3 Jun 2014

How to make Low-Sugar Jam Yourself

Ever since I posted pics of my homemade low-sugar jam on my fitness Instagram stream (check it out here), I've had numerous requests from you how I make it. I love jam, be it on a rice cake, a piece of toast, in yogurt, or on oatmeal. Normal store bought jam, however, contains so much sugar that it's not really a healthy breakfast option at all. I decided to make my own, so I can control how much sugar I consume. Not only that, but you can get super creative with your own fruit combinations and jam varieties.

Today I'll show you how I make it! Let's start with the BASICS:
  • Use best quality fruit that is picked at its prime, and perfectly ripe. This will make the jam naturally sweeter and you won't have to add as much sugar to sweeten.
  • Sterilize your sealing mason jars before starting. This will ensure that no bacteria is in the jars which might develop mold, meaning your jam will keep longer. (You don't have to buy mason jars, I often reuse old jam or pickle jars, just make sure the lid still fits tight.)
How to sterilize your jars: Place the jars and the lids in a pot of water. I like to put the jars in a huge pot, and the lids in a separate smaller saucepan. Then boil both items in the water for at least 10 minutes. Then drain the water and dry the jars with a clean towel, but don't rinse them again under the water! Basically, just make sure that after the boiling process, they stay as clean as possible. Line them up for filling with jam later.

Keep on reading to get the full recipe!

Ingredients for Strawberry Rhubarb Passionfruit Vanilla Bean Jam

600g strawberries
400g rhubarb
400g "sweetness" (sugar replacement equal to, or mixed with real sugar as described below)
2 passionfruit
enough pectin for 1kg of jam (or more, see below)
1 vanilla bean pod, scraped out
1 lemon (juice thereof)

Berries make wonderful jam, so I went to a strawberry farm nearby and picked a few kilograms worth. I also bought some rhubarb and passionfruit, so I made strawberry-rhubarb-passionfruit jam. YUM! I've also made this same basic recipe with apricots and plums, and both worked great.

Wash all your fruit, chop into bits, and measure the total weight. You'll need this later to determine how much sugar and pectin to add. Many jam recipes call for 500g of sugar for 1kg of fruit. For me, this is way too much and too sweet! I add anywhere between 250-350g of sugar for 1kg of fruit, but the great thing about making your own is that you decide the sweetness level. So don't worry too much about that.

Now dump all your fruit into a big pot with the juice of 1 lemon. Cook the fruit and lemon juice concoction until it turns mushy and gets very hot.

I love passionfruit so I added it to my jam at this point. I also added the scraped out vanilla bean.

Now for the sugar and how to make it a low-sugar jam. 

So let's say you want to add 400g of sugar to 1kg of fruit (if you like things sweet.) Use your sweetener of choice and read what the sugar equivalent is on the package. I use Stevia Crystal which is great for cooking and baking. The ratio on mine is 1:2, so 1 tsp. Stevia Crystal equals 2 tsp. regular white sugar. So naturally, you would only have to add 200g of Stevia Crystal to your 1kg of jam, to equal the sweetness of 400g of real sugar. 

However, I like to mix a bit of real sugar with the Stevia, to improve the taste. So I might add 100g of sugar to 1kg of fruit, and substitute the rest (300g) with Stevia Crystal (which would be 150g).

Make sense?

So instead of traditional recipes which would have you use 500g of sugar in 1kg of fruit, you've now only used 100g! That's like a hundred laps of running around your neighbourhood that you've just saved yourself, haha! Stevia Crystal contains virtually no calories.

Add your desired amount of sugar and sugar replacement to your fruit in the pot and bring to a boil.

Next, add your fruit pectin to the jam and follow the package instructions. Important: replacing real sugar with Stevia or other sweeteners means that you often have to add more pectin than called for to achieve a jam-like texture. Sugar is a natural thickening agent, while Stevia and the like are not.

So, I first add the called for amount (see how much pectin it says to add on the package for 1kg of fruit, they all vary) and then add more as necessary. So I always buy additional pectin packages! Add your pectin and allow to boil gently for about 5-10 minutes, stirring frequently so your fruit doesn't burn to the pot.

How to test if your jam has the right consistency:

Take a spoonful of jam and smear it onto a plate, and allow to fully cool. Once it's cooled on the plate, your jam will show its true consistency. If it's too runny for you, add a bit more pectin and boil again, and repeat the spoon test. Just keep adding pectin until it's thick enough for you. Always check for consistency on cooled-down jam, it only begin to firm up once it cools!

At this point you might notice a layer of foam on top of your jam.

