Why Do Pineapple and Kiwi Ruin Gelatin?


[♩INTRO] If you’ve ever made gelatin for a picnic
or party, you’ve probably been warned not to add certain
fresh fruits, like kiwi or pineapple. And for good reason. Add these foods to your
gelatin, and it won’t set. It will remain a big, goopy mess. The reason why is pretty straightforward,
but if you understand it, it can help you learn how to make better desserts, and how to up your cooking game in general. To understand why these fruits ruin gelatin,
you need to know what this stuff is made of. Once it sets, gelatin is basically a mesh
of interconnected collagen molecules. Collagen is a long, fibrous protein found
in things like skin and bones. And… yes, the collagen in gelatin does traditionally
come from animals. Manufacturers boil things like hides or bones
until the proteins come out, and then they turn them into a powder you
can buy at the store for, like, a dollar. When you dissolve the powder in hot liquid,
the collagen separates into individual fibers. Then, as the solution cools, those fibers
start to bind to one another and gradually form a mesh. But if you add certain fruits as you’re
making your gelatin, that last process will never happen. It’s because fresh kiwi, pineapple, and
some other fruits contain high concentrations of proteases,
or proteolytic enzymes. These are substances that digest proteins,
basically, chopping them into tiny pieces. If this stuff gets into your gelatin mix,
it will cut up those strands of collagen until they’re too short to link together,
so your dessert will come out looking like a soup. If you know why this happens, though, it’s
easy to find some ways to work around it. For one, if you cook the fruit, the heat will
inactivate those enzymes, so your gelatin will turn out just fine. This is also why something like canned pineapple
doesn’t cause issues. Alternatively, you could make your dessert
with agar instead of gelatin. Agar is made from certain types of red algae,
and like gelatin, it forms an interconnected meshwork of fibers. But it’s made of carbohydrates, not proteins,
so proteases won’t digest it. Of course, while these fruity enzymes aren’t
great for gelatin, they do have their uses. For one, they have some surprising industrial
and medical benefits. Like, they can be used to prep damaged areas
for skin grafts if someone gets a severe burn. The treatment breaks down and clears away
dead and damaged tissue. But maybe more importantly to you, you can
also use juice or pulp from protease-containing fruits in the kitchen
to tenderize tough cuts of meat. The enzymes break down stringy bundles of
proteins, making the meat easier to chew. So go ahead and save that fresh pineapple
for your steak, and stick to the canned stuff when it comes
to gelatin. Everyone will thank you. If you want to learn more science-inspired
cooking hacks, we’ve got an episode with seven more of
them for you. And as always, thanks for watching this episode
of SciShow! [♩OUTRO]

100 thoughts on “Why Do Pineapple and Kiwi Ruin Gelatin?”

  1. Note: That pineapple enzyme trick with meat is best used only up to an hour. Any more and the meat falls apart, in the bad way.

  2. I feel like I should say that I saw the thumbnail for this video right after it was posted, but I was already half asleep and was convinced that I had dreamt up the thumbnail and the question itself. I don't know why I thought this question was far-fetched for SciShow, pretty much everything is fair game by now.

  3. Is that why, when I tried to eat a pineapple for dinner, it made my mouth bleed? It wasn't Chemical-Burns from the acid, it was enzymes?

  4. Is the widespread use of gelatin over agar purely a cost based thing? I know agar is more prevalent in the east but Jesus I'd much rather cook with agar than gelatin. Nothing more appetizing then the smell of dead animals.

  5. What about "why does lemon juice curdle milk?" I just wanted a lemony twist but my chocolate milk started turning into sour cream within minutes send help

  6. Iv actually done this before. Kiwi in a big fruit jelly trifle. One hour still not set 2 hour still not set. Next day still not set. Have a google…. ah damm it. Add vodka and straw.

  7. i found out my friend is a fascist anti-egalitarian. if i spray him with pineapples can i make him melt? please? please? pleeeeeaaaasseee?

  8. Kiwi is a bird. The fruit is actually called "kiwi fruit"! But I imagine putting a kiwi in your gelatine would ruin it too.

  9. Kiwifruit. KiwiFRUIT. A kiwi is a flightless bird from New Zealand. They are endangered, so you best be not adding them to your gelsatin desserts! The green fuzzy fruit is a kiwifruit.

  10. WTF! You people are sick. Gelatin is supposed to be healthy. It's originally made from seaweeds. Why make it from animal proteins?! Seriously sick!

  11. But why does pineapple and kiwi have this enzyme, what is its purpose. Does it protect the fruit and seeds from burrowing insects?

  12. Then how does my family make apple-pineapple chunk lime gelatin?!

    (To be clear it is box gelatin and the fruit is fresh)

  13. This is also why if you marinate a steak with pineaple it will make it way more tender and juicy. Guga Foods made a few videos marinating steaks with pineapple (and no, it doesn't taste like pineapple after).

  14. Maybe this video helped me solve the riddle I had, why my mouth reacts with unwelcome feelings when I eat raw pineapple and kiwifruit, but not to cooked/boiled/baked one. I just found out that mango and other stuff I can't eat, have protease in them, too.

  15. This is something that always gets me people referring to putting Kiwi in something, A Kiwi is a bird (or a new Zealander) what you are referring to is a kiwifruit, the fruit is part of the name, you don't call a grapefruit as a grape, or breadfruit as a bread.

  16. I just made jello last night and I thought that was weird. Now I see this video coming out the day afterwards and THAT is weird to me

  17. Eating my Bacon sandwich. Hmm whats this Why pineapples ruin Jello? 0:42 happens. Me I will never eat jello again but damn i want some pork broth to dip my bacon sandwich in now.

  18. Seems to be a lot of us here who are sensitive/allergic to them…including me xD

    And yes My joints are very strange lol

  19. Michael's voice seemed really gentle in this video. It was very relaxing while I learned about fruits that destroy collagen.

  20. That explain why I have eaten agar with fresh pineapples in them. Agar dishes are more common here than gelatin based one, anyway .

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