Spread a kitchen towel on the counter. Use your jar lifter to remove a jar from canner, drain, and place on the towel. Keep the remaining jars in the canner so they stay hot.
Add citric acid or lemon juice to the jar. For pints, add 1/4 teaspoon of citric acid, or 1 tablespoon of bottled lemon juice to each jar. For quarts, add 1/2 teaspoon citric acid or 2 tablespoons of bottled lemon juice to each jar.
Use your canning funnel and ladle to add hot juice into the jar leaving 1/2-inch headspace.
Wipe the rims of the jars with a clean, damp towel. Center a lid on the jar, and screw on the band until it is fingertip tight.
Use the jar lifter to place the jar back into the canner, and repeat with the remaining jars. Try to leave some space in between the jars.
Once the jars are all in canner, adjust the water level so it is at least two inches above the jar tops.
Cover the canner and bring to boil over medium-high heat. Once water boils vigorously, process pints for 35 minutes, and quarts for 40 minutes at altitudes of less than 1,000 ft. Adjust processing time for your altitude if necessary (see notes below).
When processing time is complete, turn off the heat and let the canner cool down and settle for about 5 minutes.
Spread a kitchen towel on the counter. Remove the cover by tilting lid away from you so that steam does not burn your face.
Use the jar lifter to lift jars carefully from canner and place on the towel. Keep the jars upright, and don't tighten bands or check the seals yet. Let the jars sit undisturbed for 12 to 24-hours to cool.
After the jars have cooled for at least 12 hours, check to be sure jar lids have sealed by pushing on the center of the lid. The lid should not pop up. If the lid flexes up and down, it did not seal. Refrigerate the jar and use within a few days.
Remove the screw on bands and wash the jars. Label, date, and store your jars in a cool, dark place, between 50 to 70 degrees F. Use within 12 to 18 months. Refrigerate the juice once opened and consume within a few days. Yields about 7 quarts, or 14 pint sized jars.