Years ago, I remember my freshman year Psychology 101 professor posting a picture of a crab as his title slide on hunger.
He made the point that, looking at a crab, you'd likely have to be pretty hungry to decide you were going to try seeing if this thing was any good to eat.
That memory came to mind when I learned about isinglass and its use in beer. Isinglass, also known as finings, is a substance traditionally made from the swim bladder of sturgeon. Today most isinglass comes from tropical and subtropical fish bladders. Brewers add isinglass to help settle yeast and beer proteins out of beer. While the yeast and beer proteins will eventually settle out of beer on their own, isinglass not only speeds up the process but can also do so repeatedly. Isinglass is primarily used in cask-conditioned ales, where they are particularly helpful because casks can be moved several times before they are tapped for service.
It's been awhile since we've donned our junior scientists lab coats, so let's put them back on for a brief science lesson on how isinglass works. Isinglass contains collagen, which is a protein that has a helical shape. Most of us are probably familiar with the double helix of our DNA:
Collagen has a triple helix, which forms a mesh-like structure:
When added to beer, isinglass works ironically like a fishing net: as it passes through the beer, its positively-charged molecules attracts the negatively-charged yeast and the two combine to form a new, larger particle. Larger particles settle out of liquid before smaller particles, which explains why adding isinglass to beer helps clarify the beer quicker than if the beer were left to settle on its own.
Being a homebrewster in addition to a junior scientist, I understand the utility of using some sort of clarifying agent in beer. While yeast and protein in a beer isn't harmful, it isn't pretty to look at and some may find it unappetizing to drink. An interesting side note: clear beer and pale beer rose in popularity in part in the mid-1800s when glassware became commercially available. Prior to that, people drank mostly from opaque metal or ceramic vessels. Once people could see what they were drinking, the popularity of clear pale beers, such as lagers, rose, and the popularity of darker, muddier looking beers, such as porters, fell.
All this is fine and good, but the thing that left me befuddled is how someone looked at this:
And thought this:
"Hey, look at that sturgeon! I bet his bladder would make my beer super clear!"
Even allowing for the fact that much of what we know about topics such as medicine and longstanding popular commercial products (Dr. Pepper was once a patent medicine) was the result of old-timey people saying "I wonder what this does. Death? Okay, then let's not do it quite like that anymore. How about when I do this?", getting from a fish to its bladder to use of said bladder in clarifying beer seemed like a huge leap. Like how many other things were people dumping in beer before they got around to thinking of drying a fish's bladder and then tossing it into beer?
In researching the history of isinglass, I didn't have much luck in finding a definitive beginning to the use of isinglass as a clarifying agent in beer. I learned that, in the heyday of "I wonder what this does," the United States sent isinglass to the Berlin Fishery Exposition (sort of like a fish-centric World's Fair) in 1880 and touted its use as a fining agent, glue, and (gross) food. A lot of the information I found presented isinglass like this thing that had just always been around and in use. I was simultaneously becoming frustrated and even more curious. As I read more about isinglass, I tried to deduce from what I was learning where its use possibly could have started.
Finally, I found the "answer" for which I had been digging and had an Occam's razor moment. although in today's parlance it's probably more appropriately called a "Duh, yeah, that makes sense" moment. Although when isinglass began to be used in beer is speculative (hence why I wasn't finding anything), the hypothesis is that a fisherman at some point used the swim bladder of a large sturgeon to store his beer, much like wine was stored in animal skins, and the acidity of the beer (beer was acidic for a very long time because fermentation wasn't understood until relatively recently) caused some of the collagen to dissolve. Once dissolved, as we junior scientists know, the collagen clarified the beer.
At last! We have our answer.
One very last note about isinglass before we go: isinglass pops up in the news/social media every once in awhile for its use in beer and whether beers that have been clarified with isinglass are "safe" for vegetarians and vegans. You may recall that I'm a vegetarian* (see my standard vegetarian disclaimer I always include below), so this has been somewhat of a concern for me in the past and has previously led to me avoiding beers like Guinness. However, at least one study has shown that the levels of isinglass remaining in individually packaged (i.e. bottled and canned) beer is below the level of quantification and the levels of isinglass remaining in bulk packaged (i.e. casks and kegs) is slightly higher, but not significant. Thus, if you are a vegetarian or vegan, you can probably rest easy that you are not ingesting fish when you're drinking beer that has been clarified with isinglass, despite what Facebook memes and clickbait tell you.
*Because I’ve had a lifetime of being asked the same questions about being a vegetarian, here is a list of answers to your questions, titled Standard Questions Every Vegetarian Gets Asked By Everyone: I’ve been a vegetarian since I was 12-years-old. I’m sure I had a noble, 12-year-old reason for doing so. No, I don’t eat fish. Yes, I eat cheese. Yes, I eat eggs but not usually by themselves because I don’t care for the taste. No, I’m not a vegan. Yes, my husband eats meat. No, I don’t cook it for him, but only because I don’t know how to cook meat well and he does, not because I judge him for eating meat. No, it doesn’t bother me when people eat meat in front of me. Also, I don’t need to hear how you could probably be a vegetarian because you “don’t really eat that much meat” – it’s a personal choice and I don’t care whether you eat meat or not.