What exactly is viscosity, anyway? You are probably wondering this. Well, viscosity, which sounds like vis-cos-it-ee when you say it, is pretty much all about the thick and thin of liquids. If you suffer from food allergies or you know someone who does, you will like this experiment. It teaches about the properties of guar gum, a very important ingredient for commercial baking, and especially people who have to avoid a protein known as gluten. So read on!
Do you remember the definition I gave you in the Unit 4 Reading "The Science of Gluten-free Cake Baking" from our cooking club curriculum? Well, in case you weren't paying any attention, I'll repeat myself!
Viscosity is a way to measure how well an ingredient resists flow. In other words, it tells us how fast or slow the ingredient actually flows. Got it, now?
An ingredient that flows easily like water has low viscosity. You pour it and it moves fast! What about ketchup? Ketchup takes longer to flow out of the bottle so it has a higher viscosity. Now think about honey or molasses. Have you ever heard the saying, "You are as slow as molasses"? Do you think honey or molasses has higher or lower viscosity than ketchup, and why?
That's right! it will probably take honey longer to flow out than it does ketchup.
Take a look at the picture at the top of the page. That is guar gum with water added to it. Looks pretty thick, right? Like toothpaste! In this experiment we are going to test what vinegar does to guar gum.
I bet you are also wondering, how do we know which is the right amount of guar gum to add to a recipe? Ha! I will tell you from personal experience NOT A LOT! As you can see from this picture, a 1/4 teaspoon of guar gum is pretty thick! Wouldn't you say it has a high viscosity? Yes it does! But what if we add vinegar? What happens to the viscosity in guar gum? How much guar gum is just right to make the perfect gluten free cake? Hm, you guys have a lot of questions, why don't we put on our science caps and find out the facts!
This is what you need to get started on our experiment:
Psst!It takes about a minute for the guar gum to set up. You will see it get thicker as time goes on and it absorbs the water.
Psst!How long did it take? Did the guar gum have less viscosity when you added the vinegar?