Halloween is the month for all things creepy and it’s a great time for playing with science! There are a lot of great science projects that can carry a Halloween theme, ranging from glow in the dark potions (that you can drink!) to dancing gummy worms. Halloween is a great time to bring out the fun in chemistry, and teach some really interesting concepts at the same time!
I wanted to kick off our month of Halloween chemistry with a spooky take on an old idea. The experiment we conducted involved the science of decomposition and preventing the biological processes that cause it. We followed the simple instructions for making apple dolls, though ours would take the form of Halloween shrunken heads!
When we cut into fruits and vegetables, we injure and break the cells that build it. Some fruits, such as apples, bananas, and peaches, release Polyphenol compounds and Tryosinase enzymes from these broken cells. These enzymes react with each other and the oxygen in the air, effectively rusting the apple and turning it brown. These enzymes also work to protect the fruit from microbial attack.
We’ve noticed this when we slice apples for lunch. No one wants an unsightly brown apple, yet we obviously don’t want it colonized by bacteria! As it turns out, the trusted kitchen method of sprinkling the sliced fruit with lemon juice prevents the browning from occurring! The acidity in the lemon juice ca dramatically lower the Ph of the apple, creating an inhospitable environment for the enzymes. This works even better when you soak the apple in lemon juice as the acidity both inhibits the enzymes and kills the decomposing bacteria, leaving you with a perfect apple ready to become a shrunken head for Halloween!
SHRUNKEN APPLE HEADS
Apples (the bigger the better!)
Spoon and butter knife for digging out the core
1 cup of lemon juice
2 Tbsp salt
Large drinking glass or small bowl
Wire or yarn (to hang your apple to dry)
Paint, yarn, and scraps of fabric for decorations
1. Peel the apple completely.
2. Use butter knife and spoon to dig out the core from the bottom of the apple. You’ll want to dig as much of it out as possible, without poking through to the top of the apple.
3. Choose one side of the apple that will be the face. Use your butter knife to dig out facial features (holes for the eyes, carve out a little mountain for the nose, cut a mouth into the apple, etc).
4. Mix the lemon juice and salt in a wide glass or bowl that is deep enough to mostly submerge your apple.
5. Soak the apple for three minutes. Then turn it around and soak the other side for another three minutes.
6. Pat the apple dry with a clean towel.
Outside Drying Method: Hang or place the apple in a warm, dry area for approximately two weeks. Additional moisture may cause the apple to mold (if it is going to rain or is humid, bring the apple inside!). Make sure it is out of the way of any critters who may be looking for a snack. Check your apple’s progress everyday. It will be finished when it is dry, spongy, hardened, and wrinkled.
Inside Drying Method: Alternatively, you can dry your apple inside, by placing it in a warm oven for several hours. Set your oven to the lowest temperature and lightly wrap the apple in foil. Then place the apple on a baking sheet and let dry in the oven for several hours. As with the outside drying method, check the progress every hour, waiting for it to have the hard, dry, spongy, and wrinkled texture.
7. Decorate your apple! We used acrylic paint for the face, yarn for the hair, and fabric strips for clothing and pigtails. Some people fill small jars with rice and decorate those to use as a body for the doll. Other people have used large tongue depresses glued to the inside as a body for the apple and wrapped with fabric for clothing. We didn’t use bodies, preferring to leave the heads around the house for our visitors to find as a spooky trick for Halloween. Whatever you do, now is the time to get creative!
MAKE IT A SCIENCE EXPERIMENT:
You can really hone your science skills by conducting an experiment with your apple heads! There are many different preservatives you can use with this project. We used lemon juice, salt, and of course, a control (adding nothing to it). By using a control in your experiment, you have a basic standard with which to compare your results. In our experiment, we followed the standard apple doll recipe using lemon juice for two apples. Then we made a super saturated salt water solution for one of the other apples. When that apple was done soaking, we completely covered it in salt before hanging it out to try. The results of our experiment were really neat, but you can try your own to find out what will happen!
When all is said and done, you should have some great looking shrunken heads, just in time for Halloween! You can impale them in a mock cemetery, use them to decorate your spooky doorway for trick or treaters, or dress them up and turn them into grandma dolls! Whatever you decide to do with them, you’ll have your very own shrunken head (or doll) that YOU created! As for us, this project was so much fun, we will definitely put it into regular rotation for Halloween projects each year!