I’m puzzled by something I read in the directions on a box of Jello. It reads-
“DO NOT add fresh or frozen pineapple, kiwi, gingerroot, papaya, figs or guava. Gelatin will not set”
What is it that’s in these fruits that prevents the Jello from setting? I was thinking it was something to do with the PH, but other low-PH citrus fruits are not prohibited.
What do all of these fruits have in common?
Thanks.
Enzymes. These fruits (or several of them, that I know for certain) contain enzymes that will break down the gel-forming bonds between the protein molecules.
Fruit salad contains pineapple and yet Jell-O which contains fruit salad will set. Something doesn’t add up. Maybe it’s the amount of pineapple? Or does not setting not apply to pineapple from a can?
Notice the Fresh pineapple. Canned pineapple (and probably the other fruits) will work since something in the canning process kills the enzymes or renders them inactive.
They specify fresh or frozen pineapple. I have not studied canned pineapple, nor fruit cocktail, but I suspect that the canning process (which involves a lot of heat) breaks down the enzymes.
From the bottom of this page, http://koning.ecsu.ctstateu.edu/Plant_Physiology/ch2.html
Cecil discusses the topic here: Why you can’t put pineapple in Jell-O
So how do those ladies at the caffeteria get the pinapples ine the Jell-O in the first place?
ForumBot, please scroll up to answer that question.
The proteases from pineapple and papaya, bromelain and papain respectively, are inactivated by boiling water (212 °F). Most canning procedures get at least that hot.