Direct Thermochemical Liquefaction

Food Flavoring

Key Points

  • Food flavoring was the first commercialized product of fast pyrolysis bio-oil, predating use of bio-oil as an energy carrier
  • Liquid smoke is the aqueous soluble fraction of pyrolysis oils

Example Applications

Mankind has been preserving food with smoke for much of human history.

Smoke comprises fine solids and liquids from thermal breakdown of biomass during incomplete combustion.  Essentially these compounds are bio-oils formed during pyrolysis of the biomass in the heat of a fire.

Smoking of meat and fish is still used as a preservation technique for food, and the flavor of smoked meat is appreciated by many.  While smoking food is commonly performed at both commercial and personal scale, the liquid smoke flavoring was created to produce a similar result at industrial scale.  The development of liquid smoke as a flavoring dates back to the late 19th [1-3] century and was designed intended as a replacement for the traditional smoking process. In common practice, the liquid smoke can be produced through pyrolysis, the thermal degradation of wood in a low oxygen environment.  The aerosols and vapors are then collected and fractionated.  The smoke condensates and tars can be further processed to produce the smoke flavoring, which is sold as a product or used as a flavoring agent in food production [4].

In 2003, Regulation (EC) No 2065/2003 of the European Parliament and the Council on smoke flavorings came into force.  In order to protect human health, it required that each smoke flavoring undergo an individual safety assessment before being offered in the market or used with foods, commissioning the European Food Safety Authority (EFSA) as the assessment body.  Smoke flavoring manufacturers were required to submit technical dossiers to EFSA detailing the manufacturing process, the product chemical composition,  and the toxicological properties of each defined primary smoke flavoring product [5].

By the June 2005, 16 applications were submitted.  Of which two were found not to be valid and three applications were withdrawn.

Details for each smoke flavouring primary product provided by the applicants are reported along with opinions of the Scientific Panel on Food Contact Materials, Flavourings, Enzymes and Processing Aids (CEF) which are available from the EFSA website.


[1] Fessmann, G., Food-smoking agent, 1972, pp. 5 pp.
[2] Melville, A., Unusual stories of unusual men: Ernest H. Wright – classification: “Condensed Smoke”, The Rotarian, 240, 209-210 (1923).
[3] Miler, K. and Kozlowski, Z., Preparation for meat smoking, Instytut Przemyslu Miesnego . 1966, pp. 2 pp.
[4] Meier, D., Liquid smoke – an analytical challenge, Fleischwirtschaft International, 37-40 (2005).
[5] Theobald, A., Arcella, D., Carere, A., Croera, C., Engel, K.H., Gott, D., Gurtler, R., Meier, D., Pratt, I., Rietjens, I.M.C.M., Simon, R. and Walker, R., Safety assessment of smoke flavouring primary products by the European Food Safety Authority, Trends in Food Science & Technology, 27, 97-108 (2012).