Improve your pumpkin pie with science
Making slight changes in your ingredients could make for a better pie, or maybe not. Either way, it is a good way to learn science.
This is an article in a series related to science activities about the natural world that anyone can conduct with children. All of these activities can be done in numerous settings which include within a family, in a day-care setting, as part of school activities, a 4-H club or with any group working with young children.
Pumpkin pie can be good – or it can be not-so-good. What experiments can you do with the children in your life to learn science and make dessert at the same time? It is fun to make several pies that you can try out with the kids, and use the best one for holiday dinner. Asking why, making guesses and observing what happens are great examples of science. If you fail in making a good pie, that’s OK. You often learn more from failures than success. The pie will still probably be edible.
For this article, Michigan State University Extension is going to focus the discussion on the filling, not the crust of the pie (stay tuned for that). Classic pumpkin pie filling starts as a runny liquid with pumpkin, eggs, sugar, salt and nutmeg. Some recipes add vanilla, cream or milk, and other spices.
A basic pumpkin pie recipe we will start with:
- 15 ounces pureed pumpkin – you can use either a cooked down pie pumpkin or canned pumpkin
- 2 large eggs
- 1 cup sugar
- 1/2 teaspoon salt
- 1/2 teaspoon nutmeg
Mix the ingredients together, pour into a pie shell and bake at 350 degrees Fahrenheit for 45 minutes.
Now for the science and experiments; let’s try to change things, predict what will happen and observe (and eat) the results.
Egg yolks are the part of the egg that feeds the developing baby bird. It contains fats, proteins, vitamins and minerals. It also contains a substance called lecithin. Have you ever mixed oil and water together? They separate out quickly. Lecithin can bring those two things together. One end of lecithin can “grab” fats and the other end can “grab” water. This process allows the water that is part of the pumpkin to connect to the fat in the eggs, or any additional fats you might add, such as butter or cream. An egg is the difference between mayonnaise and vinegar and oil salad dressing. Conversely, egg whites are mostly protein. When the protein in the egg white cooks, it turns into a solid (you see this when you crack an egg into a hot frying pan). When the eggs in the filling cook and solidify, they help hold the pie together. Note: whenever you cook egg dishes, you should make sure the internal temperature of the dish is 160 degrees Fahrenheit to reduce the chance of food-borne illness.
Here are some variations you can use to experiment with your eggs and see what happens:
- Use duck, turkey, quail or other poultry eggs instead of chicken eggs. Each egg has different ratios of yolk to white, which can change the outcome of your pie.
- Vary your cooking time. If you cook your pie too long, the egg proteins shrink too much and you get cracks in the top of your pie. If you get cracks, try cooking less. You could have the children guess to see how long it takes for the pie to crack. If the pie is still a little wobbly when you pull it out of the oven, you can watch the heat left in the pie continue to cook the pie, even when it is removed from the oven. Warmth doesn’t just leave instantly when you remove something from a heat source.
- Whip the eggs before you add them to the rest of the mixture. Does that change the texture of the pie?
- Try using just egg yolks or just egg whites in the pie. What do you think will happen? Will it still result in the same finished product?
There are lots of different ways you can add sweetness to a pie and each might have different results.
- Vary the level of sugar in your pie. Try a pie with no sugar. Does it still “work?” Is it edible? Pumpkin is closely related to squash, and most people eat squash without added sugar.
- Try brown sugar instead of white sugar. Brown sugar has some molasses added to it. Brown sugar tends to absorb water (humidity) out of the air, leading to baked goods that are usually moist. What does it do to pumpkin pie?
- Add other liquid sweeteners, such as honey, maple syrup, molasses, caramel or agave syrup. How does it change the texture? Does it need more or less cooking time? Why or why not?
- Add different dry sugars, such as turbinado, raw sugar or demera sugar. Do you think the larger sugar crystals will still dissolve in the pie? Does the sugar type affect the texture?
- Try artificial sweeteners in your pie. Some artificial sweeteners do not measure the same as traditional sweeteners.
- Sweetened condensed milk can be used instead of sugar. How does this affect the flavor and the texture?
Try making a pumpkin pie without salt. Do you notice any difference in flavor or texture? Why do you think that happened? The argument for salt is that it “turns on” the taste buds by changing the chemistry of the saliva in our mouth. Even if you don’t taste the salt, it might let you taste other things differently.
There are a range of different spices used in pumpkin pie. Nutmeg is almost always used, but sometimes cinnamon, allspice, cloves, ginger (dried, fresh or candied), cardamom or other spices are added. Mix up the spices to see how it affects flavor and texture. It is recommended to use small amounts (about 1/2 teaspoon or less) when making these changes.
Many pumpkin pie recipes call for the addition of a dairy product. Different recipes call for milk, cream, half-and-half, butter, cream cheese, evaporated milk and sweetened condensed milk. Dairy products are very complex and contain some proteins, fats and sugars. In a pumpkin pie, proteins usually help the pie solidify and fats give it a smooth feeling in the mouth. How do the different forms of dairy change the final product? Experiment and find out! Try adding a small amount in different pies. Start with a half cup of dairy and adjust up or down from there.
Have fun and experiment with your pie, making mistakes (and eating them) in the name of science and a perfect Thanksgiving dessert.