ORGANIC ACIDS : and how they affect flavour
Acidity influences the flavours (sweet, sour, & bitter) and the olfactory experience (sense of smell) when tasting coffee. The different acids present are responsible for specific fruit or flower-like flavours you typically see written down as tasting notes. These acids occur naturally during the growth and development of the coffee cherries. The levels of each acid are often influenced by the altitude in which coffee is grown in, variety, type of soil and even rainfall. However, these acidic profiles can also be masked or highlighted through roasting or during the coffee's processing.
There are 6 organic acids recognised by the Specialty Coffee Association, all of which contribute to the brightness and acidity of coffees. The different acids have unique qualities that directly resemble fruit flavours of berries, citrus fruits and apples, and are the same chemical compounds found within these fruits. So when you taste a hint of orange it is the same molecules that make oranges taste like an orange.
It is important to note that there are many more organic acids found in coffee, however the 6 that will be explained in this blog are common and have an impact in the flavour experience of coffees.
THE 6 ORGANIC ACIDS
This acid is the compound that gives vinegar its pungent smell and sour taste. It’s usually less pungent and recognisable in coffee, and generally accounts for a rounded and clean tasting cup. In lower concentrations it gives us hints of strawberries and raspberries, whilst in high concentrations it has a distinct a balsamic vinegar note.
Lactic acid is found primarily in sour milk products such as yoghurt. It is also the acid that is responsible for the sour flavour in sourdough bread. In coffee it gives depth, body and a creamy mouth feel to the taste experience.
Citric acid naturally occurs in citrus fruits and is easily detectable in coffee. It brings flavours such as lemon, lime, and even a sour candy taste to your brew in higher concentrations.
Malic acid contributes to the sourness of unripe fruit, rhubarb and the tart taste in wine. It is largely responsible for the sour taste in apples. In coffee, we taste red and green apples in lower concentrations, as well as sherbet and pineapple in higher concentrations.
Phosphoric is usually added to soft drinks or sodas to brighten flavour. It has no distinct flavour but it accounts for that bubbly feel or perceived sparkling acidity in higher concentrations. This acidic helps amplify bright fruit flavours found in coffee.
Quinic acid is fairly similar to Phosphoric acid. It is the primary compound in coffee that contributes to the bitter taste. Picture tonic water qualities when found in a well developed espresso roast.
Stay tuned for part two of our Organic Acids breakdown, where we unpack how these acids form in coffee and how they react to the roasting and brewing process.