Comparing Spices, Salt and Dehydration in Food Preservation

3.7 based on 27 ratings

Updated on Mar 07, 2013

Grade Level: Elementary School; Type: Biology


Whether they salt it, dry it, or refrigerate it, humans have been preserving food for centuries. This science project involves comparing the relative effectiveness of salt, pepper and dehydration in food preservation.

Research Question:

  • Why does salting work to preserve food?
  • Why does dehydrating food work to preserve food?
  • Does pepper preserve food?
  • Which works better – dehydration, salting or spices?
  • What other spices might be useful?


  • Sliced organic bread
  • Plastic sandwich bags
  • Toaster
  • Sharpie marker
  • Tablespoon
  • Pepper and salt
  • Notebook
  • Magnifying glass

Experimental Procedure

  1. Place eight slices of bread in separate sandwich bags. Seal the bags.
  2. Toast the other eight slices to dryness. This may take ten minutes on medium heat in a toaster oven. Be careful to dry the bread and not to burn it. Place each toasted piece in a separate bag.
  3. Set two of the fresh slices and two of the dry slices aside. Label them “fresh control” and “dehydrated control.”
  4. You should have six remaining bags of fresh, untoasted bread. Treat them as follows: a) Open two of these bags and sprinkle one tablespoon of salt over one side of the bread. Label this “Salt/Fresh.” b) Open another two of these bags and spring one tablespoon of pepper over the surface of the bread. Label this “Pepper/Fresh.” c) Open the remaining two bags and sprinkle one tablespoon of salt and one tablespoon of pepper on each side. Label this “Salt & Pepper/Fresh.”
  5. You should have six remaining bags of toasted bread. Treat them as you did in step #4 and label them appropriately.
  6. Examine your bags with your magnifying lens every day for six weeks. Determine which bag became contaminated first and whether the contamination grew as vigorously in each bag. Determine which treatment provided the most protection.

Terms/Concepts: food preservation, salting food, dehydrating food, spice trade

References: Chemistryland: Early Chemistry: Preservation Chemistry

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