Hello and welcome to chemistry in your cupboard. I'm Jo, an education
coordinator at the Royal Society of Chemistry and today we're going to try
and fool one of our senses. Humans have five senses; sight, sound, smell, touch, and
taste. And today we're going to try and fool our sense of taste. You can try this
experiment with a responsible adult. So let's get started.
For this you'll need a glass of orange juice, a mirror, your toothbrush, your
normal toothpaste, and yourself to test this out on. Have you ever noticed that
when you brush your teeth and then have a drink of orange juice... oh it tastes
really weird. It's so bitter, what on earth is going on? Have you ever
taken a look at the surface of your tongue? Grab the mirror and take a look. Can you
see those little bumps on there? We have between 200 and 400 of those little
bumps and the scientific name for them is fungiform papillae. And on those
little bumps we have between 2000 and 8000 taste buds that are so small we
can't see them in the mirror. And those taste buds help us to detect the five
flavors; salty, sour, sweet, bitter, and umami. Umami is a very savory flavor
found in foods such as soy sauce, parmesan cheese, and yeast extract. Here
is a very basic model of the surface of your tongue. You can think of different
tastes has been a bit like different shapes and each taste bud is designed to
recognize different shapes and reject others. So let's pretend we're eating an
apple. Your mouth is flooded with sweet and
sour tastes, which attach to their correct shape and sends a signal to your
brain. This sorting system is usually really accurate but sometimes you can
play a trick on it. Tooth paste is made up of four main ingredients; water,
abrasives that remove bacteria from the surface of your teeth and gums, fluoride
which helps fight cavities, the tiny holes that can appear on the
teeth if you don't brush well, and detergents which create the foam, evenly
distributing the toothpaste inside your mouth. A common ingredient is sodium
lauryl sulfate and it's used in many other household products we're producing
a foam is necessary. It's great at being foamy but it fools around with our sense
of taste. Is sodium lauryl sulfate listed as an ingredient on your shampoo
pour liquid soap? Go and take a look, I bet it is.
And this is the model of sodium lauryl sulfate. It's like a long snake and being
long and slithery is what makes it great of being foamy. It can be used to explain
how substances like these are used in washing up liquids while you're removing
oily food from your plates. This bit loves water, and this bit loves oil, so
when more of them gather together the oil gathers with them and it's removed
from your dishes, making them clean and sparkling. So what's all that got to do
with fooling your sense of taste? The sodium lauryl sulfate attaches to the
bits of our tongue that recognise sweet things, and therefore blocks the sweet
substances from being able to attach. It also destroys something in our mouths
that stop really bitter things from tasting bitter.
So it's no wonder orange juice tastes so horrible after brushing your teeth. It
creates a double whammy of bitterness. You can try this experiment with a
responsible adult. Just remember, never eat soap and shampoo and always use the
correct amount of toothpaste when you brush your teeth twice a day. And that's
how we can easily fool our sense of taste. Does your toothpaste contain
sodium lauryl sulfate? If you use a different toothpaste to an adult in your
house, are the ingredients any different? What happens if you drink apple juice or
fruit squash after you've brushed? Do they taste weird too? And how long does it
take after you brush your teeth for orange juice to go back to tasting
normal? Let us know and share your results using the hashtag chemistry in
your cupboard. We'll be back soon but in the meantime please subscribe to our
YouTube channel for more chemistry in your cupboard videos. See you soon.