Back in the first week of September, a large part of the very large state of Texas was on fire. There was so much fire that the Texas Department of Transportation had a live fire map on their website. It showed many small animated flames scattered around the state, and one really enormous campfire-sized flame in Bastrop County, about 35 miles away from my home in Austin.
Local news compared the size of the Bastrop fire to the state of Connecticut. Its smoke plume was visible from space. Satellite photographs showed a dark point that widened as it traveled south until it trailed away in a ragged, fanned out fringe into the Gulf of Mexico. In Austin, we could see great black clouds of smoke on the horizon and, later, a gray-white sky. And of course, we could smell it.
Because scent is invisible to the naked eye, we tend to think of it as intangible. Once, I even saw an announcement for an academic forum on smell and architecture that referred to odor as "abstract." But though we might not be able to hold an aroma in our hands, every time we smell something we've come in direct, intimate contact with tiny bits of it.
Smoke makes the physical presence of scent clear. (As does steam: In comics, odor is nearly always drawn as series of wavy lines rising up from the smelly thing, like vapor rising from a bowl of soup.) Because smoke is made of water, carbon and particulate matter in addition to aromatic and other molecular compounds, most of the time we can see it. Even when we can’t, we can feel it scratching at our eyes, drying our mouths and throats and, if there’s enough of it, making our chests ache. Aromatics get a free ride on all that particulate matter — anyone who’s sat by a campfire, or who remembers the days when you could smoke in a bar, knows how thoroughly the scent of smoke can permeate hair and clothes.
The scratchy, clinging, insinuating nature of smoke allows us to turn its scent into a flavor. Before I moved to Texas, I found the smell of wood smoke haunting, autumnal — a sign of the first truly cold gray days of winter. Now it makes me think of barbecue — the scent of meat cooking, curing, really, in a smoky bath of the best concentrated flavor hardwood has to offer. (Smoke from softwood like pine smells great, but tastes terrible because it has high levels of the substances we distill into turpentine.)
If you have even a passing familiarity with aromachemicals, the stuff that makes wood smoke smell great is probably familiar to you. Wood is rich in vanillin, the central aromatic compound in vanilla. (As Luca Turin pointed out in Perfumes: the Guide, this accounts for the rich scent of used bookstores: Paper is wood pulp. As it decays it releases vanillin.) Wood smoke also smells of isoeugenol, a variant of which provided the scent of peppery cloves in many perfumes until it was recently restricted by IFRA. Guiacol (a relative of that mysterious "guaiac wood" note listed in some of my favorite perfumes?) and syringol provide, as far as I can tell from my limited research,1 the scent and flavor we most associate with "smokiness." When food scientist Harold McGee wants to approximate the scent of smoked meat for his oven-roasted ribs, he uses substances that contain these aromachemicals: smoked pimentón or chipotle pepper, cloves, cinnamon and vanilla.
The way the process of smoking releases and then captures these aromatics is not so different from the the steam distillation of aromatic oils. In steam distillation, the heat of the water vapor breaks down the cell walls of fragrant plant material. The volatile oils then rise up with the steam. When that water condenses, the oil rises to the top. (The fragrant leftover water is called a hydrosol — rose water, for example). In a barbecue pit, heat breaks down the wood’s cell walls and the volatile aromatics rise into the air where they are absorbed into the meat.
The crucial, delicious difference between smoke and steam is caramelization. The aromatics in wood are found primarily in lignin, the material that gives wood its stiff structure. But wood cells are mostly made up of cellulose and hemicellulose — relatives of glucose. When wood burns, its sugars brown and deepen in flavor more or less the way sugars in an onion do when you fry it (not to mention the sugar in cookie dough).
Hardwood is not the only thing that releases sweet and savory aromatics when it burns. The Wikipedia article on cooking with smoke reads like a found poem of flavor and ingenuity. In China, cooks smoke food over tea, sugar and spice. (And tea itself is smoked over wood smoke to create Lapsang souchong.) Some ham and bacon is smoked over corn cobs. (Originally left over from the corn fed to the pigs?) Barley smoked over peat is responsible for the smoky notes in whiskey, and in New Zealand “sawdust from the native manuka (tea tree) is commonly used for hot smoking fish.” While over in Iceland, “dried sheep dung is used to cold smoke fish, lamb, mutton and whale.”
