Burning Issues

[Ed. 12/2002 -This is an extremely strange report: Chocolate has anti-oxidents also as probably most plant material could have. Chocolate might be an even better and cleaner heating fuel, but do sane people want to use it? This report focuses on anti-oxidents but seem not to take into account the deadly fine particulate and gases that are emmitted from all wood burning. Ms Kjallstrand seems in favor of wood as a cooking fuel and heating fuel. We presume Ms. Kjallstrand has measured this new technology in the field? She has extracted her magic protective bullets with syringes, they are not human lungs subject to the scaring and severe inflammation that wood smoke does elicit. How much benzene or dioxin is a 'safe' amount. Excuse me, we could have to have the body do the math. Poison + poison + carcinogens + fine particulate + current age + current health - all those antioxidents! Voila - wood smoke is wonderful again. This paper has been seized upon by even government scientists who love wood smoke.]

1: Sci Total Environ 2001 Sep 28;277(1-3):69-75

Phenolic antioxidants in wood smoke.

Kjallstrand J, Petersson G.

Department of Chemical Environmental Science, Chalmers University of Technology,
Goteborg, Sweden.

Ten prominent dimethoxyphenols were determined in birchwood smoke from choked
and open laboratory burning and in chimney smoke from a tiled stove. The
structures of the methoxyphenols are similar to those of the well-known
tocopherol and ubiquinol antioxidants. The 2,6-dimethoxyphenols characterising
hardwood smoke are stronger antioxidants than the corresponding 2-methoxyphenols
present mainly in softwood smoke. The antioxidant activity is highest for the
2,6-dimethoxyphenols with 4-alkenyl and 4-alkyl groups, which constitute 60-70%
of the total amount of dimethoxyphenols. Phenolic antioxidants are scavengers of
oxygen radicals and should be considered when health hazards of small-scale
incomplete biomass burning are estimated.

PMID: 11589408 [PubMed - indexed for MEDLINE]

Subject: Phenolic Antioxidants in Wood Smoke (http://www2.lib.chalmers.se/cth/diss/doc/0 Date: Mon, 2 Dec 2002 1
Phenolic Antioxidants in Wood Smoke : Chalmers dissertations
Jennica Kjällstrand
School of Chemical and Biological Engineering, Department of Chemical Environmental Science Postgraduate Programme in Bioscience, 2002

Smoke from residential wood burning constitutes a complex mixture of organic compounds with varying environmental and health effects. This thesis focuses on antioxidants and aromatic hydrocarbons emitted from small-scale burning. Smoke samples were collected from laboratory experiments and in chimney outlets from stoves, using gas-tight syringes or adsorbent cartridges. Specific components were assessed by gas chromatography and mass spectrometry.
Primary thermal decomposition products from cellulose and lignin constituted a large part of the organic fraction from incomplete combustion of wood. The lignin-related methoxyphenols are, due to their varying chemical structures, more or less effective antioxidants. Smoke from hardwood burning contained the more efficient 2,6-dimethoxyphenols, whereas softwood smoke almost only contained 2-methoxyphenols. An alkenyl or alkyl side-chain renders the antioxidant stronger, while a carbonyl group reduces the effect. The presence of phenolic antioxidants should be considered when the health hazards of wood smoke are estimated. Antioxidative 2,6-dimethoxyphenols were the predominant aromatic compounds in smoke from birchwood burning as well as from low-temperature pyrolysis of alder chips, used for meat curing. They improve both the taste and the quality of the foods. [ ?Ed. I have lost my 'taste' for smoked foods I feel like I am becoming smoked meat myself]. Incomplete combustion of newsprint released coniferyl alcohol as the major methoxyphenol. Newsprint is often used to set wood on fire.
Methoxyphenols as well as 1,6-anhydroglucose from cellulose were released at inefficient burning. These compounds appear mainly condensed on particles at ambient temperatures. On more efficient burning, the total amount of organic compounds decreased in the smoke. However, the proportion of the hazardous polycyclic aromatic compounds increased. The carcinogenic benzene was assessed as a prominent aromatic compound in smoke from all studied types of biomass burning, although the ratio to other organic compounds increased with the combustion temperature.
A comparison was made between smoke from a tiled stove and a conventional wood boiler. Stove burning released methoxyphenols and 1,6-anhydroglucose, while the boiler emitted large proportions of benzene and polycyclic aromatic compounds. Oxidative pyrolysis of wood pellets released methoxyphenol antioxidants from the flaming combustion phase. Benzene was the predominant aromatic compound from glowing pellets. New available technology for residential wood burning, including wood pellets and eco-labelled boilers, drastically decreases the emissions of antioxidants as well as hazardous aromatic hydrocarbons through highly efficient combustion.
Keywords: methoxyphenols, biomass, wood, lignin, smoke, combustion, antioxidants, benzene

( jennica kjallstrand )



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