I've had my Sodastream carbonator for a while, and haven't done anything particularly exciting with it. I've made a fair amount of regular soda, and mixed up some of my own syrups, but nothing... innovative. The carbonator has just been sitting around, doing what it is supposed to do. And we can't have that, now can we?
I've had my Sodastream so long that my bottles are going to "expire" soon. Yes, after a few years, the polypropylene will start to break down due to UV, heat, and pressure changes. My bottles are noticeably much less rigid than when I first got them. I don't think that they are likely to explode or rupture, but it does mean that I am less worried about doing something that might void their warranty. They were living on borrowed time anyways.
I decided that I would carbonate tomatoes. I recently purchased more plum tomatoes than I know what to do with, so this would be something interesting to try.
I believe that the plum tomato will allow plenty of carbonation to permeate the flesh of the fruit, and that the carbonation should add to the perceived acidity of the tomato.
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Step 1: Several Slices
I chopped the tomatoes into 3 different slices to see how much exposing the inner flesh made a difference. I used two tomatoes for each cut.
Some tomatoes were cut into quarters, while others were cut into simple halves. A third set of two was sliced into small disks. I did not make any special effort to remove seeds, but the smaller I cut them, the more seeds they lost.
If the amount of exposed flesh makes a difference to the level of carbonation permeation, then I would expect that the halves will be less carbonated than the quartered wedges, which will be less carbonated than the small disks.
Step 2: Into the Bottle
I just dumped the tomatoes into the bottle as they were. I probably should have used more tomatoes to make more efficient use of the CO2. Ah, well.
I filled the bottle with about 3 seconds worth of gas. The feel of the bottle is much different when there is no water in it- it feels like you could put a lot more CO2 in before it starts escaping. I didn't fully pressurize the bottle, stopping after the amount of time that I would use to carbonate regular water.
Step 3: The Waiting Game
I placed the entire assembly into the refrigerator. I felt that opening the bottle to put the cap on would let the vast majority of the gas escape, so I moved the Sodastream into the refrigerator to chill and distribute through the tomatoes.
This related manufacturer's post recommends leaving it to chill overnight.
Step 4: How Do They Turn Out?
I waited about 8 hours before taking them out of the bottle. The tomatoes were unchanged visually and smelled the same, but they had a distinct "fizzing" sounds when you got close. After a few minutes in regular atmosphere, some of them got a faint froth as the CO2 escaped.
Initially, I thought that they were unaffected, as the taste was identical to normal chilled tomatoes. However, after a few moments on the tongue, the carbonation flavor becomes quite pronounced. The effect was most noticeable with the tomato halves, probably because there was much more to them than the others. They had a definite bitter aftertaste from the carbonation, which was very prominent on the tongue. The quarters and disks were had less flesh, and so the effect was proportionately reduced. The aftertaste with the disks was much less noticeable.
My beautiful wife thought they tasted "interesting." She says "It was a fun, fizzy novelty. I could feel the carbonation on my tongue! Trying these should be on everyone's bucket list."
People who like seltzer water with no flavoring or tonic water are likely to enjoy these tomatoes, as they have some acid and a strong bitter flavor. A salad with carbonated tomatoes and cucumbers would be an enjoyable novelty.
However, if you enjoy your carbonated beverages sweet, then you (and I) will probably not like them. There is just not enough sugar in the tomato to balance the bitter flavors that carbonation brings out. Sweet watery fruits like melon or oranges would be a better choice.