Roasting 101 – Roast Stages and the Use of Airflow
Hi. Dave Borton – Mill City Roasters – here in Minneapolis,
continuing segments of Roasting 101.
Today we’re going to look at roast stages…
and the use of airflow.
So, where do we start?
Okay, the unit has been pre-warmed
for 40 minutes.
I’ve got a drop temperature of roughly
three hundred ninety degrees
for this high-grown.
The burners are on, it’s hovering around
Its been pre-warmed, I’ve got my charge loaded up…
We’ll open the hopper,
and I shut the burner off for the first minute.
I’m going to turn my air down to low.
During this drying stage,
I want all of that energy…
picking up and wicking away the moisture.
Coffee starts at about 10.5-11%
And so I want to dry that bean out
to about one half of
one percent at the end of drying.
I do that with an airflow setting of low.
Now, about five minutes or so into the roast…
I’m going to have been checking the trier
and when the beans are entirely yellow,
they’ve lost all their green hues,
I’m going to mark “end of drying” and turn my
air up to medium.
During this airflow
Convective energy begins to work with
This is the carmelization stage: roughtly between
five minutes and first crack.
By using an airflow of medium,
so that we pick up convective
as well as conductive energy.
Long about 380 degrees on the bean
temperature, I’m going to be keeping an
eye on that bean
and when those beans
begin to have seam openings
and I begin to see the finest wisps of smoke
under that light – before first crack – I’m
going to turn my airflow up to high.
That is going to expel the smoke from
the unit and that smoke won’t cloud the
volatile oils that are in the coffee.
So from first crack, through the end of the roast
I’m going to go ahead and use an air
setting, or an air flow, of high.
That’s about as simple as it gets.
Three stages of roasting.
Drying to five minutes,
Before first crack, the “carmelization phase”
and “first crack” between 8 and 10 minutes
completing the third stage
which is “first crack and beyond.”
You’re going to use three airflow settings:
Low, during the -uhh – drying stage.
In the caramelization phase, I’m going to use medium.
and then 20 seconds before first crack – as indicated
by opening seams and wisps of smoke –
I’m going to use an airflow setting of high.
That’s the way we roast at Mill City Roasters.
Glad you watched in with us today
and look for other segments of