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Edible Slime

10/31/2018

Author: Maddie Van Beek

In the spirit of Halloween, we thought we’d have some more SLIMY SPOOKY FUN! Last week we made slime out of potato starch. This week, we’re going to use gelatin and corn syrup to make edible slime!

Gelatin is a product that is extracted from animal parts (usually the skin, bones and hooves of pigs or cattle) and is used for thickening certain foods. Gelatin comes from collagen, which is found in the connective tissue. You might not think of gelatin as healthy, but it is almost all protein. When gelatin is heated, the protein bonds break and form a liquid, but when it is cooled, the protein strands twist together and form a gel.

One special thing about gelatin is that it is thermoreversible, which means it thins as it is heated and thickens when it is cooled. Thermo comes from the Greek word thermos, which means heat. The Latin word reverses means to turn back. So thermoreversible means heat causes the substance to “turn back," or return to a fluid state when heated.

Because of its thickening properties, gelatin is used in many sweets and candies. It is flavorless and almost completely colorless, so it can be easily dyed and flavored.

Luckily, all these properties make gelatin perfect to use for our SLIME!

YOU WILL NEED:
* Gelatin (we used natural beef gelatin, but Knox gelatin packets will work well)
* Corn syrup
* Water
* Measuring cups
* Food coloring
* Saucepan
* Stove
* Mixing bowls
* Flavoring of your choice (any drink mix works well)

Here’s what to do!
1. Measure 1 cup of water into a saucepan and bring to a boil.
2. Add a few drops of food coloring of your choice to the boiling water.
3. Measure 6 tablespoons of gelatin into the water, stirring constantly.

4. Once the gelatin is dissolved, remove from the heat and set aside for 5-10 minutes to cool.

5. Measure 1/2 cup of corn syrup into a separate mixing bowl. If you want your slime to have a certain flavor, add two tablespoons of flavored drink mix to your corn syrup and stir until evenly distributed.
6. Pour the gelatin mixture over the corn syrup and stir… you should start to see the texture change right away.

7. Mix together and watch your slime form!

8. It may take a few minutes to thicken; as the gelatin cools the slime will get even thicker and gooier.

9. Play, taste, enjoy!

Extension: What happens when you put your slime in the refrigerator? How about the microwave? Make a prediction! Think back to what you learned about gelatin being thermoreversible.

You can actually turn this edible slime into a gummy!
This is what happens if you put your slime into the refrigerator:

Spoon some slime onto a tray and refrigerate for creepy looking slimy treats.

OR

Heat your slime for 45 seconds in the microwave and stir; notice, your slime is now completely smooth again like it was before it thickened. Pour the slime mixture into a tray and place in the refrigerator for 10 minutes. Check your slime—it should be completely firm. If it’s still gooey, wait another 5 minutes. Remove from the refrigerator and slice into bite size pieces or gummy snakes!

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Spud Mud

10/20/2018

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Author: Maddie Van Beek

Get in the Halloween mood with some slime! Today, we’re going to make slime with potato starch… aka SPUD MUD!

First, what exactly is starch? There are all sorts of important nutrients in our diet. Think about what humans need to survive. Make a list.

Carbohydrates are a crucial source of energy in the human diet and are most readily used when our body is active. One carbohydrate that we get from many of our foods is starch.

Starch is a carbohydrate found in a variety of plants and grain products, such as potatoes, pasta, or rice. Starch is stored within the plant as an energy source, and is one of the most common carbohydrates in the human diet.

One thing that we use pure starch for is to thicken foods. If you try to mix starch with water or other cold ingredients, it will eventually settle to the bottom. If starch is heated, the molecules swell, and the tiny grains of starch absorb water. Once that water is trapped in the starch molecules, the food thickens. When the food is removed from heat, it will thicken even more as it cools. For more on how starch thickens foods, click here to check out our last blog and make some pudding! This time, we aren't going to heat our starch, we're going to use it to make a non-Newtonian fluid.

That brings us to our project: we're going to make our own spud mud! If you've ever made "Oobleck," then you know what it's like! This time, you’re going to try out potato starch instead of the commonly used cornstarch.

This weird slimy substance that you’re going to be working with today is a non-Newtonian fluid. Non-Newtonian fluids behave very differently from normal liquids or solids. Instead, they sometimes behave like a liquid and sometimes behave like a solid. When you apply pressure to a non-Newtonian fluid, it resists and behaves like a solid. As soon as you release the pressure, the fluid returns to liquid form.

