Carbonated strawberries
Here’s some pictures of an experiment I did with strawberries and dry ice (solid carbon dioxide). Dry ice is frozen carbon dioxide which holds a temperature of -78 °C. What is fascinating is that dry ice does not melt – it sublimes, which means that it turns directly into carbon dioxide gas.
The idea was to create a carbonated fruit which gives a sparkling sensation in the mouth. I have used strawberries, but any juicy fruit with a moist surface could be used. Water melons would be perfect!
The chemistry explained in simple terms:
A schematic drawing of the container:
To prevent the plate from touching the dry ice (which would cause the strawberries to freeze), I put in a wooden triangle first.
Put the plate with strawberry halves on top of the wooden triangle. Cover with a kitchen towel (do NOT cover with a tight fitting cover – remember that as CO2 sublimes, it expands, and this would create a huge pressure ultimately resulting in an explosion), and leave for 30 minutes.
Eat and enjoy!
Update: Carbonated fruit the iSi way!
Filed under: experiments, fun with food, molecular gastronomy, recipe, science
November 29th, 2006 at 10:12 pm
Just a thought, if you have a pressure cooker then you probably can get a hell of a lot more CO2 in your treats and you don´t have to be worried about an explosion.
January 15th, 2007 at 1:54 am
I just made these and they’re awesome! Thanks!!
January 24th, 2007 at 11:14 pm
I tried this with orange slices (I’ll try in spring with strawberries) and it didn’t work very well, even with a cap that made a little pressure. I think this happened because in oranges water is closed in those little “drop-shaped bags” (sorry but I don’t know the correct word in English). I think I will try again with another juicy fruit, or I’ll wait for strawberries to grow in my garden…
January 30th, 2007 at 8:33 pm
Mo: Assuming you sliced the orange so as to expose the interior of the juice sacs to CO2, I can think of another possible explanation. At low pH, the following equillibrium will be shifted to the right:
CO2 + H2O ⇔ H2CO3
This means less CO2 will dissolve in the juices. I guess the pH of oranges is significantly lower than of strawberries. Have you tried it watermelon instead?
January 31st, 2007 at 11:52 am
I should try with watermelon, but I’ll have to wait some months, this is not the right season.
February 6th, 2007 at 2:07 am
Hi, sorry if this is a silly question, but how/where would you get hold of dry ice to do this? It sounds like fun!
February 6th, 2007 at 3:56 am
In Shanghai the Hagan Daz gives you dry ice when you buy an ice cream cake. I tried it with the strawberries and it’s great with the ice cream cake. Shanghai’s got strawberries allyear round, greenhouses all over Chian now.
February 12th, 2007 at 4:41 pm
Jessica, some grocery stores in the US sell dry ice.
March 20th, 2007 at 6:17 pm
When I was in elementary school my dad used to get dry ice for our volcanos from Baskin Robins, if you just go in and ask nicely I think they’ll help
April 9th, 2007 at 1:15 am
[...] blogged about carbonated strawberries some while ago. Those were made using dry ice which unfortunately is not always easy to get hold [...]
April 15th, 2007 at 12:27 pm
A question, what is the difference between leaving the strawberries in a saturated CO2 atmosphere using dry ice or CO2 gas?
If you do not freeze you cannot oversaturate the strawberries with CO2 under ambient pressure? Or am I mistaken.
Will try it nevertheless, enough dry ice (and liquid N2…) in our lab.
April 15th, 2007 at 10:36 pm
Jurgen,
At room temperature dry ice sublimes, meaning that the solid transforms directly to gas without melting to a liquid first. So if the container is filled with dry ice it will slowly displace the air as it sublimes, leavning the atmosphere saturated with CO2.
The amount of CO2 that will dissolve in the strawberries will be dependent on the temperature, pressure and concentration of CO2. The experiment is performed at ambient pressure, a temperature close to 0 °C and in pure CO2 gas. The only way to get more CO2 to dissolve is to increase the pressure. The safest way to do this is to use a iSi container which is designed for high pressures (blogpost). Do NOT pressurize a container using dry ice!
April 16th, 2007 at 8:12 am
Thanks. I guess I was surprised that you could saturate a strawberry with CO2 by just placing it in a CO2 atmosphere.
March 27th, 2008 at 1:55 am
I tried carbonating fruit by filling a 2 liter coke bottle with fruit and dry ice. How big can I get the bubbles to be, and do you have any times on getting them bigger?
March 27th, 2008 at 10:15 am
Aaron, I wouldn’t recommend using a (closed) bottle for this. When dry ice goes from solid to gas it’s volume increases dramatically leading to large pressures – and possibly an explosion…
If you wan’t to make carbonated fruit, check out this blog post where a iSi whipper is used:
http://blog.khymos.org/2007/04/09/carbonated-fruit-the-isi-way/
Regarding bubble size – I don’t know if I understand your question correctly. Why do you wan’t larger bubbles?
March 27th, 2008 at 5:26 pm
Well actually I was following the instructions on the site
http://www.instructables.com/id/How-to-Make-Carbonated-Fruit/
I think their method would work decently as the bottles can withstand decent amounts of pressure and are cheap to obtain.
I was actually planning on doing this as an activity for a club, so I have to keep the cost down. I mostly want larger bubbles so it will have more of the carbonated effect. Any smaller would be kind of a letdown, because most people would expect relatively large bubbles. How big are the bubbles with this low-pressure technique here? Currently, the bubbles are so small that they end up as just a very mild tingling rather than any popping.
March 27th, 2008 at 5:45 pm
Personally I wouldn’t dare to use plastic bottles. Unless you’re able to do the calculations required to determine a safe amount of dry ice, this experiment can take a really, really bad turn.
The iSi whippers however are safe to use with the designated soda chargers (which contain carbon dioxide). I don’t know what your budget is, but you can get whippers for less than $50.
I think what you refer to with “larger bubbles” is to dissolve more carbon dioxide in the fruit juices (based on what you write about “small bubbles” which are barely noticeable). To achieve this you can cool the bootle to right above freezing as the solubility of carbon dioxide increases with decreasing temperature and leave it there pressurized for some hours. Futhermore you can increase the pressure by adding more dry ice – which of course can be dangerous if you use plastic bottles…
April 24th, 2009 at 9:05 am
how long does the carbonation last or does the fruit go flat lol or is there a way to preserve it??? thanks aND GREat blog btw!!!
January 27th, 2010 at 3:27 am
It is simple to carbonate fruit using a co2 dispenser (under $20 at most bike shops), food grade co2 cartridge, Fizz-Giz bottle cap and plastic drink bottle. You can do it safely with a regulated co2 dispenser. Set your injector pressure to under 60PSI. 3-liter bottles have larger mouths than smaller PET bottles. That makes it easier to get your fruit in (and out). You can get caps at http://www.FizzGiz.com and co2 injectors at Genuine Innovations in Tucson, AZ. Be sure to ask for the HOT sprayers.