If you want to make your own juices at home, you should understand that they may not be safe to drink unless they're pasteurized because they may contain harmful bacteria. Pasteurization is a process of heating, holding and cooling the juice to destroy the bacteria and make the juice safe to drink. You can do this at home and it does not affect the flavor or nutritional value of the juice.
Lay a large, clean towel flat on the countertop next to the stove.
Fill the kitchen sink with cold water.
Check over the canning jars and discard any that have imperfections.
Place the jars, lids, funnel and ladle into the large pot, cover them with water and bring the water to a gentle boil. Boil it for 10 minutes. Turn off the heat. This sterilizes the jars and utensils, making them ready for use.
Using tongs to remove the lids, funnel and ladle from the pot. Place them on the towel. Leave the jars in the hot water while you work with the juice.
Heating and Holding
Heat the juice in the double-boiler to 175 degrees Fahrenheit. Keep it at this temperature for 20 minutes. Turn off the heat.
Remove a jar from the hot water using the tongs. Drain any water from the jar back into the pot and place the jar right-side up on the towel. Leave the remaining jars in the hot water until you're ready to fill them. Touch only the outsides of the jars to avoid contamination.
Hold the jar with a pot holder, and set the funnel inside the jar and ladle juice into the jar until the juice is 1/2 inch from the top. Secure the lid with the ring and set it aside on the towel. Continue until you've put all the juice into jars.
Wait 5 minutes.
Place the jars into the sink of cold water.
Add ice to bring the temperature of the water down to 40 F and keep it at this temperature for 15 minutes. Monitor the temperature by checking every minute or so, adding ice as needed to keep it at 40 F. This will ensure a uniform temperature throughout the water, jars and juice.
Remove the jars from the cold water and place them on the large towel. Dry the outsides of the jars. The juice is now ready to drink, or you can store it in the refrigerator for up to two weeks.