What's new

When life gives you lemons…

By David, 18 January 2016 Activity

Written by Mike McRae

Several squeezed lemonsand some lemon juice

Squeeze the lemons into a bowl.

Make some lemonade this summer, using this easy recipe!

food safety hazard iconhot hazard iconSafety: Use clean hands and equipment. This activity requires boiling water. Ask an adult to help.
First aid: If you burn yourself, run the burn under cold water for 20 minutes.

You will need

  • 2 teaspoons citric acid
  • 2 teaspoons table salt
  • 2 cups sugar
    Someone is pouring sugar into the bowl.

    Add some sugar.

  • 1 L water
  • Juice and rind of 3 large lemons
  • Kettle
  • Large bowl
     a large measuring cup full of lemonade.

    Enjoy with ice on a hot day.

  • Sieve or strainer
  • Wooden spoon
  • 2 L jug or bottle

What to do

  1. Fill a kettle with 1 L of water and bring to the boil.
  2. Place all of the ingredients into a large bowl and ask an adult to help you pour in the boiled water.
  3. Stir the ingredients with a wooden spoon until the sugar has completely dissolved.
  4. Allow the mixture to sit overnight.
  5. Pour the mixture through a sieve or strainer into a jug.
  6. To drink it, add one part of the mixture to three parts cold water.
  7. Add ice and serve chilled on a hot summer’s day.

What’s happening?

Few people enjoy popping a slice of lemon in their mouth, let alone sucking on tartaric acid. We’ve evolved to sense acids through the unpleasant taste of sourness, possibly to prevent us from eating large amounts of unripe fruit.

In the past, tastes have been associated with particular areas of the tongue, as a ‘taste map’. However this is a myth – while some areas of the tongue might be better at detecting certain chemicals due to the tongue’s shape and position in the mouth, taste depends on how chemicals interact with different types of cell that make up the taste buds scattered all over your tongue’s surface.

For example, acids are chemicals that release protons (or hydrogen ions). These particles cross the membrane of one type of cell and kick off a chemical chain reaction inside, causing a nerve to send a particular message to the brain.

Sweet tastes are caused by chemicals (such as simple sugars) being detected by a type of receptor that sends another signal to the brain.

It’s the brain that interprets all of the taste signals to form flavour. The mix of signals from the sweet and acidic ingredients in this recipe means you don’t notice the sourness so much, making lemonade and lemon cordial refreshing, thirst-quenching beverages rather than something that makes your mouth pucker.

Real-life science

On a trip to explore the wilds of western Africa in 1725, the French explorer Reynaud des Marchais documented a variety of fruits. Among them was the berry Synsepalum dulcificum, which has rather a peculiar effect when you eat it – it makes sour foods taste remarkably delicious.

The special chemical in this fruit is called ‘miraculin’. This molecule sticks to the receptors inside taste buds that are responsible for sweet flavours, making them send signals to the brain in response to any acids in the mouth. Although sour foods might taste nicer, miraculin doesn’t change the acids in them, making for a big belly ache if you eat too many sweet, sweet lemons.

If you’re after more science activities for kids, subscribe to Double Helix magazine!

Subscribe now! button

1 comments

  1. That’s so cool that you can eat lemons after the special chemical and then it tastes sweet!!🍋🍋😅

      Reply

Leave a Reply

By posting a comment you are agreeing to the Double Helix commenting guidelines.

This site uses Akismet to reduce spam. Learn how your comment data is processed.