Canning 101: How to Ensure That Your Jam Sets

temperature test

One of the trickiest things about making jam is achieving the set sweet spot. Cook it too long and you worry about the integrity of your cutlery as you reach in for a spoonful. Cut the stove time short and when it comes time to eat, the jam threatens to run off your toast in sticky rivulets (do know that jam this consistency is still amazing on pancakes or in yogurt. Call it a rustic syrup or old fashioned preserves and your friends will still be wowed).

plate test

First off, know that even the most experience jam maker has an off day here and there. The same recipe can yield a perfect set on Saturday and make an unfortunately sloshy batch on Sunday. Jam is influenced by the width of the pot you use to cook it, the ratio of sugar to water in the fruit, the amount of pectin in the fruit (as well as whether you add additional pectin), the elevation at which you’re cooking and even the amount of humidity in the air.

Here are a few things to keep in mind as you prepare to make a batch of jam…

  • As I mentioned above, the width of your pot can influence the set of your jam. Always choose the widest pot you have at your disposal that also has enough height to let the jam boil vigorously. More surface area means faster evaporation and ample height means you can crank the heat and let it boil. Getting the water evaporated out of your cooking jam at a speedy clip is integral to having a nice, spreadably sticky jam.
  • Take the jam’s temperature. Jam making is much like candy making in that you’re applying enough heat to the fruit and sugar to raise the temperature over the boiling point of 212 degrees and alter the structure of the sugar. The jam reaches its ideal set point at 220 degrees, so keep careful watch. Know that if you reduce the amount of sugar in your recipe too drastically, you may not be able to get your cooking jam up to the set point.
  • Before you take the jam off the heat, try the plate test. At the beginning of cooking (or even before) stash a couple saucers or sandwich plates in your freezer. When you believe the jam is cooked, grab one of the plates and plop a small spoonful at the center. Let it sit for a minute or two and then gently prod the puddle of jam with your finger. If it’s formed a surface skin and seems to be developing a certain solidity, it is done. If it is runny and saucy, give it a few more minutes.
  • Another test is the sheet test. Here, you stir a spoon through your jam and the remove it from the pot. Holding it over the cooking jam, watch as the remnants on the spoon drip back down. Do they fall back in runny drips, like rain on a window? If so, it’s not quite done. However, if they seem thick and run together in more of a sheet, your jam is finished.
  • Cooking times are estimates. When the recipe gives an amount of time for you to let the jam cook, know that that is only an approximate time. The recipe writer doesn’t know how hot your stove cooks, whether you’re in arid New Mexico verses sticky Philadelphia or what size pot you’re cooking the jam in. Use your judgment.
  • Additional pectin can help improve set, but it isn’t always a panacea. I’ve had jams that included additional pectin end up runny and then made others with no additional pectin that have firmed right up. Additionally, I’ve found recently that my beloved Certo liquid pectin isn’t working as well this year as it did in years past. I don’t know if they’ve changed the formula, but it’s thrown me off and made me remind myself of the basics of set all over again.

What are you tips for making sure your jam sets well?

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102 Responses to Canning 101: How to Ensure That Your Jam Sets

  1. 51

    […] and cook until it is reduced by more than half, reads 220 degrees F on a thermometer and passes the plate/sauce/wrinkle test. When it is finished cooking, pour marmalade into prepared jars. Wipe rims, apply lids and rings […]

  2. 52

    […] heat until the liquid is reduced and the jam has become quite thick and sticky. When it passes the plate test, it is […]

  3. 53

    […] to a boil. Cook at a bubble, stirring regularly, until the jam reaches 220 degrees and passes the plate/sauce/wrinkle test (remove the pot from the heat source while you’re testing to prevent […]

  4. 54

    […] 3.  Add the lime juice and zest and boil for additional 5-8 minutes or until the jam is at the correct consistency. […]

  5. 55

    […] add you lemon juice and cinnamon and let cook. Cook until the jam looks thick and passes the plate test. This will fill 6 half pint jars. Process according in a water bath canner for 10 […]

  6. 56
    Loquat syrupy jam in Orange County says:

    I used Certo premium liquid fruit pectin. This was my first attempt and it failed miserably. I have a very runny syrup. I am thinking that I may have put too much Certo in and under sugared. I always cut sugar because I prefer healthier. Unfortunately, I read right on the box (after I was supposedly finished) that exact amounts of sugar are crucial. So, I went back to the stove and poured the remainder of my organic sugar and let it cook for a couple of minutes. Again, not knowing really what I was doing. How do I save this beautiful chunky syrup? Maybe corn starch and blending it a bit? Thoughts?

