The activity below was contributed by Dr. Kelsey Wood during our podcast interview.
Ever reached for a juicy strawberry only to discover a fuzzy, squishy surprise? Mold is a natural part of our world, and it plays a vital role in breaking down organic matter like fruits and vegetables. But when it shows up on our food, it can be disappointing. That’s why many people wash their produce with vinegar. Does it work? You can test it out for yourself! This at-home microbiology experiment will turn you into a science detective, testing the household trick to extend the shelf life of your strawberries: the vinegar wash!
Background info about mold: Mold is a type of fungus that breaks down organic matter, including strawberries. The most common culprit on strawberries is called Botrytis cinerea, also known as gray mold. While it might not be the most pleasant sight on our food, this mold plays an important ecological role by decomposing organic materials and returning nutrients to the soil.
Now that we’ve met the mold let’s see if a vinegar wash can help keep our strawberries fresher for longer! Follow the steps for this activity to test this kitchen science hypothesis.
Remember, if you have a mold allergy, it’s best to avoid handling moldy strawberries altogether.
Materials:
- Box of strawberries (at least 6)
- 2 bowls
- White vinegar
- Water
- Colander
- Paper towels
- Magnifying glass (optional)
- Spoon (optional)
- Microscope (optional)
- Microscope slide and coverslip
Instructions:
- Divide your strawberries into three groups of at least two berries each. Label 2 bowls: “Water Wash,” “Vinegar Wash,” and “No Wash.”
- Set aside 2 berries for the “No Wash.”
- Place 2 strawberries in the “Water Wash” bowl. Fill the bowl with clean water and gently swirl the berries for about 30 seconds. Carefully transfer the berries to a colander and pat them dry with a paper towel.
- In the “Vinegar Wash” bowl, combine 1 part white vinegar with 3 parts water. Place 2 strawberries in this vinegar wash, gently swirl them in the vinegar solution, and then allow them to soak for 10 minutes. Rinse them briefly with clean water using a colander and pat them dry with a paper towel.
- Arrange all the strawberries on a paper towel-lined plate. Label the strawberries by writing on the paper towel. Then, cover them with another paper towel. Place the plate in the refrigerator.
- Every day, observe your strawberries closely. Look for any signs of mold growth, such as fuzzy patches or discoloration. Use a magnifying glass (optional) for a closer look. Record your observations, noting which group shows signs of mold first.
- After a few days, analyze your results. Did the “Vinegar Wash” seem to delay mold growth compared to the “Water Wash” or the “No Wash” group?
Bonus Challenge: Carefully scrape a tiny bit of mold (if any) from a strawberry using a spoon. Place it on a slide, add a drop of water, and cover it with a cover slip. Then, observe it under a microscope to get a magnified view!
Remember: Always discard moldy strawberries and wash your hands thoroughly after handling them.
Downy Mildew Grocery Store Hunt
