A quick note on anthocyanins and pH

I absolutely love to make jam; whether it’s ten kilograms of fruits or five hundred grams. Somehow, I’ve always found the process very calming, not unlike some sort of kitchen meditation.

One thing I find especially wonderful is how much brighter the colour of the jam becomes after the addition of acid – and for the record, I use citric acid in most cases.
This is due to a structural shape change in one of the most widely-found pigment: anthocyanins. As the pH lowers the pigments go from purple to pink to electric red.

Yes, acid intensifies the colour of anthocyanins.
And while it’s most definitely noticeable for any kind of berry or citrus jams, I love how dramatic the change is when making fig jam, as pictured above (not that I made some recently, even though spring takes forever to come around here, late summer is definitely far behind us now – maybe even more so than it is ahead).

I thought you might wonder/have wondered/will wonder about that one day. Love and jam xx


  • Lisa
    May 26, 2015 at 7:08 PM

    Will you make a post someday about how to make jam? I’ve always wanted a quick and easy way that doesn’t necessarily require the canning method. Just something to make and eat!

    • fanny
      May 27, 2015 at 6:47 PM

      Yes, I have a rhubarb jam recipe on the way. it makes three jars and will keep for one month in the fridge without sterilising the finished pots :)xx

  • ilaria
    May 26, 2015 at 7:13 PM

    HI 🙂 that’s really interesting! That means that you add the citric acid (lemon juice, right?) AFTER the whole cooking process? or before? I hate when I make Apricot jam, that after 20/30 minutes of cooking it inevitably turns from orange to burnt orange 🙁 I add the lemon juice usually before the cooking process and my apricot jam still turns brown. I even tried the Ferber method (with way less sugar) to avoid caramelization. So frustrating! -___-

    • fanny
      May 27, 2015 at 6:41 PM

      Yes Ilaria, as Arturo mentioned in the comment below I use mostly citric acid powder (with the exception of malic acid when making apple jam/jelly, and tartaric for exotic fruits) to avoid the lemon flavour.
      If using lemon juice, I usually recommend to add it last – off the heat (I do add some to my apricot jam too, which I find brightens up the flavour of apricots). When it comes to apricot jam though, the colour will always be a deep orange as they’re richer in carrotenoids.

      If you don’t use any added pectin in your jams, I’d say: add the lemon peel and pips in a mousseline bag along with the fruits and then lemon juice at the end of the process. I hope that helps a little. xx

      • ilaria
        May 27, 2015 at 6:52 PM

        Thanks Fanny! ^___^ I live in italy, but i still have to wait another month for peaches and apricots too! they’re still too sour, maybe a couple more weeks of sun will help! 😀

  • Kaitlin Flannery - Whisk Kid
    May 26, 2015 at 11:22 PM

    I NEVER would have guessed this was fig jam! Super cool!

    • fanny
      May 27, 2015 at 6:42 PM

      Yes 🙂 Made with black figs from Provence and no photo filter! xx

  • Arturo
    May 27, 2015 at 3:04 AM

    Ilaria, I am guessing she means the powder Citric acid (sometimes sold in the supermarket as sour salt) as it is more stable/consistent than lemon juice with out the lemon flavor you might not want. Also guessing she adds it at the end of the cooking process. Fanny, please correct me if I am wrong, because I usually use lemon juice (most recently with nectarines and peaches

    • fanny
      May 27, 2015 at 6:46 PM

      Thank you Arturo for your always wise input. You were absolutely right. And nectarines and peaches? Yes please! Although I might have to wait for a couple of months for summer to show up here. Aaah the north of Sweden!

  • amy
    May 31, 2015 at 4:22 PM

    oh , I also love to make jam . I can not eat as much as I produce 😉
    wonderful colour your fig jam!
    all the best


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