Thursday, October 18, 2012

Go All Out With Your Next Fermentation

I have to tell you I was a bit skeptical myself about using pure oxygen when preparing my wort for fermentation, but after having done two batches I'm already convinced it is well worth it. Let me explain, the beers I'm drinking now are way, way better tasting than anything I've brewed prior to oxygenating my wort instead of just aerating it. Using oxygen is also saving me valuable time on brewday, a one minute burst of pure oxygen is all that's needed, while eliminating any risk of contamination when aerating with air for extended periods.

420 Special Wheat And East Coast Yeast ECY12 - Old Newark Beer™

Truth be told I started adding yeast nutrients to the wort boil at the same time I began using pure oxygen to prepare my wort for pitching yeast. I now add both a capsule of Servomyces nutritional yeast supplement and half a teaspoon of yeast nutrient to the end of all my wort boils to provide the yeast with a rich blend of sugars and minerals during fermentation. Maybe it's the combination of pitching, at the time of this post a fourth generation two liter starter of ECY-12 yeast at high krausen, adding yeast nutrients to the boil and then oxygenating the wort prior to pitching the yeast but there is a very noticeable difference in the quality of the finished beer now.

Additional information: Yeast Nutrients Make Better Beer by Christopher White, Ph.D

Attenuation Chart (Courtesy of White Labs)

For one thing the pitched yeast lag time has increased by about 20-30%, I don't notice much activity in the airlock for at least 18-24 hours but the beer's final gravity is finishing several points lower than it used to in prior batches fermented without oxygenation or nutritional supplements. Using aeration you can get at the very most 8ppm of oxygen into your wort by vigorously shaking your fermentor for a minute or using an aquarium pump, HEPA filter and air stone for at least five minutes.

Rapidly Cool Full Wort Boils To Pitching Temperature

Either of these methods creates a lot of wort foaming that can lead to issues with overflowing fermentors, head retention and lacing in your finished beer as well as increasing the risk of contamination. I use a 2 micron stainless steel diffuser and run enough pure oxygen through it to form a stream of very fine bubbles and I let it run for a full minute before pitching my yeast starter. At this rate flow rate, using the chart above as a guide, I can estimate that I am putting about 9ppm of dissolved oxygen into my wort which is the sweet spot for the beers I've been brewing.

Higher Yeast Production With Nutrients

The most notable change is in the taste and flavor of the beer now each sip tastes very clean, I mean there are no distracting off flavors so every ingredient you put in the kettle comes through clearly in the finished beer. I've been focusing mostly on my 420 Special Wheat and Screwer In The Rye recipes the past several months and since improving my yeast preparation as I have described earlier they have both developed an unmistakable clean flavor and aroma that leaves a really nice taste in your mouth after each glass.

Control Fermentation Temperature For Better Beer
Since East Coast Yeast ECY12 - Old Newark Beer™ yeast has an optimum temperature range of between between 53-68° F which is much lower than most Ale (Saccharomyces cerevisiae) yeasts but it is not a true Lager (Saccharomyces uvarum) yeast. I always pitch a healthy two liter starter into my five gallon batch and keep the temperature down around 55-57° F during the lag phase and then allow it to rise to 59° F for the primary fermentation phase. Once the primary fermentation has completed I add my dry hops and let the temperature slowly rise to 68-72° F over the next week. I then move the fermentor to my refrigerator to cold crash at 36-38° F for about four days before kegging or bottling it up.

Collecting Washed Yeast After Kegging The Beer
Once the beer has been bottled or kegged it's the best time to collect and wash the yeast from that fermentation to add to your yeast library for later reuse. I fill up a large pickle jar with filtered water, boil it for 15 minutes to remove as much oxygen from the water as possible, then cool it down to the same temperature of the yeast cake in the fermentor. Then I sanitize the jar and pour the cooled water into it, dump the water in the fermentor and then swirl the solution around for a minute or two using a long handled Teflon spoon. After a few minutes I open the valve on the fermentor and pour the washed yeast into the large jar until its full, a little while later I use it to fill up the pint mason jars I use to store the yeast.

I made the decision to just bite the bullet and go all out to treat my yeast the best I could. I wanted to find out for myself exactly how much of a real difference added nutrients and oxygen would make and I was pleasantly surprised. If you have been considering making the move to pure oxygen do it you won't be disappointed.

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