Did you know that you can observe scientific changes when you cook? Even some simple recipes can tell us a lot. Let's find out what a box of instant pudding can teach us!
Here is what you'll need: one box of instant pudding (any flavor), enough milk as listed on the box, a bowl, a whisk, and a timer
Let's mix it up!
Here's the question we are going to answer: How does it thicken and become pudding?
Prepare your ingredients. Most boxes of instant pudding only require milk and the pudding mix. It then asks you to mix for 2-3 minutes. Get your milk ready in the bowl, set your timer, pour in the pudding mix, and stir! Make sure to set your timer and mix the entire time. While you mix, use the whisk to help you feel how thick the pudding is becoming. Does it change over time?
VOCABULARY: viscosity
Viscosity is a physical property of fluids. It shows resistance to flow, but we usually call it "thin" or "thick". As a simple example, water has low viscosity, as it is "thin". Molasses has greater viscosity because it is "thick" and pours slowly. The word viscous comes from the Latin root viscum, meaning sticky.
Here are a few videos to help you explore viscosity:
Making pudding is a great way to see change in viscosity. When you first put the pudding mix into the milk, there is very low viscosity. It is almost as thin as the milk you started with. But as you continue to mix, the viscosity increases as the mixture becomes thicker.
But why?
Why does the pudding become thicker, or more viscous? Well, we have to analyze the ingredients. Here is a sample from instant vanilla pudding:
Ingredients: Sugar, Modified Cornstarch, Contains Less Than 2% Of Natural And Artificial Flavor, Salt, Disodium Phosphate And Tetrasodium Pyrophosphate (For Thickening), Mono- And Diglycerides (Prevent Foaming), Artificial Color, Yellow 5, Yellow 6, Bha (Preservative).
One of the ingredients listed above is tetrasodium pyrophosphate. It does something very unique: each molecule of tetrasodium pyrophosphate can absorb TEN water molecules. So, when the pudding mix is combined with milk (which has a lot of water), the tetrasodium pyrophosphate absorbs much of the water in the milk, forming a new solid molecule. Since a lot of the fluid water gets absorbed, the fluidity decreases, and the viscosity increases. It thickens because it increases in solid molecules and decreases in fluid molecules! (That's a simple way to think of it, anyway.)
Conclusion:
1. Pudding teaches us about viscosity. It starts out less viscous and becomes more viscous as you stir.
2. Pudding is delicious.
3. Eat pudding.
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