plz help me ( different color in coffee roasted)

[diplomat_five]

hi
i have cafemino 1k toper coffee roaster,i have big problem in roasting process and that is diffrent color in roasted coffee.plz help me,tell me about air flow,temperature,time and all of things thas cause in different color.which is better slow or fast roasting?
i drop bean at 170c and end of temp about 200c,i use green bean of Arabica India and Brasil and robusta Vietnam az Indonesia.
How can we understand the upstream and downstream temperature?
How is the airflow in the roasting process ?
thank u so much

 

[slurp]

Air flow is used to increase or decrease heat quickly. Post some pictures of your problem I will be happy to help. Welcome to the forums.

 

[Redswing]

Hope you find some answers to your questions!

Here's my basic go-to profile: I drop a dense high elevation grown bean intended to be used for drip brew into the roaster preheated to around 200C (390F), the green beans take just about 1:10 to start increasing in temperature according to my temp gauge, at around 79C (175F). I aim to hit 148C (300F) at about 4:00. The next benchmark is first crack, which happens on my temperature gauge at about 197C (385F)...I like that to happen around 8:00. I try to finish before the second crack, 3:00 after first crack gets rolling, at about 212C (415F). Finishing under 207C (405F) results in pretty much undrinkable coffee for my taste. Grassy tasting.
Oh...make sure you cool the beans as fast as you can, for sure so they are cool to the touch within 3:00.

If you roast too slow (finish after, say, 20:00 maybe?), the coffee tastes flat and dull. If you roast too quickly (finish before 6:00), the coffee tastes bitter and underdeveloped. To me.

As to airflow, I think it's impossible to say without knowing your machine. I would leave the air on full bore for the entire roast, myself.

Not sure what you mean by "upstream and downstream temperature". Could you explain that one a little more?