Tropical · Fruit Banana
Banana Jam, or What to Do with Nine Overripe Bananas
Published 17 Oct 2026 · Reading time 4 min
Why this one works
Banana has no pectin, almost no acid and a pH around 5 — the least suitable jam fruit there is, and the reason most banana jam recipes taste like sweet paste. It can be done, but only with the acid and pectin added deliberately and the fruit cooked briefly so it does not turn to baby food.
In the pan
- 9 overripe bananas, about 1.2 kg peeled
- 500 g granulated sugar
- 120 ml lime juice, about 5 limes
- 5 tsp high-methoxyl pectin, whisked into 5 tbsp of the sugar
- 1 tsp ground cinnamon or 1 split vanilla pod
The numbers
- Family
- Tropical
- Fruit
- Banana
- Pectin source
- Added — 5 tsp, the highest dose in the book
- Sugar ratio
- 1 kg peeled fruit : 500 g sugar : 120 ml lime juice
- Target Brix
- 64 Brix
- pH
- 3.3
- Gel point
- 105 °C
- Sealing
- Boiling water bath
- Shelf life
- 12 months
- Crystal risk
- Low
- Yield
- 4 x 200 ml jars
- Time at the pan
- 18 min
Three stages
Prep — mash by hand, never in a machine
Mash the peeled bananas with a fork or a potato masher until you have a lumpy purée with visible pieces. A blender produces a smooth, aerated slurry, and aerated banana purée traps air that will not come out in the jar — you get a foam layer on top of every jar that looks like mould even when it is not.
Toss the mash with the lime juice immediately. Banana browns within minutes of exposure to air, and the acid slows the enzyme that does it while also bringing the pH down from 5 to a workable 3.3.
Cook — 18 minutes total, and stir like you mean it
Warm the mash, sugar and spice together for 8 minutes, stirring constantly. Banana scorches at the base of the pan faster than anything else in this collection because it is dense and low in water; a silicone spatula that reaches the corners is the right tool.
Bring it to a full boil, add the pectin blend and hold at 105 °C for 60 seconds. Banana at pH 3.3 needs the extra degree and the full minute: the pectin has more work to do here than in any other recipe. Test on a chilled plate — a good banana jam sets to the texture of a soft fruit cheese.
Seal — 12 minutes, small jars, fridge after opening
Fill 200 ml jars at 90 °C with a 6 mm headspace and process for 12 minutes — the extra two minutes matter because banana is a low-acid fruit even after the lime juice, and the centre of a dense banana jar heats slowly.
Banana jam is the only preserve in this collection that should go into the fridge once opened, even though it is shelf-stable before that. Its pH is the highest here at 3.3 and its sugar the lowest at 64 Brix; neither leaves room for carelessness.
Failure diagnosis
Four things go wrong with this preserve more often than anything else. Open the one you are looking at.
Will not set
Banana sets only on added pectin, so a loose jar means the pectin was under-dosed or the mixture never reached 105 °C. Add 1 tsp pectin in hot water, boil a full 60 seconds at 105 °C, and stop there.
Graining and crystals
Low risk because the sugar ratio is the lowest in the book, but there is a related problem: banana jam can ferment if the pH drifts above 3.5. Measure the lime juice rather than squeezing by eye.
Mould or spoilage
The foam banana throws is the risk, because foam sits above the gel line with a low local sugar concentration. Skim every spoonful off before potting, and leave 6 mm rather than 10 mm of headspace.
Colour loss
Banana browns within months and there is no way to stop it — the acid slows the enzyme but does not switch it off. A four-month-old jar is the colour of dark caramel and tastes fine, which is the point of the cinnamon.
On the same shelf
Other tropical recipes, all already published.
Recipes here are for home preserving and are informational only. Canning safety depends on your altitude, your jars and your thermometer — verify with your local extension service before relying on any single number.