Don’t have any sour candy on hand? Make something even sweeter! These glitter grapes come in all kinds of fruity flavours.
You will need
- Bag of seedless green grapes
- Colander
- 3 resealable sandwich-sized plastic bags or containers
- 3 boxes of jelly crystals in different flavours
- Lemon
- Knife
- Serving bowl
Safety
When dealing with food, use clean hands and clean equipment. You’ll need to use a sharp knife in this activity. Ask an adult to help.
What to do
Wash your hands with soap and water.
Pick your grapes off the stems and put them in a colander. Stop when the colander is just about full to the brim.
Give the grapes a good rinse under cool water.
Turn off the tap and shake the colander of grapes over the sink. When you’re done, the grapes should be damp but not dripping wet. Set the colander of grapes in the sink.
Eat one of the grapes. How does it taste?
Ask an adult to cut the lemon in half.
Squeeze both halves of your lemon over the grapes.
Use your hands to mix the lemon juice all over the grapes. Don’t worry too much about lemon seeds, they will collect at the bottom of the colander.
Eat one of the grapes. How does it taste now?
Dry your hands and then empty each box of jelly crystals into its own sandwich bag.
Put two handfuls of grapes into each sandwich bag.
Shake each sandwich bag until the grapes inside are nicely coated in colourful jelly crystals.
Grab those colourful grapes and put them in your serving bowl.
Repeat steps 9-11 until you either run out of grapes or run out of jelly crystals. You might like to rinse your hands between batches.
Share your glitter grape candy with family or friends!
Store any leftover glitter grapes in the fridge.
What’s happening
Glitter grapes are very sweet and a little sour. How do we taste the difference? Your mouth has lots of tastebuds and each tastebud has lots of chemical-sensing cells. These cells use special proteins that “catch” certain chemicals.
For example, sweet chemicals like glucose and fructose have hexagon ring shapes. Sweet tastebud cells have proteins that only catch chemicals with those ring shapes. When the tastebud cell catches a sugar-shaped ring, it sends a signal to your brain, which you interpret as sweetness.
Meanwhile, sour tastebud cells have a different kind of chemical-catching protein. This one is shaped like a donut and only lets hydrogen atoms through its centre. Remember that acids are substances with lots of extra hydrogen atoms. So, when hydrogen atoms flood this tastebud cell, it sends a signal to a slightly different area of the brain, which you interpret as sourness.
Taste is quite complex, and scientists are still figuring out how our brains interpret multiple flavours at once. Maybe one day you’ll figure out the answer – food for thought!
Getting glittery
Why do your grapes get glittery and stay that way? It’s almost as if the wetness on the grapes acts like glue!
The main ingredient of lemon juice is water, and the main ingredient of jelly crystals is sugar. Both water and sugar are what we call polar molecules. A polar molecule is a chemical where one part is positively charged, and another part is negatively charged. Those charges act like magnets, and make the molecules stick together.
The attraction between sugar and water molecules is a big reason why wet sugar gets sticky! In fact, chemists are now experimenting with acid-sugar glues that are strong but also non-toxic and biodegradable.
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