Advise on 1kg espresso roast

I have been able to roast many successful 600g filter roasts using the bullet but I have just attempted some 1kg espresso roasts but finding I am having to charge the roaster fairly high and it still seems like it isn’t high enough to get a smooth declining ROR to fit the parameters i have chosen.
I am aiming for 5 min dry, 3.30 - 4 min to FC and 2-2.30min development time with a 9-10 degree rise before dropping.

I plan to be roasting for my small coffee shop so want to keep the weight as high as possible so it reduces the amount I need to roast weekly.

It also seems like my I-R sensor doesn’t work the same on the larger roasts ?

any advise on how to improve these, or any thing I am missing would appreciate it.

I don’t roast 1 kg batches but I can confirm that IBTS vs. Bean Temp has less separation as batch size increases. However, the reversal of BT & IBTS late in these roast profiles is possibly an indication of “junk” on the IR sensor and it needs a little cleaning. Beyond that the profiles look well formed, but you need to evaluate the taste- pretty graphs don’t always translate to a good cup.


My largest batch was 850g…However I echoed Bruce’s comment on a possible cleaning of the IR sensor is required and more often than a 500g or 700g batch.
The IBTS/BT cross each other happened a bit too early (which was in the early stage of the FC or even before the FC showed in your roast above)

Your profile looks very well controlled and I am sure a lot of us can actual learn from it on how to deal with large size of beans. Again, your final taste is the most important one.

With an expresso and a 2:30 development cycle in mind, I would consider keeping the P3/F5 toward the end of the roast rather than further down to P2/F6.
Too high (higher than p5 + longer than 20 sec can impact the aroma)
The goal for me on an expresso, is to keep RoR after FC @ 5~8C. If using roast degree, is to keep Agtron within 65~73. Hope that helps.

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I didn’t know you had to clean it more often with bigger batches, I mostly use the IR reading so it was super confusing when it stops reacting near FC. Will give it a clean every day on these bigger batches.

I still find the coffee is coming out to dark for me, maybe this will be Easyer to control when I have the IR reading but any thing above 210 seems to far.

I have cupped the beans and them seem fairly sweet with no noticeable defects still a little red fruits present, will put them in the hopper today and give them a test.

I would recommend looking at some of the roasting profiles by cash0216 and lav - they both regularly roast 1kg. I’ve been basing my 1kg roasts on cash0216’s profiles and I am pleased with the results. I am not hung up on how the ROR curve looks as long as it cups well.

A preheat of 300C / 572F is needed given the amount of bean mass. The BT and IBTS will track much closer to each other since there is more bean mass for the BT to accurately measure bean temp, compared to 800g or 500g. Crossing of the BT and IBTS does happen. My last 1kg roast was after a deep cleaning and you’ll see that they pretty much overlap during development time, but as Bruce pointed out if it crosses in a significant way it means you need to clean your IBTS. I’ve had them crossed before like yours but I wasn’t too worried, and yours wasn’t a significant cross to worry yet.

In RW you can search users by their username, and if you search for the two I mentioned - they are good references.

for any one interested this roast turned out great, tested on espresso and filter.
Notes of chocolate, caramel and red fruits.

Very sweet and balanced on espresso with no roast flavor, any thing that goes over 209 tastes to roasty for me, not sure if this was a result of baking the beans but smoothing out the ROR changed the flavor massively and using the smell I pulled the coffee out when it smelt the best and it really shows in cupping.