Probatone roasting advice

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
looking_afar
Posts: 4
Joined: 9 years ago

#1: Post by looking_afar »

Hi guys.

I'm about to start roasting with Probatone 12 (gas version). While I have had experience with roasting on small machines (like Huky and 1 kg Diedrich), my experience with large roasters is quite limited. I understand that generally the procedure is very similar to roasting with Diedrich, but I would still like to get some simple guidelines from people who roast on large roasters like Probatone 12.

As far as I can see, the procedure looks like this for half load (6 kgs for Probatone 12):
1) Preheat the roaster to 180C-190C, no airflow
2) Turn off the burners at around 160C
3) Dump the beans at 180-190C
4) Turn on the burners at 2:15, 30-40% heat
5) After the drying end, increase the heat level to 60%, use small airflow (or don't use at all)
6) Aim for FCs at around 9 minutes, turn off the burners at FCs, increase the airflow
7) Either drop beans after around 2 min or turn on the burners after 1:15-1:30 if roasting beyond City.
8) Drop the beans

What would you say? What about the full load?
I have the following questions regarding the guideline:
1) What temp to preheat the roaster to for half the load and for the full load
2) When do I turn off the burners when preheating the roaster?
3) Do I turn on the burners at TP or before/after it? What level of heat do I use during the drying stage?
4) What level of heat do I use after drying end? Any airflow?
5) Do I turn off the burners before or just after FCs? At what batch size? What airflow do I need at this stage?
6) If I aim for C+ - FC roast, when do I turn on burners again? Heat level?

I would appreciate any help on this one.

Thanks!

chang00
Posts: 638
Joined: 16 years ago

#2: Post by chang00 »

I don't have any experience with the Probatone 12; howeverI have observed and played with the BellaTaiwan/Yang Chia 5kg roaster.

In general, the 5kg Yang Chia behaves similarly to the small 500g roaster.

Preheat to 160-180C. Charge beans (in your case 6kg or 12kg), and turn off gas. Turning point generally is at around 1:30, turn ON gas. Vent closed. The rest of your procedures are similar to mine.

Be certain the temperature probe is within the "bean mass". Check to see if the bean mass actually touches the temperature probe at 6kg and 12kg.

"1) What temp to preheat the roaster to for half the load and for the full load"
You will need to have different charge temperatures for half and full load. You will also have different gas pressure profiles for the 6kg and 12kg charge weight respectively. The temperature curve however should be similar.

The charge temperature for the first roast of the day is generally about 20C higher. For example, first roast charges at 180C, and subsequent roast can be at 160C.

"2) When do I turn off the burners when preheating the roaster?"
At charge temperature

"3) Do I turn on the burners at TP or before/after it? What level of heat do I use during the drying stage?"
At turning point, turn back on the burners. In general, start about 1/2 of the heat.

"4) What level of heat do I use after drying end? Any airflow?"
At at 1/1 of the heat after drying ends. Air flow mid level to maximize convection.

"5) Do I turn off the burners before or just after FCs? At what batch size? What airflow do I need at this stage?"
For softer beans, the heat can be turned down to 1/3 about 30 seconds before anticipated first crack temperature. For harder beans, at first crack or about 1 minute into first crack, depending on roast level. Turn off the gas about 30 seconds prior to dropping the beans. For "Nordic" style roast, increase airflow to attenuate heat to just enough to maintain temperature rise of ~<1c/min. For "regular" roast, adjust vent to maintain about 5c/min during first crack.

"6) If I aim for C+ - FC roast, when do I turn on burners again? Heat level?"
No need to turn on burner again if you time the burner right. See #5 above.