If you didn't catch the comment from James you should read it. He asks about incorporating air into the ice cream. I won't reiterate my response, you can read his question and my response here.
After my response, we went back and forth for a while through e-mail. I learned that he is using 10% milkfat and 12% sugar. This really better defines why he is having problems. Here in the USA, 10% milkfat is the minimum amount allowed in a frozen product to have it called ice cream. It is at this level of fat content that manufacturers pump air into their product to improve texture. Also, 12% sugar is too low for 10% milkfat. He should have 14% sugar. That will help some, but will really help him is increasing the fat content to 14 or 15%.
From these conversations, I realized that this fellow is doing it wrong. I do not show you the breakdowns of contents of my ice cream for fat, MSNF (milk solids non-fat), sugar, and other solids. So I have developed a spreadsheet based on the format given by Caroline Liddell and Robin Weir in Frozen Desserts.
The banana ice cream recipe will be posted tomorrow. Starting with it, I will include a copy of this worksheet and a discussion of contributions of the various components to the overall flavor and texture of the finished product.