Concentrating lemon or orange juice is a great way to save space in your freezer and make sure you have juice all year long. A few years ago we had a really big freeze in Phoenix and the citrus all froze. Basically we had 2 weeks to use up our fruit or it would rot. Usually lemons are useable on the tree for most of the year, even when they are green, so preserving them isn’t something we think about. However, if you want to make sure you have a constant supply of juice, this is how you do it.
The first thing you want to do is juice your citrus and put it into a plastic jug, leaving enough space for it to expand when frozen. Place it in the freezer for 24 hours.
Once it is completely frozen, remove the lid and invert over a container that the juice concentrate can fill. I used my Vitamix container. The temperature outside on this day was about 75° F.
The reason this works is because the sugar in the juice thaws faster than the water. What you get will be a much more intense and slightly thicker concentrate.
After 5 hours, this is what I ended up with – one quart of concentrate from one gallon of juice.
The jug is still full of ice. It is a very diluted juice/water that is left over. You can still taste the juice, but it is much weaker. The intense flavor of the citrus is now in the concentrate. You can repeat the process to further concentrate it, but I think this is pretty good at this point.
I like to freeze it in ziplock bags or or in small ice cube trays. Because of the sugar content in the concentrate, it will remain slightly sticky, so you may want to just leave them in the ice cube trays placed in a gallon ziplock. You don’t have to fill the trays either. Leave some compartments only half full. That way you can pop out a smaller amount when necessary.
The one thing you will want to make sure to do is have a space in your freezer to place these trays full of liquid. Once they are frozen you can store them in any position, but they must be flat until then.
If you would like to can the juice, simply pour the juice in clean jars, seal and process in a waterbath canner for 15 minutes (10 minutes under 1,000 ft above sea level).