We get asked quite often – what is a soak?
When we refer to a soak in our Roasting 101 class, we’re generally talking about an initial period of time at the start of the roast where the burners are intentionally turned off to manage heat transfer. So before charging your beans, the ignition is cut for a delayed period and then turned on. Think of this as the beans simply soaking up the radiant heat from the drum.
This is what Steve says:
"The soak technique is a control method that works best on high thermal mass roasting machines where the latent heat in the system – in addition to – constant heat from the burners make it difficult to slow the roast enough to produce an optimal roast profile.
On our roasters, it’s often beneficial to turn the air off during the soak to reduce the cooling effect of dilutive air.
None of this automatically produces better coffee, but it often makes it much easier to achieve more precise control, repeatability, intentionality, and consistency.“
When do I utilize a soak?
Bryant shares some insight with us:
A soak is not a rule, but a tool you can use when deemed necessary. One thing I like to ask is, “Are my roasts moving so quickly that my adjustments don’t have any room to breathe? Do I feel rushed in my roasting?” If so, you may benefit from using a soak.
If the opposite is happening where roast times are running long using a soak and you’re losing brightness in the cup – you may benefit from eliminating the soak.
A reason why we utilize the soak in so many of our videos is that we are roasting on our smaller machines, or utilizing less than 100% capacity with a higher charge temperature.
Is it necessary?
While they can be beneficial on smaller systems and a way to maintain a static charge temperature, one can also argue that either lowering your charge temperature or the combination of lower initial fuel + charge temperature would be the route to go.
Ultimately, you should ask, “Can I consistently make the same adjustments to get a great cup of coffee utilizing or not utilizing the soak?” Whichever method gives you the answer “yes,".
Stay tuned for more informative roasting tidbits from the Mill City Roastery.