On the origin of cigar plume (bloom)
Warning: ramblings of a scientist are below, read at your own risk, LOL. I was warned not to post a thread like this, but I'll take my chances and see if we can get some discussion going here. :-)
Ok, so I’ve been wondering about plume/bloom on cigars for quite some time and thought I’d go see what I could find about where it comes from, basically I wanted to know what causes it to form. It seems to be universally accepted that plume comes from the tobacco oils that rise to the surface of the cigar’s wrapper leaf; I doubt that anyone will argue that point.
My question then is this: when have you ever seen an oil crystallize, especially one at room temperature? I haven’t. This leads me to ask: what is in the tobacco oil that could crystallize? Well, I found an analysis of tobacco oils where the group identified the individual chemicals in tobacco oil using two-dimensional gas chromatography with flame ionization detectors and a time-of-flight mass spectrometer. Fancy chit right there! Here’s the information on the journal article where I found this information:
“Quantitative determination of compounds in tobacco essential oils by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry.”
Journal of Chromatography A, Issue 1086, Pages 107–114 (2005).
The results are pretty interesting (to me at least, LOL, but I’m a scientist). Here are the top 10 most abundant chemicals and what percent of the total they make up (there were dozens of other chemicals that made up the remainder of the sample):
(The chemicals were identified in the journal article I mentioned above, then I just went to various online sources to learn more about each chemical, so the info below is not off the top of my head, some is directly copied and pasted omitting quotes for an easier read, although I throw in some of my ramblings here and there.)
14.53% Propylene glycol
Propylene glycol, known also by the systematic name propane-1,2-diol, is an organic compound (a diol alcohol), usually a faintly sweet, odorless, and colorless clear viscous liquid that is hygroscopic and miscible with water, acetone, and chloroform. If this is formed as a fatty acid ester, this can yield a white solid form of propylene glycol. Propylene glycol esters of fatty acids are mixtures of propylene glycol mono- and diesters of saturated and unsaturated fatty acids derived from edible oils and fats.
1.72% Ethyl acetate
Ethyl acetate is a colorless liquid that is a volatile and somewhat polar solvent commonly found in nail polish remover. This likely will not crystallize as it would more likely evaporate once it hits the surface and comes in contact with air. However, as a polar solvent, it is possible that it could dissolve sugars within the tobacco and act as a carrier to bring the sugars to the surface. Once at the surface, the ethyl acetate would evaporate and leave behind the sugar, which would be in crystalline form.
1.62% Propanoic acid (ethyl ester)
Propanoic acid is a colorless liquid that can be solid if it's the anion of a salt. Propanoic acid as a solid salt is commonly either: sodium propionate, calcium propionate, or potassium propionate. The calcium and potassium propionates form white crystals, and the sodium propionate forms transparent crystals. So depending on the soil that the tobacco is grown in, different amounts of sodium, calcium, and potassium could lead to different forms of the propionate crystals.
1.32% Benzyl benzoate
Benzyl benzoate is the ester of benzyl alcohol and benzoic acid. This colorless liquid is formally the condensation product of benzoic acid and benzyl alcohol.
1.07% Ethyl maltol (4H-Pyran-4-one, 2-ethyl-3-hydroxy-)
Ethyl maltol is an analog of maltol, where the methyl group on maltol is substituted with an ethyl group. It is a stable white crystalline powder at room temperature and easily dissolves in many polar liquids. This chemical has a sweet odor that can be described as caramelized sugar and cooked fruit. It is an important flavourant for the food, beverage, and fragrance industry. Ethyl maltol is non-toxic, highly pleasant to human sense of smell, and easily detected by the human, with as little as 10 parts per million perceivable in air.
0.97% Isoamyl acetate (1-Butanol, 3-methyl-, acetate)
Isoamyl acetate is a clear colorless liquid that is only slightly soluble in water, but very soluble in most organic solvents. Isoamyl acetate has a strong odor (similar to juicy fruit), which is also described as similar to both banana and pear. Banana oil is a term that is applied either to pure isoamyl acetate or to flavorings that are mixtures of isoamyl acetate, amyl acetate, nitrocellulose and other flavors.
5-ethyl-2-methylpyridine is a colorless, clear liquid with a very strong odor of nuts, raw potatoes, and earth.
Acetophenone is an organic compound and is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances. Acetophenone is used to create fragrances that resemble almond, cherry, honeysuckle, jasmine, and strawberry, and it occurs naturally in many foods. It is used in chewing gum. At one time it was used as a hypnotic under the name of "hypnone." In a 1994 report released by five top cigarette companies in the U.S., acetophenone was listed as one of the 599 additives to cigarettes.
0.43% Amyl acetate (Acetic acid, pentyl ester)
Amyl acetate is an organic compound and an ester with a scent similar to bananas and apples, which is not detectable by all people.
0.37% Dihydroxyacetone (2-Propanone, 1,3-dihydroxy-)
Dihydroxyacetone is a simple carbohydrate that is primarily used as an ingredient in sunless tanning products. It is often derived from plant sources such as sugar beets and sugar cane, by the fermentation of glycerin. Dihydroxyacetone is a triose carbohydrate. It is a hygroscopic white crystalline powder and it has a sweet cooling taste and a characteristic odor. It is the simplest of all ketoses and, having no chiral center, is the only one that has no optical activity.
So, the chemicals in highest abundance that are either solids or can form solids are: propylene glycol, propanoic acid (as propionate crystals), ethyl maltol, and dihydroxyacetone. Also, ethyl acetate could be acting as a carrier to bring sugars to the surface of the cigar.
Yeah, I recently had some free time and got bored. My mind is a dangerous place when it's not working... so I did this to keep it active. :-)