Posted By on January 21, 2010

What’s the difference between top and bottom fermenting yeast?

It’s pretty simple really. Top fermenting yeasts do not ferment at the top, and bottom fermenting yeasts do not ferment at the bottom.

All varieties of yeast fully permeate the wort during fermentation. “Top fermenting” yeasts are called so because they tend to generate a thick foamy layer along the top, contributing to krausen. “Bottom fermenting” yeasts, most often used for lagers, do not contribute as much this foam layer. All yeast will settle to the bottom of the fermenter leaving a sediment.

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I've been homebrewing and learning about good craft beer since 1999. My wife, Cindy, and I enjoy road trips, exploring new places and finding great brewpubs and breweries. Explore with us through as we continue on our quest of Road Trips and BrewPubs!


2 Responses to “The Facts: Top & Bottom Fermenting Yeast”

  1. Well, you’ll want to make sure you use hops and malts are typically used for lagers. But basically, yeah, if you’re using a lager yeast and have designed your beer to be a lager, you need to ferment around 55 degrees, for a couple of weeks, then rack to secondary and lager it for another few weeks before bottling. Then, keeping the bottles at 40 degrees or so to let them settle out and crisp up. I rushed a lager just before Christmas. Fermented it outside so it was nice and cold (PA Winter) for two weeks, then I had to bottle it, so basically I skipped the secondary lagering step and just lagered in the bottle for three weeks, but it still turned out pretty good.

    Lagers take much longer than ales from fermentation to finished beer.

    Let me know how it turns out if you brew one!

  2. Aaron says:

    So, does this mean that the only difference I have to worry about when creating a lager at home is the temperature during fermentation?

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