Adapting roast profile to larger batch size

[gap]

Hi, I was wondering if anyone had a rule of thumb for adapting a roast profile to a larger batch.

Eg., from experimenting maybe I know I can roast 500g of Bean Type A for 30 mins at 150C. What if I now want to roast 1000g? How long and what temp?

I'm hoping there's some way of approximating a good starting point which I can then experiment from - surely there's some mathematical formulae for this :-)

My hunch is to keep the 150C constant and increase the roast time but my gut is telling me I probably don't just double the roast time

Any help appreciated

[Sebastian]

Depends on the specifics. you're going to have a higher mass to bring up to thermal equilibrium - so it's going to take more time. how much more time depends on lots and lots of variables. it's likely only 2-3 min difference tho. Keep your bed depth the same, preheat your roasting rack if you use one so you're not spending energy heating things that don't matter.

[gap]

Thanks Sebastian. I had a feeling it would be that sort of answer :-) but good to know. I guess I'll try increasing the time and just watch for signals like smell.

For home roasting (other than smell) what do you and others use as signals for your beans. Do people taste during roasting to get a feel for when they're done? Or measure bean temperature? Other things?

At the end of the day, if it falls to me to test multiple batches of chocolate, so be it.

[Sebastian]

The temp of your bean will be the single most critical (and controllable) point for you to measure. there's good ways of doing it, and bad. It's very hard to translate hot bean flavor to cold chocolate flavor in my experience.

[gap]

Thanks for the lead Sebastian