Tag Archives: food science

#TryThisTuesday: Rock Candy

This weeks Try This Tuesday takes a while, but you end up with a tasty treat!

You will need:

  • A wooden skewer or chopstick
  • Peg
  • 1 cup of water
  • 2-3 cups of sugar
  • A narrow glass or jar

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Clip the wooden skewer into the peg so that it hangs down inside the glass and is a couple of centimetres off the bottom.

Put the water into a pan and bring it to the boil. Pour about a quarter of a cup of the sugar into the boiling water and stir until it dissolves.

Keep adding more and more sugar, each time stirring it until it dissolves, until no more will dissolve. This might take quite a while!

When no more sugar will dissolve remove it from the heat and leave it to cool for about 20 minutes.

Pour the sugar solution into the glass or jar almost to the top. Then put your skewer back into the glass so it hangs down and doesn’t touch the sides.1st

Leave your glass in somewhere it won’t be disturbed. The sugar crystals will grow over 3-7 days. Once these have grown you can eat them!finished-product

The Science

By mixing the sugar and water together when they were really hot, you have created a super saturated solution. This means that the water contains much more sugar than in could in normal circumstances. As the water cools back down the sugar leaves the solution (mixture) and becomes sugar crystals again, forming on the skewer.

Supersaturated solutions are used in real life. In a sealed fizzy drink the drink is saturated (full) with carbon dioxide, as the carbon dioxide is put in using pressure. When you open the drink, the pressure of the carbon dioxide is decreased, which causes your drink to be supersaturated as there is much more carbon dioxide dissolved than there would be at normal pressure. The excess carbon dioxide is given off as bubbles.

#TryThisTuesday: Guess The Flavour

For this Try This Tuesday all you will need is some starburst or chewy fruit sweets.img_4490

Close your eyes and pick a starburst at random without looking. Unwrap it with your eyes closed.

Hold your nose and eat the starburst, make sure you keep holding your nose the whole time.

Can you guess the flavour without looking at the colour of the sweet or the wrapper? You might get some of them wrong!

If you let go of your nose halfway through chewing, you might suddenly be able to taste the flavour.

The Science

Smell and taste are really closely linked, so it is really hard to guess the flavour of the starburst when you hold your nose. About 90% of what we taste is due to smell. Both senses use similar receptors and rely on the same molecules to send messages to the brain about what you can taste and smell. Flavour is actually a mix of taste, smell, texture and other cues like temperature.

It is also important to close your eyes when you eat the starburst, as you can make unconscious links between colour and flavour. Our brain is really good at picking up associations such as a purple coloured sweet is likely to taste of blackcurrant. When the colour makes us expect something to taste a certain way, we taste what we expect unless it’s really different.

This colour association affects some people worse than others,  the pathways to the brain can get crossed over causing synaethesia. This might mean that when they see yellow Рthey taste lemon.

#TryThisTuesday: Honeycomb

honeycomb

Honeycomb or Cinder Toffee not only makes a great Bonfire Night snack, it’s also a fun and quick science experiment! Here’s our simple recipe for the honeycomb reaction:
1. Grease a baking tray with butter and set aside.
2. Mix 100g sugar with 2.5 tablespoons of golden syrup in a pan. Mix the two well before you heat the pan.


3. Gently heat the pan, try not to stir the mixture at this point just let it gently begin to melt.
4. Once you can see the sugar start to melt you can push the sugar around to ensure in melts evenly and doesn’t burn.
5. When all the sugar has melted turn up the heat so the sugar begins to boil and forms an amber coloured caramel
6. Turn off the heat and add one teaspoon of bicarbonate of soda, beat the mixture quickly as it begins to bubble up to incorporated all the bicarb then tip onto the greased baking tray.


7. Leave to set for 30-60 minutes then enjoy!

The Science

The heat causes the bicarbonate of soda (NaHCO3) to break down and release the gas, carbon dioxide (CO2). The gas gets trapped within the sugar, this results in the bubbles in your honeycomb.

honeycomb

#TryThisTuesday: Make your own Sherbet

sherbet

This week we’re taking on the science of sweets! Here is a super easy way to make your own sherbet powder at home.

All you will need is:

  • 7 teaspoons of sugar (either caster sugar or icing sugar)
  • 1 teaspoon of bicarbonate of soda
  • 3 teaspoons of citric acid in powder form

Mix your ingredients in a bowl and then take a small amount on a teaspoon and have a taste. It should fizz in your mouth.

Where does the fizz come from?

When you place the mixture on your tongue it reacts with the water in your mouth and produces carbon dioxide, this causes the fizzy feeling.

sherbet-equation

The reaction occurs because  acids, like the citric acid used here, release charged hydrogen particles when added to water. These particles will attack an alkaline (the opposite of an acid) such as bicarbonate of soda. The reaction produces more stable molecules Рwater and carbon dioxide.

If you pour water onto your mixture you should be able to see the reaction that’s happening in your mouth. You can actually feel the carbon dioxide gas being released if you hold your hand close to the surface.