Kumquat jam is a wonderful way to enjoy an otherwise tart but flavorful little fruit. Make them into a jam and all that tartness comes through as a glorious full-flavored spread, perfect for your morning toast or elaborate treats.
The first time I tried kumquats was right off the tree in California. Even growing up among the citrus groves, I had never seen or heard of kumquats until high school. One afternoon my team was playing on a new field, and there was a giant kumquat tree hanging over the fence right into the dugout.
We were all curious about them but no one knew what they were. I plucked one off, carefully peeled it and got the surprise of my life. SO incredibly tart!
What I didn’t know was kumquats are eaten whole, peel and all. The inside is very tart, but the skin is mild and sweet. Together they’re a treat with a bit of zing, but without the peel, it’s sour enough to make your eyes water.
When making homemade kumquat preserves, that begs the question, is it a jam or a marmalade? Generally, marmalade is a citrus-based spread that includes peel to add subtle tart/bitter notes to balance the sweetness. But what happens if it’s a type of citrus where the peel isn’t bitter, and you can’t reasonably eat the fruit without the peel?
I call it kumquat jam, you can call it kumquat marmalade if you like, but my kids…they call it delicious.
There are a few different ways to prepare kumquats for kumquat jam, but regardless of the method, the peel is always central to the preserve. In my method, I simply slice the kumquats across the equator, which leaves full rounds of the tiny fruits in the finished jam.
I’ve seen other methods that slice the fruits into strips vertically, cutting them into eighths. That leaves you with thin 1” slices of peel throughout the jam almost like confetti, and that gives a look much more like a traditional marmalade.
Since I want to really play up the uniqueness of these tiny fruits, I find the rounds make for a striking presentation. There aren’t any other citrus fruits tiny enough to cut into rounds for jam, so this kumquat jam catches your attention.
Beyond their tartness, another surprising thing about kumquats is the seeds. For such a small fruit they have some impressively large seeds. Those will need to be removed before the slices go into the jam.
As you’re slicing the kumquats, you’ll find a pocket of seeds towards the center. Simply use the tip of your knife to pull them out and set them aside.
Now you’ll notice I said “set the seeds aside” not “toss the seeds in the compost.” The seeds are actually important to this jam, believe it or not!
Citrus fruits contain quite a bit of pectin naturally, and the seeds have some of the largest concentrations. Those large kumquat seeds are the source of pectin for this jam, and they’ll help it thicken up beautifully without any store-bought pectin.
The trick is, while you need the seeds in the jam pot as a thickener, you don’t want them in the finished jam. Wrapping the seeds up in a bit of cheesecloth means you can put them into the boil as a pectin source, but then remove them towards the end for a clean seedless kumquat jam.
I’ve read that you can also place the citrus seeds in water overnight and they’ll cause the water to gel. That gel can then be added to the jam, instead of the seeds in a cheesecloth packet. I haven’t tried that method yet because I always have plenty of cheesecloth on hand from my home cheesemaking.
The thing you do need to keep in mind though is this jam needs to sit for a while before boiling. All the kumquat slices and the packet of citrus seeds go into the pot with a bit of water, and then they need to soak for 3-4 hours before cooking. At least so they say.
I’ve tried making kumquat jam the inpatient way, and just turned it on and started boiling. It does work and it will gel, but the yield is slightly lower since there’s less pectin. It’s harder to make a low sugar kumquat jam that way since in a low sugar jam the yield is already lower.
If you’re pressed for time and want to just get to it, go ahead. Just keep in mind your last jar of jam might not be all the way full, and you should probably use the full amount of sugar.
Sugar Amounts for Kumquat Jam
The amount of sugar in this jam recipe is a matter of preference. Just like any fruit, kumquats can be really tart or only mildly tart, depending on their source.
If you have fruit that is pretty sweet to start with, less sugar might be a good choice. Likewise, if you have very tart fruit (or like very sweet jams) more sugar is always an option.
