I was expecting caramel to make for a fairly easy scent study, but as it turns out, caramel is surprisingly complex.
Not only is the history of caramel hard to trace, but the scent of any given caramel depends on both the ingredients and the cooking process.
It seems unbelievable, but many of the odorants that make the scent of caramel have yet to even be identified!1
Where is caramel from?
A quick google search will tell you that the answer isn't so simple. There is very little evidence for the actual origin of caramels as we know them today.
Some sources claim that caramel was an American invention, created around 1650 by sweet toothed European settlers who cooked sugar and butter until chewy. Others claim that caramel can be traced back to the year 1000 in the Middle East, where sugarcane was already being cultivated and boiled down to create a golden hard candy. Meanwhile, dulce de leche can supposedly be traced back to the early 1800s in Argentina, and caramel au beurre salé was reportedly popularized in 14th century France.
(There are, apparently, no readily available primary sources for any of these histories—in trying to track historical documents down, I ended up realizing that most articles about the history of caramel end up referring to each other as sources.)
Tracing caramel's etymology doesn't help much, either. The word caramel in English comes from the French caramel, which dates back to the 17th century. In turn, that word came from the Spanish caramelo, which is given two alternate histories. In one, caramelo comes out of the Medieval Latin cannamellis, which referred to sugarcane2; in the other, it originates with kora-moħalláh, an Arabic word that is (nebulously) claimed to mean "ball of sweet".3
Essentially, we know that something like caramel existed in each of these regions of the world at some point over the last 1000 years.
But if caramel existed so distantly across time and place, spanning at least four continents and a millennium, how can we be sure we're talking about the same candy?
The answer is caramelization!
Even across such great distances of geography and history, caramel-makers would have to start with the same basic ingredients in order to achieve caramelization: sugar and heat.
When sugar is slowly heated, the crystals begin to melt, and after a certain point, the sugar reacts further to the heat and begins to brown.
As the sugar breaks down over the heat and the chemical reaction for browning begins to occur, volatile odor chemicals are released, putting the sweet nutty smell of caramelization into the air.4
Arguably, any sweet treat that is made mostly of caramelized sugar could be called a caramel! But in the US and western Europe, caramel has a more specific meaning, because it includes at least two other ingredients in addition to sugar: butter and milk.
The addition of butter and milk add protein to the mixture. When cooked, the amino acids in them react with the reducing sugar in a Maillard reaction5, which gives caramel its distinctive color, taste, and scent.
When this type of caramel is prepared, dozens of volatile odor compounds influence the scent that our noses pick up.
Quite a few of these compounds are identifiable by GC-MS (gas chromatography mass spectrometry) analysis, and can be isolated in a lab setting, but few of them are available to perfumers—for example, acetylformoin, dihydromaltol, and (E or Z)-3- (2-furanyl)-2-propenal are important components of caramel's odor4, but they aren't commercially available (at least, not to small perfumers).
Luckily, there are other key odorants that we can study more easily!
Among various samples of caramel studied between the 1990s and mid 2000s, furfural, acetoin, maltol, and cyclotene have been identified as important aroma compounds.6–7
In addition to these four, I've decided to add a fifth aromatic material to the scent study—sotolone, or caramel furanone—because it just fits so perfectly with a caramel accord.
Furfural, also called furfuraldehyde, is also found in coffee, oak wood, whiskey, bread, cake, wheat bran, oats, and sawdust. It smells nutty, bready, and warm, with slight nuances of almond. It's very gently woody, and has a distinctly baked aroma—like the smell of baked bread, rather than bread dough.
Even though furfural is quite common in natural extracts, it is highly, highly restricted for fragrance use.
