I spy with my little eye something that begins with the letter ‘i’
Did you ever play that game? Or it’s less sing-songy cousin, “20 questions?” The traditional first question is, “Is it an animal, a vegetable, or a mineral?” I’ve always thought there was sort of an unspoken rule that the answer would never be “Er, two out of three.” Apparently, I have not been hanging out with enough brewers.
I’m reading a WONDERFUL (and concise) book on brewing called How to Make Table Wine, Country Wine, and Beer (1975). In the section on Clarifying agents they write, “The two most effective clearing agents are isinglass, available in both dried and liquid forms, and Carrageen (Irish) moss, a seaweed originating in Ireland.”
We’ve all had carrageenan, it is a popular thickener in commercial ice cream. And I was strangely proud last summer, when after years of singing Surrey With The Fringe On Top (“…with isinglass curtains you can roll right down, in case there’s a bend in the weather.”) I finally learned that isinglass is a name for very thin, translucent sheets of mica, a common mineral inclusion in rocks.
I have some friends who live near a mica mine, and I immediately had visions of making vats and vats of beautifully translucent beer with local mica.
And then I thought, ‘liquid form?’
Turns out isinglass is ALSO a gelatin made from ground Sturgeon air bladder. Oh yeah. Right of course. Ha ha. Duh. Sturgeon bladder gelatin, how could I forget?
Look, I’m totally willing to believe that Sturgeon bladder gelatin kinda looks like the thin clear pieces of mica but why use the exact same obscure word for two totally different substances?
Brew well and you may never need a clarifying agent. If you do, isinglass is not rocks.