Boost kit- larger batches roast darker?

[mmorgan]

Hey,

New happy Kaffelogic owner here. I have questions about the boost kit and how to iron out some inconsistencies in the roasts.

I am experiencing that larger batches (150g, 180g) finish at markedly darker colors with the same end temps than smaller (100g or less) batches.

Initially I experienced this with the DarkCDFP profile. I thought it might be because that was an older, user-contributed profile that somehow didn't allow for boost kits. But today I saw something very similar with the Kaffelogic provided "SuperDark" profile.

Bottom line: larger batches roasted to the same end temps look and taste like they were roasted to much darker specs. EG, a SuperDark 150g batch roasted to 441F/227C (3.0) looks like it was roasted to 451F/233C/the beginning of second crack. I've roasted about 50 batches overall, and I feel like I'm developing a pretty good eye for what "451F/233C" looks like.

I'm OK with just adjusting this via trial and error, but is there something else I should be doing differently?

Thanks for any advice!

[kaffelogic]

Check that you have the latest firmware installed on the roaster. If you have firmware earlier than v7.15.7 you will not be getting optimal profile-following for all profiles. If the temperature is significantly above the profile line this will affect the end colour.

Use fan preview before starting the roast. This will help ensure correct air flow in cases where the standard BOOST algorithm is not delivering the optimal amount.

Apart from that, what you are doing is correct: making your own assessment and adjusting your process accordingly.

[mmorgan]

@kaffelogic,

Thanks for the feedback!

My fan calibration did seem to be a bit off. I ended up adjusting it and did a test roast.

Color/temp relationship seems much closer to what I would expect now, thanks!

[Squirt]

Out of interest, was your fan too high or too low?

[mmorgan]

It was too low. The beans weren't moving much toward the beginning of the roast, not exactly sure why that resulted in them roasting darker than expected, but...?