Looking at the World Coffee Research Sensory Lexicon, a universal language of coffee’s sensory qualities. There's a lot of good stuff in here, especially in the way they come up with 'reference smells' for their descriptors. For example, for "Fermented" they have two seemingly dissimilar things to give you the idea of what it is - 1. Guinness Extra Stout beer in a glass, and 2. grass left in a sealed jar for two weeks (to ferment).
The category for "Sour" seemed way simpler than I expected, with only four substances, all acids. There's plenty of good stuff in here, but I'll start with this brief category.
They begin by reminding you what Sour is: "The fundamental taste factor associated with a citric acid solution," and this is best represented by Citric Acid. They then go on to describe Sour Aromatics: "An aromatic associated with the impression of a sour product," and this is best represented by Bush's brand Pinto beans from a can (go figure, I'll have to remind myself what this smells like). Then we get into the acids themselves; there's only four.
A sour, astringent, slightly pungent aromatic associated with vinegar.
A sour, fermented-dairy aromatic associated with certain aged cheeses such as Parmesan.
A pungent, sour aromatic associated with sweaty, perspiration-generated foot odor and certain aged cheeses such as Romano.
A mild, clean, sour aromatic with slight citrus notes accompanied by astringency.
A sour, sharp, somewhat fruity aromatic accompanied by astringency.
Now for the good part. All of these, except for citric and malic acid (I think) are the core of body odor aromas. Can I call them aromas then?
The smell comes not from the body itself, but from the skin flora, the critters that live on your body, digesting your excreta and then themselves excreting the odorful products. They break down the fat in your sweat to get energy for themselves, and their waste product is a smelly acid. Different species of bacteria produce different acids, and these listed above are the big three. I guess they're in your coffee too.
World Coffee Research Sensory Lexicon, 2016
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