Next, we learned about proteins and did two experiments with proteins. In our first experiment we placed a cube of jello in a Petri dish with either fresh pineapple juice or canned pineapple juice. We observed changes over a 4 hour period and by the end of that period our jello cube in the fresh pineapple juice had shrunk dramatically, where the canned pineapple juice did not change much. (See pictures below where the dark yellow liquid is fresh pineapple and lighter yellow liquid is canned pineapple). Fresh pineapple contains a protein, bromelain, that tenderizes collagen proteins, like those in gelatin. Canned pineapple has been through the canning process and the bromelain becomes denatured and does not function.

Our last experiment of the day was to study an enzyme called catalase. Catalase is an enzyme found in humans and also in some vegetables including potatoes that catalyzes the reaction of hydrogen peroxide into water and oxygen, causing bubbles to form. We took a solution of mashed potatoes and heated it up to 85 degrees Celsius and measured the functionality of the catalase as we increased the temperature. We learned that temperature affects the catalase activity and our hotter samples did not produce bubbles when we added hydrogen peroxide. The students did a great job learning a bunch more new content today. Most future chemists don’t get a lesson in enzymology until graduate school!

Dr. LaPointe

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