Science & Tech: Science for breakfast

Taste is chemically picked up on our tongue by taste bud receptors which can identify salty, sweet, bitter, sour and umami. Photo / Getty Images

Exploring the world around us through science can be fun, says Dr Michelle Dickinson. Today she uses food to explain the complexities of taste and smell.

I'm a passionate advocate for science being seen as a non-intimidating way of life that helps us understand the world around us.

Parents often come up to me asking for fun and easy science experiments they can do at home which use common things found around the house.

With it being the last weekend of the school holidays I thought I'd recommend some of my favourite and easiest home science experiments that are suitable for all the family to try.

The word science might conjure up thoughts of tubes and bunsen burners, but my favourite home experiments just involve food as learning and eating at the same time seems to be a win-win.

The science of how we experience the sensation of flavour is quite a complex one which involves a combination of both taste and smell.

Taste is chemically picked up on our tongue by taste bud receptors which can identify salty, sweet, bitter, sour and umami.

The chemicals that we taste are much more easily detected when they are dissolved in saliva and this is easily shown by rubbing the moisture off your tongue with a paper towel then placing salt on your dry tongue.

The salt doesn't taste very salty without the saliva, but as soon as you wet your tongue again the dissolved chemicals give you an instant salty sensation.

Smell is also crucial to flavour perception and involves molecules from the food diffusing in the air and passing through the nose to stimulate the olfactory nerves in the nasal cavity.

Cut an apple and a potato into cubes of the same size then mix them into a bowl together. With your eyes closed, pinch your nostrils so you can't breathe through your nose then chew on the cubes from the bowl.

You should find it really hard to tell the difference between the potato and apple as their textures are very similar and their flavours are subtle.

We usually differentiate the taste of apples and potatoes from their chemical molecules which enter the nose as we breathe and dissolve on the mucous membrane 7cm up into the nose.

When you block your nostrils this reaction doesn't happen meaning differentiating taste is difficult.

I'm a passionate advocate for science being seen as a non-intimidating way of life that helps us understand the world around us. Photo / Paul Petch

You can then really mess with your sensations by pouring a few drops of vanilla essence onto a cotton wool ball and placing it under your unblocked nose.

Now if you chew on the apple cubes they should taste like vanilla as the smell of the vanilla is much stronger than the smell of the apple which overpowers your olfactory neurons responsible for converting the smell compound into a neural signal that is sent to your brain.

Food also contains vitamins and minerals including iron, needed in our diet to make haemoglobin to carry oxygen through your blood to all the cells in your body.

It is a magnetic metal not just found in bridges and gates but also in fortified breakfast cereals.

Place two spoons of your favourite fortified cereal in a sandwich bag then smash it into a powder using a rolling pin. Pour the crushed cereal onto a white sheet of paper you should see the tiny black particles of iron.

Now bring a fridge magnet close to the powder and watch the black iron flecks jump onto the magnet, not only showing you your food is magnetic, but also that you eat metal on a daily basis!

Science for breakfast, now that's how we should all start our day!

Dr Michelle Dickinson, also known as Nanogirl, is an Auckland University nanotechnologist who is passionate about getting Kiwis hooked on science. Tweet her your science questions @medickinson