A chocolate fountain to teach changes of state

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A chocolate fountain to teach changes of state

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courtesy of mrphancy

Heston Blumenthal’s new series started on Channel 4 last night – and what a great start to what looks like a magical journey into the appliance of science to cooking.

Heston is somewhat of a hero to me as he combines two of my favourite things: food and science.  He makes amazing, fantastical food and the way he does this is to understand and apply scientific concepts.

If you watch his shows, you will also see that he experiences the highs and lows of a scientist.  Most of his culinary challenges start off with a seemingly impossible task, but after a few setbacks (and in this programme this is demonstrated nicely with an exploding duck), he refines his method and gets the results he wants in order to amaze his diners.

Last night he created a child’s dream dinner – a 60s style Charlie and the Chocolate Factory feast complete with lickable wallpaper and a chocolate fountain.

It’s the chocolate fountain that he created that I found most interesting. Showing some of the techniques he uses in the classroom would be a great addition to lessons on changes of state.

If you play the video from 41:41 (warning: this video contains some bad language, but I promise the important clips are student-friendly) you will see what I mean.  He begins by asking how you could use a chocolate fountain to unmix, rather than mix, chocolate.  Impossible task?

His method involves mixes powdered chocolate with liquid nitrogen.  This creates an amazing bubbling liquid chocolate effect and as the nitrogen boils – voila!  Unmixed chocolate.  Students could watch this and then explain how it works using ideas about changes of state, boiling points etc.  It would be also great to pause it just before he says ‘watch this’ and get them to predict what they will see happen.

For a bit of extension work, Heston demonstrates how he uses distillation to separate the water from a chocolate/water mix to produce chocolate-flavoured water.  Again, students could explain how his bit of kit works and at the same time see how science can make food that little bit more exciting.