LIGHT VERSUS DARK
There seems to be a myth where people associate light roast with specialty coffee and dark with the commercial variety, but that is not necessarily the case.
First, lets start with some background knowledge about roasting. This is the process where heat is applied to green coffee beans to produce chemical changes that develop a desired profile. This profile accounts for both colour (degree of roast) and sensorial analysis (aroma, body, taste and fragrance) of the coffee.
Not every coffee is the same and even the same coffee can produce very different profiles depending on the degree of roasting. So how do we decide whether light or dark is better? Let’s define the two types of roast levels.
Light roast happens when you roast coffee beans to just pass the first crack, which usually occurs around 200°C - 205°C. It is light brown in colour with a dry surface and typically has high acidity, brightness, a light body and more caffeine. Light roast can sometimes be unbalanced, but it highlights the unique qualities of certain coffees and the beans would preserve for longer periods.
Dark roast refers to coffee that has reached a certain level of temperature (generally between 225°C - 245°C) and has achieved second crack. This roast is dark brown in colour and displays a shiny surface. If it is a very dark roast, oils may be present on the surface as well. Taste converges towards chocolate and vanilla flavours, with more body and leaving just hints of floral, berry, fruit and citrus.
So how does light roast make a coffee “specialty”? It doesn’t, really. The truth is the term “specialty” in the coffee industry refers to high-grade coffee beans, which due to the quality and processing method have achieved a score above 80 by a Q-grader. Each coffee bean can display different characteristics and flavour profiles dependent on the roast level – ultimately it’s a matter of the roaster’s preference and style.
“A good roaster, in my view, is a master at roasting both light and dark coffees, and knows how to match a good roast profile to a given batch of green coffee.” - Joaquim Eichner