I'm using all prepackaged ingredients, and following good sanitization (QA) procedures of utensils and work area. Do I need to re-pasteurize my mix before feeding it into the machine? The machine has been sanitized using QA as well.
I would think that if all the ingredients are pasteurized then you wouldn't need to re-pasteurize anything.
Where I've heard of people getting into trouble is when they add something like raw fruit to an ice cream mix, and the fruit hasn't been pasteurized (cooked to a particular temperature for a particular amount of time).
But note that just because it's prepackaged doesn't necessarily mean it's safe for raw consumption. For example, you can make "cake batter ice cream" by adding boxed cake mix to an ice cream base, but the flour from the cake mix isn't pasteurized or safe to eat raw.