Apple Browning: How Can It Be Prevented?

...

volumes of solutions will be put in the test tubes for fair testing.

4) The same amount of time will be allowed when dipping pieces of apples for accurate results.

5) The same amount of time was allowed exposing each apple piece to the air in the same conditions for accurate results.

6) Care will also be taken so as not to contaminate the apple pieces with different solutions.

7) The test tubes will be labelled to identify which solution is present.

Diagram:

Table of Results:

Variable: Temperature

Water Room Temp. (24oC) At 40oC At 60oC

Colour

Variable: pH

Colour

Hydrochloric Acid

Ethanoic Acid

Distilled Water

Ammonia Solution

Sodium Hydroxide

These tables are required to observe whether apple browning will occur.

Part 3: Obtaining the Evidence

Date: 11th October 2013

Apparatus and Materials:

• 5 Test Tubes

• Test Tube Rack

• 3 Beakers

• Tripod

• Gauze

• Bunsen Burner

• Matches

• 5 Measuring Cylinder

• 5 Pipettes

• Mass Balance

• 3 Petri dishes

• Knife

• Apple

• Chopping Board

• Foil

• White Tile

• Forceps

• Camera

• Thermometer

• Stopwatch

• Solution of pH 2 (Hydrochloric Acid)

• Solution of pH 5 (Ethanoic Acid)

• Solution of pH 7 (Distilled Water)

• Solution of pH 9 (Ammonium Solution)

• Solution of pH 11 (Sodium Hydroxide Solution)

Diagram:

Method:

1) Five different solutions which were: pH 2 solution (hydrochloric acid), pH5 solution (ethanoic acid), pH 7 solution (distilled water), pH 9 solution (ammonia solution) and pH 11 solution (sodium hydroxide) were prepared.

2) A different measuring cylinder was used to measure 10ml of each solution. Then this was poured into five different test tubes, where one test tube contained only one type of solution.

3) A fresh apple was obtained and it was equally divided into ten fresh apple pieces using a knife.

4) The apple pieces were weighed on the mass balance to make sure that their masses were approximately equal, and only a difference of ±3g was accepted as this does not affect results.

5) Five out of ten apple pieces were put into five test tubes by means of forceps, where each test tube contained one type of solution.

6) The apple pieces were left to stand in the test tubes for 2 minutes. Then they were removed from the test tubes using forceps and were put on a tile leaving them exposed to the air. The apple pieces were then observed the following day to check if browning occurred.

7) A control was made by not putting an apple piece into any solution. This was observed at the same time as the experimental apple pieces and checked if browning occurred.

8) In another experiment to test the effect of temperature on browning, another three fresh apple pieces were put into three beakers containing water at different temperatures. One beaker at room temperature (26oC), other at 40oC and the other at 61oC.

9) Using a measuring cylinder 50ml of each solution of water at different temperatures was placed in separate beakers.

10) The beakers were covered with foil to prevent heat losses and a thermometer was placed in them to measure the temperature.

11) After approximately 2 minutes, the apple pieces were removed from their beakers and then the apple pieces were exposed to the air. The colour of the apples pieces was observed and recorded the following day.

12) A control was made by not putting an apple piece into any solution. This was observed the following day and checked if browning occurred.

13) Measurements and observations were recorded in a table.

14) Photos were taken to record the colour of the apple.

Precautions:

1) Care was taken as not to damage the apples before conducting the experiment especially with the knife.

2) Approximately equal pieces of apple were cut from the same apple for fair testing.

3) Equal volumes of solutions were put in the test tubes and beakers for fair testing.

4) The same amount of time was allowed when dipping pieces of apples in different solutions for accurate results.

5) The same amount of time was allowed exposing each apple piece to the air in the same conditions for accurate results.

6) Care was taken so as not to contaminate the apple pieces with different solutions so for each solution a different