Fresh tomato juice is high in potassium and can be made at home from fresh tomatoes. This is a good and nutritious way to use extra tomatoes from the garden. This recipe yields approximately 1 quart of tomato juice, but it may be doubled or tripled as necessary. As a general rule, use 3-¼ pounds of tomatoes for each quart of juice you wish to produce.
Wash the fresh tomatoes in cool water to remove any external debris and carefully remove the stems with a sharp knife. Cut each tomato into quarters, and remove any green, white or mushy spots.
Immediately place the tomato quarters into a large stainless-steel saucepan or kettle to prevent the juice from separating. Bring the tomatoes to a simmer over medium-high heat, stirring constantly, just until soft and juicy. This takes about five to eight minutes.
Place a large bowl under a fine mesh sieve to catch the juice, and transfer the tomatoes to the sieve. Push the fruit through using your hands to separate the skins and seeds. Discard any remaining pulp in the sieve.
Return the tomato juice to the saucepan or kettle, and reheat to boiling over medium-high heat. Remove from the heat, and then prepare the canning jar and boiling water bath for processing.
Add lemon juice to the sterilised canning jar, and enough water to a large stockpot to cover 1 inch over the canning jar's top. Bring the water to a rolling boil over medium-high heat.
Transfer the tomato juice to the prepared canning jar using a funnel to prevent spilling. Leave about ½ inch of space at the top of the jar. Secure the lid in place, and lower the jar into the boiling water bath using metal tongs.
Allow the jar to process in the boiling water for 40 minutes, and then remove it using the metal tongs to prevent overcooking. Place the jar on a dry dishtowel to cool and seal.
Allow the tomato juice to stand for 12 to 24 hours, and then test the seal by pressing the flat part of the lid in the centre with your finger. If the lid is slightly concave and does not move, it is properly sealed.
Label the jar of tomato juice with the date and contents, and store in a cool, dark place for up to one year. Store the juice in the refrigerator once the jar has been opened for up to one week.
Sterilise canning jars by boiling in hot water for 10 minutes prior to filling with juice. Use ½ tsp of citric acid instead of the bottled lemon juice, if necessary or desired.
Be very careful not to splash hot water from the stockpot while adding and removing the jar of tomato juice. Wear oven gloves to protect your hands from accidental burns.