Science Buddies: "Ask an Expert"

Hi! I am doing an experiment on emzyme activity. I am looking at catalase enzyme in pineapple as I read on the interent that it is rich with it. Unfortunately, non of my samples reacted with hydrogen peroxide eventhough I know I did the experiment correct. I have also seen some on YouTube who have not got results too. I am trying to find the reason behind that as I will be using it to explain why it did not react in my rapport, but couldn't find anything about it. I only found some articles and experiments to test how hydrogen peroxide preserve pineapple from browning. Can you help me?

Hi Shaaban,

Welcome to Scibuddies. I'll try to help you make sense of your experiment results.

My first question is--What is your source of pineapple? Did you use fresh pineapple? If you used canned, then the canning process could have destroyed the catalase enzyme.

My second question is how fresh is your hydrogen peroxide? The 3% H2O2 solution that you buy in the drugstore breaks down fairly quickly, so if your peroxide was from an old bottle, the peroxide may have already been converted to oxygen and water so that the catalase from the pineapple had nothing to work on.

There are many fruits and vegies that contain catalase:

https://www.leaf.tv/articles/vegetable- ... -catalase/

I would suggest getting a fresh bottle of 3% hydrogen peroxide and then buying a fresh pineapple and a number of other fresh fruits and vegies and testing them for oxygen production (catalase activity). If you do the experiment this way you should see good catalase activity.

Do let me know what happens when you try this as it will be helpful for other students who may someday do this experiment.

Sybee

Hi! I did use a concentration of 4% of hydrogen peroxide. My samples where fresh pineapple, fresh pineapple juice and canned pineapple. I allready tried on avocado and it did work, but need to explain why there wasn't a reaction with pineapple. Because this shows more understanding of the topic and may give me more points.

I'm glad to hear that your peroxide worked at least with some food. That shows that the peroxide solution is OK. As to why there was no reaction with fresh pineapple or juice, I don't know, but it might have been because of an enzyme called bromelain which is able to break down some proteins. That is why it is sometimes used to tenderize certain cuts of meat:

https://chemistry.stackexchange.com/que ... ising-diss

It is possible that the bromelain inactivated the catalase before it could decompose the peroxide to release oxygen. Here's another description of this project from Scibuddies that you might not have seen:

https://www.scientificamerican.com/arti ... g-enzymes/

I hope this helps. If you want more help and information, please post again. There's a lot to learn in science but it is really worth it because the more you know about tour world and how it works, the better you can interact with it and the greater will be your pleasure in understanding the nature of Nature.

Sybee