Monday, October 31, 2011

Carbonated fruit

I loved the idea of carbonated grapes as described in Modernist Cuisine (vol.2 page 469 ). They used a pressure chamber (such as a cream whipper or soda siphon), added the grapes and pressurized with carbon dioxide cartridges.  This pushed the carbon dioxide into the fruit and caused it to fizz once the pressure is released and the grapes removed. Martin Lersch on his Kymos blog used this technique successfully on strawberries with a great scientific explanation.

I don't have a soda siphon - only a chemistry department.  Inspired, I looked for alternative techniques.

The book on page 472 uses an alternative method to add fizz to an orange.  According to MC take a plastic container with a tight-fitting lid and fill the bottom with dry ice (frozen carbon dioxide - be careful those pellets are cold cold cold!  -78 degrees Celsius in fact) and if you happen to use a metal container to hold them, DO NOT touch it with your tongue like my son did...

Then place some paper towels or kitchen towel on top of the dry ice and place the fruit on top of that - this keeps the fruit from becoming frostbitten by the ice.  Close the container and let the pressure build up inside - the lid may pop an number of times but just re-close it.  After 30 minutes for grapes or much longer (overnight) for whole oranges or apples, you should have carbonated fruit.

I did try this but I think I did not have the right container because my fruit just got cold not fizzy.  Here is an Instructable on another similar method:

So I began to think about other ways to maintain a pressure while allowing some release.  No one at my Chemistry Department had a container that was big enough or could release pressure as needed. Then I thought of my handy dandy pressure cooker!  It held pressure and could release the excess.  So I tried it with the grapes - no luck.  Turns out a pressure cooker only goes up to about 15 psi and I really needed at least 30 psi to get grapes to really fizz.

I then tried using my pressure cooker with watermelon - thinking that it is not so dense so would therefore absorb the gas faster.  And it did! The pressure is too low to get visible bubbles coming off but the watermelon did fizz on the tongue.  A big hit at the Chemistry Nuit Blanche food chemistry booth!

I forgot to take photos so I repeated the experiment recently using raspberries - yum!
I left them in for about 30 minutes.
Dry Ice at the bottom
Raspberries on top of an insulating layer

Odd to see the pressure up
when it is not on the stove!

I did find a couple of videos where they use a similar technique:

Next purchase will be a cream whipper - it does not only make whipped makes carbonated fruit!

Thursday, October 27, 2011

Saturday, October 22, 2011