9: Smell Molecules - Ancient and New!

The flavour of food is a combined response to two chemical senses, taste and smell. Smell is the more sensitive of the two and is the most important factor for recognising flavours. These activities focus on the molecules responsible for smells.

A: Scratch and Sniff Cards

What you will need

access to a fridge gelatin card cut into small pieces ester smell molecules, 1-2 drops provided by your teacher

What you do

  1. Take your pieces of card to your teacher who will place a few drops of a different ester on each one. Label each smell clearly.
  2. Dissolve about 2g of gelatin in 75cm3 of water. You may need to heat it slightly to ensure all the powder dissolves.
  3. Coat the smelly card with the gelatin and put it in a fridge to set.
  4. Test your friends’ sense of smell by blindfolding them and asking them to identify the smell. Scratch each card with something sharp. This should release the smell on the card.
Flammable
FLAMMABLE
some esters

B: Cleopatra's Secret Frangrance

Cleopatra reigned in Egypt over 2,000 years ago. By then the Egyptians had been making fragrant oils for 3,000 years. Alexandria, where Cleopatra had her palace, was the centre of the world perfume industry. You can recreate the smell of ancient Egypt using a little chemistry.

What you will need

small plastic bottle with a well fitting lid
four clean pipettes
jasmine oil
lily of the valley oil		heliotrope oil
apple oil
peppermint oil

What you do

  1. Put the following quantities of each scent oil in the plastic bottle. Be sure to use a clean pipette for each oil: jasmine 30 drops, lily of the valley 8 drops, heliotrope 2 drops, apple 1 drop.
  2. Shake the mixture well.
  3. Now take a careful smell.
  4. How many scents can you recognise?

C: Something else to try

You may like to try to make Napoleon’s scented glove’s perfume.

Napoleon was Emperor of France about 200 years ago. He too was fond of perfume and ordered his special fragrances from the perfume houses of Paris. Napoleon would anoint his gloves before he left for battle. The formula for his scent is peppermint 25 drops, apple 4 drops, lily of the valley 3 drops, heliotrope 3 drops.

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