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.
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.
