Reference point
A pile of straw burning in the fields after the harvest.
Do this before you read on. An entry only works when you have just smelled the thing.
Dry, burnt, slightly sweet, with notes of tobacco and tar. It clings to hair and fabric stubbornly, sometimes through a wash.
The compounds behind this smell — guaiacol, syringol and their relatives — are also found in wood used to smoke food and in some teas. The same family of molecules in three quite different settings: a field after the harvest, a smokehouse, a teapot.
Burning straw and burning firewood differ. Straw gives a lighter, sweeter, less tarry smell; hardwood gives a heavy smell with more tar.
How to smell it
If you are near the countryside, find a pile of straw burning after the harvest and stand downwind about twenty metres away. Otherwise, burn a handful of straw or dry leaves in a metal bucket outdoors. Smell the thinned smoke, not the dense smoke.
Why this one is hard
Because smoke stings the eyes and irritates the airways, so people retreat before they can analyse. Standing well back and downwind is essential.
Don’t confuse with
This entry
Straw smoke
Smoky & Mineral family
Straw gives sweet, tarry smoke; charcoal has burned off all its volatile part, so only a dry, mineral heat remains.
This entry
Straw smoke
Smoky & Mineral family
Straw smoke is sweet, with plant resins; asphalt is burnt, dense, entirely mineral and without any sweetness.
Scientific note
Straw smoke is the product of low-temperature, oxygen-poor pyrolysis of cellulose and lignin. Lignin yields phenols such as guaiacol and creosol; cellulose yields furfural. Hardwood contains more lignin than straw, so its smoke is richer in phenols — which is why wood smoke and straw smoke do not smell the same.
In Vietnamese life
Burning straw after the harvest is a long-standing practice now restricted because of air pollution. For many people born in the northern countryside it is the smell of the sixth and tenth months of the year, and it is fading from the memory of later generations.