Key Lime Marmalade

I never quite understood marmalade. It was one of those things the early pioneers must have made: fresh fruit was precious, the vitamins scarce, and therefore even the seemingly inedible peel had to be used in any way possible. So they’d chop it up, boil it down into a thick goop, and eat it on toast. And to add insult to injury, the peel’s offensive, acerbic bitterness was masked with an obscene amount of sugar to make it even barely palatable.

No, thank you. Sugar-soaked garbage is still garbage.

Perhaps I was being a snob. But thanking the gods of modern agriculture (and our glorious Mediterranean climate), I was content to enjoy only the juicy, sweet citrus flesh that is always available in abundance, and (because I have always been an ecologically responsible snob), whisk the peels away to their duty in the compost bin.

So certainly I was surprised when Rick told me that though he loved all the jam I was making, he really missed having toast with marmalade. I mean, Rick generally has pretty good taste and there are very few things that he enjoys eating that I do not. So was I missing something? Was there some magic in those sticky, slimy bits of castoff peel that I had previously not experienced? I knew that lemon zest was a wonderful thing, but…marmalade? Maybe I could find a way to make it work.

So I read recipes. And more recipes. 13 cups sugar to 8 cups water and pulp. Add gelatin. Add pectin. Use a food processor. Use a cheese grater. Don’t make it, buy it. 1 lb sugar for every half cup of pulp. Never EVER use anything other than Seville oranges or Spanish ghosts will haunt you forever (and force-feed you marmalade made the right way)…

…there is seemingly a lot of argument in what the “right” way is. I will not get into a huge diatribe about the history (other than a mention of the fascinating etymology that brought us the name “marmalade“), but I will tell you that after trying out many recipes and a LOT of prep time I have finally come upon a recipe that is right for me. Not too sweet, not too bitter. Spreadable on toast, but not drippy. Never cloudy, never off-color. Keeps in a jar in the cupboard for up to a year.

This recipe, and the culinary journey that produced it, have changed marmalade for me completely. It is now something that I enjoy quite a bit (plus it makes Rick awfully happy to have it around the house)!

Key Lime Marmalade
4 c prepared citrus (see below for instructions)
4 c water
4 c sugar (or white evap. cane juice)

This recipe works well with any citrus, and the directions are the same for all kinds. Feel free to experiment with mixing several types of fruit, including grapefruit, eureka or meyer lemons, standard or key limes, tangerines, kumquats, or any type of orange (blood orange marmalade would be beautiful). Make sure to wash the fruits thoroughly before starting this process, as the peel is incorporated into the recipe and not discarded.

Not sure how much fruit you should start with? Here are some basic amounts that would give you the right amount of marmalade-fodder:
3-5 large thin-skinned grapefruit
5-6 large thick-skinned grapefruit (you will not use the white spongy pith)
5-8 large oranges
8-10 regular oranges, blood oranges, or large lemons
10-15 small lemons, tangerines, or large limes
15-20 key limes

To prepare the fruit:
Using a paring knife, carefully peel the citrus leaving as much of the white pith attached to the fruit as you can. The object here is to only take off strips of the “zest” part of the peel. Finely julienne the slices of zest, either long- or short-ways (depending on your degree of comfort using a knife and the intended aesthetic of the finished marmalade – long, thin strips are the toughest to accomplish, but make the prettiest preserves). Section out the citrus following a basic suprême method: remove the pith, collect all the juice and flesh, and leave all the membranes and seeds behind.

Depending on the ripeness and size of the fruits, the supremes might be able to be slid out by hand without too much fancy knifework. The limes I was working with were fairly easy to section out by hand.

Place the julienned zest, the supremes of flesh, and any juice into a bowl roughly twice the volume of the lime mixture. Add enough water to cover the mixture, which should be around 4 cups and appear “soupy”. This recipe is VERY basic, and can be adjusted to any amount you wind up with after preparing the fruit; just adjust the water and sugar accordingly.

At this time, you may add any other flavors you’d like. I *love* grapefruit marmalade with fresh-grated ginger. I also made some lime marmalade with a pinch of salt and a fresh jalapeño (diced finely, seeds and all), which I intend to use as a condiment for meats or an addition to a grilling glaze.

Cover this with a lid or plastic wrap, and leave for at least 4 hours (it’s better overnight). This resting period leaches some of the bitterness and softens the zest, making the final marmalade quite palatable. It also allows the flavors of the different citrus and spices to meld together.

Once the mixture has rested, transfer it to a non-reactive stock pot that is at least double the capacity of the marmalade (once it starts to boil, it can increase in volume very quickly and is napalm-hot). Add an equal amount of water by volume (you can eyeball it), and a little less than an equal amount of sugar. It takes FAR less sugar than most recipes call for to make a sturdy marmalade – there is quite a bit of pectin in citrus.

