I made two batches of freezer jam using Sure Jell, and neither batch got thick, so I found this solution .
Using corn starch as the thickening agent….
I used: 3 cups of runny jam
2 Tablespoon corn starch liquefied in 2 Tablespoon cold water— I try to use any runny jam left in the freezer containers to replace the water, as it’s flavor that is left behind after dumping the jam into your measuring bowl. Mix with a fork to ensure you’ve removed all lumps…and make sure you only use COLD water, as warm water causes issues.
Note: I started with 2 tablespoons of corn starch, because you don’t want to start with too much, as the amount needed may vary based on how humid it is where you are, and how hot. I didn’t want to ruin anyone else’s jam, so as I do this, I continue to add corn starch and cold water until it thickens to the degree I want. My jam didn’t get thick enough with the initial corn starch, so I added another 1 1/2 teaspoon corn starch and the same amount of cold water. Even with the additional corn starch, your jam still isn’t thick enough, add another small amount of corn starch mixed in cold water until you get to the desired consistency (once it’s boiling–corn starch doesn’t get to it’s full potential until it’s boiled…)
Note: I started with two batches of jam with Sure Jell in them, and combined them into four or five batches when adding corn starch, as it was a lot easier to boil in smaller batches. I used a 2 qt sauce pan on medium heat, stirring constantly..Once it starts to boil, add the corn starch mixture and continue stirring. If you don’t notice it getting thick once it’s at a full rolling boil (boiling even while you are stirring), you’ll want to add more corn starch/cold water. Take your pan off of the heat while you’re preparing more corn starch. Put the pan back on the heat and add your corn starch mixture. I always use a fork to make sure I get rid any lumps, and you must use COLD water, as warm water will give you lumps too..
After adding corn starch, if you have a batch that’s overly thick, remove about 1/3 of the thick jam from its freezer container, and put that back into your sauce pan, and when that batch gets a little thick, take your ladle and add the 1/3 back to your freezer container, mixing it in so the whole container is the same thickness.
I use a wood spurtle to stir the jam (I recommend any material that’s not metal for the utensil you use to stir with–metal gets hot) a ladle to skim any foam off and a small bowl to put the foam in a plate to house my utensils while stirring the hot jam (as this can make a big mess and the plate will hold any jam left on your ladle a funnel used in canning Freezer safe containers for the hot jam…don’t wait until your jam is cool to put it into freezer safe containers, as it will difficult (or in frank terms, a nightmare) to remove once it’s cooled.
After putting the jam in freezer containers, wait until it has reached room temperature, then put into the freezer. I put one container in my refrigerator and showed the results after about 10 days…Here are the notes I thought you might want to consider before trying corn starch to thicken your freezer jam.
End results to consider:
1. I found my jam to be nice and thick, but had a slight “skin” on top of some of the containers. It’s easy to stir the skin into the jam and it doesn’t cause any issues by leaving it there, but I wanted to make sure you knew it might happen to your jam.
2. The jam has a more starchy consistency and taste. It’s not significant, but I wanted to make sure I noted it.
3. My jam seems like it’s more tart once I added the corn starch, and if you don’t like a tart jam, you might want to add more sugar when you are heating it (and before you add the corn starch), as the sugar needs to be completely dissolved before adding the corn starch.
I’m happy with the end result, and if you think you can handle the three points I mention above, you might want to try this remedy for runny freezer jam…