“Salt of the Earth” – Apple Mummy


Salts played an important role in preserving mummies, but they also had another purpose. Before refrigerators and freezers, people had to preserve food by pickling, drying, salting, and smoking. Visit a local food store and see how many foods you can find that have been preserved the same way as mummies. In this activity, you will experiment with different salt compounds and discover which makes the best mummified apple. (Based on a Newton's Apple activity.)





Objectives:

  • To see which salt compounds make the best mummified apple
  • To practice making qualitative and quantitative observations

Materials (per lab group)

  • 1 fresh apple
  • large boxes of table salt, Epsom salt, and baking soda
  • knife
  • four 12-oz disposable plastic cups
  • measuring cup
  • large mixing bowl
  • permanent marker
  • roll of masking tape
  • sensitive balance or food scale


Procedure


1. Slice the apple into quarters so that you have four slices similar in size.
2. Decide what salt mixtures you will use. Keep one apple uncovered. This will serve as a “control” or a comparison.
3. Place a piece of tape on each cup and label with the type of salt or “control.
4. Select one slice, weigh it, and record the mass in the data table. Follow the same procedure with the other three apple.
5. Measure and add preservatives as follows and make sure you label each cup with what you have added.

CHOICES:
• Add exactly 1/2 cup of baking soda, making sure to completely cover the apple.
• Add 1/2 cup Epsom salts.
• Add 1/2 cup table salt.
• Add a 50:50 mix of Epsom and table salts
• Add a 50:50 mix of table salt and baking soda
• Add a 50:50 mix of baking soda and Epsom salts
• Add a mixture of 1/3 baking soda, 1/3 Epsom salts, and 1/3 table salt.
• NOT A CHOICE - YOU MUST DO THIS ONE) Cup 4 -- Add nothing and make this a control.

6. Place the cups on a shelf out of direct sunlight and let them sit for seven days.
7. After a week has gone by, take out each apple slice, brush off as much salt as possible, and reweigh. (Do not rinse the apple off because that will rehydrate it.)
8. Compare the starting and ending weights of each slice and calculate the percentage of mass (which is moisture) lost for each by dividing the difference in weight by the starting weight.

Download student lab packet by clicking this link.

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