If the pineapple juice is pasteurised, nothing too special.
If the pineapple juice is freshly squeezed, it may unset the jello, and it will certainly prevent it from setting properly if added to the mix from the start.
There is a naturally occuring enzyme in pineapple, called bromelain. Bromelain basically acts to break protein down. That's why meat eaters are often encouraged to eat a bit of pineapple (think pineapple rings with pork, pineapple on pizza, etc.). Because it helps the body digest the high amounts of protein in the meat.
Jello (American tradename for what's called "Jelly" in Europe) is mostly made of gelatin, a protein. So add an protein-destroying enzyme to Jello, and it won't congeal because the protein molecules have been torn apart.
But, if the pineapple is heated enough (precursor for canning or packing in juice cartons and bottles), the bromelain enzyme gets destroyed. Hence the trick is to use canned pineapple chunks when making Jello.
If the pineapple juice is freshly squeezed, it may unset the jello, and it will certainly prevent it from setting properly if added to the mix from the start.
There is a naturally occuring enzyme in pineapple, called bromelain. Bromelain basically acts to break protein down. That's why meat eaters are often encouraged to eat a bit of pineapple (think pineapple rings with pork, pineapple on pizza, etc.). Because it helps the body digest the high amounts of protein in the meat.
Jello (American tradename for what's called "Jelly" in Europe) is mostly made of gelatin, a protein. So add an protein-destroying enzyme to Jello, and it won't congeal because the protein molecules have been torn apart.
But, if the pineapple is heated enough (precursor for canning or packing in juice cartons and bottles), the bromelain enzyme gets destroyed. Hence the trick is to use canned pineapple chunks when making Jello.
