Low Sugar Strawberry Freezer Jam + Tips and Tricks to Setting Jam

The fruity taste of strawberries really shines in this low-sugar strawberry freezer jam made easy in the microwave. Plus tips + tricks for setting jam!

One of the supermarkets in my area had a ridiculously good deal on strawberries. $3.99 per flat! For those who don’t know, a flat is 8 pounds of strawberries! I needed some fruit for a party I was having, but there was plenty to spare, so I decided to make some freezer jam.

Low-Sugar Strawberry Freezer Jam

I searched for a good recipe, and found some I liked, but was shocked about the amount of sugar in almost every recipe I found. I wanted a low-sugar strawberry freezer jam, so I decided to try and make it with less sugar.

At first, it was unsuccessful, which I am sure had nothing to do with the sugar and I will tell you why in a minute.

I ended up with jam that separated as soon as I poured it into my jars: fruit on top and liquid on bottom. I knew it wasn’t going to set, so I added more Pectin and re-heated my mixture, and it worked great.

The Science of Sugar and Pectin in Jam

Sugar draws liquid from fruits, which is also known as maceration.

When my low-sugar strawberry freezer jam was still runny after my first attempt, the fact that I used less sugar had nothing to do with it. After all, I had used less sugar, so hypothetically, there wouldn’t have been as much liquid drawn from the fruit, right?

Maybe or maybe not, but none of that mattered anyway because the sugar is not going to make a jam more thick or less thin; it’s not a thickening agent. The Pectin is the key thickener in jams.

Fruits naturally have Pectin, but the riper the fruit, the less Pectin the fruit naturally has. Strawberries are already lower on the Pectin spectrum.

Heat makes Pectin form into a gel. So when I added more Pectin and re-heated my mixture, the heat helped the Pectin gel up and it worked beautifully.

Tips and Tricks to Setting Jam

I am pretty confident in saying, if you have runny jam, extra Pectin (start with 1 Tbsp more) AND Heat will fix your problem.

Here is some Pectin, fruit, and jam science facts for you:

“When dissolved and let cool, Pectin forms invisible strands that hold liquid in. Acid (such as lemon juice) helps draw even more Pectin out of fruit when it is heated. Water is attracted to sugar. Adding sugar causes some water to be drawn to the sugar molecules, leaving the Pectin molecules free to more easily get at and bind with each other, setting the preserve.” (Source: http://www.cooksinfo.com/pectin)

So now that you know why you might be having problems with strawberry jam setting, you can go ahead and try this recipe! I hope it brings you success!

Ingredients for Low-Sugar Strawberry Freezer Jam

For this low-sugar strawberry freezer jam recipe you need four ingredients.

1. Fresh Strawberries
2. Lemon Juice
3. Low/No Sugar Pectin
4. Granulated Sugar

How to Make Strawberry Freezer Jam

To make the strawberry freezer jam, you will:

1. Crush the strawberries by pulsing them in a food processor or blender. Do not purée completely.
2. Stir in the lemon juice and pectin. Let sit at room temperature for 20 minutes.
3. Add the sugar and stir until mostly dissolved.
4. Heat in microwave on high for 10 minutes until boiling and foamy.

How to Tell if Your Freezer Jam will Set

Once the jam has boiled sufficiently, the best way to tell if it will set is looking at the mixture from the side.

It’s best if you use a clear bowl to cook it in. You can also look through the container you will be storing the jam in, as long as it is clear.

If the mixture has a consistent texture of fruit and liquid throughout, it should set properly.

If the mixture separates into liquid on bottom and fruit on top, you will need to add additional pectin (1 Tablespoon) and bring the mixture back to a boil. Then check it again.

Filling the Jars

• Once the jam mixture looks consistent, skim the foam off the top and discard it.
• Use a ladle and funnel to fill jars, leaving 1/2-inch head space for expansion.
• Immediately top with lids and let stand at room temperature for 1 to 2 hours to cool down before placing in the freezer.

Will this Recipe Work with Other Fruits?

Yes! Just keep in mind the natural pectin in the fruit you are using and adjust the pectin as needed. Check out this pectin chart to help you. We’ve tried this recipe with strawberries and peaches.

How to Store Freezer Jam

You can store this un-processed strawberry freezer jam in the fridge up to 3 weeks or in the freezer up to 1 year.

It’s best to use a freezer-safe container. Here are some options:

• Glass Mason Jars – are freezer safe as-is. I prefer to use the 8 oz jars, or half-pint size. The mini 4 oz jars are so cute and great for gifting. Stick with brand names here, Ball or Kerr have been around for years and make quality products.
• Plastic Lids – You can use the lids and bands that typically come with the glass mason jars, but since you are not canning this strawberry freezer jam, I prefer to use these screw on plastic lids that come in regular or wide mouth.
• Plastic Jars – If freezing glass makes you nervous, try these Ball Plastic Freezer Jars or these Screw Lid Freezer Containers.

NOTE: Be sure to add the date to the jar so you know when you made it. ( I write the date with a sharpie onto some masking tape attached to the lid.)

More Strawberry Recipes

Looking for more ways to use a lot of strawberries? Try these strawberry recipes:

• Strawberry Crisp  
• Strawberry Cream Pie
• Cheesecake Stuffed Strawberries
• Strawberry Bars
• Strawberry Delight

If You Make This Recipe, Please Rate and Review it in the Comments Below. THANKS!

*Originally published 5/7/13. Photos updated March 2022.