I’ve seen some kumquat jam recipes that use 2 cups of kumquats and 8 cups of sugar, and in my mind, that’s just way over the top. At that point, you’re making candy, and the fruit is just in there for color.
This recipe has 2 cups of fruit and 1 cup of sugar, or roughly 1/8th the amount of some you’ll find. Still, I find it pretty darn sweet, and only ever so slightly tart, just enough to taste the fruit. I’d make it like this for my mom, who has a pretty good sweet tooth.
For myself, I’d reduce the sugar further to 1/2 cup of sugar for 2 cups of sliced kumquats. That reduces the yield a bit but suits my tastes better.
Either way, the jam gels just fine since the citrus seeds are in there adding extra pectin and helping to bring everything together. Regardless of the amount of sugar you choose, cook the jam to gel stage (220 degrees F) or test it for consistency on a plate kept in the freezer before pouring it into canning jars.
If you’re at a higher altitude, gel stage adjusts a bit.
For every 500 feet above sea level, drop 1 degree from the jam finished temperature. For example, at 1000 feet gel stage is actually 218 degrees instead of 220.
Kumquat jam is a great way to use an otherwise tart fruit. It makes a beautiful presentation and is perfect for your morning toast or an exotic treat.
- 2 cups sliced kumquats (roughly 3/4 lb)
- 3 cups water
- 1 cup sugar (see note)
- Slice the kumquats into thin slices horizontally across their equator, removing any seeds and setting them aside.
- Wrap the seeds in a bit of cheesecloth, tie it up and place them in the jam pot.
- Add in 3 cups of water and the sliced kumquats.
- Allow the fruit and water to sit for 3-4 hours, so that some of the pectin can extract into the water (this step can be skipped for a slightly lower yield).
- Turn on the pot and bring the mixture to a simmer. Cook for 35 to 45 minutes, adding a bit of water if necessary. At this point the jam should be starting to thicken.
- Remove the packet of citrus seeds and add sugar.
- Simmer the jam for another 5-10 minutes until the jam reaches gel stage (220 degrees F) or gels promptly when a bit is placed on a plate that's chilled in the freezer.
- Funnel into prepared canning jars, remove air bubbles and apply 2 part canning lids.
- Either store in the refrigerator for immediate use, or process in a water bath canner for 10 minutes to make the jam shelf stable.
I often choose to use less sugar, adding only 1/2 cup instead of the full 1 cup in this recipe. That makes a tarter jam, and lowers the yield slightly. Adjust to your preference.
More Citrus Preserving Recipes
- Canning Lemons 3 Ways
- Simple Orange Jam
- 20+ Ways to Preserve Lemons
- Homemade Limoncello Liqueur
- Salt Preserved Lemons
- Lemon Wine
When you add less sugar (the 1/2 cup only), for how much longer do you need to cook it to reach the gel consistency?
Thank you –
I haven’t timed that, but not too much longer. The fruit have already cooked down considerably, and you’re only cooking it for a short period with the sugar. I’d guess maybe 5 minutes longer to reach gel stage, but that can vary based on your fruit. It’s best to test it on a plate or with a digital thermometer and just watch your jam. But either way, know it’s not that much more time.
My kumquats have patches of white fine mould..the fruit is still firm..can I wash it off and still use for jam
Personally, if it’s just on the surface and it wipes right off I’d still use them. This gets boiled a long time at a high temperature, and if the fruit are still firm I’d still use them. It’s a judgment call though, since you’re the one that’s going to be eating it.
The kumquats that grow here in Pensacola do not have juicy segments , and are not as tart as you described . There is a sweet rind and mildly tart pith with seeds. I tried your recipe using 3/4 cup sugar . It took me 25 minutes to cook it down to the gel stage , and yield was 1 and 1/2 cups of jam . The consistency of mine was good , but the jam is more bitter than regular marmalade. I suspect it was from cooking the white pith . I would like to try a marmalade using the skins alone.
