Coffee Roasting Airflow During Soak
@Matt
Posted in Coffee Roasting
Airflow During Soak
This past year, I've found myself using a few different fan settings during soak (1kg). What I've seen from other roasters online is that some will use their low air setting, some will begin with an even lower air setting, and a few will kill the fan entirely during soak. Recently, I find myself leaning toward a low to no air approach during the soak. When cupping, I find less astringency and a higher quality acidity in these coffees. Anyone else experience this?
My thinking is that leaving the fan on during soak could bring cooler air into the drum which:
1. Cools the drum quicker than it otherwise would without added airflow and
2. Makes it more difficult for the seeds to take on heat from the drum, stunting early momentum in the roast
On the flip, I realize that some airflow during soak could pull residual heat through the drum and, subsequently, the beans, creating early momentum. And so I suppose my question is how much air is too much air during soak? Or would it be beneficial to cut airflow altogether at this time?
If you perform a soak, what are your airflow settings?
Hi Matt.
Years ago, we routinely turned off the air on small machines during the soak. With the development of the digital drum pressure gauge, we've got much tighter control over airflow and no longer feel the need to do so. YMMV.
We still soak on small roasters, but with minimum airflow. Typically, something like 1 pa on the drum pressure gauge. Much higher on the 2kg because of a slightly different airflow geometry.
We usually calibrate drum pressure airflow with the lighter trick. Once we find a value for minimum negative pressure through the drum at the tryer port, we repeat it as a drum pressure value.
There is no "right or "wrong way to do this. Only the way that works for you on your roaster with your customers coffee.
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