Tart, bright, and the very embodiment of spring, this low sugar strawberry rhubarb jam allows the fruit to lead the flavor charge.
Last week, I taught a class for the Brewerytown Community Garden. It was a lovely evening in the garden and more than twenty hardy folks came out to spend it with me. I demonstrated how to make a basic batch of strawberry jam and we talked canning safety, low sugar preserving, and good things to preserve this time of year.
At the end of the class, as we were cleaning up, the event organizers asked me if I might like to take home some farmstand strawberries and several stalks of rhubarb grown right in the garden. I’ve never been one to turn down the offer of produce, and so said yes.
Once I got home, I took a trip through this site’s archives, looking to see if there were any variations on strawberry and rhubarb that I’d not yet written about. Here’s what I found that I’d done in the past.
- Small batch strawberry rhubarb jam with rosewater
- Strawberry rhubarb jam (not a huge yield, but lovely nonetheless)
- Strawberry rhubarb butter (so smooth and spreadable)
- Roasted rhubarb and strawberry compote
I decided that was what I was most craving was a low sugar jam combining the strawberries and rhubarb. I wanted to be able to taste that essential rhubarb tang and knew that using any more sugar would bury it under a blanket of sweet. And so I opted for a ratio of four parts fruit to one part sugar, and used a bit of Pomona’s Pectin to establish the set.
I used three pounds of strawberries and one pound rhubarb because that’s what I had in my kitchen at the moment of making, but I could just as easily see doing this with equal parts berries and rhubarb. I’d also love to do a version of this same preserve with raspberries and rhubarb a little later in the season, though we’ll see if that happens or not (my available energy is limited these days as these babies I’m carrying grow bigger and bigger).
Good Uses for Low Sugar Strawberry Rhubarb Jam
This jam is particularly good with nut and seed butters like this sunflower seed butter. It would make an excellent middle layer in these jam bars. You could do as I’m doing a lot these days and eat it stirring into cottage cheese or plain yogurt. Or you could make a batch of whole wheat crepes and use this jam as the filling.
Low Sugar Strawberry Rhubarb Jam
- 3 pounds strawberries cleaned, hulled and chopped
- 1 pound rhubarb cleaned and chopped
- 2 cups granulated sugar
- 1 tablespoon calcium water
- 1 tablespoon Pomona's Pectin
- Prepare a boiling water bath canner and enough jars to hold 3 pints of product.
- In a low, wide, non-reactive pot, combine the strawberries, rhubarb, 1 3/4 cups sugar, and the calcium water. Stir to combine.
- Set pot over high heat and bring to a rolling boil. Reduce heat to medium-high and cook at a vigorous boil for 20 to 25 minutes, until the volume has reduced by at least one-third.
- Stir pectin into the remaining sugar and stream it into the cooking jam, using a whisk to stir to help prevent clumps.
- Return the contents of the pot to an active boil and cook for an additional 2 minutes and then start looking for signs of thickening (it should be pretty clear as Pomona's pectin sets quickly). Once you see some thickening, remove the pot from the heat.
- Funnel the jam into the prepared jars, leaving 1/2 inch headspace. Wipe the rims, apply lids and rings, and process in a boiling water bath canner for 10 minutes.
- When the time is up, remove the jars and set them on a folded kitchen towel to cool. When the jars have cooled enough that you can comfortably handle them, check the seals. Sealed jars can be stored at room temperature for up to a year. Any unsealed jars should be refrigerated and used promptly.
Was that 4:1 fruit to sugar? Or 2:1?
Two cups of sugar weighs approximately one pound. So the end result of this recipe is a four to one ratio. I just noted the sugar in cups because I thought it would be easier for the home cook.
The recipe is four pounds of fruit to one pound of sugar.
I’m confused. The fruit is measured by weight and the sugar is measured by volume. How do I get the proper ratio if I have more or less fruit?
