods inhospitable to bacterial life, while the smoking gives the vulnerable exterior surfaces an extra layer of protection. For oily fish, smoking is especially useful, as its antioxidant properties delay surface fat rancidification. (Interior fat isn't as exposed to oxygen, which is what causes rancidity.) Some heavily salted, long-smoked fish can keep without refrigeration for weeks or months. Such heavily-preserved foods usually require a treatment such as boiling in fresh water to make them palatable before eating.
Health effects
Eating a diet high in smoked, cured, or salted meats has been shown to be a risk factor in stomach cancer. Recent changes in processing techniques to decrease the amount of salt and sugar in smoked fish, however, have increased the risk that these food products may contain botulism toxin.
In addition to sugar and salt exposure, smoking can directly create compounds known to have long-term health consequences, namely polycyclic aromatic hydrocarbons, or PAHs, many of which are known or suspected carcinogens. These compounds result from incomplete combustion of the fuel; hotter wood fires make more PAHs; hot-burning mesquite produces twice as much as cooler-burning hickory. Drippings can also turn into carcinogens, which can deposit onto meat the same way that grilling has been found to be carcinogenic.
Some smoked foods and drinks
- Fish
- Lox
- Smoked salmon
- Kippers
- Arbroath Smokies (haddock)
- Many pork products are cured and smoked
- Pastrami, pickled, spiced and smoked beef brisket
- Various sausages
- Traditionally-prepared jerky
- The malt used to make whisky
- Rauchbier
- Lapsang souchong tea leaves are smoked and dried over pine or cedar fires
- Prunes, which are dried plums, can be obtained through smoking
- Wumei are smoked ume fruit
- Chipotles are smoked jalapeño peppers
- Smoked cheeses, such as smoked gouda
- Smoked salt
- Smoked paprika
Other home food preservation methods
- Canning
- Drying (food)
See also
- Braising
Notes
Further reading
- McGee, Harold (2004). "Wood Smoke and Charred Wood". On Food and Cooking (Revised ed.). Scribner. pp. 448–450. ISBN 0-684-80001-2.
External links
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