Making Sugar-Free Jam

Adventures in Jam Making

Jar of marmalade on table with pan
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There is nothing quite like homemade jam. It seems to taste so much more like the fruit it came from than jams you buy at the store. However, it’s no secret that jam is mostly sugar, and in fact, jam is one of those things that is tricky to make sugar-free. This is because it is sugar that gives jam its characteristic mouthfeel, and also because it acts as a preservative.

It being the height of the berry season, and having just purchased a flat of my favorite berry – a local variety of blackberry called the olallie berry, I decided to give sugar-free jam making a try.

Hunting for methods, I saw a few approaches to making sugar-free jam, so I decided to experiment, both with blackberries and strawberries.

The Issues

Since sugar is part of what preserves jam, most recipes I found were for what is often called “freezer jam.” This is because you can’t keep it on the shelf for any length of time. It generally will keep in the fridge for a couple of weeks, but any jam you want to keep longer than that should be stored in the freezer.

The other issue with jam is that for most fruits, commercial pectin is added, which has sugar in it. Some fruits, such as plums, have enough pectin that you don’t need to add any, but berries generally need to have pectin added. Blackberries have some of their own pectin but strawberries have essentially none.

There is such a thing as commercial pectin without sugar, which should be the first thing to try, but I couldn’t find any in my little town, and I was impatient.

Next year, I will order some and try it.

Approach #1: Boil it Down

The first thing I tried was the simple route: I just added some water and artificial sweetener (I favor liquid forms of Splenda which don’t have the off-flavors and extra carbs of powders) and boiled them down, hoping that the natural pectin would be enough.

This produced a spreadable puree with the blackberries, but it was very concentrated (2 cups of berries made ½ cup of jam), and was generally lacking in jamminess – it wasn’t cohesive enough, for lack of a better word. By the next day, small pools of liquid needed to be stirred in.

The strawberries didn’t work at all using this technique, even when I pureed them in the blender first. The resulting mush in no way resembled jam.

Approach #2: Gelatin

I had seen recipes for sugar-free strawberry jam which included strawberry Jello. Since I was going for a fresh flavor, I decided to try using unflavored gelatin. For the blackberries, a bit less than a packet (a little less than 2 teaspoons) worked well for two cups of blackberries mixed with 2/3 cup of water and sweetener to taste. This produced a little less than a cup and a half of jam, and I liked the consistency. It was a little “bouncy”, and needed to be stirred, but it produced a credible and spreadable jam.

The strawberries did not come out as well, but it was OK. I used the full packet (a little more than 2 teaspoons) for 1 cup of puree produced by blending 2 cups of chopped strawberries with half a cup of water. The taste was good, and it was spreadable, but the consistency wasn’t quite right.

Next time, I might try cooking the strawberries longer.

Approach #3: Using ThickenThin not/Sugar thickener

I found a recipe for jam, and since I use some of their products and I had some not/Sugar on hand, I thought I would try it as I’ve been happy with it in other recipes. To two cups of blackberries, I added the sweetener, ½ cup water, and 2 Tablespoons of the product. It produced a little more than a cup of the most “jammy” product of the three methods – the consistency was right on. Unfortunately, it also produced an “off” flavor compared to the gelatin method, which was disappointing. On the other hand, when I made a dessert out of the jam by mixing it with whipped cream and nuts, I didn’t notice the off-flavor, so maybe it wouldn’t bother most people.

I might not have noticed it except that I was doing a side-by-side comparison, and the contrast was obvious. I didn’t try this product with strawberries.

Recipe for Sugar-Free Blackberry Jam

Combine fresh or frozen berries and water (1/4 cup per cup of berries for not/Sugar and 1/3 cup for gelatin). Bring to a boil and cook berries for 4 to 5 minutes. Mash the berries against the side of the pot to break them down (or you can use a potato masher or stick blender). Whisk in thickener in amounts as described above. Spoon into clean freezer-safe containers, and cool.

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