Sweetness is my favourite attribute in a cup of coffee. The best coffees I've had have been floral or fruity with a nice dose of sweetness. In coffee, we do not talk about sweetness the same way we talk about white sugar. Speciality coffee does not have any added sugars. This is why you will see some people refer to sweetness in speciality coffee as "perceived sweetness." Indeed, no sugar is added. As a drinker, you perceive compounds in the drink which impart a sweetness onto the final cup.
What causes sweetness? Great question. Sweetness is caused by the development of sugars in the coffee bean. These sugars are compounds like sucrose and polysaccharides. These sugars develop differently in each coffee fruit depending on the terrior of the bean. For instance, some varietals of coffee are sweeter than others. Coffees grown at higher altitudes are generally sweeter because the coffee cherries develop at a slower rate and thus have more time to develop.
I am writing about this today because I just read an interesting article on Barista Hustle about sweetness in coffee. The article addresses the question: why does coffee taste sweet even through the sugars in the coffee have been caramelised?
Before I share my thoughts, I need to give some context. Most of the sugars—like the sucrose I mentioned earlier—are caramelised in the coffee bean during roasting. This happens at a slightly higher temperature to the Maillard reaction. Caramelisation produces some of the compounds that are extracted during the middle of the extraction process, like nutty flavours. So how is coffee sweet?
We say coffee has "perceived" sweetness because we are seldom tasting actual sugars. We're perceiving a sweet flavour based on the aromas in the coffee. It is true that our mouth plays a role in tasting coffee but without our noses we would get a very different impression of each coffee. Try drinking a sip of coffee with your nose pinched and then take a sip without pinching your nose. You'll notice that you do not taste nearly as much in the first sip as you do in the second.
Some aromas impart a sweet impression on us which is why some coffees taste sweet. In speciality coffee, sweetness is an incredibly desired aspect of a coffee. Sweetness is so important that experts consider sweetness one of the primary factors when they are evaluating coffee. Coffee cupping forms have a box for the perceived sweetness in a coffee.
It is important to make a distinction between the natural sweetness in a coffee and added sugar. If you taste white sugar next to a coffee and then sip the coffee, you'll notice that the coffee has a different type of sweetness. Do not expect to be blown away by lots of sugar in a coffee because that sugar does not exist. Coffee has subtle sugars and most of those are caramelised. It is the aromas our coffee emits that makes us feel like a coffee is sweet.