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What equipment are you using? 30 minutes does seem like an awfully long time for a roast to take. Different beans do definitely take different times but that feels like maybe the heating isn’t sufficient for the amount of coffee used

mikegm Have been roasting my own beans now for a few months. This afternoon I have roasted an Indonesian Bali Kintamani & an Ethiopian Yirgacheffe. Both a Medium Roast @ 210°C The Indonesian 14 minutes while the Ethiopian 30 minutes. Does anyone know why the difference in time for roughly the same outcome. Does 30 minutes seem too long. Or is it just that different beans take different amounts of time? Please see Uploaded photo. Thanks

As InfamousTuba asked - the first thing is how you are roasting, to make sure the conditions haven’t changed between roasts. For example, when I roasted with a gas bottle, as the gas bottle deflated the roasts time were longer. Different quantity of beans can also affect the time, and of course different coffees take different times to roast.

However, I normally don’t get such a huge variation in time. My roasts always complete within less than 16 minutes, so 30 does sound excessive, especially that the other roast took 14 minutes.

You say both are medium roasts, but in the picture they look quite dark to me. How do you gauge the roast and decide when to stop? Usually it is done relative to first and second cracks, I think.

They do look like medium roasts, though the one on the right seems to show some getting close to second crack or scorched, could be more towards medium-dark. Judging roast by the colour tends to be done with grounds rather than the whole bean because the outside colour doesn’t necessarily match the inside colour. I was quite surprised to find some of what I always thought were well into medium roasts coming out as light and light-medium when I used a roast colour analyser just because I’d only ever been able to look at pictures on an uncalibrated monitor to compare.

Whatever roasting method you’re using is obviously causing some problems getting an even roast. Yes, 30 minutes is too long and the reason for the difference (assuming no defects like improper drying) are going to be due to density of the beans, though I am surprised there’s THAT much of a difference.

Is that just a 210c flat profile? As others have asked, what are you using the roast?

mikegm As roast time goes I tend to go on colour.

Do you hear the cracks? I think that tends to be a better indicator than colour, easier to use and more accurate/consistent.

mikegm - You should hear first crack at least. The beans will pop, pretty much like pop corn. Just google coffee roasting first crack and you’ll understand.

Wait 30s-45s seconds until all the cracks finish and then start the cooling process to stop the roasting.

No idea how your roasting apparatus work, so can’t comment on that.

Good luck!

The roaster is not likely to be capable of good roasting. I’m surprised you managed to even get a 14 minute roast out of it. It’s a design inspired by the “turbo crazy” DIY hacked up design using a stir crazy popcorn popper and a halogen oven lid for enough heat. If you can turn the roaster up to a hotter temp you might be able to get a reasonable roast time for the Ethiopian but not sure there’s anything you can do about the uneven roasting.

If you enjoy the process of roasting my advice is to move to a more capable machine as soon as possible.

Rob1 didn’t want to rain on the parade but you wrote exactly what I would have written. There is no getting around it unfortunately. The unevenness of the roast is a concern.