CanningCraft Creates: Strawberry-Banana Jam

picture of Allison Carroll DUffy

Allison Carroll Duffy

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Here’s Allison:

No doubt some folks in mild climates have fresh, locally-available fruit in April, but here in Maine, that’s still a long way off. It’s a lovely thought for sure, but somehow it seems a particularly humorous one at this moment, given that it’s April 1, and we still have over a foot of snow on the ground.

So, what to do when it comes to jam? Well, it seems to me to be a good time to give a little love and attention to a fruit that is pretty much a permanent fixture in my fruit bowl, no matter the season, but that I often overlook: the banana. Dense, sweet, and filling, if there was ever a fruit that could qualify as a comfort food, the banana would be it.

Bananas sound great for jam, but if you’ve been making jam for a while, you might have noticed that there are not a lot of recipes out there for banana jam. The primary reason is that a straight banana jam would be too dense to safely can. Additionally, unlike most fruits, bananas are considered “low-acid,” which means that a specific amount of acid (usually in the form of lemon juice) would need to be added to the bananas to make them safe for boiling water bath canning.

To address both of these issues, I’ve used a good quantity of strawberries in this recipe in combination with the bananas, along with some lemon juice. To ensure safe canning, please don’t adjust the quantities of either of the fruits, or of the lemon juice. However, if you are crazy about bananas and absolutely must include more banana in your jam, then just be sure that you freeze your jam rather than can it.

For this recipe, you can of course use fresh strawberries if you have them, but I used frozen berries and they work just as well. And, for the bananas, be sure they are ripe enough that you can mash them easily. Enjoy!

Strawberry-Banana Jam on Toast

Strawberry-Banana Jam on Toast

Strawberry-Banana Jam

Strawberry-Banana Jam is a low-honey cooked jam made with Pomona’s Pectin. Pomona’s Pectin contains no sugar or preservatives and jells reliably with low amounts of any sweetener.

Yield: 4 to 5 cups

Before You Begin:
Prepare calcium water. To do this, combine ½ teaspoon calcium powder (in the small packet in your box of Pomona’s pectin) with ½ cup water in a small, clear jar with a lid. Shake well. Extra calcium water should be stored in the refrigerator for future use.

Strawberry-Banana Jam Ingredients

 bananas and frozen strawberries2¾ cups mashed strawberries
1¼ cups mashed bananas
¼ cup lemon juice
3 teaspoons calcium water
½ cup honey
3 teaspoons Pomona’s Pectin powder

Strawberry-Banana Jam Directions

1. Wash and rinse jars, lids, and screw bands. Set screw bands aside until ready to use. Place jars in boiling water bath canner with a rack, fill at least 2/3 of the way full with water, and bring to a boil. Boil jars for 10 minutes to sterilize (add 1 additional minute of sterilizing time for every 1000 feet above sea level), then turn down heat and let jars stand in hot water until ready to use. Place lids in water in a small pan, bring to a low simmer, and hold there until ready to use.

2. If you are using fresh strawberries, place them in a colander, rinse them well, then remove and discard stems. If you are using frozen strawberries, defrost the berries.

3. Place fresh or defrosted strawberries in a mixing bowl and mash well. A potato masher works well for this.

4. Measure out 2¾ cups of mashed strawberries. (If you have extra, simply use for something else.) Pour the measured amount of strawberries in a large saucepan, then set aside.

mashing bananas with fork5. Peel the bananas and discard the peels. Place bananas in a mixing bowl and mash well. A fork works well for this.

6. Measure out 1¼ cups of mashed banana. (If you have extra, simply use for something else.) Pour the measured amount of bananas into the large saucepan with the strawberries. Add lemon juice and calcium water, then stir to combine.

7. In a separate bowl, combine the honey and pectin powder. Mix well and set aside.

8. Bring the strawberry-banana mixture up to rolling boil over high heat. Add honey-pectin mixture, then stir vigorously for 1 to 2 minutes, still over the highest heat, to dissolve pectin. Return jam to a boil, then remove from heat.

