I'm looking for the basic formula for fruit ice cream when you already have fruit puree. I often freeze fruit puree so I have the sweetened puree as the starting point. Most recipes for fruit ice cream give you the amount of raw fruit in the ingredients list, and don't tell you how much puree this yields. Basically I'm looking for 2 formula's.. how much cream (or a mixture of cream/joghurt/buttermilk) and sugar for how much sweetened fruit puree, and how much custard for how much sweetened fruit