The natural acidity of lemon juice prevents it from spoiling as fast as many other fruit juices, but there are several ways that you can preserve your fresh-squeezed lemon juice even longer. Regardless of what method you use, you should always prepare your materials first. Afterward, you can either can or freeze your lemon juice. Alternatively, you can also try an old-fashioned preservation technique, which will work just as well.
The fresher the lemons, the fresher your juice will be from the start. Beginning with fresh juice is one of the most essential steps in preserving fresh juice. You can use lemons of virtually any size and variety, but any lemon you juice should be firm, ripe, and unspoiled.
The equipment you need will vary depending on the method you use. Glass jars with metal lids are required for canning, while plastic ice cube trays are required for freezing. If using an older technique, glass bottles may be in order. Regardless of the method you use, all equipment and supplies should be sterilized with detergent and hot water. If the supplies are dishwasher safe, you can sanitize them using that method. Otherwise hand-wash the supplies in hot, soapy water and rinse them with boiling or near boiling water.
- Only use jars that are approved for canning. Jars that are not specifically designed to work with canning should be avoided since the glass may not be able to withstand the heat. You can use pint (500 ml), quart (1000 ml), or half-gallon (2 liter) jars, but pint (500 ml) jars tend to preserve the juice best. After all, you will be able to go through the juice in a small jar faster than you would a large jar.
- Leave 1/4 inch (6.35 mm) of empty space in between the top of the juice and the rim of the jar. Wipe off any spilled juice.
- Canning jars have a special lid made of a flat lid piece and a ring. Seat the flat lid piece over the mouth of the jar and secure the ring around the lid piece and the mouth of the jar. Screw it on as tightly as possible.
- Place the jars in your canner and cover with water. In the absence of a canner, you may also use a large, heavy stockpot. Either way, the jars should be covered by about 1 or 2 inches (2.5 or 5 cm) of water.
- Cover the canner or stockpot and boil the water until the pressure can process and seal the jars. The amount of time you should boil the water depends on the size jar you use and the altitude you live at.
- For pint and quart (500 and 1000 ml) jars, boil the water for 5 minutes.
- For half-gallon (2 liter) jars, boil the water for 10 minutes.
- Add an extra 5 minutes onto these times if you live at an altitude between 1000 and 6000 ft (305 m to 1.8 km) or an extra 10 minutes if you live at an altitude above 6000 ft (1.8 km).
- After the jars have rested in the boiling water for an appropriate amount of time, turn off the heat, remove the lid of the pot, and carefully lift the jars out of the hot water using canning tongs. Allow them to cool at room temperature in an area free from drafts. The cooling process should take several hours to overnight.
- Gently press down on the center of the lid. If it “pops,” the jar is not properly sealed. If this happens, you should boil the contents of the jar and redo the canning process to create a better seal.
- To make the fruit easier to juice, roll firmly on the counter with the palm of your hand to loosen up the flesh. Cut the fruit in half crosswise and juice it using a handheld juicer, food processor attachment or whatever tool you happen to favor.
- Using a small ladle or a small pitcher with a spout, pour the citrus juice into ice cube trays. Each standard-sized ice cube will contain about 2 tablespoons of liquid. However, a suggestion is measuring the capacity of your ice cube tray to be sure.
- Freeze until solid. Juice will freeze to a stage that is slightly softer than regular ice cubes. Remove cubes from the tray and place in a freezr re-sealable bag.
- When you are ready to use the juice, remove the number of ice cubes from the freezer that you desire and defrost them.
- For every 1 quart (1 liter) of juice, add about 1 ounce (30 ml) of cream of tartar. Cream of tartar has preservative qualities. Stir the two together until thoroughly mixed.
- Allow the lemon juice to stand. Letting the juice stand at room temperature lets the cream of tartar and lemon juice combine more effectively. Stir the mixture frequently during this time.
- Filter the lemon juice. Remove pulp and chunks of un-dissolved chunks of cream of tartar by pouring the juice through muslin or a coffee filter rested inside of a strainer. Use a mesh strainer with small holes to achieve the best results.
- Pour the lemon juice into glass bottles. Use a funnel to prevent juice from spilling out as you pour.
- Fill the neck of the bottle with olive oil. Olive oil is another natural preservative. It works by cutting off the supply of air to the contents of the bottle. As a result, air is unable to reach the lemon juice in the bottle, preventing it from spoiling.
- Tightly fit a cork or other seal into the mouth of the bottle.
- Remove the olive oil prior to use. Do not shake the bottle when you open it, since doing so would combine the oil and juice. Once you do open it, pour off the oil from the top of the juice before using the juice itself.