Two cups of sugar weighs approximately 1 pound. I just thought it was easier to keep the sugar in cups, but apparently that’s caused confusion. You are essentially using four pounds of fruit to one pound of sugar.
How many jars and what size?
It’s in the first sentence of the recipe. It makes three pints.
I love what you do.
What would be the shelf life of this jam and how long will this jam last in the fridge once opened?
Like most jams, this one will keep about a year on the shelf. It may experience some color fading towards the end of that year because of the reduced sugar content, but it should still taste fine. Once opened, it should keep 4-6 weeks in the fridge.
Is pamona’s pectin a requirement? (The specific brand /type). If I can’t find it, what type of pectin am I looking for?
Yes. To make this recipe, you need the Pomona’s Pectin. This jam will not set up with other brands.
I am so excited you are on the internet!! I’ve been using your book for a few seasons now. I love love love your guidance and inspiration. Also, I love how you talk about Trader Joe’s….
Anyways, please explain the calcium water. Where do I get it, etc.
It’s part of the Pomona’s Pectin system. I talk about it in this video: https://www.facebook.com/FoodinJars/videos/321592628781787/
I love the idea of less sugar, but I don’t want a tight set. I’d like a softer consistency so I can use it in yogurt or as a thicker sauce. Can I use half the amount of pectin?
This jam doesn’t have an aggressively firm set as it is written, but there’s no safety reason why you can’t reduce the pectin down further.
In these photos it looks like you have almost no headspace. Headspace in general is something I am struggling with in my canning; for a yellow squash pickle I make, the headspace appears to adjust during processing.
Can you comment specifically on the appearance in this photo, and also refer me to any more detailed headspace help? Thanks in advance.
Rhubarb has a tendency to expand a little in the canning pot. These jars started with 1/2 inch headspace before canning. When it comes to headspace, you need some in order to effect the seal. Too much and the jar won’t vent all the oxygen effectively and too little and the jar won’t seal.
I love your cookbook that uses the natural sweeteners. Is it possible to sub honey or syrup in this recipe?
You sure can. Sub in 1 1/3 cups honey for the sugar and follow the recipe as written. Make sure to save out some of the honey to use to integrate the pectin at the end of cooking.
Hello lovely Marisa!
Fii I revive me for what may be an already answered question, but this is my first gander at Pomona’s and I am wondering if the calcium water called for is in the package with the Pomona’s pectin?
I am unsure what it is and how one gets their hands on it, but I will hopefully figure it out!
I started canning last year and made stacks of jars taller than I am—and I’m tall—using mostly your recipes!
Thank you for sharing your wisdom and passion so freely????☺️????
Yes. When you buy a box of Pomona’s Pectin, you will find that it contains two pouches. One holds pectin powder, the other has calcium powder. You mix the calcium powder into water to make the calcium water.
Hello. Is it no longer necessary to include lemon juice when canning jam?
Lemon juice has always been optional with high acid preserves. In jams, it’s typically there to balance flavor and help with set. And since the rhubarb is quite tart, it’s just not necessary here. That said, you could always add it if you’d like.
Thanks so much! ☺️
If I’m okay with a sauce/compote texture instead of set jam, is it okay to leave out pectin in this (or any other) recipe? Any safety concerns if I follow the rest of the recipe as written? Thank you!
If you’re okay with that, then feel free to leave the pectin out.
Why calcium water? Can I use regular water? Can I skip the water?
Calcium water is part of Pomona’s Pectin. It is a pectin that allows you to get a good set without a great deal of sugar. When you buy a box of this pectin, it comes with a large packet of pectin and a smaller packet of calcium powder. You combine that calcium powder with water to make the calcium water. This recipe will not set well if you don’t use Pomona’s Pectin. You can try it with other low sugar pectins, but I cannot guarantee the results.
Hi Marisa! I’m a huge fan (own all 4 books, listen to your podcast, etc). Love this recipe!!
Thank you so much! And I’m so glad you like it!