To make this type of non-Newtonian slime, you need two basic ingredients: starch and water. Typically, cornstarch is used to make this kind of slime, but any type of starch will work. What about something else that contains starch, like flour?

Test this out: Compare potato starch to flour.
Scoop 1/2 cup of potato starch into one cup and half a cup of flour into a second cup. Mix 1/2 cup of water with each and stir. What happens?

Above, flour ball. Below, potato starch ball.

You probably noticed that the starch easily transformed into the slime you know and love, but the flour just left a goopy mess. Why didn't the flour work the same way? Think about what these two ingredients have in common. They are both powders, both processed, both from grains, but while potato starch is from potatoes, flour is from wheat. Potato starch is pure starch, while flour is a mixture of starch and proteins, such as gluten.

Add a few drops of food color if you would like. If your spud mud is too runny, add a little more starch. If it’s crumbly, add more water. A little goes a long way!

Next, we're going to try to extract our own starch from potatoes! Your job is to determine which potatoes have the most starch. This project requires some wait time,
so after you complete the first part of your project, you can continue to get messy with your spud mud!

Choose three different potatoes to compare. Some varieties of potatoes are "starchier" than others. There are starchy potatoes, such as Idaho or Russet, waxy potatoes, such as red or baby potatoes, and some that are in between. Sweet potatoes are also very high in starch content. New or "baby" potatoes have less starch, because they were harvested before much of their sugar could develop into starch. Out of your three varieties, which do you think has the most starch?

Make your predictions before you start.

YOU WILL NEED:
* Food processor or knife
* Large bowl
* Water
* Stove or microwave
* Strainer
* 3 Jars or clear bowls

Here's what to do!
1. Choose your first potato variety.
2. Wash the potatoes off well to remove any dirt.
3. Put two-three potatoes (of the same variety) in the food processor and process until they are in small chunks. You will need enough for two cups of chopped potato.

4. Scoop two cups of chopped potatoes into a large bowl.
5. Heat four cups of water over the stove.
6. Pour hot water over the potato chunks (just enough to cover them) and stir for 3 minutes. Notice that the water starts to change color as you stir!

7. Place a strainer over clear bowl or jar and pour the potatoes and water through the strainer (so you are left with only the starchy water)

8. Notice the texture and color of the water. What do you think will happen as it sits?
9. Over the next 10 minutes, check back every 2 minutes and write down any observations.
10. Repeat the process with the other two potato varieties. Make sure you use the same amounts of potato pieces, water, and jar size so results are comparable!
11. As you check back, you should see that the water has begun to separate. You might see a layer of water on the top or a layer of white on the bottom. The white layer is your starch!

Above, you can see the brown potato (left) and red potato (right) starting to form layers.
Below, the sweet potato formed a starch layer on the bottom within minutes.

12. Let all three jars sit as long as it takes to see good separation. You will begin to see layers within an hour or so, but it will be more obvious if you leave it for several hours or overnight.
13. Compare your results. Do you see any big differences? Does one potato obviously have more starch on the bottom than the other? Did your results match your predictions?

Notice the defined layer of starch on the bottom of the sweet potato glass.

Above, after two hours. Below, left overnight.

Dip your finger in the top layer—what does it feel like? Try pouring the top layer off of your potato water. The clear-ish colored layer should easily pour off, and you’re left with a thicker, goopier layer. Compare the consistencies between the different potatoes.

If you extracted enough starch, you could even use it to make more spud mud!

More starchy experiments:
Make your own gravy and test foods for starch: www.discoveryexpresskids.com/blog/science-of-starch

Compare gelatin and starch in two chocolate pudding recipes:
https://www.discoveryexpresskids.com/blog/cornstarch-vs-gelatin-make-your-own-chocolate-pudding

Get in the fall mood with some pumpkin slime: https://www.discoveryexpresskids.com/blog/fall-fun-make-your-own-pumpkin-slime

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Cornstarch vs. gelatin: Make your own chocolate pudding

10/2/2018

6 Comments

Author: Maddie Van Beek

Corn Starch vs. Gelatin

Today we are going to learn about two different food thickeners, and compare their effects by making a delicious dessert! Why would we need anything to thicken our food? Can you think of any examples? Make a list.

One common food thickener is cornstarch. Many people use cornstarch to thicken gravies, soups, or sauces. The result is a creamier texture with an opaque appearance.

Another thickener is gelatin. Gelatin is more often used for custards, pie filling, or Jell-O® desserts. Unlike cornstarch products, gelatin allows foods to hold their shape more rigidly, and the appearance of these foods is typically more transparent.

