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27 February 2010 @ 11:49 pm
These Are Not Red Blood Cells  

Not cells

So I read on the Internet that there's a way to seal liquids inside a gelatinous membrane by mixing the right chemicals. (The reaction being exploited is the cross-linking of alginate chains with calcium.) Itching to try this out myself, I ordered sodium alginate and calcium lactate gluconate and started playing. Last night I used some fake blueberry juice and made fake blueberries. Here's one that came out particularly round:

Fake blueberry

Yes, they are indeed edible. (Popping them with your teeth is fun!) If you want to try this yourself, do a search for "reverse spherification". I'll warn you of a couple of difficulties I've run into so far:

  • You may want to intensify the flavor with a bit of sugar; these bubbles are about the size of little candies, and juice tends to contain less sugar than candy does.
  • Making the bubbles round is tricky, since the liquid being enclosed usually produces a tail of gel as it descends into the alginate bath. I've worked around this by gently using a spoon to roll each bubble over, so that the bubble's tail sticks to its side.
  • The bubbles start out pretty delicate, and you might have trouble lifting them out of the alginate bath without breaking them. Having rounder bubbles will help, as will practice. You'll actually find that once they come out, they're sturdy enough to rinse and even touch!


r33nar33na on March 25th, 2010 06:00 am (UTC)
Whooooooooooooaaaa. o.O
ze top blurberry: wineztbb on August 30th, 2010 02:36 pm (UTC)
I experimented with this a bit a month or two ago but had trouble getting any satisfactory results -- not round enough, and membranes thick enough that eating the bubbles is unpleasant. So mixing the calcium into the liquid and dropping into an alginate bath is working better for you than the reverse?
Pteromys Fortissimuspteromys on September 6th, 2010 06:57 am (UTC)
It's not clear to me; I haven't actually tried the other way around (alginate dripped into calcium bath) with anything but small (about 0.6 cm diameter) drops--and those ended up gelling all the way through. Meanwhile when I tried drops that small with calcium-into-alginate-bath, I couldn't manage to make them round.

I think the reason I started off doing it this way was that my first few practice rounds used milk; I don't usually have blueberry juice on hand.