A yeast primer
By Gregg Smith
Fermentation, where would a brewer be without it? Certainly beer wouldn't be the same.
Without yeast doing its job beer would be a very sweet cup of tea indeed. Of course you
usually don't give it a second thought, just add a pack of yeast and let those little guys go to
town right? Sure, and not quite.
Let's take some time to cover what can be done with the yeast to make your homebrew
more like the commercial beers you enjoy. First, what's your favorite type of beer?
Homebrew shops usually start new brewers off with ale kits, and there's a very good
reason. Ale yeast is a unique strain (consider a strain the same as a purebred) which has a
natural characteristic of working best in warm temperature ranges of approximately 60-75
degrees fahrenheit. Lacking sophisticated temperature control required for the fussier lager
beers, ale is a logical place for most brewers to begin.
Perhaps you've continued to buy kit beers. That's okay because the suggestions made here
can be instituted without changing anything else about the kit. Should you continue to use
the packet of yeast under the can's plastic lid it's understandable; that packet is very
convenient and frankly it's a no-brainer. Problem is you don't really know what conditions
that yeast has seen. Yeast is very susceptible to temperature extremes and if it was stored in
a hot warehouse it may have caused irreparable damage to the tiny yeast cells inside.
Luck may be with you, but the probability is high for kit yeast to result in a sluggish
fermentation, or worse, one which never starts. Instead of using the packet you get with the
can see if your homebrew shop carries refrigerated packs of quality dry yeast. (There's also
liquid yeast for more advanced styles and brewing) When arriving home treat it just as you
would hops; place it in a zip plastic bag and store it in the 'fridge.
So you've switched to a high grade, known yeast variety, what's next? If you have been
opening the packets and simply sprinkling the dry yeast into the fermenter you're overdue
to make a little change. Before pitching (adding) the yeast allow it to acclimate first. You
wouldn't go from couch potato to overnight marathon running would you? Don't expect
this of your yeast either. Give it a chance to get in shape. At the start of your brewing day
take the yeast out of the fridge and let it warm to room temperature. There, now that was an
The next step takes place about fifteen minutes before the end of your boil. Get a sanitized
bowl and fill it half way with tepid (about 90 degree) water. Open the yeast, pour it in, stir
gently,and let it sit. This process is called "rehydrating the yeast", It can be thought of as
some warm up stretching in the morning. When the wort is cooled to around 70o degrees
add the yeast. The other thing needed is oxygen so when you first pour water into your
primary fermenter slosh it around a bit, but be careful not to slosh it after the yeast is
Once you've pitched the yeast treat it like an invited guest. Don't place it in the hottest room
in the house. Pretend you're running a fine hotel and supply your boarder with a steady
temperature range of 60 to 75 degrees. Over the next day or so you can check the fermenter
for signs of activity; it should look like it's churning and bubbling. Ferment comes from
the Latin word fervere "to boil" so the activity is normal and routinely begins within a day
to a day and a half. The best overall advice is don't fret. Mother nature and the yeast will
take care of everything over a week's time.
As you brew more you'll start to hear of liquid yeasts. These are yet another improvement.
Liquid brands are a more pure strain sealed in an inner pack which is surrounded by an
outer packet of sterile wort. Keep it in the 'fridge and remove the pack a day before you
plan brewing. Allow it warm to room temperature and follow the directions which call for
puncturing the "inner" pack while the outer package remains sealed. Over the next day
you'll notice the pack begin to swell. Don't panic, although it might resemble a zeppelin it's
normal. This is the yeast getting a head start and in fact is called "a starter". After brewing
and cooling the wort you only need open the liquid pack and add it to your primary.
Advantages of the liquid yeast are low levels of off flavors and aromas. The reason for this
is because liquid yeasts are very pure and because the "head start" leaves little room for
wild microbes to establish themselves in your beer. Liquid yeasts cost a bit more but
experienced brewers swear by the results.
One other fermentation hint; place the fermenter on a table. This will make life a lot easier
when it comes time for racking (transferring it to a secondary fermenter or bottling bucket).
Secondary fermenter? Quite simply it's a method of letting your beer age a bit while
removing it from contact with all the trub and other gunk in the bottom of your fermenter.
After active fermentation appears complete (a couple of days after it quits churning and
bubbling through the airlock) sanitize a hose and carefully siphon the beer into another
fermenter called a secondary. When siphoning don't slosh the beer and be sure to siphon
from a level just above the layer of gunk at the bottom of your "primary" fermenter.
Now you just let it sit there for 5 to 10 days 'till you're ready to bottle. The effort will yield
a more mature beer with a thinner layer of sediment in the bottom of your bottles.
So the simple steps toward better yeast care are: buy a wellknown quality yeast, store it in
the refrigerator, rehydrate the yeast, maintain fermentation temperatures in the correct
range, and rack to a secondary fermenter. Next time we'll discuss priming, bottling and
storing. Until then I've got a date with a cold home brew.
One last temperature factor can ruin all the efforts you have taken so far.
The best temperature for ale yeast to do its work is about 60 to 70oF. Once you start
fermenting above 75o you enter the range where fusel oils can be produced. Fusel oils add
a solvent like aroma to your beer, a very undesirable character.
In warm weather locations it's very common to be above 70o for much of the year. What's
a poor amateur brewer to do? First, try putting the fermenter in the north east corner of a
basement. Don't have a basement? Place it near your air conditioner (and cover it from
light). Still a bit too warm in either the basement or near an air conditioner? No problem,
wrap a towel around the primary fermenter and place it in a pan of shallow cool water.
The towel will wick up the water and natural evaporation will give you and additional 2-4o
of cooling. Need a little more cooling? The breeze of a small fan can buy you a couple
more degrees. If it's still too warm you may need to invest in a second-hand refrigerator
and modify it with a thermostat kit.
© Gregg Smith