Liquid smoke is a substance produced from smoke

Smoke

Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires , but may also be used for pest...

 passed through water. Liquid smoke is used for both food preservation

Food preservation

Food preservation is the process of treating and handling food to stop or slow down spoilage and thus allow for longer storage....

 and flavoring. While some worry that liquid smoke contains carcinogenic compounds, research suggests that the concentration levels are well under the acceptable limit formed by the FAO and WHO.

History

The idea to capture the flavor of smoke into a liquid form is not new. In 1895 a man by the name of Ernest H. Wright began bottling and selling what he named "condensed smoke". When Wright was 15 years old he worked at a print shop. One day while working, he noticed that there was black liquid dripping from the stove pipe. This image had followed him through to his adult life when he became a pharmacist in Kansas City, Missouri. Wright always had an interest in chemistry, so when he eventually bought his own drug store, he began to explore the combustion of wood. Wright discovered that he could collect a liquid with the flavor of smoke, through condensation. As wood was burned, the smoke produced would enter the stove pipe, and as it was introduced to cold air, the smoke would condense.

Using this liquid "condensed smoke", Wright prepared a ham and fed it to his friends. He wanted to experiment, to see if the taste would be comparable to traditionally smoked ham. When his friends asked for more, Wright knew he had created a product that would sell. His next plan was to sell it to farmers as an alternative to traditional smoking techniques used to preserve meats. Wright was able to build his business through the connections he had build with local farmers. Eventually, Wright began selling his condensed smoke to farmers outside of the city.

As his company began to grow, Wright was able to hire a German chemist who was able to perfect Wright's method of creating his condensed smoke, as well as save Wright from a hefty lawsuit. At first Wright had refused to have his condensed smoke patented because then he would have no choice but to keep a record of his methods with the government. Wright was worried that his secret method would get into the wrong hands. This secrecy raised concerns at the government of the United Stated of America, and so they tried to sue Mr Wright and his company on the terms that his condensed smoke contained wood alcohol. If it wasn't for Wright's German chemist, Wright would have probably lost that lawsuit, as the final product of condensed smoke using Wright's old method did contain wood alcohol. In 1997, B&G Foods purchased Wright's Liquid Smoke, where till today, it is still being sold under the same name.

Production

Liquid smoke consists of smoke

Smoke

Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires , but may also be used for pest...

 produced through the controlled burning of wood chips or sawdust, condensed

Condensation

Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

 into solids or liquids and then dissolved in water. This method is called destructive distillation. This solution can be modified to develop a wide range of smoke flavors.

Uses

Liquid smoke can be used as a seasoning to add a smokey flavor to foods. Liquid smoke is often used in the processing of bacon

Bacon

Bacon is a cured meat prepared from a pig. It is first cured using large quantities of salt, either in a brine or in a dry packing; the result is fresh bacon . Fresh bacon may then be further dried for weeks or months in cold air, boiled, or smoked. Fresh and dried bacon must be cooked before eating...

 and hot dog

Hot dog

A hot dog is a sausage served in a sliced bun. It is very often garnished with mustard, ketchup, onions, mayonnaise, relish and/or sauerkraut.-History:...

s, sprayed or atomized into the smokehouse, and is one of the main flavors in the curing solution used for bacon. It is also used to flavor jerky

Jerky (food)

Jerky is lean meat that has been trimmed of fat, cut into strips, and then been dried to prevent spoilage. Normally, this drying includes the addition of salt, to prevent bacteria from developing on the meat before sufficient moisture has been removed. The word "jerky" is a bastardization of the...

 and tofu

Tofu

is a food made by coagulating soy milk and then pressing the resulting curds into soft white blocks. It is part of East Asian and Southeast Asian cuisine such as Chinese, Japanese, Korean, Indonesian, Vietnamese, and others. There are many different varieties of tofu, including fresh tofu and tofu...

. Liquid smoke is also used in some soft cheeses and tempeh

Tempeh

Tempeh , or tempe , is a traditional soy product originally from Indonesia. It is made by a natural culturing and controlled fermentation process that binds soybeans into a cake form, similar to a very firm vegetarian burger patty...

. It can be used in a marinade on steaks, sausages, chops, roasts, or ribs, or in soups, vegetables and gravies as a replacement for bacon flavor.

Aqueous, as well as gaseous, smoke can also enhance seedling germination and emergence. Greenhouse tests on seeds and on wild seedbanks support this trend, but field trials of aqueous smoke remain inconclusive.

Safety

While smoke condensates such as tar and ash are removed from the solution during production, the European Food Safety Authority

European Food Safety Authority

The European Food Safety Authority is an agency of the European Union that provides independent scientific advice and communication on existing and emerging risks associated with the food chain, created by European Regulation 178/2002....

 (EFSA) is investigating the safety of liquid smoke as a food flavoring. One of the smoke flavorings being assessed, named Primary Product FF-B, raised concern. The EFSA Panel on food additives, flavourings, processing aids, and materials in contact with food (AFC) concluded that Primary Product FF-B can be regarded as weakly genotoxic in vivo

In vivo

In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...

(i.e. animal testing has shown it can damage DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

, the genetic material in cells). The Panel, therefore, could not establish its safety in use when added to food. However, no comparison was made against traditional smoked goods on the market. Primary Product AM 1 was described as potentially toxic to humans by the EFSA on 8 January 2010.

In a study by Guillén, Sopelana, and Partearroyo , it was discovered that different concentrations of Polycyclic aromatic hydrocarbons (PAHs) were present in different liquid smoke flavourings depending on the type of tree used to produce the liquid smoke. In general, the concentration of PAHs found in the liquid smoke samples decreases from: poplar, vine shoot, oak, cherry tree and beech woods.

It should be noted that liquid smoke produced with Poplar wood produced the greatest amount of carcinogenic PAHs at 0.78 íg/kg), however this is a small amount. The only PAH with an acceptable limit of 10 íg/kg, fixed by FAO/WHO, is benzo[a]pyrene, because it is highly carcinogenic. This was also found to be present in Poplar and Beech liquid smoke, however, the concentrations are well below the acceptable limit.

The researchers also discovered that, independent of wood type, the concentration of carcinogenic PAHs were the lowest when the temperature used during the production of the liquid smoke was 530-559°C. This temperature range did not compromise the quality of the liquid smoke produced and is is comparable to a previous research study that suggested 400-600°C to be the optimal temperature range for wood pyrolysis.

External links

• Leffingwell & Associates, Smoke Flavor I. Includes chemical and chromatography information.