9. Remove hot jars from canner and fill jars with jam, leaving ¼ inch of headspace. Remove trapped air bubbles, wipe rims with a damp cloth, and put on lids and screw bands, tightening bands only to “fingertip tight” (until resistance is met, and then just the tiniest bit more).

10. Place jars in the hot water, on the rack inside the canner. (Make sure jars are upright, not touching each other or the sides of the canner, and are covered with at least 1-2 inches of water). Place the lid on the canner, return the canner to a rolling boil, and boil for 10 minutes. (Add 1 minute additional processing time for every 1000 feet above sea level.)

11. Turn off heat and allow canner and jars to sit for 5 minutes. Then remove jars from canner.

12. Allow jars to cool undisturbed for 12-24 hours. Then, confirm that jars have sealed. Remove screw bands from sealed jars, rinse off outside of jars if necessary, label jars, and store for later use.

Recipe and photos by Allison Carroll Duffy

Printable Copy of the Recipe Only here!

9 thoughts on “CanningCraft Creates: Strawberry-Banana Jam

  1. I made this jam a few days ago (my first with Pomona pectin) and was extremely careful with my measurements, per your warning. Sadly, the results were not to my taste. The jam came out much too stiff (I like it very loose) and the banana overwhelmed the strawberry taste. Plus the jam wasn’t sweet enough for me (but that’s an easy fix). The good news is I was able to combine one jar of the strawberry-banana with a recently-traditionally-made too-loose strawberry jam; the combined result was quite good. I’m keeping it in the frig and may do the same combo trick with the other jars once I’m finished with this one. Or I may even combine all the jars, reheat, and reprocess; we’ll see.

    The whole effort leaves me with a major technical question regarding the chemistry of strawberry-banana jam. I need to solve it if I’m ever to try the combo — which I do love — again.

    Am I right that it is the banana that causes concern? And, if I’m right about that, can I decrease the proportion of banana to strawberry (i.e., less banana, more strawberries) without worry? What about the amount of pectin and calcium water? Since it came out too firm for my taste, I would be inclined to decrease both pectin and calcium water (keeping the lemon juice the same), but again, don’t want to run into safety concerns. Any insights you might be able to share would be much appreciated.

    • Hello Elizabeth,

      I too prefer my jam to be a bit more loose. You can reduce the amount of pectin in any of our recipes to accommodate your preference, if you would say that your jam came out about 50% too firm, then use 50% less pectin. However, if you are wanting to reduce the amount of banana, and are increasing the amount of strawberry (which is just fine), then you may only want to reduce the amount of pectin by 25%, as strawberries have more natural pectin in them than bananas.

      The lemon juice, calcium water and honey would all stay the same.

      Happy jamming!

        • Just so you know, my remake of the strawberry-banana jam came out great! I added another 3 cups of smashed bananas (2 might have been enough, but 3 was fine), reheated the previously-made jam, added the strawberries and a bit of sugar and lemon (pectin and calcium water in original was too much, so didn’t add more). Everyone who has tried it has raved about how great it is (friends even took it back to England after trying it at my place).

          If I started from scratch again, I would reduce the amount of bananas by half; that should produce the taste and consistency I prefer.

  2. Hi. I am wondering if this recipe has been lab tested to ensure a safe pH level? How do you know that the added acid and the strawberry mixture is high enough pH to compensate for the low acid bananas, especially since ripe bananas have a higher pH than green or slightly underripe bananas?

    • Dear Linette,
      You are asking a good question. Allison Carroll Duffy, who created and tested the recipe, is a certified Maine Master Food Preserver, very aware of pH and other issues related to canning safety. She used ripe bananas, as she suggests in the recipe, and tested the pH of this jam before we published the recipe. We can assure you that if you follow the recipe it will be safe for water bath canning.

      I hope this helps — and please don’t hesitate to contact us if you have additional questions.

    • Hi Patte,
      Yes, you can use sugar instead of honey for the Strawberry-Banana Jam recipe. We would recommend 3/4 cup of sugar, but you could use up to 1 cup of sugar to replace the honey.

      I hope this helps — and Happy Jamming!

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