  7. 57

    […] constantly, bring to a boil and cook 10 minutes, or until mixture has thickened (and passes the plate test). Cool […]

  8. 58
    Allie says:

    So, being a total newbie to jam making, I do wish someone had mentioned that it is possible to burn jam. I was watching my temps quite avidly and it just did not seem to want to get to 220 and them all of a sudden was at 225 and I smelled burning. Am pretty perturbed, but I guess I will at least know for next time. Maybe something to warn others of?

    • 58.1
      Barbara says:

      In the ways that sugar absorbs heat before it changes its characteristics, it takes a long time, relatively, for a “stage” to be reached. Once that stage is reached, the temperature tends to shoot up rapidly until it is near the next “stage.” Keep this in mind when/if you do candy, too.

  9. 59

    […] making your own jam you will never buy it from the grocery store again.  Check out Food in Jars,  foodinjars.com/2010/07/canning-101-how-to-ensure-that-your-jam-sets/, it has a wonderful posting on how to make great jam every time. Homemade jam is also a wonderful […]

  10. 60

    […] boil and let cook for 25-30 minutes, skimming off any foam that appears. After 25 minutes, start testing the jam to see if it’s set. (I use the plate-in-the-freezer method.) I did not process this in a water-bath to be shelf […]

  11. 61

    […] use the cold plate concept to see if my jam is ready to set.  Put some jam on a plate that was frozen.  If  the liquid […]

  12. 62

    […] to a boil and cook for 15-20 minutes, stirring frequently, until the jam thickens and passes the plate test. Ladle into sterilized jars. Put on lids and rings. Process the jars in a boiling water bath for 15 […]

  13. 63

    […] cannot be stirred down, add the pectin and boil hard, stirring constantly for one minute. (Check jam consistency at this point. Add more pectin/ cook more if needed.) Remove from the heat and skim off the foam. […]

  14. 64

    […] Funny thing, you can’t always count on jam to set the way you want. Luckily, there are ways to test it before you put it into the jars that should ensure a perfect set.  […]

  15. 65
    Lucy Dugger says:

    If I am making a jam and the recipe calls for 1-3/4 oz. powdered fruit pectin, can I substitute the Certo liquid pectin and if so, how much do I use. I believe it comes in 3 oz pkg. Any help would be appreciated.

    • 65.1
      Marisa says:

      Lucy, I actually don’t recommend the Certo liquid pectin. I find that it doesn’t hold particularly well. That said, 2 packets of liquid pectin equal one box of powdered pectin.

  16. 66

    […] by half and reaches at least 220 degrees on the thermometer. (Mine cooked 25-30 minutes). Use the plate test to check and make sure it will set. (Super short version: put a drop of boiling hot marmalade on a […]

  17. 67

    […] to bubble more rapidly, about 10 mins. Add the ginger and continue to cook until the jam is set: this information from Food in Jars is very helpful in determining set point, if you have questions. I have made this jam a dozen […]

  18. 68

    […] or need to fix a runny batch, these articles from Food in Jars really helped me save my batches: How to Ensure That Your Jam Sets and How to Save Runny Jam. I’ll be experimenting with this in the future and hope I’m […]

  19. 69

    […] In a small bowl, whisk sugar and pectin until well incorporated. Add sugar-pectin blend to violet water and whisk until completely dissolved. Turn heat up to medium high and bring mixture to a boil, stirring occasionally. You want to stay close to the pot because it does have a tendency to bubble over if left unattended. Continue cooking until mixture has thickened slightly, about 5-10 minutes, skimming off any foam as you go (there will be a lot). Jelly is ready when it passes the chilled plate test. […]

  20. 70

    […] zest of two lemons. While it has a looser consistency (which I prefer anyways) it still passed the freezer test and the temperature test. And of course my personal taste […]

  21. 71
  22. 72

    […] mixture along with lemon juice. Continue cooking fruit until it reduces slightly and reaches the jellying stage, about 30 minutes. Remove fruit heat, discard vanilla beans and skim any […]

  23. 73
  24. 74
    Jo-Anne Lemaire says:

    Hello. I clicked on the couple of spots on your site where it indicated that I might find help for my poor runny crabapple jelly. But both links have been removed so that this help no longer exist.

