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Yeast Starter:
A yeast starter is useful
if you are making a strong 5 gallon batch of
beer or a 10 gallon batch of beer that might need more yeast cells than
what comes from the original package. Yeast starters are also
useful when culturing yeast from a bottle. The process is
basically the same either way, just keep in mind that you want to begin
the starter 1 - 5 days before brewing the beer that you will be
pitching the yeast into. This will give your tiny yeast army time
to prepare for the feast.
The most important part of making a yeast starter is to be sure you
have everything sanitized that will be coming into contact with your
wort. This is particularly important if you are going to be
culturing from a bottle. The yeast in the bottle will be weak and
you will not have many cells, so you don't want anything in the bottle
growing faster than your yeast. For equipment you will want to
have a large enough flask or mason jar that fits the needs for your
starter. A stir plate is good to have but is not needed to make a
good starter. The steps below should be used as a guide to making
a yeast
starter.
- Begin by sanitizing a
flask or mason jar to be used
as a fermentation vessel. Be sure to also sanitize anything that
will be coming into contact with your cooled wort.
- Make a mixture of about
0.25 - 0.5 cups of dry malt
extract to 1 quart of water. You want the final gravity of the
wort to be about 1.030 so that the yeast are not stressed.
- Bring the mixture to a
boil for at least 20 minutes
to pasteurize the mixture.
- Cool the wort to
pitching temperature, around 70
degrees Fahrenheit using an ice bath.
- Now transfer the cooled
wort into the flask or mason
jar and cover with a sanitized piece of aluminum
foil. Note: if you have a gas stove you
can heat the wort while in a flask (not a mason jar), leaving less
chance of contamination.
- Now transfer the yeast
from the package or bottle
into the flask and reseal with the aluminum foil or a stopper and
airlock. If transferring from the package be sure that the
package is sanitized before transferring. If transferring from a
bottle make sure that about an inch of beer is left in the bottle to
swirl around and get all the stubborn yeast off the bottom of the
bottle. Before transferring from the bottle be sure to flame the
opening for less chance of contamination. At this point you could
also use some of the yeast to streak some plates or slants for yeast
culturing.
- If you have a stir plate
you can drop a sanitized
stir bar in to the wort and use the stir plate to keep the yeast
suspended. If not just make sure to swirl the mixture around
whenever you get a chance. You should start to notice activity or
yeast cake forming within a few days.
- Once ready you can
either pitch directly into a
waiting batch of beer, or cool the mixture so that the yeast will
settle to the bottom, at which point you can then pour off the top
liquid and only pitch the yeast into the beer. Be sure to let the
yeast warm up to room temperature if you will be cooling before hand.
Keep in mind that your
starter could be infected, so if it looks or
smells funny don't pitch it. Chances are if you have taken proper
steps to keep everything sanitized you will not have a problem, but as
you know from brewing beer some times you get a bad batch.
Bottle Culturing:
Culturing yeast from a
bottle is a technique used to culture brands of yeast
that are not commercially available. Keep in mind that most beers
can not be bottle cultured, because they either have no yeast (filtered
beers) or the yeast are dead due to pasteurization or high alcohol
content. Even if you
find a beer that has been bottle conditioned, which you can tell by the
yeast in the bottom of the bottle, chances are the yeast they used to
bottle condition is not the same yeast used during the fermentation
process. The most popular beers used to bottle culture yeast is
the Rogue Brewing Company's beer. I believe Rogue actually
mentions on the bottle if the desired 'pacman' yeast was used for
fermenting their beers. They use a different strain of yeast for
the Lagers than they do for the Ales. The steps for culturing
yeast from a bottle start more or less the same way as making a
starter. This is done to wake up the yeast and get them to
multiply by feeding them. The only addition to the above steps
are to be more cautious of contamination. Yeast from a bottled
condition beer are very weak. In addition to the technique above
you could also use lower gravity wort around 1.020 to do 'step
ups'. Doing a step up has the advantage of not stressing the
yeast out. Basically you perform the procedure above using a
lower gravity wort as mentioned then after a few days add more wort at
a slightly higher gravity. This is done a few times until the
desired results are achieved.
Streaking/Slanting/Harvesting
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