Data driven roasting...
Thermocouples allow the coffee roaster to understand what is happening from a temperature perspective both inside the drum and also in the air current that is passing through and exiting the roasting chamber. Thermocouples are devices made up of two different metals within a probe. The voltage between the two metals is measured and that potential difference is temperature dependent.
There are a few types of thermocouples available. An important distinction is the diameter of the probe and therefore its sensitivity. The larger the probe the slower it reacts to changes in temperature as the probe possesses greater thermal mass.
My roaster has two thermocouples. One is placed to read the temperature of the coffee bean mass as it moves in the drum. The second measures the temperature of the exhaust as air leaves the roasting drum. It's important to be able to interpret probes given different circumstances. For example, when there is a small bean load in the roaster then the bean temperature will read higher than the true temperature because the bean probe is exposed to a higher proportion of burner heated air which is hotter than the beans. The ability to understand these differences comes from lots of trial runs and measurement.
ROASTERY CLOSURE REMINDER
Our family is taking two weeks of holiday between January 10 and January 24... so there will be no roasting during that period. Last orders prior to the holiday will be taken Friday January 5, 2024 for roasting Saturday/Sunday January 6/7, 2024 and dispatch Monday January 8, 2024. Roasting will recommence on the weekend of January 27/28.
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