While cornstarch and gelatin are different in some ways, both thickeners require heating to work their magic. Cornstarch thickens food as it is heated, but gelatin thickens food as it cools.

How exactly do these ingredients work?

Starch is a carbohydrate that can come from a variety of plants or grain products, such as potatoes, pasta, or rice. Starch is stored within the plant as an energy source, and is one of the most common carbohydrates in the human diet. If you try to mix starch with water or other cold ingredients, it will eventually settle to the bottom. As starch is heated, the molecules swell, and the tiny grains of starch absorb water. Once that water is trapped in the starch molecules, the food thickens. When the food is removed from heat, it will thicken even more as it cools.

Gelatin is a product that comes from collagen derived from animal skin or bone. In contrast to starch, gelatin is actually a protein. When mixed with cold ingredients, gelatin will not readily dissolve. Once heated, the protein strands lose their bonds with one another and the gelatin becomes a clear syrup. While warm, gelatin causes some thickening, but not much. Once cooled, the protein strands twist together, trapping liquid in between the amino acid bonds, creating a gel. The longer it cools, the firmer the gel becomes.

Now that you understand these two culinary ingredients, let’s move on to the fun part! Today you’re going to make two chocolate pudding desserts! Make sure you take notes along the way to compare your two recipes. Chart the differences in appearance, consistency, and at the end, taste!

YOU WILL NEED:
* 2 ¾ cups Milk
* 3 tablespoons Cocoa powder
* ½ cup Sugar
* 1 teaspoon Vanilla
* ¼ teaspoon salt
* ¼ cup Cornstarch
* 1 tablespoon Gelatin
* 2 Saucepans
* Measuring cups and spoons
* Mixing bowl
* Whisk and stirring spoon

If you want to track the differences side by side, prepare both recipes at the same time using two different saucepans.

Before you start, look at the cornstarch and gelatin. Write down observations, feel it, notice differences in texture. You may even try mixing each with a bit of water. What happens?

Here’s what to do!
1. Measure the dry ingredients, excluding the gelatin (sugar, salt, cocoa, cornstarch), into one saucepan and mix together. Set aside.

2. Measure the gelatin powder into the mixing bowl. Add ¼ cup milk and whisk together. You should see a thick paste. Don’t worry if the gelatin doesn’t fully dissolve. Set aside.

3. Measure the same amount of the dry ingredients, this time excluding the cornstarch (sugar, salt, cocoa) into a second saucepan. Add the remaining 2 ½ cups milk.
4. Measure 2 ¾ cups milk into the first saucepan of dry ingredients.
5. Place both saucepans on the stove over medium heat. Remember which one is which!
6. Stir both as they heat. You should notice the ingredients begin to dissolve as they heat.

Above, right after placing over heat. Cornstarch on the left, milk mixture on the right. Below, after a few minutes of heating and stirring.

7. After about five minutes, both saucepans should be relatively well mixed with no big clumps. Remove the gelatin pan from heat.

8. Continue stirring the cornstarch pan until it boils, and keep stirring until the pudding seems well-thickened. It will be darker in color and noticeably thicker. This process should take about 2 minutes after boiling.

Left, after pudding begins to thicken. Right, after two minutes of stirring after boiling.

9. Pour the heated milk mixture into the mixing bowl of gelatin and whisk until evenly distributed.

10. Scoop one cup of cornstarch pudding into a glass or bowl, cover, and refrigerate. Do the same with the gelatin pudding.
11. Now we wait! You can eat the leftover warm cornstarch pudding while you wait for your gelatin pudding to set. This will take about 2 hours.
12. Once two hours is up, remove both puddings from the refrigerator. Compare the appearance. Scoop a spoonful of each and compare consistency. Try them both! What do you notice? Record your results!

Above after two hours of refrigeration: Gelatin pudding on the left, cornstarch pudding on the right.

Results:
If you want a recipe that’s done fairly quickly, cornstarch pudding is the way to go. It’s thickened within 10 minutes or so, and can cool off in the fridge or even be eaten as a warm creamy treat (yum!).

Gelatin pudding does take a while to set, so you have to plan a few hours in advance. But the result is decidedly different! If you want a fancier dessert that holds its shape and can be layered (think different flavors, colors, or toppings) this is the way to go! Even the basic chocolate recipe we used settled into two different layers, which was really cool! The top layer was a little more jelly-like while the bottom was creamier. You can whip the pudding to have an even consistency, but leaving it in layers makes for an interesting dessert!

Either way, have fun comparing and consuming your delicious puddings!

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Edible Slime

Spud Mud

Cornstarch vs. gelatin: Make your own chocolate pudding

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