Pyrazine composition of wood smoke as influenced by wood source and smoke generation variables

Abstract

AbstractA series of 8 pyrazines (pyrazine, 3‐ethyl‐2‐methoxy‐, 2‐ethoxy‐3‐ethyl‐, 3,6‐dimethyl‐2‐propyl‐, 2‐butyl‐3,5‐dimethyl‐, 2‐butyl‐3,6‐dimethyl‐, 2‐acetyl‐3‐methyl‐, 2‐acetyl‐3,5‐dimethylpyrazine) were identified in the smoke generated from 17 different wood sources (white and red oak, walnut, chestnut, apple, redwood, red alder, cherry, aspen, birch, hard maple, eastern cedar, hickory, Lodgepole pine wood and bark, Douglas‐Fir heartwood and sapwood).Hickory produced the largest amount (41.03 mg 100 g wood) of total pyrazines while redwood had the least (10.33 mg). Total and individual pyrazine levels did not appear to correlate with wood nitrogen content nor with the levels of cellulose, hemicellulose or lignin.Smoke generation variables relative to pyrazine formation were evaluated with hickory smoke. Increasing the moisture content from 4 per cent to 20 or 30 per cent resulted in decreased total pyrazine levels. The absence of air decreased total pyrazine concentration while increasing smoke generation temperature from 290 to 450°C increased the total amount of pyrazines formed. Collection of hickory smoke volatiles in an alkaline solution resulted in lower total pyrazine levels than condensate trapped in water.