I found a site that sells gelatin, 250 bloom. I had never heared of such. Admitted, I have never thought about gelatine. And most of you here probably never thought about this too.
Anyway, its an indicator of how gelatin gels. It might be an approach to standardize the variations household products have and help to reduce the uncertainty when adding gelatin for capping.
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The reason for using gelatin is not because it gels. If that was the protective mechanism, then it would not work at all because at processing temperature it is not gelled but does protect the particles from growing out of control. The reason I initially tried gelatin was because it is (somewhat) water soluble and is a
very large molecule. Molecular weight or its related size is the important factor, not how strong its gelled state is. Gelatin is a stearic stabilizer and is electrically neutral at the alkaline pH used in this process.