Furfural is hazardous: not only is it carcinogenic to small animals, but even in minute quantities, it can be toxic when inhaled, absorbed through skin, or ingested.8
Due to the potential for harm, the International Fragrance Association (IFRA) restricts the use of furfural to 0.001% of the finished product.9
Although furfural won't be included in our caramel accord for this reason, it's a part of our scent study because it's so common in caramel! Furfural was detected in 83% of caramel samples in a 2014 study.10
Since furfural is a product of dehydrated sugar, and the process of caramelization involves the dehydration of sugar, it's no wonder that furfural is so common in caramel!
Butter is essential to the creation of caramel—so let's talk about a butter molecule!
At full strength, acetoin has an intense aroma of sour dairy, but when heavily diluted, it gets creamier, sweeter, and mouthwateringly gourmand.
Artificial butter flavoring often relies on the taste and scent of acetoin11, which might be why this molecule also reminds some people of the smell of buttered popcorn!
Fascinatingly, acetoin provides a creamy butter note to lots of other odors and flavors, both natural and synthetic.
Naturally occurring acetoin can be found in apples, blackberries, leeks, brussel sprouts, scallops, beer, wine, milk, honey, coffee, wheat, maple syrup, and lots of other foods.
Acetoin's sour fruity nuances make it useful in artificial strawberry flavoring, but it's also used to give a creamy, buttery, or gourmand effect to lots of pre-packaged food products.12
In a caramel accord, acetoin provides the creaminess of milk and butter. It smooths out the sugary aspects, making the accord smell like caramel rather than maple syrup or cotton candy.
Both maltol and ethyl maltol are commonly used in perfumery to create the smell of sweetness and sugar, but our scent study focuses on maltol for two reasons: first, maltol is one of the most important odorants in most forms of burnt sugar13, and second, maltol's sugary note suits our caramel accord better because of its baked nuances.
Although maltol can be found in a variety of foods, it gets its name from the maltose found in roasted malt. Unsurprisingly, maltol is common in dessert-like artificial flavorings.
To my nose, the sugariness of ethyl maltol is reminiscent of cotton candy, red berries, and fruit jam; the scent of maltol leans more toward the sugary notes in cake, butterscotch, candy, and chocolate.
There are lots of sugary aromachemicals, but our caramel accord uses maltol for its warm, bakery gourmand vibe.
Just a touch of maltol is needed for a caramel accord. With such a distinct sugary scent and an odor that lasts a week or more on a test strip, a little maltol goes a long way!
Our next molecule, cyclotene, goes by many aliases!
Among the most common are methyl cyclopentenolone (a name which refers to its chemical structure) and maple lactone (because it's a key odorant to the smell of maple syrup!).14
Cyclotene has a sugary aroma, but it very specifically smells like cooked sugar, complete with golden-brown color and syrupy richness. To me, the smell of cyclotene is also textured—like the feeling of sticky syrup or chewy fudge. It's not a light-smelling sugar note, but a heavy one.
In small doses, cyclotene can be used in gourmand perfumes, but also to add depth and richness to florals, vanilla, and fruity notes, but also to smooth and sweeten ambers and woody accords.
In a caramel accord, cyclotene is indispensable for its aromatic texture. Without it, a caramel accord can smell like glassy caramelized sugar—caramelized but clear, like a burnt sugar syrup, or like homemade candy scraped off the bottom of a hot pan.
Cyclotene adds not only the rich aromatic texture of real caramel, but also the distinctly browned scent of caramelized sugar!
Meet the last molecule in our scent study: sotolone!
With other names like sugar lactone and caramel furanone, you can probably guess what sotolone smells like.
Sotolone has an extremely intense sugary aroma. It's not technically restricted by IFRA, but you probably wouldn't want to use sotolone at more than a fraction of a percent of a formula.
In my studio, my tiny vial of sotolone is double-bagged (in case of leakage) and then stored in a series of three tupperware containers that get progressively larger. I have to open the windows before even opening the outermost container, because within minutes, the smell of sotolone can fill the studio and start drifting out into the rest of the building!
