How to interpret roasting suggestions?

[lancruiser]

Often I come across descriptions in green bean sale site that says "requires a fair amount of heat early".

In the context of a drum roaster, I would interpret it as "pre-heat the roaster to a higher temperature and/or apply more heat after charging".

In the context of Kaffelogic, how should I translate this into a profile?

I am thinking that higher initial heat does not necessarily mean higher initial temperature. It could just mean that the bean has high moisture content or has lower heat conductivity. With Kaffelogic, the roaster should automatically apply more heat to bring the bean to the temperature specified in the profile.

Is this thinking correct?

Would appreciate some help in this matter. Thanks.

[kaffelogic]

With Kaffelogic, the roaster should automatically apply more heat to bring the bean to the temperature specified in the profile.

Is this thinking correct?

This thinking is correct, but only after the first 1 to 2 minutes of the roast.

The Kaffelogic does not need to be preheated because of the ultra-low thermal capacity of the roasting chamber. This is why it starts the roast cycle from cold (unlike a drum roaster).

However, the roast control system (algorithm) needs time before it has enough data to properly take control of the temperature of the beans. During the very first part of the roast the heater is set to a constant power level defined in the profile settings as 'preheat power'. This is not a true preheat like a drum roaster, but is more accurately pre-algorithm. If the preheat power level has been carefully matched to the profile then it is possible for the temperature to start out following the profile curve from the very start. Actually we often set the preheat power level high so that the roast starts out above the curve, and we rely on the control system to bring it back onto the line after the first couple of minutes. This approach may seem unusual, but it tends to give good results.

So in conclusion, to apply more heat early on you might not need to make any changes to the actual profile curve, but instead simply increase the 'preheat power'. You may also need to make changes to the curve, but 'preheat power' and the curve are more or less independent at the very start of the roast.

[lancruiser]

Thanks, Chris. Yes, I viewed the recording of the workshop yesterday that covered this topic. Very insightful. I would have liked to attend the workshop but work commitments prevented participation.

It would be interesting if Wayne could explain what kind of flavour he is trying to get from increasing the pre heat power.