What is the difference between a Light, Medium, Medium-Dark and Dark Roasted coffee?
I have eight coffees in my range, all roasted to different levels, but what does that mean and how does the roast level affect the taste? I'll try to explain, starting with the lightest and working through to the Darkest roast in my Little Birdie range.
When roasting coffee, the beans go through a lot of chemical changes. Visible from the outside, the beans first changes colour from green to yellow, to tan, to light brown, dark brown and if you roast if long enough, to black. As a roaster, I decide how much heat is applied to the beans at various different stages of the roast to develop the desired flavour profile and also when to 'drop' the beans (removing the beans from the roaster and cooling them down rapidly).
As the roast develops, we hear two distinctive 'Cracks' from the beans - First Crack and Second Crack. When the beans reach an internal temperature of around 196°C First Crack is the audible release of built-up water and CO2 pressure from inside the bean. Typically at around 224°C more CO2 and oils are released from the inner bean, with an audible Second Crack.
LIGHT ROAST (Roast level 2)
Roasted to about 'City Roast' level, just after First Crack. At a City Roast level a lot of the flavour characteristics and origin of the individual coffee beans can be tasted, as it has not been overpowered by the strong 'roasted coffee' flavours that develop later on in the roast.
A light roast requires a much shorter roasting time than a dark roast, meaning that the internal temperature of the bean does not reach as high a level where some chemical reactions takes place. Lighter roasts tend to taste more acidic (the sharpness toward the front of the mouth), less sweet, have prominent fruity flavours and a delicate aroma.
MEDIUM ROAST (Roast level 3)
Little Birdie Single Estate Mexico La Lalaja Decaf
Little Birdie Single Origin Brazil Cerrado
Little Birdie Single Origin India Monsoon Malabar
Roasted to about 'City Plus' level between First and Second Crack, you can still taste the individual character and origin of the beans and some roasted coffee flavours. At this point of the roasting process the beans are a bit darker, it has developed more body and still have prominent acidic properties.
MEDIUM-DARK ROAST (Roast level 4)
Little Birdie Strathmore Roast
Roast to Full City Roast level, just before the onset of Second Crack. The beans have a smoother surface and darker colour.
At this point of the roast there is a good balance between the flavour characteristics of the individual beans and origin and the roasted coffee flavours coming through, which makes it a very popular roast level. The coffee is less acidic and fuller bodied.
DARK ROAST (Roast level 5)
Little Birdie Perthshire Roast
Roasted to the Vienna level, the beans are dropped into Second Crack.
At this roast level the delicious roasted coffee flavours are more prominent than the flavours from the bean origin. With little acidity and bright flavours, darker roasted coffees tend to be a bit sweeter as the sugars in the beans caramelise at higher temperatures.