Activity 1: Why you need your nose to taste food
Why does everyone say you shouldn’t play with your food? Here are three ways to do just that – and learn about science at the same time …
You might think you taste food with your mouth – but as you’ll see, your nose has a very important part to play in the process.
You will need:
- Several different flavours of crisps (but not salt and vinegar). The crisps should all have the same texture, even though the flavours are different (to eliminate cheating!)
- A scarf to use as a blindfold
- A volunteer
First blindfold your volunteer and ask them to hold their nose. Pass them a crisp – but don’t tell them what kind. Ask them to chew on it and tell you what flavour it is. They probably won’t be able to.
Ask them to release their nose, and see if they can tell you the flavour now. Chances are, with their nose unblocked they’ll be able to do it …
PS you can try an even simpler version of this experiment on yourself. Pinch your nose and eat a crisp. The crisp will feel like a crisp in your mouth, but it won’t taste of much. When you release your nose, suddenly the flavour becomes obvious. Pinch your nose, and the flavour disappears again.
PPS you can also try this experiment with differently flavoured sweets.
The taste buds in your nose help you to taste food – but you need your nose too, because it’s the aromas from food that give us most of our sense of flavour. Normally, when you eat, these foodie aromas travel between your mouth and your nose and the flavour you taste is a mix of what both your mouth and nose have ‘tasted’. This means that when you hold your nose, you stop some aromas from reaching inside it, and so you’re not getting as much ‘flavour’ information as you usually do, which is why you can’t taste flavours as well as usual.
Why doesn’t it work with salt and vinegar crisps? Is it because they are the ‘king of crisps’ as Dom suggested? Well, not necessarily! It’s because your taste buds are very sensitive to the sour flavour of vinegar, so even with your nose blocked, that’s one thing you can taste.
Activity 2: How to extract iron from breakfast cereal
We need iron in our diet to stay healthy. The iron is used by our bodies to create a substance called haemoglobin, which is what gives blood its rich red colour, and helps to carry oxygen to every part of the body. If someone was lacking in iron, they’d be pale and tired, and might even faint.
Some breakfast cereaIs are fortified with iron – and this experiment demonstrates that the iron in cereal really is the same as the iron as you’d find in a metal object like a nail!
You will need:
- An iron-fortified breakfast cereal (check the ingredients list if you’re not sure)
- A mortar and pestle, or a coffee grinder
- A neodymium magnet also called a ‘rare earth’ magnet
- Cling film
- A piece of white paper
First, grind up a few handfuls of cereal. You can do this with your mortar and pestle, or if you want extra quick results, use a coffee grinder! Pulverise the flakes until they’re like very, very fine dust.
Now cover the end of your magnet in cling film. The reason you’re doing this is so that any particles that end up attracted to the magnet can be lifted off it simply by unwrapping the clingfilm.
Now take your magnet and stir it slowly through the pulverised cereal. Keep moving it in the powder until you see particles sticking to the magnet – this could take a while so be patient. When you’ve picked up enough of it to get a good look at, carefully unwrap the clingfilm and drop the particles onto the piece of white paper. Now place the magnet under the piece of paper, and see if you can “pull” the cereal powder around from underneath … If you can, that’s iron you’ve got there, and it’s being attracted to your magnet, just like a nail normally is!
Activity 3: The incredible rice and pencil demonstration
Believe it or not, it’s possible to pick up a bottle containing rice, using just a pencil … Here’s how!
You will need:
- A small drinks bottle. The neck of the bottle must be narrower than the body
- Enough (uncooked) rice to fill the bottle
- A pencil
Stab the pencil into the rice vertically and jab it quickly up and down several times. Suddenly, you should feel the rice ‘grip’ – and then you’ll be able to pick the bottle up off the table. Have patience, and keep going as this demo doesn’t always work straightaway … It’s cool when it does though!
This is a demonstration of friction. Jabbing your pencil into the rice causes the rice grains to move around a little so that more of their surfaces are in contact with each other and the pencil. The more surface contact there is, the more friction there is, which is the force that you feel as resistance, and is a force that can stop things from moving. All of a sudden the pencil will become effectively stuck due to this friction so you can use it to pick up the weight of the bottle.