Undeveloped coffee in low winter temperatures

Undeveloped coffee in low winter temperatures.

How can I deal with the temperature difference between summer and winter Bean Probe when roasting small batches?
The end roasting temperature for winter batches is higher in IBTS and lower in BT compared to summer, and the taste of the coffee is underdeveloped.
However, the end roasting temperature of the summer batch was lower in IBTS and higher in BT, but the coffee was very sweet and tasty.
Probably the reason for the underdevelopment is the low BT, but I don’t know if it can be corrected only by adjusting the airflow because of the considerable temperature difference.
I would like your advice.

The overlay graph is a summer badge .

End IBTS 205°C / BT 186°C / 8:27
GREEN 200g
Ambient Temp 31°C
Taste was Good.

END IBTS 210℃ / BT 180℃ / 9:34
GREEN 200g
Ambient Temp 11°C
Taste was underdeveloped.

Hi, have you looked at all of your roasts to confirm a dependency of the BT-IBTS spread on the ambient temperature?

I believe the fields ‘drumDropTemperature’ and ‘beanDropTemperature’ in the roast log correspond to IBTS and bean probe temperatures, respectively. If I do a scatter plot with the sensor temp difference and ambient temperature I see:

The correlation coefficient I compute for the data is 0.05, so, if the above assumption about log data is correct, there’s not any real dependence between sensor temperature spread and ambient temperature in my case.

Could the difference be attributable to preheat duration? It may be that you need to preheat a bit the roaster longer at that lower temperature.

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