Use a ladle to spoon off the foam as best as you can. It will bubble to the surface. Try to remove as much foam as possible, so you are left with this:

Now you're ready to fill your piping hot jam into your prepared jars. Use a funnel or a ladle spoon to fill your jam into the prepared, sterilized jars, all the way to the top. Your jam should be as hot as possible (still lightly boiling.) Use a clean washcloth to remove any mess or spillage along the top, then immediately seal the jar with the lid as tight as you can. Then stand the jar upside down on its lid. The heat of the jam will create a vacuum seal as it cools. I usually get some help at this point; one person fills the jar with jam, the other person quickly seals the lid on.

Let the jam cool down completely, or overnight. In the morning, turn the jars right side up and see if all the lids have sealed properly. If one of them is open, I just put it in the fridge and eat that one first. However, if a bunch of them have not sealed, you probably did something wrong, bought the wrong jars, or the jam wasn't hot enough. You can try to reseal them by placing the entire jar with the contents in a boiling pot of water and heating it up, then letting the jar cool down again.

Label, then store your jam in a cool, dry place. I often keep a couple of them in my basement where it's dark and cool, and bring up the jam as needed. Sometimes the lids will seal extremely tight (tighter than store-bought), so just run the lid under very hot water in the sink for a minute or two and it will open much easier.

I have never had an issue with my low-sugar jams spoiling or going bad. If you do all the steps properly, your jam will last you a long time, if you store it in a dark cool place.

Happy jam making!! Let me know what flavor combinations your try out.


  1. faster and more comfortable way how to sterilize jars - put them to the oven for few minutes.

    and..."400g "sweetness" at least some part from that must be sugar. if you use only stevia without sugar it will spoil. sugar is conservant

    1. Like I said, my jam has never spoiled. I mix a tiny bit of real sugar with Stevia. No problems so far!

  2. I never made jam, but what if you use honey? That would make for good taste, too.

    1. But then honey is basically the same as sugar in calories. So there's not much difference.

    2. Oh, ok. Did not know that. I thought it was just supposed to be healthier.

  3. Anonymous1:12 pm

    Hallo Julia,
    wenn Du 3:1 Gelierzucker verwendest, brauchst Du den anderen Süßungsstoff Stevia o.ä. nicht.

    1. Der Punkt ist ja Zucker zu vermeiden...! Gelierzucker ist auch nur Zucker. Stevia hat keine Kalorien. :)

  4. Kann man auch Tiefkühlbeeren verwenden?:))

    1. Habs noch nicht probiert, aber ich denke wohl schon.

    2. Okay, dankeschön, viele Grüße aus Deutschland:))

  5. Anonymous4:55 pm

    A comment on drying the cans: if you want to keep them as clean as possible, it might actually be best to let them air dry rather than using a towel! If they were in boiling water, they'll dry off pretty quickly and you can probably just leave them be while you make the jam. :)
    Liebe Grüße aus den USA!

  6. i dont know if i can find pectin in Malaysia hurmmm :( is rhubarb optional? i dont think i can rhubard too here if i can, it must be super expensive :(

    1. Pectin you will probably need if you want to make it without the sugar, but if you make it with normal sugar you might not. You don't need rhubarb, this is a basic jam recipe that you can make with pretty much any juicy type of fruit. Just get whatever is local there.

  7. Thanks so much for sharing this. My husband has recently been diagnosed as pre diabetic and we have to really watch the sugar now. I have been looking for a low sugar jam and this recipe sounds perfect.

  8. Thanks for sharing! It will be strawberry season here soon enough and we will definitely try this out!

  9. carissa r2:35 am

    How long does homemade jam last once it's been opened and refrigerated?

  10. Great live the recipe just made the jam but just with strawberries and one just with apricots. You can buy finished mixed packages from dr. Oetker with stevia 350g i just tried that didnt add any extra sugar cos ut says there was still some sugar in it. The apricot one i did like you wrote here. Hope it will work out cant wait to try it :)

  11. Hey Julia
    Thanks for sharing. Not many people know how to make homemade jam ;-)
    I always use the sugar 3:1 (Gelierzucker) which means 1,5kg fruit and 500g sugar. But I just put in more fruits, up to 2kg so it will be approximately 25% sugar and 75% pure fruits which works very well for fruits that are already really sweet like strawberries. In the end I just add a little package of citrus acid because this is what helps the jam to become less liquid like my mum told me. Works out perfectly and it takes only 4min of cooking. Besides I just put some boiled water into the jars and then clean them
    Since I use real sugar this is enough conservative ^.^

  12. Hmmmm great recipe as I am a totally fan of Strawberry-Passionfruit Jam by Mövenpick. But this one is full of sugar. So I absolutely need to try this out!