I have recently gotten into making my own soft drinks, and I would like to attempt making a cola. I found an online spice retailer that sells Kola Nut and bought some, but I have no real idea how to prepare them for use. I also don't know how much I should use for a liter or two of soda, but I can figure that out via experimentation if I have to.
But what should I do with the kola nuts? Do they need to be ground before I boil them in a simple syrup, or should the pieces just be dropped in as-is? How much time does it take to extract the flavor from them?
Edit: I have made my own ginger ale using fresh ginger and my own berry soda using a bag of frozen berries, and I am a homebrewer and have a kegging system and a carbonator cap for soda bottles. I really just want to know if there are special considerations for how to treat kola nuts.