For the last in our Sensory Series, we turn our senses to Finish.
Often associated with a negative connotation, finish is an important – and can be an enjoyable – final sensory experience that comes with enjoying a quality cup of coffee. Here we explore the science and terminology, the good and the bad, and how to better understand those final, lingering notes that present themselves after you’ve finished your cup of coffee.
WHAT IS FINISH?
In simple terms, finish is formed by the taste and aromas left in the mouth after swallowing, a result of chemicals from food and drink that remain on the taste cells in the mouth, including the tongue, and back of the throat. Gustatory cells respond to several primary tastes: sweet, salty, sour, umami (savoury), and fat. Essentially, finish is the sensation that remains once other factors of overall taste, such as smell and texture, are no longer influencing the brain.
WHAT IS FINISH IN COFFEE?
Finish in coffee is the final step in the sensory analysis after the visual, olfactory (smell), and gustatory (taste) experience; finish concerns the taste—or, rather, the memory—a reminder of the coffee that remains in the mouth once your cup is empty.
Finish in coffee is largely the product of all the sensory elements that we find in every sip: all these elements mix to form finish. Compared with other drinks, flavours present in coffee can hang around for a long time; the finish of an espresso can last up to fifteen minutes.
WHAT CAUSES FINISH: THE SCIENCE IN YOUR COFFEE
The finish of coffee is different to the initial taste you experience. Different compounds have different lengths of finish—this means the balance of tastes in the finish will likely be different to that first sip of coffee you experience.
The biggest difference lies in flavour rather than taste. This is the result of some molecules remaining in the mouth longer once you’ve swallowed the coffee. These molecules pass into the naval cavity through the back of the throat, so we continue experiencing their aroma. This is called retro-nasal olfaction. The aroma compounds that stick around for the longest are thought to be the largest, and the least water-soluble molecules; larger molecules are the least volatile, which means they don’t evaporate as easily. Aroma molecules need to vaporise to reach the naval cavity, and the weight of larger molecules means they take longer to escape the liquid and reach the nose. Many of the larger molecules in coffee are those created from dry distillation in roasting, often associated with woody, spicy, and ashy flavours.
Less water-soluble molecules also stay in the mouth after swallowing because they are more likely to be bound to or dissolved in the oils in coffee. After swallowing, fats and oils coat the mouth and retain odour molecules. The natural surfactants found in coffee, such as melanoidins, allows coffee oils to coat the mouth more effectively. Oils and melanoidins are particularly concentrated in espresso, which is one reason the finish of espresso can be so strong. Both large molecules and less water-soluble molecules are associated with some of the less pleasant flavours in coffee, which explains why finish can be associated with unpleasantness.
HOW TO DETECT FINISH IN COFFEE
Despite something of a poor reputation, finish in coffee can be a pleasant and enjoyable part of the sensory experience. The best way to detect finish? Simply sip, savour, and sit back to consider what you taste when you’ve finished your cup of coffee. What stands out? What are the key notes? How different is it from those original tasting notes? Does it make you want to brew another cup, or cleanse your palate?
A quality coffee will have a sweet, clean, and persistent finish without unwanted sensations after swallowing. The persistency of the finish – good or bad – is an indicator of the quality of the coffee too: those lingering, sweet notes of caramel are pleasant; bitterness, while celebrated in the cup, if it lingers in the finish, is not a good indicator of quality, hinting at poor roasting, or badly timed extraction. Good acidity in finish can be prolonged, whether bright, clean, or soft. Aroma, rising to the nasal passages, perceived by our sense of small and interpreted by our brains as flavour, play a part in finish, too: it is out olfactory bulb, through the indirect link to swallowing, that helps us to distinguish good and bad notes that remain on the palate. Mouthfeel plays less of a role in finish, but you’ll note that, the fuller the body, the more persistent the finish.
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