What is the Chemistry behind the Aroma of Dark Chocolate?
The article I choose is discusses work by researchers who were looking for the chemical reasoning behind the smell of dark chocolate. The researchers in the study were observing dark chocolate with 90% to 99% cacao content, which has grown more popular in recent years. Using a variety of analytical techniques, the performers of the study found that 77 unique chemicals could be contributing to the chocolate aroma. Of those 77 unique chemicals 30 were chemicals able to be detected by humans.
The compounds were identified using the systematic sensomics approach using, including solvent extraction, separation of the volatiles, identification using aroma extract dilution analysis (AEDA) based on gas chromatography-olfactometry (GC-O) combined with GC-MS, and quantified by stable isotope dilution analysis, calculation of odor activity values , and recombination experiments.
The interesting thing about their discovery is that many of the substances by themselves have awful smells, but that they combine to form a pleasant scent people want to eat. The article brings up the fact that acetic acid, which makes up a large portion of chocolate, smells like vinegar, which is a smell that most wouldn’t want their chocolate to smell like. The compound 3-methylbutanoic acid was also detected in the sample and has a "rancid, sweaty stench. Dimethyl trisulfide found in the chocolate samples smells like cabbage on its own, in fact it is a common organic byproduct produced in bacterial decomposition, according to the paper the article references.
Table of Identified Compounds and their Odors
Using the knowledge of the known compounds in the dark chocolate aroma, the researchers were able to recreate the aroma of chocolate using only 25 of the compounds in the study. The research they performed will help future researchers determine what may have gone wrong in many other food samples when the smell or scent of the food is off.
References:
J. Agric. Food Chem. 2019, 67, 20, 5827–5837
Chem Draw Online. PerkinElmer
We are all interested in chocolate so this is a sure-fire topic. The New York Times evidently thought so as well. Your explanation is a good deal more technical than the times piece. It is very interesting to me, but perhaps a little less so to the general reader. The thing to do in a piece like this is to hit the general interest stuff early and tack the more technical stuff on the end for the truly determined. Thus your third paragraph should perhaps be your second paragraph. Your second paragraph should perhaps be tacked on at the very end. On the whole though, an interesting piece.
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