As a craft beer lover and avid home brewer I was thrilled when Linda Bowden, ECHO's Life-Long Learning coordinator, announced that she w...

Are there fish in your beer?

As a craft beer lover and avid home brewer I was thrilled when Linda Bowden, ECHO's Life-Long Learning coordinator, announced that she was planning the beer-themed event called "FeBREWary: The Science of Beer." As an aquatic biologist, I'm always seeking ways to link our local aquatic fauna to things that people really identify with and care about... like beer!

As it turns out, there is a quite a long history of using fish parts to clarify beer and other fermented beverages. Many fish would sink without some extra buoyancy provided by a structure called an air bladder. An air bladder is essentially a bag made of collagen into which fish can add or remove gas as they move up or down in depth. This allows fish to maintain neutral buoyancy- not sinking or floating, but hovering in one place. As with many anatomical features, air bladders can provide additional functions beyond buoyancy control.

For example, drum use the air bladder to produce and amplify a thumping sound (like a bass drum) during spawning season. Other fish, like long-nose gar and bowfin, can thrive in warmer waters that have low amounts of dissolved oxygen by gulping air and passing oxygen from surface air into their blood stream via their air bladders.

The air bladder is an essential structure for many fish, but it's the collagen from which it's made that matters to beer lovers. Consumers of the vast majority of beer styles look for clarity in the glass along with satisfying flavor. Most modern breweries use some form of clarification to achieve the bright clear appearance that consumers expect. Among several options for achieving clarity is isinglass, which is made from- you guessed it- fish air bladders. By extracting and processing fish air bladders, the collagen building blocks are dissolved into an acidic solution to make isinglass. When the isinglass is added to beer, millions of tiny charged collagen particles bind to oppositely charged particles of suspended yeast cells and other dissolved by-products of fermentation (hop oils, protein, etc.) that can make beer cloudy. Once added, the binding action of isinglass forms larger, more dense particles that sink to the bottom of the container and the beer "drops clear." In as little as two days, a batch of beer will go from hazy (photo on left) to clear (photo on right) and be ready to carbonate and drink.

How the use of fish parts in the brewing process got started is not well known. One of the most likely scenarios that I've come across is one in which ancient people used air bladders to carry liquids, including beer. Acidic beverages, like beer and wine, likely dissolved some collagen and created favorable conditions for clarification to occur. Perhaps some ancient ale drinker set down his or her bladder of beer for a day or two, only to discover a clearer drink later on.

Want to find out more about intersection of science and the enjoyment of good beer? Join us at ECHO on the evening of February 9th. Prost!

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  1. Irish moss, an edible red seaweed, was also used in the past to clarify wort.

    1. Very true. Commercial beer drinkers who don't like the idea of trace amounts of fish parts or seaweed in their beer do not fear! The vast majority of commercially available beers are clarified by some combination of cold-storage, mechanical filtration, or choice of yeast strain. These older methods are more likely to be used on the homebrew scale than the big guys.

    2. yeah but mate c'mon, Irish moss and Isinglass act quite differently and aren't really fungible - I mean some beers even use both!


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