What is best to use to keep a coffee frappe from separating?

I am wanting to use my Magic Bullet to make a coffee frappe. But it keeps separating and is gross! I got some pectin and gelatin. Can I use either one of these to add to my mixture to keep it from separating? If so - does any one know how much to add. If not - what does anyone recommend to use that I can get at the grocery store.