This is an interesting experiment. Gelatin keeps desserts like Jello semi-solid. The enzyme that breaks down the proteins in gelatin is gelatinase. (Most enzymes are named after what they do and end in “ase.”) When the enzymes break down the protein, the jiggly block turns into liquid.

As you know, some fruits contain gelatinase. A good way to find them is to test for yourself. Have an adult help you make a batch of gelatin and pour it into a big, flat container, then cut the sheet into blocks when it solidifies. Or pour small amounts into lots of small containers, like bottle caps or those cups they put ketchup in at some fast food restaurants. (If you ask nicely and explain why you want a dozen or so, they will probably give them to you.)

Each cup or block will be one sample. Scientists use multiple samples that they treat the same way. This helps us avoid making decisions that would only apply to one sample. For example, say that one cup got a drop of pineapple juice in it, even though you were testing apples. Or one was in a warmer place than another one.

Then use small pieces of fruit. Have an adult help you with knife safety. Make sure you keep track of which fruit you’re using. Put a small piece of the test fruit on a set of test gelatin cups or blocks and observe any changes. Use a timer and write down your observations. You may want to make a table first, with times across the top and each sample down the side. Numbering each sample will help. Record things like “no change” or “top looks wet” or “all liquefied” for each sample.

Some fruits that you might want to test include: papaya, kiwi, mango, guava, oranges, apples, figs, peaches. I put in some fruits that have gelatinase and some that don’t so that you can have the fun of finding out for yourself. You don’t have to test them all. If you explain what you’re doing at a place where you normally buy fruit, they may have some old or damaged fruit they can give you for free.

After you have found one or more fruits that have gelatinase, the fun really starts. Brainstorm as many questions as you can think of about the enzymes and pick one or two to test. I’ll get you started by suggesting some general ideas like temperature (boiling, freezing, warm, cold), dilution (mixing fruit pulp with different amounts of water), pH (acid like lemon juice or alkaline like baking soda), and time.

As you come up with fair tests for your ideas, think about how you will show your results in a graph.

Be sure to thank everyone who helps you with your experiment.

Enjoy! Thanks for asking,

I like your project. You could try green banana and papaya. Pineapple makes the surface of my tongue sore, and I think those 2 fruits also sometimes make the surface of my tongue sore, too. The type of enzyme you want is a 'protease'. You can look it up on Google. Then there's meat tenderizer, which has proteases. I suppose one can still buy that at the grocery store. One protease enzyme is Papain - I looked on the internet and discovered that it comes from papaya, which is another reason to use papaya on your gelatin.

Thank you for your curiosity!

A plant enzyme named bromelin will cause gelatin to lose its setting properties. The enzyme bromelin will break down the protein chains that help the gelatin to hold together. Bromelin can also be found in kiwi, ginger-root, papaya, figs, and guava. To find out that the enzyme bromelin will disrupt gelatin, I visited the website General Chemistry Online in the FAQ section. read her

Pineapples are bromeliads - I might look at the fruit of other members of that family.