Prized more for its ornamental value than for its fruit, the calamondin tree originated in China. Around 1900, this unique citrus tree was introduced into Florida from Panama and later distributed to Texas and California. Apparently, the tree was not widely distributed, because I have never met another soul who knows what a calamondin is.
Here in southern California, we have one small calamondin tree that produces more fruit than we know what to do with. The aromatic orange fruit is round, about 1 to 2 inches in diameter, and highly acidic with a thin edible peel that is tender and sweet. One way to preserve these tiny, tangy fruits is to make marmalade. It takes some time, because the calamondins are so small, but it is worth the effort.
The right tools make any job easy. If you are new to canning, invest in a basic home canning kit or a canning tool set.
calamondins (depending on their size, there are about 10 calamondins per cup)
Wash calamondins. Cut in half and remove seeds. Slice thinly with a sharp knife. Measure fruit and place in saucepan.
For each cup of fruit, add 3 cups water. (I usually end up with 8 cups calamodins. I use two 5-quart stockpots and put 4 cups fruit and 12 cups water in each one.)
Bring to boil; cook 15 minutes to soften the peels and release the juices. Let stand overnight to intensify the flavor.
Measure 6 cups calamondin stock into large stockpot and bring to a boil. Add 3 cups sugar. (This is equal to 1/2 cup sugar per cup of stock. This will give a sharp, almost bitter taste. If you like it sweeter, try adding up to 1 cup of sugar per cup of stock.)
Stir to dissolve sugar. Bring to a rolling boil and cook rapidly to 220°F on a deep-fry or candy thermometer. It takes about 30 minutes to reach this point. (Note: Some recipes suggest cooking the mixture until it reaches 225°F. I find this makes the marmalade too dark and too thick for my taste.)
Remove from heat; cool to 180°F. As it cools, the marmalade will thicken slightly. Pour into hot, sterilized jars, leaving 1/4-inch headspace. Adjust caps. Process 10 minutes in boiling water bath. (Start your timer after the water boils firmly.) Make sure the jars are always covered with water during the pasturization process.
Leave the jars in the water until they are completely cool. You should hear a metallic pop when each jar cools enough to seal the lid. If the seal has not formed, repeat the pasturization process with a new lid.
The mixture reduces significantly as it cooks. Using 6 cups of stock makes about two 10-ounce (0.3-L) jars of marmalade.