Yes, if the recipe calls for heating, do it. Many gelato recipes (most, even) are frozen custards, where you heat the dairy/egg yolk mixture to ~180F/80C both for safety and to thicken the mixture & provide a creamier texture. The proteins & emulsifiers in egg yolk help keep ice crystals small, & in ice cream, small ice crystals = smoother texture. I'm sure somebody else here can explain it better.
1/22/11 at 3:24pm