Simmer the mixture over medium heat until it reaches its jelling point, which is 8 degrees above boiling on a candy thermometer (roughly 220 degrees Fahrenheit), or until a small amount dropped onto a cold plate and placed in the freezer for 1-2 minutes forms a solid “skin” that wrinkles when it’s poked at. With some practice making jams/jellies without added commercial pectin, you’ll be able to tell a jelling point by the sound and appearance of the bubbles and won’t need to check with these other methods.

(Nifty little tip: take some basic commercial jelly out of the fridge and melt it in a pan until it’s a bubbling liquid. THAT’S what jelling point looks/sounds like. Now pour it over a fruit tart. There y’go. Yum!)

Carefully transfer the very VERY hot marmalade into sterilized jars and fill to within 1/2 inch of the top. Making sure the edge is clean (I LOVE my canning funnel!), place the lids on the jars and screw down tightly. If you are planning on putting these up for later, process them in a basic water-bath canning system for 10 minutes. Here are some basic safety guidelines regarding canning, provided by the National Center for Home Food Preservation. Read this before you attempt to can any kind of food on your own – canning is easy and fun, but can be very dangerous if done incorrectly.

Key lime marmalade on a toasted whole wheat/oat roll. Dee-lish.

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  1. In the UK they serve marmalade with every breakfast. I've never really been a fan of it, but damn! That stuff was good. Tom now wants me to make it (he didn't really like it either until we went to the UK). Your post couldn't have come at a better time (we just got home from the UK yesterday as it turns out).

  2. . . . Lisa and Robb . . . says:

    Funny — I just read another marmalade article (by the amazing Shuna at Egbeater). She says that limes and grapefruit are not the best citrus to learn on, because of the hardness of their rinds.

  3. Oh, I never do things the easy way. Also, I like the flavor/intrigue around non-standard marmalades better.Then, I am currently unemployed and *have* 8 hours to sit around peeling and julienning tiny key limes…

    Rachel – I'll send you some of mine, if you (or Tom) want to try it.

  4. Right on! This looks like a fabulous base recipe, with a very demure amount of sugar (for marmalade, that is.)
    I never appreciated marmalade until I began making my own, either. My favorite kind was meyer lemon with vanilla bean, and I once made a grapefruit honey one that turned out well, too. And rhubarb orange is good too. And I've been wanting to do blood orange ginger, but never seem to catch them when they're in season. I use a T shaped veggie peeler to strip off the colorful peel; good for bakers too lazy to sharpen their knives! Thanks for making marmalading accessible – jamming can seem so daunting!

  5. I WISH my veggie peeler would do key limes! As it is, I actually watched about 4 hours of stupid TV shows and peeled them all by hand.

    Because I'm OCD like that.

    I just brought home a CASE each of limes, grapefruits, and oranges from camp. Not sure yet what they will turn into, but it might be time to have that canning party…

  6. shelby-knitz says:

    Hi Jessa,
    Thanks for posting this. I was hoping you could help me because I am feeling discouraged after trying to make it. I followed the directions, but cooked the stuff in my crock pot. The whole mixture turned dark brown instead a beautiful golden like yours. And it tasted a kinda burnt, I felt like all that prep I did was for nothing :( My crock pot gets uneven and quite hot on its hottest setting. Do you think I should just try it again on low. I am just a beginning canner. Thank you and I very much admire your preserves.

  7. Shelby-Knitz: Sounds like the marmalade burned…what a bummer! I've never tried to make marmalade in a crock pot, so I'm not exactly sure what happened for you. Sugar turns very dark when it caramelizes, but you would have had to boil out all of the water from your mixture to get to the point where it would have started to burn. How long was it on the heat?

    I usually do mine in a non-stick stock pot over medium to med-low heat, stirring frequently. Also, I rarely go by temperature, and find it easier to use the cold plate test described in the post.

    You could certainly try again on a lower setting in your crock pot, but watch it like a HAWK! When sugar starts to brown, the process is very quick!

    Good luck to you.

  8. 6pairsofshoes says:

    shelby, don't use a crock pot.

    I've been working my way through a variety of citrus this season: various meyer lemons, blood orange, pink grapefruit, cara cara navel oranges, but have not yet tried lime.

    I'm intrigued by the Key Lime idea, but my back gets so sore from removing that zest it might do me in. Your posts encouraged me and the flavors of those wonderful limes are calling me, so I'll probably make the effort later this week. Thanks for letting us know about your experiences, they are very helpful.

  9. shelby-knitz says:

    Thanks, I'll try to muster up the will again when my finger heals. The peeler went right through the top of my nail :(
    Be careful!

    • Just a note to Shelby— i wouldnt use the crock for trying to make jams & jellies. They cook much faster in a standard pot on the stove… your batch most likely burnt because it was on for so long with no stirring… if you’re still a bit unsure, try regular jams a try first… they are really easy and take ~45min defending on the H2O ration to your fruit. Then give the marmalade another go! I’ trying marmalade for my 1st time this am with limes from my tree. Good Luck and Enjoy! ~: )

  10. @Shelby-knitz – I use a zester to remove the zest. That way I don't have to try and use a knife or peeler when my hands are slippery. The bonus is that you don't then have to julienne the zest, cutting a step. It's similar to this one:

  11. 6pairsofshoes says:

    I have this cheapo Ginzu type cerrated edge knife that I use to zest fruit. It enables me to remove just the zest with only a tiny part of the white pulp. I then slice that into tiny (1/8-1/16 of an inch) slivers. When I have about 1/4 volume of this julienned zest to the total amount of flesh/juice, I stop.

