Pumpkin Preservation Experiment

As Halloween approaches, pumpkins become the centerpiece of seasonal décor and celebrations. Heading to the pumpkin patch and our annual pumpkin party are highlights of the season every year! The centerpiece of the party? Carving jack o’lanterns! Then, every year when we’re done – there is the one big challenge— how do you keep your pumpkins fresh until the big night? Pumpkins, like all other plants and vegetables will begin to break down over time, especially once they’re cut open and exposed to the air. In this pumpkin science experiment, we’ll explore different methods of preserving pumpkins to help them last longer after they’ve been carved. We will also carve our way through some fun science behind the decay process!

Pumpkin Preservation Experiment
How to Keep Your Jack O’Lanterns Fresh for Halloween

Pumpkin Preservation Halloween Science Experiment

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Why do pumpkins decay?

It is always just as important to understand why something happens before you try to prevent it from happening! Pumpkins have a high water content, as soon as they are harvested, they begin to lose that moisture. This moisture loss leads to shrinkage and softening, nicks, bumps and especially cuts are more susceptible to rot because it’s damaged skin. When pumpkins are carved, the process speeds up because the exposed flesh creates an ideal environment for bacteria, mold, and fungi to grow. These microorganisms break down the pumpkin’s cellular structure, causing it to rot.

So, to preserve a pumpkin we need to slow down the processes of dehydration and hinder bacteria from growing. Preservation techniques typically aim to retain moisture in the pumpkin while preventing bacterial or fungal growth. It’s a balancing act for sure, but if you can get it right – you’ll have a beautiful jack-o-lantern that will last all month!

How to Preserve Pumpkins: Experiment

In this experiment, we’ll test several pumpkin preservation methods to see which ones are most effective at prolonging the life of carved pumpkins. We’ll also consider the environmental impact of each method, especially if you plan to compost or donate your pumpkins after Halloween.

What do I need?

4 pumpkins
Petroleum Jelly
Bleach solution (1 tablespoon bleach per quart of water)
Disinfectant Spray
White Vinegar
Disinfectant Wipes
Carving Tools
Bowl
Battery Powered Candles

Directions

First, wipe down the outside of each pumpkin with a disinfecting wipe to make sure the outside is clean of dirt and bacteria. Then rinse the outside well and dry it off.

Preserving Pumpkins first step, clean with disinfecting wipe

Now for the fun part – CARVING! Carefully cut the tops from the pumpkins and scoop out all of the guts – or as we like to call them – Pumpkin Brains! Once it is all cleaned out you can carve your spooky, cutie pumpkin faces.

Now we conduct our pumpkin preservation experiment! This is where we play with our variables. In this experiment our variable is the materials used to preserve the pumpkins. We are testing Petroleum Jelly, Bleach, Disinfectant and Vinegar.

Method A: Petroleum Jelly

The simplest method to preserve a carved pumpkin is by applying petroleum jelly to all of the cut surfaces of the pumpkin. This forms a protective barrier between the flesh and the air, reducing moisture loss and slowing down microbial growth. You can coat both the inside and outside edges of the carving to seal the pumpkin. Note: petroleum jelly is oil-based, which may affect composting or feeding to livestock, as it’s not a natural substance.

Pumpkin preservation with petroleum jelly
Method B: Bleach Solution

Another popular method for protecting carved pumpkins is to soak or spray them with a diluted bleach solution. The bleach kills bacteria, mold, and fungi that would otherwise cause the pumpkin to rot. After soaking the pumpkin in the bleach solution for 5-10 minutes, allow it to air dry. You can also spray the solution on the inside of the pumpkin every few days to extend its lifespan. Bleach is a disinfectant that kills harmful microorganisms on contact. By reducing microbial growth, the pumpkin stays fresh longer. However, using bleach may affect the ability to compost the pumpkin, as chemical residues may disrupt the composting process.

Pumpkin preservation with bleach solution
Method C: Disinfectant Spray

The third choice we’re testing is simple disinfectant spray. Generously spray the pumpkin with the spray all over inside and out. The spray kills germs on contact which will – just as bleach does kills harmful microorganisms on contact. Again, this method would prevent composting as the chemical residue would be left behind.

Pumpkin preservation with disinfecting spray
Method D: White Vinegar

For a more natural approach, you can use white vinegar to preserve your pumpkin. Like bleach, and spray vinegar has antimicrobial properties but is safer for the environment. Spray or soak the pumpkin with a vinegar solution (equal parts water and vinegar) to help prevent mold and bacteria from growing. Vinegar is acidic, and the low pH prevents bacteria and fungi from thriving. Since it’s a natural product, vinegar-treated pumpkins are more compostable or suitable for animal feed after Halloween.

The final step is thinking about how we light up our pumpkins. Heat is a factor in bacterial growth so traditional methods of lighting up a jack-o-lantern can speed up the decay process by essentially cooking the inside of your pumpkins. A better choice is the battery powered tealight candles that are very inexpensive and can be used year after year. These candles still have that spooky flicker but won’t cook your pumpkin prematurely! They also won’t leave any wax residue in the pumpkin.

Carved pumpkins

The Results: The Best Pumpkin Preservation Method is…

The bleach bath was definitely the winner in the preservation game, the pumpkin didn’t show any signs of breaking down – even after a week. The others all look great as well but you can see a little softening and shriveling around the cuts.

So for our experiment bleach won – however, after Halloween, many people wonder what to do with their pumpkins. Some preservation methods can affect the pumpkin’s ability to be composted or used as livestock feed. However, as mentioned earlier, pumpkins preserved with bleach, petroleum jelly or disinfectant spray may leave chemical residues that could harm the composting process or be unsafe for animals. If composting or donating pumpkins is a priority, stick to natural preservation methods like vinegar. This method will help prolong the pumpkin’s life without leaving harmful substances behind.

Try this experiment and discover the perfect pumpkin preservation method for you! Happy Halloween!

Pumpkin Preservation Experiment