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Apple Enzyme Lab
243
To determine which substance(lemon juice, baking soda solution, vinegar, oxygen) prevents the browning of the apple the best, which means the polyphenol oxidase inside the cells of the apples are reacting with the oxygen in the air.
Polyphenol Oxidase Lab
by
Luke Hosman, Peter Walker, Kyle Faddis
Before Experiment
Procedure
- Gather materials.
- Dress all group members in protective gear.
- Slice 2 apples into 8ths.
- Place the 16 apple slices evenly onto 4 paper towels.
- On 1 group apply 50ml of lemon juice to apples, on the next group apply 50ml of baking soda/water solution, on another apply 50ml of vinegar, the final group is to be left alone, therefore the reacting substance is oxygen.
- Record data/results every 10 minutes for the next 30 minutes using the provided oxidation scale.
- Clean up lab area.
- Draw conclusions and compare results to the hypothesis.
Hypothesis
The hypothesis that we formed at the initialization of the experiment is that the more acidic the substance put on the apples, the less the apple will become discolored, because the acidity will keep the polyphenol oxidase contained in the apple, absorbing less pigments causing it to discolor.
Materials:
Pictures of the Solutions/Materials
50 ml of lemon juice.
50 ml. of 50/50 water and baking soda solution.
50 ml of vinegar.
2 apples.
Paper towels.
Camera/phone.
Paper.
Pencil/pen.
Knife.
Graduated Cylinder.
Oxidation Scale.
Measuring Cup.
Purpose
Variables
Dependent Variable: Coloration of apple slice.
Independent Variable: Substance/pH applied to apple.
Control Variable: Oxygen group of apples.
Conclusion
- Generally the more acidic of pH in independent variable, results in less browning of the apple slices. This is because the polyphenol oxidase has to react to the acidic solution before reacting with the oxygen, causing longer preservation of the apple.
- The results could greatly vary if the amount of substance (independent variable) applied to the apple slice were to be varied, or if different substances were used with the same pH.
Human Error
After Experiment
A human error that may occur is if the apples are affected by any one of our group members, for example if we were to put the wrong amount of solution on the apple slice, as well as the measurements possibly being slightly off. The baking soda was combined with water to make it possible to be poured onto the apple slice, so that may have triggered an error.
20 Minutes
Oxidation Scale
10 Minutes
pH levels of solutions
Vinegar has a pH of 3.
Lemon juice has a pH of 2.
Baking soda has a pH of 8.
Oxygen has no pH.
30 Minutes