Fresh coffee has a rich smell. Some people find coffee smell attractive, while others feel it is too strong. But believe it or not, coffee has a smell comparable to that of skunk spray. If your olfactory sense is extremely sensitive, you may notice this smell.
But why does coffee smell like skunk to me? It is the aroma chemicals found in coffee that closely resemble those of skunk spray. Although these chemicals are relatively similar, they are not identical. Fortunately enough, the skunk smell in coffee is weak and not as strong as skunk spray.
The Chemical Composition of Skunk Smell
The chemicals responsible for the skunk spray smell are thiol derivatives. To be specific, n-butyl mercaptan (CH3-CH2-CH2-CH2-SH), which is a derivative of sulfur alcohol gives skunk spray its smell. The –SH group portion of this compound is responsible for the smell.
It is a sulfur atom that is bonded to a hydrogen atom. It is similar to the alcohol group (-OH). The –SH group is also modified chemically using acetic acid (CH3-COOH), which forms thioacetate.
The most unpleasant skunk spray mercaptans are 3-methyl-butanethiol and (E)-2-buten-1-thiol. These mercaptans make up about 2/5 of the dreaded skunk spray. Its double bond intensifies the skunk smell.
The Chemical Composition of Coffee Smell
Coffee aroma is brought about by two thiols (mercaptans). These mercaptans are furfural mercaptan (C4H3O-CH2-SH) and methyl mercaptan (CH₃-SH). It is the same furfural mercaptan used in the fragrance industry to manufacture coffee scents.
The molecular structure between coffee and skunk smell mercaptans has some similarities. The sulfur bonded to hydrogen (SH) is the common denominator linking skunk and coffee smells. However, these mercaptans are only present in small amounts in coffee. It is hard to detect them, unless when using a gas chromatograph. Thus you do not have to worry about drinking coffee due to the skunk smell as you can hardly notice it.
Why does coffee smell like skunk to me? The last thing you would want is for your delicious cup of coffee to have an awful smell like skunk spray. Essentially, coffee and skunk spray have a relatively similar chemical composition in their naturally occurring aromas. It is only that coffee has a skunk-like smell in very small amounts.
Also, coffee beans can smell like skunk spray as a result of degradation by moisture, light, and heat. Thus, if you fail to store roasted coffee beans properly, do not be surprised if they end up smelling like skunk.
The chemicals responsible for sunk smell in coffee, known as thiols, are released when you heat coffee beans. Thus, store your coffee beans in a sealable jar. Place the jar in a cool, dry place away from heat and sunlight. That way, they will retain their freshness and aroma.