McDonalds Fizzy Drink Dispenser

[dangerboy]

After recently being in a McDonalds where you get your own fizzy drink - from a machine similar to those in service stations - why is that you can fill a cup in a matter of seconds without it fizzinfg over.  Filling a cupful from a new 2 litre bottle takes much longer as it can be volitile.  However, both have equal-tasting fizziness afterwards, but one can blast into a cup without the fizzing over effect...How do the machines do it?

[MPerry]

errr they do flow over the top

[Kilala]

Bizarrely, the bubbles are different sizes...

When you buy a bottle of coke it is made in a factory and shipped out fizzy, and so to keep it fizzy it is packed full of gas as much as possible. The machines are filled with syrup and soda water, which is aerated via a gas cylinder under the achine.  This means you have syrup and soda water pouring into your cup, not  Coke, which is why it fizzes up more.

A quick tip, when pouring coke for yourself at home, and it fizzes up really high, stroke down your nose once with the tip of your finger, or across your forehead, the draw a circle in the foam, it will go straight away but not go flat!

[ElegantVixen]

The Mcdonalds machines use a postmix syrup whereas a bottle is already mixed and contains the gas already the machine has a postmix box containing syrup and seperate gas cylinder ...........  hope this helps