I had purchased a jar of %70 fruit blueberry jam. After consuming about %25 percent of it, I added into the jar some blueberries (10-15) that I purchased recently and I mixed it. A day after, the jam has become very very runny.

What shall I do to fix its consistency?

  • 2
    I have no idea what happened to your jam (shot in the dark: enzyme activity from the blueberries), but I wouldn't add fruit to jam for food safety reasons. Fruit is mostly water; when you mix it with the sweet jam, you reduce the shelf life of the mixuture to maybe 3-4 days refrigerated, or a few hours on the counter.
    – rumtscho
    Mar 11, 2012 at 19:31
  • 2
    I expect you don't need enzyme activity to explain this - adding a couple tablespoons of water wouldn't help the jam either.
    – Cascabel
    Mar 11, 2012 at 23:22

2 Answers 2


Jam is fruit, sugar, and pectin. You added more fruit but all that liquid in the fruit wasn't gelled with the pectin and sugar.

You could try adding sugar and heating the jam to get the pectin to gel with the new juice. This could work but is likely to be error prone. Pectin gelling is tricky and it might not re-gel.

I would recommend adding some sugar, boil it for a bit, and use it as delicious syrup.

In the future, if you have fruit and want jam, just buy some pectin and make your jam from scratch. It's easy to do.

  • Hello! Yesterday I did exactly what you have recomended. In low heat, I warmed up the jam and let it get rid of excess water a lil. It worked perfectly fine. Thank you.
    – Phil
    Mar 13, 2012 at 19:14

Throw it out and replace it with a fresh jar - and don't adulterate the new one.

What was your goal in adding the blueberries? You could make a thicker jam yourself, or a sauce (without the same keeping properties as a preserved jam).

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