Hello there sciencegirls-ga, and thanks for your question...this was a
fun one to work on.
There is a lot of scientific information available on enzymes in
pineapples and other fruits, but much of it is written at a college or
professional level, and is not well-suited for an 8-year old student.
I have a 6-year old and a 10-year old at home myself, so I've tried to
present the information below in a manner that would be suitable for
them, as students.
I hope I've succeeded. But before rating this answer, let me know if
you need any additional information or explanations. Just post a
Clarification, and I'll be happy to assist you (and your daughter) further.
For starters, What is an enzyme? A straightforward and pretty simple
definition can be found here:
enzyme -- A protein that encourages a biochemical reaction, usually
speeding it up. Organisms could not function if they had no enzymes.
Note that the site also includes a link to listen to a spoken
explanation of enzymes from a prestigious scientist, if you're so
To put it even more directly, an enzyme:
--is a type of biological chemical known as a protein
--is produced by living things like animals, plants, bacteria
--speeds up chemical reactions
--and is essential to life
Different enzymes do different things. Many enzymes are involved in
biochemical processes that breakdown large, complex molecules into
smaller units. For instance, when people eat foods, digestive enzymes
help to break down the food into nutrients the body can use.
Enzymes that breakdown proteins are known as protease enzymes
Pineapple contains a powerful protease enzyme called bromelain. Other
fruits can have protease enzymes as well, though they are different
bromelain, and have different names.
Not all fruits contain powerful protease enzymes, however.
describes an experiment at the student level (though a bit advanced
for an 8-year old, I would think) that compares the actions of
different enzymes from
different fruits, and separates fruits with protease enzymes from
those that do not.
The gist of the experiment is to place bits of fresh fruit in gelatin
(which is probably most familiar to your daughter as Jello). Since
gelatin is a
protein, the introduction of protease enzymes such as bromelain will
interfere with the gelling of the Jello. In other words, it won't
set, but will stay
Turns out that pineapple (with bromelain) and papaya (with an enzyme
called papain) and kiwi fruit and figs all contain protease enzymes
that can interfere with the gelatin setting properly.
[NOTE: This only works with fresh fruits -- processing often
deactivates enzymes, so that fruits like canned pineapple don't affect
Apples and oranges -- although they certainly contain enzymes -- don't
have any powerful protease enzymes similar to bromelain, so that you
daughter) can readily put apple and orange pieces in your Jello
without interfering with how it sets.
A teacher's guide to the above-linked experiment provides some
additional details and discussion on this topic:
and another discussion of essentially the same experiment can be found here:
LAB I: What Fruits Contain Enzymes that Digest Protein?
You and your daughter can conduct a simple kitchen experiment with
either Jello gelatin or an unflavored gelatin such as Knox gelatin.
The hypothesis can be: Some fruits have enzymes that digest proteins.
The experiment can be to mix gelatin with various fruits (again --
they must be fresh). You can use chunks, but will probably get a more
with a combination of both chunks and pureed fruit.
The observations will (likely) be that some fruits allow gelatin to
set, while others do not, and the gelatin stays in a liquidy form.
The conclusion will (likely) be that some fruits -- notably pineapple,
kiwi fruit, figs, papaya -- contain enzymes that can digest proteins,
Other fruits -- apples and oranges for instance -- do not have such
enzymes, and therefore, do not interfere with gelatin setting.
I hope this is the sort of information you were looking for. I think
it's already a lot for an 8-year old to (ahem!) digest. But as I said
at the outset, if you'd like even more information, I'd be more than
happy to oblige.
Just let me know how I can be of assistance, and I'm at your service.
All the best,
search strategy -- Google search on:
[ enzymes pineapples oranges apples papaya ]