Fill the bottles with milk and store them in the fridge for up to 24 hours. Keep bottles in the main part of fridge, as it is colder than the door. Keep away from raw food. Boiling is another method of sterilizing baby bottles. All the bottle-feeding items need to be boiled for a minimum of 10 minutes. You must have a separate pan, only for the purpose of boiling these items. Some items like nipples or teats will have to be replaced more often if you use this method, as they get sticky.