Of course, smoke can also smell like a warning against danger: Where there’s smoke there’s fire. And it can smell like poison — many materials become deadly when burned, and even woodsmoke contains carbon monoxide. While the Bastrop fire and others burned around the state, I am sure that for many smoke became the scent of fear and of loss. It was for that very reason that I felt the need to read more about smoke and its scent, even while my head ached from breathing it in, and from keeping up with the news of evacuations. I wanted to remember both sides of smoke — the cloud on the satellite photo and the plate of barbecue offered to a tired firefighter or a Bastrop resident in need of a taste of home.
1. The Wikipedia article I mention above is startlingly helpful — it was just what I needed. But I don't fully trust Wikipedia. So I cross-referenced its claims as best I could, partly through Harold McGee's books, New York Times column and website, partly by looking up the aromatic compounds in question, and partly by talking to the air quality engineer I mentioned in this post. Mistakes in interpretation are my own. As usual, I welcome corrections from our knowledgeable readers.
Note: top image is Massive Fire Across Lake Bastrop [cropped] by GalgenTX at flickr; some rights reserved.
Wow, what a very interesting article. The fact that paper has vanillan in it, this making old books smell sweet, is a link I would have never made on my own. I will have to pass that tidbit on to my librarian friends. : )
Hi Everyone! Sorry for the late replies–I was traveling yesterday.
Halimeade–do look up the exact quote in The Guide if you can. Luca says this really wonderful thing about that smell being divine providence’s reward for our search for knowledge–very funny and wonderfully written as always.
Now if they could just produce a scented Kindle…
I hope your nose and lungs were not too adversely affected by the unwanted Texas smoke. The effects of that drought are not widely understood in the East. Whereas you had a drought, we had record rain levels. We were drowning (literally in the case of an unfortunate volunteer rescue worker in New Jersey) with the rain that you so desparately needed in Texas.
Nonetheless, I know your drought was severe as your post so clearly portrays.
Thank you, Dilana. I’m sure the effects were relatively mild compared to what the residents of Bastrop experienced. And yes, I have relatives in upstate New York, so I was tracking the floods at the same time that I was watching the fire map. Something is so clearly out of balance.
Years ago at an American PX store I bought a bottle of liquid smoke., and it certainly upped the bar-b-que aspect of my oven-baked ribs…
Ha! Oh, Annie, liquid smoke is very–shall we say, controversial?–in the barbeque world. And it is a world unto itself, just like perfume, with a history, and rules and hierarchies and arguments. But I’d bet that guaicol and syringol play a part in that liquid smoke.
I got to enjoy the concert of a lifetime las night in Austin (Willie Nelson, Lyle Lovett, Dixie Chicks, George Strait) to benefit our neighbors in Bastrop. My heart is heavy for all who are putting their lives back together, but it was very uplifting to see such community support. Hope all are having a blessed and count your blessings day.
Oh, MAN, I wanted to go to that! Lucky you! Did they do any special tributes to the firefighters in the audience? I heard there were a thousand of them there as special guests.
The effects of the Bastrop fire were truly devastating.
It was a great show! And they did recognize a big group of first responders.
I am just up I-35 from you. The school my kiddos attend collected tons of stuff and drove it down. And we always made sure to donate every time we shopped at our local HEB. It’s been a rough summer for us Texans, and those affected by wild fires this year.
Sadly, I think the smell of smoke in the air will have a tinge of fear for us for a while.
It’s great to hear about that school drive, Joella. And yes, I do agree with you about that tinge of fear. My husband and I went for a walk the other night. I smelled smoke and was pretty sure it was only someone grilling (but how stupid, anyway, to be doing that) but I couldn’t help listening for sirens and wondering if I should call 911. I can only imagine what it’s like for folks who were directly affected by the fires.
Wonderfully informative! My favorite “smokey” scent is that of tanned moosehide slippers or mitts. In the far north of Canada, moose hide is still tanned in the old way and smoked, which gives it a deep, rich color. Then the women make slippers (aka moccasins) and mitts with beautiful beadwork and trimmed with fur, usually beaver. These garments remain fragrant with smoke for a year or more and ….I think it’s a beautiful scent! I love it when my husband comes home from the far north with a new set of slippers or mitts, a gift from one of his clients.
