Fermenting The Homebrew Once the yeast is added the beer will ferment for 1 to 3 weeks. During fermentation, yeast will eat the available sugar in the wort and expel alcohol and CO2 gas, until either all of the fermentable sugars are gone or the alcohol level becomes too high for the yeast to tolerate. During this time, there is very little that needs to be done except for providing a stable environment.       Preparing For Fermentation Before we ferment, we take a hydrometer reading. This will tell us our original, or starting gravity of the beer. This is a measurement of the density of the wort, which should be much higher than water (1.000) because of the high concentration of malt sugars. We take a sample of the brew with a wine thief or siphon hose that has been pre-sanitized, and fill our test jar with the sample. We place the hydrometer into the sample jar and give it a quick spin to release any bubbles that may be trapped on the bottom of the hydrometer that could affect our reading. To properly read the hydrometer we look at the line between liquid and air at eye level. The bottom of this line is where we take our reading. Our starting gravity reads 1.048, which is right on target for our Red Ale. Now that our yeast has been added, it is time to seal the fermenter. Because we are using a 5 gallon carboy as our primary fermenter, we will need to set up a blow off tube. The blow off tube will allow CO2 and foam to escape the fermenter without letting any airborne particles in. Our blow-off system (pictured left) uses a sanitized rubber stopper and a sanitized 3' length of food grade plastic tubing. The end of the tubing is placed in a container of sanitizing solution to create a closed system. If we used a six gallon carboy or bucket, a blow-off tube would not be necessary, because a larger container would allow enough room for the foam produced during the early stage of fermentation. In this case, we would close the fermenter with an airlock (pictured below, left). The airlock is filled halfway with sterile water or a neutral sprit such as vodka. This allows escaping gasses to bubble through the airlock without allowing any unwanted airborne organisms into the fermenter. We place our fermenter in a cool dark place, that has a fairly constant temperature of 60- 70 oF. If our chosen location is not dark, we will wrap a towel or heavy cloth around the fermenter to prevent light from hitting the fermenter and to provide some insulation. It is especially important that strong light does not reach the fermenting beer as this can affect the flavor of the finished beer, causing what is often called a "cardboard" taste. 12 to 24 hours later, our beer is actively fermenting. A thick layer of foam has formed on top of the beer- this is called the kraeusen. Also, because we used a glass fermenter, we can see the brew actually moving in a churning, swirling motion. It is good that we used a blow-off tube, because the foam is starting to get pushed out of the fermenter. If we had used an airlock, it could get clogged, causing a buildup of pressure that could blow the cork out of the fermenter or even break the glass carboy. 3 to 5 days later, the kraeusen has all but disappeared and the fermentation activity has slowed considerably. It is time to transfer the beer to a secondary fermenter. Although this step is not necessary, it will produce a more complete fermentation, and a beer with a cleaner taste and appearance. We will siphon the beer into the secondary fermenter, to prevent air from being mixed into the beer. Siphoning is not too hard to do once to get the hang of it- see the next section (siphoning) for a good trick for doing this. After transferring we put an airlock on the fermenter and allow the fermentation to complete, for another 5 to 8 days. Our total fermentation time will be 8 to 14 days. We know the fermentation is complete because: 1. The airlock bubbles less than once every 60 seconds. 2. We take a hydrometer reading and it is in the range of the final gravity for the recipe we have made (1.012 to 1.016). The next day we take another hydrometer reading, and it has not changed. The hydrometer reading is lower at the end of the fermentation because the sugar molecules (heavier than water) have been converted to alcohol molecules (lighter than water) and CO2, which has been pushed out of the fermenter. 3. The beer is almost clear; the top to thirds of the fermenter are relatively clear, but the bottom third is still somewhat cloudy, which is O.K. Now it is time to bottle, but first we should review siphoning techniques, to make sure we get it right!   NEXT

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