How to conserve natural fruit juices without alcohol?
This is basically making must but not adding yeast to it and making wine.

I would do one of three things to your juice:


Boil the juice(must), or heat to 85 deg C for 15 min, then bottle into sterilised bottles.
Treat with a Campden Tablet, then again bottle into sterilised bottles.
Pasteurise after bottling as EZ suggests.