Quick Hits 03: Homebrewing Questions Answered

In the last Quick Hits, we answered homebrewing questions about hops and hop spiders, secondaries, head retention, and more. This time around we're answering homebrewing questions regarding yeast, oxidation, dunk sparging, and more;

• What's so Great About Liquid Yeast?

• How Long Does Saved Yeast Last?

• Problems Caused by High Fermentation Temperature

What is a Dunk Sparge?

• Preventing Oxygen Exposure at Bottling Time

What's So Great About Liquid Yeast

A long time ago, when homebrewing was relatively new, brewers only had the limited choice of a few dry ale and lager yeasts. There were available by brand instead of listed strain and then brand. How times have changed. There are now dozens upon dozens of different yeast strains available between liquid and dry yeasts. But what is so great about them? They cost more, and you usually want to think about a starter, but with dry yeast you can set pitch it and forget about them?

Yes, they are a few more dollars than dry yeast, but dry yeast typically produces fewer esters that are sometimes required by the style. For example, many dry wheat yeasts don't product as much of the banana characteristic as some available liquid strains. This is also particularly true with English ale yeasts, where you want those fruity yeast flavors. If you are brewing a clean blonde ale or something similar, US-05 or any other clean dry ale yeast are actually fine.

How Long Does Saved Yeast Last?

homebrewing questions saved yeast

Fresh unopened yeast will stay good in your fridge for up to six months past the manufacture date. However it can still be used after the fact, just make sure to create a starter to ensure viability and cell count.

Reusing yeast for your next batch from the last one? Yeast stored under the beer (in a mason jar for example), will keep in the fridge for about a month. It's always advisable to make a starter using this method.

Yeast that has been properly frozen can keep for a year or more.

Problems Caused by High Fermentation Temperature

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One of the biggest factors making the difference between good beer and great beer is temperature control. You can find that fact posted just about anywhere. It's true, but what can exactly happen to your beer if the fermentation temperature gets too high?

First, ester production gets kicked up to unpleasing levels. It can make your beer's flavor profile muddy and throw it out of style, which is bad news if you were trying to brew for a competition. Your beer won't be what you planned the recipe to be. Some yeasts, saison strains in particular, typically thrive in higher temperatures where they produce their uniquely characteristic flavors.

In addition to making an "estery mess", you'll also be creating a higher amount of fusel alcohols. These are sometimes called "high alcohols". They add a harsh burn to your beer or mead reminiscent of drinking a shot of hard alcohol (if high enough). This is what is usually causing the "rocket fuel" flavors in mead. In addition to off flavors and harsh tastes, they also are attributed to worse hangovers.

Higher fermentation temperature also increases the rate of fermentation, meaning these flaws will be produced in your beer fairly quickly. Yeast also produces most of its fermentation flavors in the early stages of fermentation, so pitching warm isn't usually ideal.

What's A Dunk Sparge

homebrewing questions dunk sparge

A Dunk sparge is a pseudo-sparging method used by brew in a bag brewers who don't have a way to suspend the grain bag for an extended period of time. If you have a pulley system and can suspend the bag to let it completely drain, you don't need to do a dunk sparge, as the prized sugary wort is drained almost completely. However without some sort of support system to hold the grain bag, manually holding the heavy mash over the kettle for the amount of time total drainage takes is pretty much impossible. Enter the dunk sparge.

The principle behind a dunk sparge is this. Let's say you have mash that is removed from the kettle. And in the wort being absorbed by the mash is 50% sugar (This number is made up for the example). If you dunk the mash bag in a few gallons of fresh water, the sugar trapped in the wort will equally disperse between the fresh water and the grain, reducing the sugar that ends up being trapped in the spent grain.

You can expect to see a 3-5% increase in efficiency over trying to hold the grain bag manually over the kettle. However being able to suspend the grain bag for an extended period of draining is the best way to remove sugar from spent grain when brewing in a bag.

Preventing Oxygen at Bottling Time

homebrewing questions - oxygen at botling

The last of our homebrewing questions this week involves oxygen and beer. Oxidized beer is one of the biggest reasons for a failed batch. It dulls flavors, scrubs hop aroma and flavor, and adds some bland cardboard flavors on top of that. So how do we prevent oxygenation at bottling time when beer is the most exposed?

Invest the extra few cents in oxygen absorbing caps. While they won't save a horribly oxidized batch, they will remove some of the oxygen that gets mixed in at bottling time. Once the caps get wet, they do begin to scrub oxygen. Some people will sanitize them before capping and others do not, as we don't know just how fast the process takes effect. If you do go the sanitizing route, don't save the wetted caps for a later date as their absorbing capabilities will surely be spent.

Reduce splashing while transferring to a bottling bucket and bottles. When transferring to a bottling bucket, leave the end of the siphon hose submerged to there is no splashing. Consider using a bottling filler attachment. This will allow you to fill from the bottom of the bottle.

For a full list of Quick Hits answers, go to the table of contents and scroll down to the Quick Hits section.

by David Doucette
David is a full blown fermentation enthusiast who has dedicated much of his free time to learning and sharing the art of homebrewing. He's spent several years documenting and writing homebrewing information on his blog Hive Mind Mead. He's written over 60 articles between Homebrew Talk and Homebrew Supply.
written by David Doucette

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