Coffee is unique among all the other artisanal beverages, this is because the brewer plays a key role in its final result at the point of consumption. In contrast, people buy beverages like beer or wine as finished products; their only consumer-controlled variable is the temperature at which you drink them or if you decide to add other ingredients to them.
Coffee lovers ask: why does the coffee made by a barista at a café tastes different than the same coffee that I brew at home?
In part it may be due to the barista’s years of training, but in a more profound instance, it’s their ability to harness the principles of chemistry and physics.
The variables of temperature, the particle size of the grounds, the water-coffee ratio, and time. They all play crucial roles in producing a tasty cup. It’s how we control these variables that allow for that cup to be reproducible over and over again.
Did you know ?
Coffee’s flavor involves over 1,000 chemical compounds. The primary tastes perceived on the tongue are important, but the hundreds of aromatics in coffee are smelled rather than tasted.
So what Makes it Taste so Good?
The sweetness comes from sugars, which mostly caramelize during the roasting process to produce a toastiness and dark tones of caramel. This is complemented and accentuated by caramel-like aromatics.
Bitterness is crucial because, without it, coffee would be unrecognizable. Bitterness helps to balance the acidity in all brews. Aromatics , in turn, balance the bitterness, making it altogether a beverage full of equilibrium and cadence. The balance of complementary tastes is key to the perfect flavour. Caffeine provides about 10% of the bitterness of coffee, but it’s not the only compound in the bean. Trigonelline (a.k.a niacin) is bitter, but when the beans are roasted it converts most of it to pyridines , which taste warm and toasty.
The acidity is another complex matter. Fruit acids contribute fine acidity that can be noted at the table. Citric acid is one of the strongest, but malic (also found in apples) and tartaric (found in grapes) are nuances in comparison. An acid profile is considered more complex with a balance of these, typical of beans grown at high altitudes (Robusta).
Compounds such as Chlorogenic Acids (CGA) degenerate in roasting into caffeic and quinic acids, and phenols. The CGA are perceived as more bitter on the palate, while quinic acid is rather sour and bitter.
Aromatic acids (such as lactic and acetic acids) can be smelled as well as tasted by most of us. Some develop when the fruit is separated from the seed, others during roasting as sugars caramelize. A little is pleasurable, but in bigger quantities, it sours the coffee, too much of this can ferment the coffee.
Aromatic compounds. As their name suggests, make the aroma and are caused in part by Maillard reactions, which occur when a sugar adhere to an amino acid (the building blocks of a basic protein).
Furans are the most abundant and frequent class of aromatics in all species of coffee and contribute to its taste with caramel aromas from the sugars decomposed from the heat of roasting.
Pyrazines are the second most abundant kind, with deeper, more toasty aromas. They can be perceived even in small doses, and so contribute much to the aroma. One pyrazine, which gives an earthy, strong aroma, is also a flavour constituent in bell peppers.
Coffee is a complex beverage, yet rich and full of unique flavours.