We like the results, BUT it takes more than 45 min to get to the jell point with that much water and that amount of sugar. Water boils at 212 degrees and the sugar is required to raise the ”boiling” point to 220 deg. So it takes a good hour plus to boil off all that water or more sugar. Laws of physics.
Very easy recipe to follow yielding great results! Loved my kumquats!
I used 3/4 Cup Sugar and let it boil for the time as the recipe required, then canned using a water bath. I expected it to gel, but it turned out quite runny and will have to use as a pancake syrup or something! Not sure why, but the seeds did not really act as pectin and I should have added pectin. Tastes great though. Thanks.
Excellent recipe. Turned out perfectly. Used 1/2 cup of sugar, it was plenty…I let it sit overnight (due to time constraint), removed the seed pouch, brought it back to simmer, added the sugar and it worked fine! Thanks so much!
Followed the recipe and my jam turned into soup. What did I do wrong? Too much water I think
So sorry to hear that happened. Did you use the seeds and let the mixture sit for several hours before boiling? You can also test the mixture on a plate kept in the freezer to test the consistency before pouring it into your jars.
Elizabeth A Preston
the first time that happened to me too , so I added chia to thicken . It was sooo good.
This is a great tip. Thanks for sharing.
Mine is too thin! Can I try to reboil after cooling??
Yes you can definitely cook it again and even add some pectin or additional sugar if you wish.
The recipe does not say at what stage to add the sugar so I presume it is at the start of bringing the mixture to a simmer?
Adding the sugar is step 6 of the recipe.
Do you keep the skin on the Kumquats?
Yep, I use them whole, otherwise, they’re too bitter.
I kept the skins on and removed the seeds like in your recipe and they turned out very bitter, like inedible. Was I suppose to also remove the pulp?
Kumquats really vary in taste, and some have very bitter pulp. The ones I use and that we can get around here have tart pulp, but it’s not bitter. I don’t know how you’d remove the pulp and still get a good jam, unless you added something like orange juice to the peels to have liquid. If you have kumquats with bitter pulp I imagine they just won’t make good jam?
So many different types of Kumquats. I have 3 tree varieties. All are different. One is sour, another sweet and the Changshou is just right.
Don’t know if anyone knows, but Kumquats grow well in pots. Unlike other citrus, kumquats can really take the cold being able to take the 15 degrees.
Even though they can take this cold, the fruit would freeze so best to bring the tree inside or just cover.
Can I use this recipe without sugar? I am cooking for someone on a diabetic diet, he does not mind tartness at all. We have the really sour ones here, he likes to eat them without the peeling, if that says anything. Thank you !
The sugar is necessary to get the jam to gel, unfortunately. You can make it using Pomona’s pectin completely without sugar though. Try following this process, but omitting (or reducing) the sugar: https://pomonapectin.com/kumquat-marmalade/
Followed the recipe exactly, took way longer than 10 minutes to get to 220 and then the final jam DID NOT set. It tastes good but very disappointed it didn’t set.
So sorry to hear that happened. Did you use the seeds and let the mixture sit for several hours before boiling? You can also test the mixture on a plate kept in the freezer to test the consistency before pouring it into your jars. You could also try turning your heat up a bit if it took a lot longer to reach temperature. What was your total cooking time?
Fruit is definitely different in different locations. I’ve found that cooking jams and jellies takes practice and each person may have different results. I’m by no means an expert but enjoy making jams. I would suggest that anyone read general information on canning jams and jellies from online sources and have a better understanding of the process. Making jams and jellies is not an exact process, but with practice gets easier ‘to just know what to do’.
If it doesn’t work, try again. Our mistakes help us learn a better way. I’m almost seventy and I’m still learning the process.
I am trying to use your method by using the seeds and kumquat to make pectin in these few days. How could I use “water bath canning for 10 minutes”. I need to mail some of the jam to my son. The jam will need to stay on the shelf for a while. Please help. Thanks
Here is a Beginners Guide to Water Bath Canning which takes you step by step through the process. This will result in shelf stable jam. https://practicalselfreliance.com/water-bath-canning-beginners/
This came out so good. I was skeptical because some reviewers said it came out watery but I did like one reviewer and left it overnight in water before cooking it. Super delicious!
