Liquid smoke is a substance produced from smoke passed through a tube from a combustion chamber filled with select wood chips to a condenser. In the condenser, the smoke cools and forms a liquid, aided by the addition of water. Liquid smoke is used for both food preservation and flavoring.
The European Food Safety Authority has found that some liquid smoke products contain genotoxic compounds.
Wright's Liquid Smoke
The idea to capture the flavor of smoke into a liquid form is not new. In 1895, 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 a 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 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 built 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 States 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, which continues to be sold under the same name.
Liquid smoke consists of smoke produced through the controlled burning of wood chips or sawdust, as the smoke rises it is captured in a chamber, condensed and cooled into liquids. This method is called destructive distillation. This solution can be modified to develop a wide range of smoke flavors.
Liquid smoke can be used as a seasoning to add a smokey flavor to various foods. Liquid smoke is often used in the processing of bacon and hot dogs, 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 and tofu. Liquid smoke is also used in some soft cheeses and tempeh. 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.
While smoke condensates such as tar and ash are removed from the solution during production, the European Food Safety Authority (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, flavorings, processing aids, and materials in contact with food (AFC) concluded that Primary Product FF-B can be regarded as weakly genotoxic in vivo (i.e. animal testing has shown it can damage DNA, 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. Liquid smoke produced with poplar wood produced the greatest amount of carcinogenic PAHs at 0.78 µg/kg); however, this is a small amount. The only PAH with an acceptable limit of 10 µg/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 concentrations 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 comparable to a previous research study that suggested 400-600 °C to be the optimal temperature range for wood pyrolysis.
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