Liquid smoke

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Pyroligneous acid extract
Other names
wood vinegar, char smoke flavor
Appearance Yellow to red liquid
Odor acrid smoky
Solubility in alcohol miscible
Solubility in propylene glycol miscible
Solubility in oils immiscible
Related compounds
Related compounds
Pyroligneous acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
A bottle of hickory liquid smoke sauce

Liquid smoke is a yellow to red liquid used for flavoring. A tar-like phase insoluble in alcohol and water can separate on standing.[1]


In 1895, pharmacist Ernest H. Wright began bottling and selling what he named "condensed smoke".[2] In 1997, B&G Foods purchased Wright's Liquid Smoke, which continues to be sold under the same name.[3]


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.[1]

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.[4]


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.[5]


The European Food Safety Authority has found that some liquid smoke products contain In Vitro (in "petri dish" conditions) but not In Vivo (in a living organism) carcinogenic genotoxic compounds.[6]


The European Food Safety Authority (EFSA) is investigating the safety of liquid smoke as a food flavoring.[7] 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.[8] Primary Product AM 1 was described as potentially toxic to humans by the EFSA on 8 January 2010.[9]

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.[10]


  1. ^ a b 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 
  2. ^ Melville, A. (1923). Unusual Stories of Unusual Men: Ernest H. Wright - Classification: "Condensed Smoke". The Rotarian. pp. 209–210, 240. 
  3. ^ "B&G Foods, Inc. - Company History". Retrieved October 9, 2011. 
  4. ^ George A. Burdock (2010), "HICKORY (NATURAL) SMOKE FLAVOR", Fenaroli's Handbook of Flavor Ingredients (6th ed.), Taylor & Francis, pp. 896–897, ISBN 978-1-4200-9077-2 
  5. ^ 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]
  6. ^ "EFSA - Opinion of the Scientific Committee/Scientific Panel: Safety of smoke flavour Primary Product - Fumokomp". doi:10.2903/j.efsa.2009.1343. Retrieved 2014-08-20. 
  7. ^ "EU Food Law News (07-44)". Retrieved 2010-01-06. 
  8. ^ "Safety of smoke flavor Primary Product — Fumokomp". European Food Safety Authority. Retrieved 2010-01-06. 
  9. ^ "'Smoked' flavour food concerns". BBC News. 2010-01-08. Retrieved 2010-01-08. 
  10. ^ 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. 

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