How do I design a Turkish coffee mixture? I am trying to create a Turkish coffee mixture, by combining Colombian, Brazilian, Robusta and a few other types together in some percentage.
I could not find a base at which to stand in designing such mixture. What are the ideal characteristics of Turkish coffee ? How much caffeine, glucose, other chemicals should it contain ?
There is no recipe for preparing a perfect blend.

Before beginning, please read this somewhat relevant question first:


What are the basics of creating an espresso blend?


I, personally, prefer to use Ethiopian Harrar single origin beans, light-to-medium roasted. However, this may all depend. When you go to a commercial Turkish firm, they mostly consume Dos Santos beans from Brazil, which itself is a kind of blend itself, and roast them to charcoal.

To prepare a Turkish blend, all you need to know is the characteristics of the brewing technique (See this previous post for a discussion) as you can see in the previous post. Opposite to the espresso, Turkish brewing is the least acidity revealing technique out there as it uses decoction. Therefore,


you can safely use acidic beans
you don't need to roast a lot to get rid of acidity
and, as a result, you can taste the fruitful notes, go for fruity beans
you may safely try dry/honey processed beans


Then, about the chemicals... You should not put any additional chemicals in it. It should be just ground coffee. I know some commercial products that already mix some herbs or sugar with fine ground coffee; but it has nothing to do with the reality apart from marketing. Think of it as 3-in-1 instant coffee products. You probably don't want to drink them.