    I took the intermediate step of placing the inner membranes and seeds in a cheesecloth bag and simmering it with the juice/flesh mix. After about 30-40 min. I take the bag out, cool it and then squeeze it to milk pectin from the contents, then discard it, return the pectin to the mix, add the sugar and cook until done. This is pretty much what June Taylor does. I must say my back was pretty sore after cutting up 36 of those little limes. I ended up with about 3 cups of juice and flesh (not counting the inner membranes). I'll let you know how this turns out, but there's a good reason you don't find this stuff for sale. It's impossible to ask enough to justify the labor!

  12. Fun Mama - Deanna says:

    Mine burned too – while I was transferring it into jars. I think I got at least two jars out of it.

  13. Just did mine this morning, it turned out very bitter and too tart. (I soaked the zest over 24 hours) There really wasn't a lot of juice to my limes either. I might try this with a simpler fruit and work my way back up. :)

    It didn't gel completely, I simmered for about 45 minutes then upped the heat. It probably needed another 15 or 20 minutes.

  14. Jacquie says:

    Key Lime Marmalade Recipe = Huge success.

    Your previous views on marmalade were what sold me on trying your recipe over all the others I had found online.”Sugar soaked garbage was still garbage.” etc.

    Well, I’m a convert.

    The recipe works, and, if you just zest, peel & chop the citrus then strain it through cloth once all the cooking is done, it also makes wonderful jelly. A much shorter process if you’re using small citrus like limes or lemons.

    I work in a place where food donations are sometimes the only source of food for our residents, and you get some odd and strangely voluminous donations.

    This time it was tons of key limes.

    It’s also a place where many of our residents have had little exposure to “do it yourself-ing” or interesting and different foods, so you know it’s a success when our residents seek out the recipe to make their own!

    Thanks so much for all your research and work!

    • Jacquie, I’m so glad you like it! After finding this way of making marmalade I’ve become an addict at making marmalade.

  15. Sue Fielding says:

    Didn’t set. My attempt at the lime marmelade recipe was a flop. What did I do wrong? It didn’t set. I may have put in too much water. Any other suggestions. Boohoo.

    • Sue, you may just want to try cooking it longer until it does set. I like to keep a bowl filled with ice and a spoon next to me when I make preserves and marmalade so I can test the firmness before going to the trouble of canning it all. Just scoop a small bit out with the spoon and set it in the bowl of ice to chill quickly.

      • Sue Fielding says:

        Thanks rachel,
        I did boil it for 2 hours- I think the problem is i didn’t get the measurements accurate. Too little sugar, a bit too much water and perhaps the fruit was not ripe enough. I know there are many varieties of limes, all with different qualities. I live in central Australia, in the desert. I’m not sure what variety of lime I used, but will try to find out.

        Thanks for your help. I will keep trying!
        Love your website-

  16. I made it last night (citrus prep) and this morning (cooking). Mine seems to have 1 or two jars that are more liquid-like, which I guess is what you mean by not-set? Also, it seems quite dark. I used a non-stick pot. I am sure it didn’t “burn” as it tastes fine. Any ideas?

  17. Also wondering… How long can this keep in my basement pantry?

  18. Pollyanna says:

    I don’t know if anyone is still watching the threads to this aged post. I tried this lime marmalade but added some grated ginger – but mine did not set. I have successfully done a mixed citrus marmalade and hadn’t removed much of the pith to produce the needed pectin. I wonder if I remake this and perhaps do as one commenter did, and that is to put the pith in a muslin bag and simmer it, then discard. I will be trying this again this weekend — if anyone has any further advice, I’d love to read it!

    • Pollyanna, the trick with doing any preserves without added pectin is patience, and a lot of it. It can take quite awhile for the pectin and sugar to react – sometimes over 30 minutes. It will start to foam up. Once it’s done foaming and returns to normal it is done reacting and will set up when canned.

      • Pollyanna says:

        Thank you for the tip – I used a candy thermometer and after reading your advice, I am pretty sure I didn’t do it long enough because I did not get foaming. I am excited to try this again this weekend. My results were quite tasty, just ended up being a syrup (which I think I will use as a basis for mojitos!)

  19. This is all new to me, and I’m a bit confused. You added about 4 cups of water to the fruit and rind, and let it rest. The next day you added about another 4 cups of water to make it about 8 cups? Or is it the original 4 cups of liquid that you’re adding the sugar to?

    Thank you in advance for the clarification.


  1. [...] some for dinner. Only a few days old, and still totally edible. * Key limes (left over from the marmalade I made a few weeks back) * That delicious jar of spicy fennel seed pasta sauce I…oh, no. [...]

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