Chemical Reaction Lab Report

Introduction: A chemical reaction involves the breaking and forming of bonds in order to create the necessary energy required to cause movement. Each reaction is catalyzed (an increase in rate because of a present catalyst) by a specific enzyme. Enzymes are able to denature proteins, meaning that a protein loses its original shape by uncoiling, giving it a random, unstructured shape. The pineapple plant contains bromelain which, because of its unique characteristics, keeps gelatin from thickening into the solid, commonly consumed food. That bromelain contains two enzymes that have the capability to digest proteins (proteases). Gelatin receives its structure from collagen (an important protein that provides structure within bromelain), in which
breaks the gelatin links as fast as they form. Even though bromelain has the unparalleled ability to fulfill its task of liquefying substances like gelatin, it is like all other enzymes, in that bromelain can be denatured by extreme differences in temperature, and other enzymatic factors. Canned pineapple juice, because of a prior state in which heat was applied, may not have the functioning bromelain to keep gelatin in liquid form. Likewise, concentrated pineapple juice has been heated and then frozen to stay preserved for store distribution. With an extreme change in temperature, bromelain has lost its power to maintain the liquid state of the gelatin dessert and one can enjoy their dessert in a solid state.
Purpose: To gain an understanding of the characteristics of enzymes, how they function, and their susceptibility to denature when exposed to various temperatures, through an experimental process using the pineapple plant.
Hypothesis: If pineapples contain bromelain, then the gelatin submerged in the fresh pineapple juice will denature and stay in a liquid state, while the others, containing non-functioning bromelain due to the extreme temperature changes, will solidify.
Materials:
For every 3 groups For each group For entire class
1 envelope Knox gelatin 4 test tubes water
Measuring cup 1 test tube rack pineapple juice
1 spoon 4(1ml) disposable pipettes hot plate for heating water
100ml graduated cylinder 10ml graduated cylinder Marking pen and tape

Procedure:
1.
For identification purposes, number the test tubes “1-4,” and label with the initials of group members.
2. Locate two other groups and prepare one package of gelatin in the measuring cup using 90ml of boiling water and 30 ml of cold water. Stir thoroughly with a spoon until the gelatin is properly dissolved.
3. Place 3 ml of the designated pineapple juice into each test tube. Note: Use a separate pipette for each type of juice, so as to not mix juice types and result in inaccurate conclusions.
• Tube 1- water only
• Tube 2- fresh pineapple juice
• Tube 3- canned pineapple juice
• Tube 4- concentrated pineapple juice (thawed)
4. Add 10 ml of gelatin mixture to each test tube. Shake well to ensure proper mixing and place your samples in the refrigerator overnight using a test tube rack.
5. On the second day, check the contents of each test tube to conclude whether or not the gelatin turned solid.
6. Record your observations appropriately.

Data:

Test Tube Juice State of Test Tube Contents on Day 2
1 Water Solid
2 Fresh Pineapple Juice Liquid
3 Canned Pineapple Juice Solid
4 Concentrated Pineapple Juice
Solid

Discussion/Analysis:

As hypothesized, the gelatin containing the fresh pineapple juice did not solidify as did the other “juices,” because of the presence of bromelain. In the canned and concentrated pineapple juice the bromelain was not in a functioning state because of the canning and preserving process. The extreme temperatures that the pineapple and bromelain were exposed to, resulted in a lack of operative bromelain, therefore allowing the gelatin to solidify correctly. Due to the existence of functional bromelain, test tube two stayed in the form of a liquid, while the others solidified.

An enzyme is a substance that acts as a catalyst to bring about a specific chemical reaction. When a protein denatures, it loses its original shape by uncoiling into randomness. Because of the change in pH and temperature, a denatured protein loses its ability to function. The enzyme experimented upon is bromelain, in which is found in the pineapple plant; the food source being used to complete the experiment is gelatin. When collagen is heated, it melts into the form of a liquid because of the denaturing of proteins. Water is used as a “juice” to act as a control, so one can identify any true differences.