||It has been suggested that this article be merged with Pyroligneous acid. (Discuss) Proposed since October 2015.|
wood vinegar, pyroligneous acid, smoke flavor, smoke flavouring, condensed natural smoke
|Appearance||Yellow to red liquid|
|Solubility in alcohol||miscible|
|Solubility in propylene glycol||miscible|
|Solubility in oils||immiscible|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Pyrolysis or thermal decomposition of wood in a low oxygen manner originated prehistorically to produce Charcoal. Condensates of the vapors eventually were made and found useful as preservatives. The term wood vinegar for centuries was the popular term used to describe the water based condensates of wood smoke. Presumably, this is due to its utilization as food Vinegar. Pliny the Elder recorded in one of his ten volumes of Natural History (Pliny) the use of wood vinegar as an embalming agent, declaring it superior to other treatments he used. Widely recognized as the father of chemical engineering, another naturalist documentarian Johann Rudolf Glauber outlined in Furni Novi Philosophici  the methods to produce wood vinegar during charcoal making. Further, he described the use of the water insoluble tar fraction as a wood preservative and documented the freezing of the wood vinegar to concentrate it. Use of the French derivation, pyroligneous acid as a widely used term for wood vinegar emerged by 1788.
In the United States, the commercial distribution era of pyroligneous acid under a new term, liquid smoke that subsumed it began with E.H.Wright in 1895. Among Wright’s innovations were the standardization of the product, marketing and distribution. Wright’s liquid smoke and its modern day successors have always been the subject of controversy about what they are and how they are made. But in 1913 Wright, prevailed in a federal misbranding case. Case judge Van Valkenburg wrote:
The Government, in trying to show that this is not smoke produced by combustion, has shown that it is produced in exactly the same kind of way that is stated on that label. The fact is that they have produced something here which they say has something of the flavor and properties similar to the curative properties of smoke; they get it out of wood and they get it by distillation and it turns out to be a substance like, if not exactly identical with pyroligneous acid. Well, nobody could be deceived into thinking it was specifically what the indictment charges they are being deceived with. It is a thing which is produced in such a manner from the art and methods employed in it, that the application of the term “smoke” to it seems to me to be apt or applicable instead of deceptive, and it does not deceive in the sense this statute implies.
Historically, all pyroligneous acid products, Wright’s product and many other condensates have been made as byproducts of charcoal manufacturing which was of greater value. Chemicals such as Methanol, Acetic acid and Acetone have been isolated from these condensates and sold. But with the advent of lower cost Fossil fuel sources, today these and other wood derived chemicals retain only small niches. It was in 1959 that the era of modern condensed smoke based products began with the establishment of Red Arrow Products Company in Manitowoc Wisconsin. The important distinction marking this era from the past is the production of modern condensates to be used industrially as a replacement for smoking food directly with non-condensed smoke. Today there are many manufacturing locations around the world, most of which pyrolyze wood primarily to generate condensates which are further processed to make hundreds of derivative products. These are now referred to less so as liquid smoke products rather as smoke flavourings, smoke flavors, and condensed natural smokes.
Liquid smoke is produced by the destructive distillation of wood, preferably birch. The crude product (pyroligneous acid) contains methanol, acetic acid, acetone, furfural and various tar and related products. The extract is rendered free of water, acid and tar by (1) alkali washing, followed by (2) re-acidification and (3) solvent extraction.
Hickory smoke distillate (CAS # 74113‐74‐9) is produced by condensation of smoke bearing water vapor resulting from the controlled burning of hickory (Carya species, Juglandaceae family). It consists primarily of acetic acid, dimethoxyphenol, 2-butanone and water.
Liquid smoke is used as a seasoning to add a smokey flavor to various foods.
Aqueous and gaseous smoke can enhance seedling germination and emergence.
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. The types of trees listed from those generally producing the highest concentration of PAHs to those producing the lowest concentration is: 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.
- George A. Burdock (2010), "PYROLIGNEOUS ACID EXTRACT", Fenaroli's Handbook of Flavor Ingredients (6th ed.), Taylor & Francis, pp. 1775–1776, ISBN 978-1-4200-9077-2
- Glauber, Johann Rudolph (1658). Furni Novi Philosophici, Sive Descriptio Artis Destillatoriae Novae .... London: Joannem Janssonium.
- "Merriam Webster dictionary". Retrieved October 9, 2011.
- Unusual Stories of Unusual Men: Ernest H. Wright - Classification: "Condensed Smoke". The Rotarian. 1923. pp. 209–10, 240.
- U.S.Department of Agriculture Division of Publications Service and Regulatory Announcements, 1914. Item number 2828. Alleged misbranding of liquid smoke. U.S.v.E.H.Wright. F.&D.No 3410.I.S.No 14393-c. Washington: Government printing office. 1915. p. 59.
- "Red Arrow About us". Retrieved November 26, 2016.
- George A. Burdock (2010), "HICKORY (NATURAL) SMOKE FLAVOR", Fenaroli's Handbook of Flavor Ingredients (6th ed.), Taylor & Francis, pp. 896–7, ISBN 978-1-4200-9077-2
- Abella, S.R. (2009). "Smoke-cued emergence in plant species of ponderosa pine forests: contrasting greenhouse and ﬁeld results" (PDF). Fire Ecology. 5 (1): 22–37. doi:10.4996/fireecology.0501022.[dead link]
- "EFSA - Opinion of the Scientific Committee/Scientific Panel: Safety of smoke flavour Primary Product - Fumokomp". Efsa.europa.eu. doi:10.2903/j.efsa.2009.1343. Retrieved 2014-08-20.
- "EU Food Law News (07-44)". Rdg.ac.uk. Retrieved 2010-01-06.
- "Safety of smoke flavor Primary Product — Fumokomp". European Food Safety Authority. Retrieved 2010-01-06.
- "'Smoked' flavour food concerns". BBC News. 2010-01-08. Retrieved 2010-01-08.
- Guillén, M.D; Sopelana P.; Partearroyo M.A. (2000). "). Polycyclic Aromatic Hydrocarbons in Liquid Smoke Flavorings Obtained from Different Types of Wood. Effect of Storage in Polyethylene Flasks on Their Concentrations". J. Agric. Food Chem. 48 (10): 5083–5087. doi:10.1021/jf000371z.
- Leffingwell & Associates, Smoke Flavor I. Includes chemical and chromatography information.