Does jelly not set when you add fruit to it?

[headfairy]

I'm a bit of a jelly virgin but made some up yesterday for the dcs, two with pineapple chunks in, one without. The two with the pineapple still havent set, but the one without has.

What's going on? All were made from the one packet of jelly in one batch and then poured in to smaller bowls so the problem can't be in how I made the jelly up.

Pineapple and kiwi are no friends of jelly.

It says on the packets that kiwi and pineapple will cause the jelly not to set. Which I find quite confusing as you can buy ready made jelly in the supermarket with pineapple in it!

If you used fresh pineapple, the enzymes will stop the jelly setting.

A few pieces of tinned pineapple should be ok though.

Aha.. It's fresh pineapple, so that's what's happened! Well you learn something new every day. Thanks everyone. Serves me right for trying to sneak some fruit in to their pud!

Yup fresh pineapple, mango or passion fruit all stop jelly setting

Science of fruit jellies

Oooh I love a bit of science , thanks for that link Seona!

I make lots of fresh fruit jelly by blitzing the fruit with or without sugar depending how sweet the fruit is and then setting it with sheet or powdered gelatine. I know that fresh pineapple and kiwi will not set. Today I noticed on your website that someone said that using mango will stop the jelly from setting. I beg to differ I have just made a fresh fruit jelly using blitzed and sliced mango with sheet gelatine and it has set beautifully. I'm not sure if this would be the case if you used shop bought jelly mix.