(To use it, I keep a bottle of sotolone diluted to 0.1%. All of my formulas are small batch, and even a drop of the the pure stuff would overwhelm any of them. When it's time to mix up more of the working dilution, I try to work as quickly as possible so that I don't blow out my sense of smell. Sotolone is incredibly stong!)
Sotolone is also likely responsible for the maple syrup smell that's been occasionally drifting over New York City since 2005! Sotolone is the major odorant in fenugreek seeds, and since the compound is so strong, the aroma travels from a fenugreek seed processing plant in New Jersey.15
In addition to smelling like sugar, fenugreek, and caramel, sotolone also has notes of maple syrup, rum, molasses, curry, and even sweat, depending on the dilution level.
Sotolone can be used to add sweetness to a fragrance, and is especially useful for gourmand notes, as well as alcohol notes like whiskey, rum, and wine.
While sotolone isn't strictly necessary for a caramel accord, I've added it to ours because I like a mouthwateringly sweet caramel! For a caramelized note rather than a straight caramel, sotolone is probably best left out.
CARAMEL ACCORDS IN PERFUME
Like any accord, the ingredients used for a caramel note will always depend on the goal of the perfumer. And of course, this list isn't exhaustive—every perfumer has their preferred ingredients. But these materials are a good starting place!
For more caramellic ideas:
🍬 caramelized sugar: maltol/sotolone/maple lactone + smoky materials (guaiacol, syringol, rectified cade)
🍮 the caramelized crust on crème brûlée: sotolone, homofuronol, vanillin, heavily diluted sulfurol
🥞 caramel syrup: cyclotene, methyl laitone, butyl butyro lactate/acetoin, isobutavan, tonka bean absolute
Always check IFRA guidelines, read safety data sheets, and follow proper lab protocols before blending any materials!
Normally, these scent studies end with a simple accord. But since caramel accords can be so different depending on what goes into them, I wanted to do something different this time!
Instead of sharing a basic accord that demonstrates how the compounds in our scent study fit together, I'm sharing a formula that shows how these compounds fit into a larger scent.
This caramel candy accord is the backbone for our very own Caramelo—the next time you smell that perfume, come back and look at this accord!
As always, this is just one example—there are always other paths to caramellic goodness. Take joy in the process of experimentation and discovery!
Happy blending! :)
1: Paravisini, L., Gourrat-Pernin, K., Gouttefangeas, C., Moretton, C., Nigay, H., Dacremont, C., & Guichard, E. (2012). Identification of compounds responsible for the odorant properties of aromatic caramel. Flavour and Fragrance Journal, 27(6), 424–432. https://doi.org/10.1002/ffj.3111
2: Caramel. Wiktionary. (n.d.). Retrieved November 21, 2022, from https://en.wiktionary.org/wiki/caramel
3: Wikimedia Foundation. (2022, November 20). Caramel. Wikipedia. Retrieved November 20, 2022, from https://en.wikipedia.org/wiki/Caramel
4: Paravisini L et. al. (See 1.)
6: Pons, I., Garrault, C., Jaubert, J.-N., Morel, J., & Fenyo, J.-C. (1991). Analysis of Aromatic Caramel. Food Chemistry, 39(3), 311–320. https://doi.org/10.1016/0308-8146(91)90148-h
8: Reed, N.R., and E.S.C. Kwok. “Furfural.” Encyclopedia of Toxicology, 2014, 685–88. https://doi.org/10.1016/b978-0-12-386454-3.00147-0.
10: Paravisini L et. al. (See 1.)
12: Sampling and Analytical Methods: Acetoin, Diacetyl, n.d. http://www.aresok.org/npg/nioshdbs/oshamethods/validated/1012/1012.html.
14: “Flavor Bites: Methyl Cyclopentenolone.” Perfumer & Flavorist, November 30, 2018. https://www.perfumerflavorist.com/flavor/ingredients/article/21856905/flavor-bites-methyl-cyclopentenolone.