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

Abstract

A 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-acetyI-3,S-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.

Fingerprints of acacia aging treatments by barrels or chips based on volatile profile, sensorial properties, and multivariate analysis

“…Based on the literature, 2‐acetyl pyrazine, 2‐acetyl‐3‐methylpyrazine and 2‐acetylthiazole have recently been identified as distinctive of acacia wood due to their powerful sensorial features described as toasty, popcorn, nutty . These compounds come from the degradation of cysteine hexose as consequence of the Maillard reaction . Although, the presence of these odorants could not be detected in acacia extracts by gas chromatography–mass spectrometry (GC–MS), probably because their concentrations were below detection limits, they were confirmed by gas chromatography coupled to olfactometry (GC‐O) due to their powerful sensorial impact.…”

The flavor chemistry of wood smoke

“…However, when taste was considered, the smoke produced with high air levels required less to be most desirable, perhaps indicating that a wider variety of compounds or compound concentration was a factor that should be considered. The presence or absence of air significantly influenced the amount of pyrazines formed in hickory smoke (70). With air the total amount was 41.03 mg/ 100 g of wood while when air was excluded during smoldering, the total pyrazine content increased to 51.33 mg/100 g. In all probability, the lack of air minimized formation of certain classes of unstable compounds, thus resulting in larger amounts of more stable pyrazines.…”

“…In evaluating variables that influence the types and amounts of pyrazines formed during wood smoke generation, Maga and Chen (70) reported that the concentration of eight pyrazines increased from 41.03 mg/100 g dry weight wood when hickory sawdust was thermally degraded at 290°C to a total of 59.05 mg/100 g when a temperature of 450°C was used.…”

“…A series of eight pyrazine compounds-pyrazine, 2-methoxy-3-ethylpyrazine, 2-ethoxy-3-ethylpyrazine, 2-propyl-3,6-dimethylpyrazine, 2-butyl-3,5-dimethylpyrazine, 2-butyl-3,6-dimethylpyrazine, 2-acetyl-3-methylpyrazine, and 2-acetyl-3,5-dimethylpyrazine-were identified in the smoke generated from 17 different wood sources (70); and as seen in Table 30, the total pyrazine content ranged from a low of 10.33 mg/100 g of redwood to 41.03 mg/100 g of hickory. There did not appear to be any obvious differences between hardwoods and softwoods.…”

Smoke and liquid smoke. Study of an aqueous smoke flavouring from the aromatic plantThymus vulgaris L

“…31 In addition to the above± mentioned compounds, some alcohols and other compounds such as 2,4-dimethyl-1,3-pentadiene, 2-methylindanone and a lignan, whose mass spectrum has the molecular ion m/z 330 and the base peak m/z 194, have been detected in this liquid smoke. 23 It must be pointed out that in spite of the large number of hydrocarbons present in the smoke, these were practically absent in this smoke¯avouring because they are retained in the glass wool ®lter.…”