Pop Rocks combine candy with explosions in your mouth. Obviously a genius idea. It first popped up in 1975 and as soon as it caught on the urban legend evolved that eating Pop Rocks and drinking soda at the same time would cause death-by-stomach-explosion.
The rumour was so widespread that the FDA (Food and Drug Administration) in the USA (United States of America) set up a special hotline to assure concerned parents there was no danger.
The ingredients of Pop Rocks are identical to any other hard candy like lemon drops or lollipops. The magic comes with the addition of carbon dioxide. When the candy is in syrup form (heated to about 150 degrees Celsius) it is injected with pressurized carbon dioxide that bubbles through the syrup. It is then cooled so the syrup hardens trapping these bubbles, still at high pressure.
When the mixing chamber is de-pressurized, the candy shatters into small pieces and crumbs as the high-pressure bubbles try (and mostly succeed) to escape their candy confines. However, many micro-bubbles of carbon dioxide remain securely encapsulated in the candy.
These bubbles are still pressurized at 600 PSI. (pounds per square inch) For the sake of comparison, your car tire is about 32 PSI, a bike tire is 65 PSI, and the boiler of a steam locomotive is 300 PSI. The explosion is caused when you bite down on the candy and let the 600 PSI carbon dioxide escape. That’s two tiny steam engines blowing up… in your mouth!
When the process was invented and patented in 1956 the goal was to create a tablet that could instantly carbonate a drink. That didn’t work so well, but it did make for a great candy!
- Source: Pop Rocks – Wikipedia