mgrayson wrote:I have yet to learn what differentiates Washed profiles from Natural profiles. I can look at Ikawa curves, but I'd like to understand. It's easy to find information on the basics of roasting, but with the next level it's harder to get a coherent treatment. Reading a lot of threads in the roasting forum is helping, but when I try to dig down, it seems to stop at "well, this seems to work, and that doesn't". Even Rao's decreasing RoR is essentially an appeal to authority (I read his original paper on it). That doesn't mean that it's not a great methodology, just that it's hard to form any kind of larger understanding.

From what I've gathered so far, natural-processed beans are coated with a layer of carbohydrates (sugars) that are vulnerable to burning. The City + and Full City recipes for the washed Huatusco have a temperature spike early in the profile that may overcook the sugars of a natural-processed bean, leaving the resulting brew with a burnt taste.

Natural processed Panamanian Catuai is next on my to-do list, for which I'll try to be more careful with the heat application compared to the Huatusco recipes.

kidloco wrote:Generaly I noticed that first crack is off by 30-40 seconds even in Ikawa's beans and profiles? What do you guys do then? What we need in app is something like "move to the next stage" button, or mark first crack button. I do not know if that is possible ...

I suspect part of the problem is Ikawa's hubris for even suggesting when first crack should happen. I'm sure they're good at what they do, but they develop their recipes from a smaller set of beans than what they ship, and if the beans sit around for six months they might behave differently when I finally get around to roasting them.

I second the motion for an "adaptive" app that learns the behavior of your specific batch of beans. That would be epic - but I still wouldn't pay $33.99 a month for that. Methinks someone slipped an exponent when deciding how to price the Graph Editor.

In the meantime, this is what I do:
1) Ignore their stated first-crack timing.
2) Use small batches, 50-60 grams, light enough for the beans to lift off the bottom of the chamber. I'm not an expert in thermodynamics, but I assert the small batch size will more closely follow the Ikawa's temperature profile. I confirmed this by putting a thermocouple in the spinning bean mass during the roast and noted that first and second cracks started within 30-60 seconds after the air around the beans hit the typical crack temperatures - but only for a 50-60g load. Larger loads just swirl around, don't intermix as well, are prone to scorching, and have uneven roast uniformity.
3) Choose recipe adjustments that hit the highest temperature with the longest development time, and have a finger ready to punch the button to override the program and start cooling once the roast is developed properly. My problem with this step, is knowing how long to wait after first crack...
4) Custom edit Ikawa's recipes to find the second crack point, then back off a bit - that's how I address the question raised in step #3.

To clarify my point #3: I choose in-app adjustments to Ikawa's recommended profile for the specific bean for which they intended it. I wouldn't use that profile on a different bean.

I only tweak their temperature setpoints in the back half of their recommended profile, leaving the first half unchanged. Theoretically I might need to ramp down the fan speed a bit more towards the end of the roast to keep the now-lighter beans from being ejected into the chaff, but I've only seen that happen to a few (2-3) beans, which for all I know were bad beans anyway. Ironically, I read a post from a professional roaster that complained how the Ikawa was automagically rejecting the bad beans from the lots he was sampling - boo-hoo, and thank you Ikawa!

Ikawa may be trying to 'Nespresso-ize' their roaster and recover their margins on the sale of curated beans. That might explain their emphasis on storytelling in the sourcing info and roast descriptions. Peeps that want to edit their own recipes for their own (non-Ikawa) beans may not be the demographic they're chasing, as they would have sold a machine at a reduced profit with no ongoing revenue stream from that buyer. May not be a coincidence that their graph editor costs about as much as a couple bags of their green beans...

myso wrote:
Since android app is still not updated Android users don't have the option other than to use the recommended profiles from ikawa.

If I were you, I'd plump down ~$75 for a used iPhone 6. Here's a listing on eBay:

https://www.ebay.com/sch/i.html?_nkw=iP ... eName=GSTL

I have some Aida Battle washed Kilimanjaro green beans. After some experimentation, I have settled on the IOS app recipe Espresso Medium +++. The result is a lightish roast that measure #110 on my Tonino meter. The flavours are complex, balanced and delicious.

myso wrote:For example It's med dark ++ for the Guatemala blue ayarza and it spends quite a long time above 250C.

I put a thermocouple probe directly in the spinning bean mass and determined that actual bean temperature is about 40C lower than the Ikawa setpoints. So 250C translates to closer to 210C (for a 'half-load' of 50-60g green beans). My observations so far show that a 250C setpoint will hit first crack and never make it to second crack.

I'm conflicted over what constitutes a 'long' development time, given the Ikawa is pretty close to an ideal convective heating system. There's a 25% rule of thumb for development time in drum roasters - but they can take over 2x longer to complete a roast compared to the Ikawa. Maybe the ideal percentage should be higher for the Ikawa?

GDM528 wrote: I'm conflicted over what constitutes a 'long' development time, given the Ikawa is pretty close to an ideal convective heating system. There's a 25% rule of thumb for development time in drum roasters - but they can take over 2x longer to complete a roast compared to the Ikawa. Maybe the ideal percentage should be higher for the Ikawa?

When I tried Ikawa's recommended espresso profile (Medium Dark ++) for the Guatamala Blue Ayarza, I found the percentage of development time, measured from first crack at 4:52, was 36.7%. This seems very high, but the resulting flavours, according to my notes, were "tasty and complex" as espresso and "citrus, chocolate" in a flat white. The degree of roast measured on my Tonino colour meter was #92 (City in Tonino's opinion).