ira wrote:A question about this. Yesterday I did my first roast of my new CROWN JEWEL COSTA RICA CAÑUELA CAFÉ DE ALTURA RAISED BED NATURAL and while I can tell that it's a really good coffee, I can also tell that was not the optimal profile, does that belong here?

Yes! 100% I think such examples will help new roasters to work out whether they are looking at a roast or a green issue.

I'll give it a shot.

Here is a roast that I have of Rwanda Nkara, a 2021/2022 harvest red bourbon. From the information that is given to us, it's harvested, pulped, fermented overnight, then soaked in water for a day before being dried, so it seems similar to a kenyan coffee process. This means that I'm expecting it to have more fruit than a more bland washed coffee where there's little fermentation, but I'm also expecting it to be scrupulously clean. Because it's a Rwandan coffee, I'm on the lookout for potato defect.

This roast hit first crack at 194.5c and I ended the roast at 202C, 46 seconds after the start of first crack. (No one should use these as absolute values for their roaster. I'm just providing these because I'm going to discuss them later. Also the line that is labelled drum temperature is actually inlet temperature.)

In the cup, this is slightly green, a bit bland (maybe like a slight raw oat character) and high in acidity. It's very sweet and lowish in body. It also has a bit of fruit to it; kind of cranberry, maybe a little stonefruit (peach, probably) and maybe a bit of black tea. Now, the caveat with this is that I didn't write anything down; these are just the QC results I can remember after I ground this and cupped it basically immediately after roasting.

So the slight green character, the raw oats and the low body point towards underdevelopment, but there's nothing wrong with the green coffee, at least from what I can tell here.

This coffee is probably underdeveloped. There's a small chance that if I let it sit for a few weeks it will come good, because it's pretty close. My issue with this was that I was too focussed on the absolute bean temperature value and timidly dropped it early as soon as it hit 202C, with only 45s development time. This works well for many natural processed coffees with these roast conditions, so I wanted to see if it would work for this Rwandan coffee and the answer is no; generally washed coffees need more development time than natural processed coffees and honeys, with my roaster and settings.

One thing that this kind of illustrates is something that might become useful for people - if you want to work out if something is a roast or a green issue, one way to check is to roast super fast and light and cup that. Of course not all such roasts will be good; it could be too hot and flick or it could have not enough heat and bake out or underdevelop, but if you can get the coffee developed to a point where you can taste the origin flavours pretty clearly, short and fast light roasts should usually eliminate a lot of roast defects like bakes and flicks. So the only roast defect you'll have will be underdevelopment. So if you can identify underdevelopment and you have developed the origin characteristics, if there is something else in it that you hate, it's more likely to be green and not roast. Hence why people cup at these levels to make buying decisions.

mkane wrote:We're looking for green coffee defects that show in the cup.

I think it would be useful if we did both green and roast issues and discussed what they are so people can learn how to distinguish them from each other. It doesn't have to be defects in any technical sense; it can be things that people don't like. For example, there are a number of coffees that trade as premium coffees that have pretty distinct rubber to them and that I can't stand and avoid buying. I don't know if that's a technical defect or not, but if you don't want it in your cup, you don't care, but you probably want to know if it's avoidable through roast or if it's unavoidable and part of your green.