Wow, that is such a cool thing to know about, thank you for telling us! Did you know that one of the early uses for perfume was to counteract the scent of tanned leather?
Bushfire is an awful reality every summer in Australia. Bushfire smoke is certainly the scent of fear and loss for many people. Many Australians can name their ‘Ash Wednesdays’ and their ‘Black Saturdays’ – the fires of their district. The tiniest whiff and people squint apprehensively at the sky, searching for the signs. A couple of suburbs in my city were burned pretty completely in 2003.
Thanks for your article – a sensitive subject nicely handled. I too love the scent of old bookshops!
So true! As a small child we had devastating fires here, it came up to the school. We were evacuated and had to sit in the ocean. Now, in summer, if I catch the smell of burning eucalyptus I panic.
Understandably! And that makes me realise that the scent of forest fire would vary according to the local trees, in different regions and countries. I had not that about that much. For Australians, as you say, it is eucalyptus.
Annemarie and Debbie, I grew up in Idaho and we had terrible wildfires every summer, largely in the unpopulated center of the state, thank goodness, so my memories aren’t as fearful as Debbie’s, but I know a little about what it’s like to smell smoke and wonder. (But not eucalyptus smoke, which is surely a very specific smell–they probably know it Northern California, though.) When the fires happened in Texas I was much more panicked about it than my husband. Once you know how fast flames can move with the wind it’s hard to feel completely safe.
But I also grew up looking forward to campfires and fires in the fireplace, and I always loved the smell that clung to my hair and my wool sweaters. I imagine that Australia has similar traditions including, famously, grilling over an open flame. Always the two sides…
Yes indeed, fire can be a force for good. In Australia it was used by Aboriginal people for thousands of years as a means of controlling the landscape and the food supply. I’m not much of a camper but people here do love an open fire. Of course at mid-summer, total fire bans mean you can’t light fires of any sort in the open.
Yes but its such a shame that there are those few idiots who, each summer, purposely light bush fires. If i lived in the suburbs it would be so much easier, but we live in a semi bush setting. We had 30c yesterday and, yes, some idiot was burning off! But I do love summer and I do love the smell of bbq smoke!
Thank you for a very interesting & informative article Alyssa.
I have a couple of friends in Texas and was worried about the severe drought conditions there this past summer. I believe things are slowly improving for you these days, thankfully.
The first I learned of the connection of old books to the smell of vanilla was in Perfumes: The Guide, as part of the review for Dzing!, and loved learning that little tidbit.
Yes! The Dzing review–that’s the exact bit.
We have gotten a bit of rain lately and the heat broke a few weeks ago, thank god, but I remain worried about long term drought. It was scary to see how fragile the system really is.
Fascinating post -thank you! Even north of Dallas, we could smell the smoke from your area, and worried about all of the people affected. Our recent rains have been welcome, but the danger hasn’t passed us by yet – we’re still in drought conditions. Send us some rain, y’all!
Maggie, I do believe there were some fires closer to Dallas as well as south of Austin, but it’s amazing how far that scent carries, isn’t it?
I’m still worried about drought, too. Did you see the news of the dust storm in Lubbock? Grapes of Wrath territory.
I’ve been wearing Barbara Bui perfume a lot lately, which smells just like old paperbacks to me. Very appropriate, as I drive to work – at the library.
A librarian in Barbara Bui. Surely that is the opening line to some wonderful short story…
What a GREAT article. Kudos
Thank you!
Wonderfully written article and very timely for the season. Thank you for the information, you kept me interested in the science aspect while making it very visceral as well.
I’m glad you enjoyed it, Ruth.
Fascinating! Thank you, Alyssa!
Thanks, H!
Here in California we’ve had several fires in the nearby mountains in the past few years that have spread smoke and ash—like snow on sidewalks, on leaves, on cars—and really brought home the “physical presence” of the scent of smoke. But I never really thought about the different components of the fragrance of burning wood, like vanillin or caramelizing sugars. Fascinating article, thanks!
Janice, that caramelized sugar thing was a real revelation to me. It made so much sense with the smell once I learned it.
Ash like snow–the last time I encountered that was when Mt. St. Helen blew. Stay safe.
Now I know why I like to smell wood and wood smoke so much. Thank you for such a great article.
I so glad you liked it.
Make that “I’m.”