Plum Jam with Walnuts and Rum – Small Batch, Low Sugar
The easiest plum jam is made with nothing but plums and sugar, but sometimes I enjoy mixing things up a little. This plum jam recipe has a small amount of commercial pectin, which lets you use less sugar, and speeds up cooking time. Try it as a topping for ice cream or cheesecake, on toast with butter or nut butter, or mixed into yogurt.
Plum Jam Q&A
First up, let’s cover some common jam making questions.
Do I need to add lemon juice to plum jam?
To safely water bath can foods, the pH of the food must be 4.6 or lower (acidic). The normal pH of range for plums is:
- blue plums – 2.80-3.40
- red plums – 3.60-4.30
- green gage plums – 3.60 – 4.30
- yellow plums – 3.90 – 4.45
Therefor plums should be safe for water bath canning without adding lemon. That said, if your plums are extremely ripe, the pH may be borderline, so a little extra lemon isn’t a bad idea.
See pH Values of Common Foods and Ingredients and Master List of Typical pH and Acid Content of Fruits and Vegetables for more information.
Are plums high in pectin?
Plums are naturally high in pectin, especially the skins. Ripe plums make sweeter jam with less added sugar, but plums that are not as ripe have more pectin. If you want to make plum jam without added pectin, use plums with a mix of ripeness for faster gelling.
Do you skin plum before making jam?
Nope! At least, I never do. The skins are high in pectin, fiber and nutrients, and help give plum jam that beautiful deep red color. I do like the cut plums in quarters or pop them in the food processor for a bit for a more even texture in the jam.
How do you process plums for jam?
To prep plums for jam, first wash the fruit. Cut in half and remove the pits. At this point you can either dice up the plums, or chop them briefly in the food processor. I don’t usually leave them in halves unless the plums are small, because the skins don’t break down completely during cooking.
How to Make Plum Jam
Start with room temperature plums for faster cooking. Prep your fruit by washing, pitting and chopping. (Don’t peel the plums.) This recipe uses about 2 pounds of ripe plums.
Measure out chopped walnuts. (I use crispy walnuts.) Grate the lemon peel and then juice the lemon.
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If you are water bath canning your jam, you don’t need to sterilize the jars. (Processing the jars also sterilizes them.) Simply wash them in the dishwasher or warm, soapy water and keep warm.
Prep your boiling water bath canner along with your jars and lids. Always inspect jars for any damage prior to canning. Although it is no longer required by the two piece lid manufacturers, I still like to keep my canning lids in warm water prior to use for a better seal. (Don’t boil the lids before they are on the jars.)
Place plums, lemon peel and juice, walnuts and calcium water in a stockpot. Mix sugar and pectin. Heat fruit mix until boiling, stir in sugar mix. Return to boil and boil for one minute. Remove from heat. Stir in rum.
Ladle hot jam into jars. Process plum jam with 1/4 inch headspace for 10 minutes in a boiling water bath canner. Turn heat off and allow to rest a few minutes, than place jars on a towel on the kitchen counter to cool completely.
Remove rings, wipe tops, date and label. Store in a cool, dark location. Best used within 1-2 years.
PrintPlum Jam with Walnuts and Rum
This plum jam recipe has a small amount of commercial pectin, which lets you use less sugar, and speeds up cooking time. Try it as a topping for ice cream or cheesecake, on toast with butter or nut butter, or mixed into yogurt.
- Prep Time: 10 minutes
- Cook Time: 20 minutes
- Total Time: 30 minutes
- Yield: 5 cups 1x
- Category: Jam
- Method: Canning
Ingredients
- 4 cups prepared plums (about 2 pounds fully ripe plums)
- 1/2 cup walnuts, finely chopped
- 2 teaspoons grated lemon peel
- 1/4 cup lemon juice
- 1 1/2 cups sugar
- 2 teaspoons Pomona’s Pectin
- 2 teaspoons calcium water (included with Pomona’s Pectin)
- 1/2 cup dark rum
Instructions
Pit plums; do not peel. Grind or finely chop. Measure 4 cups into a 6- or 8- quart sauce pot. Stir in walnuts, lemon peel and juice.
Prepare jars (wash, inspect rims, clean in sink or dishwasher). Keep lids warm until ready to fill jars.
Measure sugar and pectin into separate bowl.
Bring fruit mixture to a full rolling boil on high heat, stirring constantly.
Stir sugar/pectin mix into fruit mix in sauce pot. Return to full rolling roil and boil one minute, stirring constantly. Remove from heat.
Gently stir in rum. Skim off any foam with a metal spoon, if desired. (I usually skip skimming.)
Ladle quickly into prepared jars, filling to 1/4 inch of top. Wipe jar rims and threads. Cover with two piece lids.
Process jars for 10 minutes in a boiling water bath canner. When processing time is done, let rest a few minutes in the water bath, then place jars on a towel on the kitchen counter. Allow to cool completely.
Remove rings for storage. Wipe tops and test seals. Date and label and store in a cool, dark location. Best if used within 1-2 years.
If any jars did not seal, refrigerate and use within a month.
Are plums good for you?
A study on plums published in the Journal of Food, Nutrition and Population Health notes:
Plums have abundance of bioactive compounds such as phenolic acids, anthocyanins, carotenoids, flavonols, organic acids, (e.g., citric and malic acids), fiber (pectin), tannins, aromatic substances, enzymes, minerals (e.g., potassium, phosphorus, calcium and magnesium, organic) and vitamin A, B, C & K.
What to do with lots of plums?
Enjoy your plums fresh, or try them in place of rhubarb in rhubarb pudding cake. Plums freeze well for later use, too. Just wash, remove the pits and freeze.
For basic plum jam, combine 5 cups chopped plums, 3 cups sugar and 3/4 cup water in a large saucepot. Bring slowly to a boil, stirring frequently. Cook, stirring occasionally to prevent sticking, until jam reaches the gelling point. Remove from heat and process as above.
You can also make honey sweetened plum preserves, plum wine, dried plums, plum sauce – use your imagination!
Originally published in 2011, last updated in 2019.