a stomachache can be because of lots of things, coffee might be it.
as for arabica making sour coffee?
im not sure about that.
what i have found is that robusta is alot more acidic...and im sure plenty of the other guys will confirm it.
where did you get the 'sour arabica' from?
was it pure arabica?
or was it arabica blend?
check the packet and please post again...i would love to hear
Arabica, if good quality and roasted well, should be not sour, but sweet! I am not sure how you drank your coffee- maybe it was an espresso? If so then maybe the strength of the coffee may have been the issue?
You might want to try Health Wise coffee. Supposedly they have a special process that takes out all "excess acid and irritants". I've ordered some, actually they sent me a free sample, but I haven't tried it yet.
I only have stomach problems when I switch brands sometimes.
Sour coffee?? Winey or sourish acidity maybe, but acidity should be a positive trait.
How dark is the coffee roasted? Chemical reactions that occur in dark roasts are known to cause acid reflux...and make sure you don't confuse coffee acidity with acidic foods that can cause stomach upset. Acidity in coffee is a trait that makes up much of what you taste.
I have to disagree with your comments about drum ('flame') roasting. This in absolute;y no way affects the percieved sourness or biterness that the original poster is taking about. Poor roasting technical- whether it is with a hot air, fluid bed or drum can cause roasting faults that affect the cupping character of the coffee... but NOT using a drum roaster per see.
poor roasting can be partially the problem, as well as perhaps a bad quality bean.
i have experienced it where the packet says its arabica and turns out to be something realy unpleasant.
but the fact that you used an extract....that does make me wonder...did you add enough water?
and are you use to the taste of such coffee?
ive seen that when people are not familiar with some speciality coffee...they describe an unpleasant taste as something totally off key...make sure to not get muddled with your tastes...ie bitter could come accross as sour etc