I'm trying to make cheddar sticks from scratch What are common commercial food additives that keep the cheese 'melty', but not runny?

I have tried making fried cheddar sticks but the cheese just oozes out, like thick water...

Freezing first?  Freeze the breading too?
Sodium Citrate is the most common emulsifier for cheese, it keeps it soft and flexible when cold, and like a smooth sauce when hot. Being an emulsifier it stops it separating too

See http://modernistcuisine.com/recipes/sodium-citrate-creates-silky-smooth-macaroni-and-cheese/

You can make Sodium Citrate at home, heat a tbs of lemon juice, add 1/2+ tsp of baking soda and stir. Add this to a cup of melted cheese (all very rough measurements). Experiment to get the best results for your cheese of choice!