Thanks for letting us know. So glad you enjoyed the recipe.
I think there is way too much water. I soaked and simmered the fruit with pips per the recipe. It will not set and I have been boiling it for an hour. My mother made marmalade, so I know how to test, let it cool on a plate, then push and see if it wrinkles. It’s like juice. Next time I will reduce the water and try 2 cups of everything. Tastes alright though.
When left overnight, was it put in the fridge or left out?
The kumquats, seeds and water need to soak for 3 to 4 hours, not overnight. If you want to soak the seeds alone and then use that water for your gel rather than putting the seeds in cheesecloth and soaking with the fruit, that can be done overnight. Either way there is no need to refrigerate.
This has so much liquid! Cooked and cooked, added more sugar and it didn’t set. All the hard work cutting up the fruit lost, as it disintegrated from the prolonged cooking.
I then remembered that I had tried this recipe a few years ago, with the same results.
Was there a step that was skipped in the instructions? Did you drain the juice from the fruit before measuring the two cups? Etc.
Maybe it is better to give a weight measurement instead of cups. Maybe your fruit was smaller, with a higher ratio of peel to insides. Maybe mine was bigger with more juicy bits or with a thinner peel etc
Can you tell me how you cut the fruit? Did you slice it as described in the post or did you chop it up? There is a weight measurement in the recipe section that shows approximately 3/4 of a pound. It is also suggested that you let the mixture sit for 3 to 4 hours before boiling, did you do that or did you just boil it right away?
I’ve made this several times and it’s great! Today I made it and my jam never did set up. It’s yummy, but very runny. I used the same amounts of ingredients. Wonder why?
Maybe you just needed to cook it longer.
I made this last year and it came out wonderful. I even doubled the recipe. I have a new batch of kumquats ready to go!
This is the best. Thanks so much for the wonderful recipe.
You’re so welcome. We’re glad you enjoyed the recipe.
What if instead of water i add brandy. And then instead of cooking it i just blend it. I feel like that would turn down the color intensity but the flavor would be even more fantastic.
You could certainly try it. It wouldn’t really be jam then. Let us know if you decide to give it a try.
I used Meiwa kumquats from my tree. I too thought the 3 cups of water was too much initially but it did thicken and the
jam was better than any I’ve had. Use the seed pouch in the first boil and just simmer “forever” in the second boil for heaven on toast. Thanks fopr this.
You’re very welcome. So glad you enjoyed it.
I doubled the recipe, using 2 lbs of kumquats and 6 cups of water. I also soaked the seeds and fruit for almost 5 hours before cooking as directed and put the jam in a 10 min water bath for 10 mins. That was last night. This morning, the jam is still very watery.
Should I reprocess to cook off some of the water?
Maybe turn up the flame from a simmer to a light boil?
If you suggest adding pectin, how much?
Doubling the recipe most likely affected the gel in the jam. It’s often better to do individual batches rather than a double batch in order to ensure that it cooks down properly. I wouldn’t recommend turning the heat up. You will most likely end up burning the jam instead. You can definitely reprocess the jam. Always wait 24-48 hours before doing so though because sometimes the extra time will allow it to set. You don’t want to recook more than 8 cups at one time. For every 4 cups of jam, you can mix together 1/4 cup of sugar and 1 Tablespoon of powdered pectin if you choose to use it. Add this mixture to your jam when you cook it.
Can I freeze this jam? I usually make freezer jam which you don’t have to cook.
But will it freeze well?
I haven’t personally tried it but I don’t see why it wouldn’t work.
We just tried this recipe ( my son got a bag of kumquats ) and we’re almost done simmering. I am noticing the mixture seems watery and hoping this congeals a bit when it cools.
Yes, the mixture should thicken as it cools.