    Please, if you’ve any solutions for me, contact me. Thank you very much.
    Jo-Anne Lemaire, greenjo@xcelco.on.ca

  25. 75

    […] IN JARS wrote a lovely post on How to tell if your Jam has set. Now I […]

  26. 76

    […] or need to fix a runny batch, these articles from food in jars really helped me save my batches: how to ensure that your jam sets and how to save runny jam. i’ll be experimenting with this in the future and hope i’m […]

  27. 77
    Illene says:

    have you ever used Pomona’s pectin? i’m looking for wholesale pectin and buying ball brand liquid pectin is so expensive.

    • 77.1
      Marisa says:

      I have. It’s good pectin, but sets up differently than classic fruit pectin. You have to adapt your recipes to use it.

  28. 78

    […] For me, canning season really won’t begin in earnest until July, maybe August (beans, tomatoes, beets — I can’t wait!) but in the spring, I ease into the routine with a few small batches of things. I started out with a round of rhubarb jam. I think next to plum, it’s my favorite jam and it thickens really easily without the use of commercial pectin or the addition of high-pectin fruits. My first few attempts at this jam actually produced more of a paste which while delicious, was a bit of a challenge to eat. That was in my early canning days, before I knew about the frozen plate trick. Do you know about that? You should. Check it out. […]

  29. 79

    […] a delicious jamlike consistency. Don’t just take it from me, check out this great post from Food in Jars. So put a candy thermometer in your jam, keep stirring every few minutes to make sure it’s […]

  30. 80

    […] reached a thick “jammy” consistency. Marisa McClellan, of Food in Jars, has some great tips on how to know when your jam is ready. I have used this recipe quite often that I just eyeball […]

  31. 81
  32. 82

    […] frequently, until the tomatoes have softened and the syrup has thickened. You might want to use the plate test to determine if your jam is […]

  33. 83

    […] includes a vast amount of information on canning basics, as well as a helpful little article on ensuring your jam sets; not to mention a slough of fabulous […]

  34. 84
    patricia says:

    i have made jelly, and this batch is runny, new season, i dont want runny jelly. i see that meny things can make it thin and runny, i am about to start jelly, i have heard a wooden spoon is a must, is this true, also adding a teaspoon of butter will help make it a dark color , lets get to the point, how do i make normal jelly not to thin, and runny

  35. 85

    […] See Food In Jars’ post on ensuring the set of your jam. More questions? Consult her amazing Canning 101 page. […]

  36. 86

    […] a knife. Make certain your marmalade reaches 220 degrees during the boiling process, and passes the plate/saucer/wrinkle test. Mine turned out a wee bit runny, but has been absolutely delicious on scones, and as a topping for […]

  37. 87
    Rae says:

    Just a suggestion. On the previous page it says “bring to temperature”. Perhaps that could also say, “usually 220 deg.”

  38. 88
    Teanessa Atkins says:

    Thanks so much for the info about the 220 degree set point! I had runny jam, so I put it back in the pot with just a tablespoon of extra pectin, and brought it to the 220 degrees. It set perfectly! The next batch I made, no extra pectin, but brought it to 220 degrees and it is PERFECT! Obviously my cook time was much shorter than needed to make the jam!! Thanks again!!

  39. 89

    […] minute. Skim the foam formed on top. Reduce the heat and let it simmer for 15-30 minutes. I follow these steps to check whether my jelly or jam is done. Once it passes the “doneness” test, turn the […]

  40. 90

    […] the marmalade constantly until set, 30 to 35 minutes. (Test the set on your marmalade with any of these tips.) Take the marmalade off the heat, let it cool for five minutes, and then stir in the […]

  41. 91

    […] Did you check for set while the jam was cooking? Any time a recipe gives you a cooking time, it’s simply an approximation. During cooking, you also need to be checking for signs of set. You do this by using the frozen plate test, watching how the jam sheets off the spatula, and taking the temperature of your cooking jam. More on those techniques here. […]

  42. 92

    […] A quick method to see if your jam is done, specially when using softer fruits like any of the berries, plums, apricots or the like, you can use the frozen plate method. Put a few ceramic salad/small plates in the freezer at the beginning of the cooking process. When it is time to check if the jam is set, drop a dollop of the jam onto plate and let it rest for a few minutes. When you run your figure through it. If it feels runny and doesn’t leave a “trail” through it, then it isn’t done and needs few more minutes. If it leaves a clear “trail” through the jam then it done and ready to be devoured! For more in detail about how to check if your jam is done, this link on Canning 101: How to Ensure That Your Jam Sets helps. […]

  43. 93

    […] has thickened. Add thyme sprigs to mixture and continue boiling until the mixture can pass the frozen plate test. When it does skim foam and discard thyme […]

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