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A Post about the Centrifuge.

From The Iron Horse Brewery Blog

A Post about the Centrifuge.


Part one, the actual centrifuge.

We received the first piece of our centrifuge last week and, while it is just a big hunk of painted steel, it is still pretty exciting.

Centrifuge base plate

Some of you may have heard we are getting a centrifuge and might be wondering what the heck does it do? Well, I’m going to tell you in not so general terms.

This fun equation is Stokes Law. Basically it takes the size of a particle, the difference in density, and throws in that damned gravity to tell us how fast a particle will settle out of solution. This is of great interest to brewers because we like stuff (yeast, haze) to settle out of beer before we send it out. The options to speed this process up are relatively limited. Some breweries add finings (usually made up of the swim bladders of tropical fish cut with sulfuric acid which greatly angers vegans, not that I care). This is common in traditional cask ales. This increases the particle size (R3) by coalescing particles together to make a larger diameter. Some breweries use horizontal conditioning tanks which decrease the distance a particle has to travel to settle out. And a growing number of breweries are turning to centrifuges, also known as bright beer separators.

What do they do?
Gravity (g) is a constant 9.81m/s2. What a centrifuge does is multiply that number by as much as 10,000. This increases the velocity of the particle out of solution and allows for much faster clarification. So in a nutshell, think about what happens when the person three seats down from you on the Gravitron barfs. That is what is happening to the yeast and haze particles in the beer. They are thrown outward to a series of cones that guide them upward and out of the beer. Result: Brighter beer, quicker with a consistent level of brightness.

What does this mean for Iron Horse Beer?
It means more beer, quicker. It means clearer beer with less variability. Boom! It still means our beer is unfiltered. That last part is important. Why you ask? Because unfiltered beer should be cared for differently.

Part 2 Unfiltered Beer
It is important to know if a beer is filtered or not and what to expect if it is not. Unfiltered beer will be cloudier (unless the fish gut stuff is used). There may be a layer of yeast and other stuff that has settled to the bottom of the bottle or keg. When pouring a bottle of unfiltered beer, be gentle and don’t be tempted to pour the last bit into a glass. “Good to the last drop” does not apply to an unfiltered product. Another thing to remember is that it is a “live” product. That yeast is sitting in there clinging to life in a terribly inhospitable environment. This balance can be upset with ill treatment. Let a bottle get warm and the yeast dies, the cell membranes rupture, and all kinds stuff leaks out. The dead yeast increases the cloudiness and aggregates into blobs and bits and alters the flavor.

Why don’t we just filter?
Well the answer has many reasons:
-Filtering sucks and we are lazy
-Most filtering methods use DE which has ramifications (arsenic, getting rid of it)
-Yeast adds to the flavor
-Filtering strips hoppy goodness

-Buy bottles that are cold, ask if the retailer always keeps them cold.
-Be prepared to pour out a little bit.
-Take care of it, don’t piss off the yeast

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