Enzymes and the browning of fruit and vegetables

Topics: PH, Enzyme, Measurement Pages: 3 (799 words) Published: October 13, 2013
Research question:
What is the effect of altering the pH of the solution that pieces of apple are placed into on the degree of colour change that occurs when the pieces of cut apple come into contact with atmospheric oxygen, as measured by a colour scale?

Hypothesis:
Altering the pH of solution that pieces of apple are placed into has an effect on the degree of colour change that occurs when they come into contact with atmospheric oxygen. As the pH of solution increases, so does the degree of browning of the apple slice. Low pH solutions will cause the enzyme to be inactivated and therefore cause the degree of browning to decrease. As the pH increases so does the degree of browning, because the pH becomes closer to the enzymes optimum pH level.

Independent Variable:
The pH solutions that the apple pieces are placed into. Range of pH levels to be tested is 3, 6, 8, 10, and 12. Each solution needs to have 5 trials to ensure reliable results.

Dependant Variable:
The degree of colour change that occurs when the pieces of cut apple come into contact with atmospheric oxygen Measured by a colour scale shown below

12 3 45

Controlled Variables:

VariableHow Controlled
Amount of pH solutionsMeasure 20ml of solution for each trial using a measuring cylinder. Make sure to measure from the bottom of the meniscus to be more accurate. Size of apple pieces2cm x 2cm with no skin. It is important to have all the pieces the same size because otherwise some might have a larger or smaller surface area. Pieces must have no skin! Time apples are in and out of solutionPlace apples in solution for 5 minutes, (time this using the stopwatch.) Then leave the apples over night, about 24 hours. Type of appleAll the apples need to be of the same brand, and bunch. There must be no previous bruises / discolouration. Some apples may already be brown in areas from bruising, so it is important to either cut off the area or use a...
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