Funny Tasting Coffee

[green beans]

I am not sure which forum I should post this in but I have a question about a coffee flavor.

Does anyone know what the cause of a chalky or almost tart taste is that some coffee has? I really do not even know how to describe it acuratley but it is very distinct to me, it is a light sour taste almost.

I have tasted it a few times starting when I began to roast my own beans. I thought it was a result of some variable I had not managed in the roasting process. I just had a cup from a local cafe and experienced a similar taste. Any ideas?

It is not burnt coffee or too strong.

Anything would help here, thanks a lot.

 

[Jackson]

I don't know what kind of coffee you are roasting, but sometimes dry processed coffee will almost ferment before it dries completely. This could result in a slightly sour taste. I have had some Brazils that tasted that way, and I do not like them. A tart taste could also result from drying the coffee with the cherry still attached. The chalky taste however, I have no answer for.