Deconstructing Coffee - Aroma
Have you ever had coffee with a wild fruity flavour? Perhaps a coffee with robust floral notes? If you nodded vigorously in response to either of these prompts, you might be surprised to know that these flavours were primarily a function of the coffee’s aroma, and not the taste itself. Our sense of smell plays a significant role in our ability to taste. This is why our favourite foods seem to taste rather dull when we have a cold or stuffy nose. Brewed coffee has over 800 aromatic compounds with new ones being discovered regularly owing to advances in testing equipment. Fun fact - wine sits at a meagre 250 aromatic compounds, a far cry from the complexities of coffee.
So, what is aroma?
At it’s most basic, aroma is the smell of coffee. It is responsible for many of the flavour attributes, not directly perceived by the tongue (sweet, salt, bitter, sour and umami). Because aroma is the release of flavourful compounds from coffee through the air, fresh coffee has a much stronger aroma than older, stale coffee (also why it tastes better). As a rule of thumb, the darker a roast gets, the aromas become that much more detectable. Aroma, flavour, acidity and body: all of these attributes are a response to different chemical compounds. Experts analyse them with their senses – but chemical reactions still come into play. They evaluate the dry aroma, followed by the aroma as the crust is broken, followed by the taste. Different stages, different molecules.
Lets’s break it down further.
The Specialty Coffee Association classify the aromas of coffee into four main umbrellas. These broad categories help process the 800+ aromatic compounds by lending context and an efficient way to get specific with descriptors. Don’t let the names intimidate you - the explanation is what’s relevant.
Some of the most pleasant and unique aromas in coffee are by products of enzymatic reactions that take place in the beans themselves during growth and processing. These aromas are the result of careful growing and processing. These include:
- Fruity (blueberry, apple, apricot)
- Citrus (lime, lemon)
- Floral (tea rose, cardamom)
- Herby (garden peas, cucumber, basil)
Sugar Browning Aromas
These aromas comes about during the Maillard Reactions of the roasting process, when the sugars are caramelised (browned) and flavours develop. These aromas are highly coveted by roasters across the world. These include:
- Chocolatey (vanilla, dark chocolate, butter)
- Caramel-y (caramel, honey, hazelnut)
- Toasty (roasted peanut, walnut, toast)
Dry Distillation Aromas
These aromas are the product of burning plant fibres during roasting and are highly dependent on the roaster’s style, goals, and willingness to roast on the darker side. These include:
- Woody (cedar, pine)
- Spicy (anise, clove, pepper)
- Carbon-y (tobacco, smoke)
This category of aromas contains the aromas that are the result of low quality or diseased coffee. Sadly, a clever roasted can only do so much to eliminate these when they come with these aromas built-in to the beans. These include:
- Ferment-y (bad wine, spoiled fruit)
- Leathery (rubber, leather, beef)
- Grassy (straw, potato)
Aromas add so much to coffee’s sensory landscape, and learning to appreciate them apart from flavours discerned by the tongue makes coffee that much more enjoyable and interesting. Don’t be afraid to guess. Guessing helps our brains process what we’re experiencing, even when we’re not very confident in our guess. It’s much better to make a careful guess than to not try at all. Remember, coffee aromas don’t stick around for very long. The aromatic oils evaporate, the acids break down, and the organic compounds decay after just two to three weeks of being out of the coffee roaster. To make matters worse, coffee only has 20-30 minutes of peak freshness once the beans are ground. Integrating the habit of buying freshly roasted coffee in small amounts and ideally, grinding the brans right before you brew them will up your coffee experience dramatically.