Mold can be really gross! But is it really dangerous?
You’ve probably seen moldy bread before. Sometimes we forget about food in our cupboards and come back to find some fuzzy green intruders that we didn’t invite. A while back, we did a blog on moldy bread. If you missed it, you can check it out here: http://www.discoveryexpresskids.com/blog/whats-eating-that-moldy-bread
Today, you’re going to learn more about mold, what it grows on, and how it grows fastest.
What is mold?
Mold is a decomposer. While you might find it kind of icky, it actually helps us and the earth around us by breaking things down and recycling them back into the soil. Mold may be gross (and bad to eat) but it does an important job for us! If you look at the picture of the nitrogen cycle below, notice the decomposers. Decomposers help break down that plant and animal waste to return it to usable nitrogen, a necessary nutrient.
Mold can be found in any environment during any season of the year, but mold likes warm, humid areas. Mold might appear to grow only on the surface of things, but that’s just the part you see. Once mold has grown on the surface, tiny microscopic mold roots may have already penetrated the food beneath the surface.
According to the USDA, eating mold can cause all kinds of problems such as respiratory issues and may cause toxins that can make you sick. Obviously a little mold will not immediately give you any life-threatening disease, but a lot of mold over time could hurt your health. If you’re wondering about moldy food, follow the old saying, “when in doubt, throw it out.”
Even though we just learned about the dangers of mold, there are times that mold is safe. Did you know that mold is actually used to make cheese? Without mold, we wouldn’t even have some medicines! There are also times that you can just cut mold off and save most of the food. How do you know what to throw and what to save?
Check out the list below. What do you notice? What kinds of foods are dangerous to eat when mold is found on them? What do these foods have in common? What kinds of foods be saved from mold? Look for common attributes in these foods and write them down. You will come back to this list later.
YOU WILL NEED:
- 15 slices of bread
- 15 plastic ziplock bags
Here’s what to do!
- Label your plastic bags 1-15 and place a piece of bread in each plastic bag.
- Make sure the bags are all tightly sealed and leave them sealed for the entire experiment.
- Place bags 1-5 in the freezer, 6-10 in the refrigerator, and 11-15 in the basement. The reason you placing 5 in each environment is to get the most accurate results possible.
- Check your bread every two days. Write down the first appearance you see of mold. How long did it take to appear? Which bags did it appear on first?
- Measure how many centimeters of mold are on each bag and record. Continue to do this every two days for two weeks.
- At the end of two weeks, find the average mold growth for each environment. To do this, add up the final centimeters of mold for bags 1-5, then divide by 5 to find the average. Do the same for bags 6-10 and 11-15.
- Which group of bags had the highest mold growth? Lowest? Does your findings match up with your predictions?
- Do NOT open up the moldy bags at the end of your experiment and THROW them out!
Now for the second activity! You can either do this after the bread-molding or at the same time. In the last activity, you compared mold growth in different environments based on temperature and discovered which temperatures promoted the most mold growth. Now, you will compare mold growth on different food items.
Predict which food items will grow mold the fastest/slowest. Think back to what you learned about mold and what kinds of environments it likes to grow in.
YOU WILL NEED:
- Plastic bags
Here’s what to do!
- Select a banana, a slice of cheese, 1/2 cup milk, and a slice of bread. Place each food item in a plastic ziplock bag. Seal the bags and leave them sealed for the duration of the experiment.
- Make your predictions. Which food item will mold first? Which one will grow the most mold over time? Think about refrigeration requirements. Will the milk and cheese mold faster when left out of the fridge? If you’ve already done the bread experiment, think back to your results.
- Place the four items in an area where they will not be disturbed. Make sure all four are in the same place so you know your mold growth can actually be compared. (In an experiment, you always want to make sure there is only one thing you are altering or comparing. In the bread experiment, the food item was the same, but the environment was different. In this case, the environment should be the same, but the food item is different.)
- Check back each day for the next 7-14 days and record your observations. Make sure you mark down which item grew mold first! After that, continue to observe and measure mold grown on each item.
- Remember NOT to open the moldy bags at the end of your experiment and THROW THEM OUT!