Adding The Yeast Adding yeast is a critical step to making great beer. As with all the stages covered thus far, good sanitation is important. Temperature, quantity and quality of yeast, and aeration (oxygen dissolved in the unfermented wort) is also critical. Pitching the yeast Now that our beer has been transferred to the fermenter, it is time to add the yeast. The yeast we are using for this brew is a Wyeast smack pack, which we activated yesterday. We have sanitized the yeast package in our iodophor sanitizing solution. We'll use scissors to cut the corner of the package open. We have sterilized the scissors by holding the metal blades over an open flame for about 30 seconds, being careful not to burn our hands or melt the plastic handles. Our yeast is pitched (added to the unfermented wort) by carefully pouring into the fermenter. We have checked to make sure that the temperature of the wort in our fermenter is between 65 and 75 oF, and our yeast is at about the same temperature. Yeast is a living organism, and will not perform properly or will even die if conditions are not right. If the temperature is too low (under 60 oF for ales and under 50 oF for lagers) the yeast will be very sluggish or may not start fermenting at all. If the temperature is too high (over 80 oF) the yeast will be killed and more yeast will have to be added once the wort has cooled down. If you are adding a different type of yeast or using a yeast starter, the process of pitching the yeast is pretty much the same. A tube or vial should have a protective plastic seal around the cap, which makes sanitizing the container unnecessary. The vial or tube should be shaken well before pitching. Dry yeast should be rehydrated for the best results, as covered in our yeast preparation section. A yeast starter can be added directly to the fermenter as well. You may want to sanitize the lip of the container with the starter in it with a cotton swab dipped in rubbing alcohol or a strong liquor (such as vodka or rum) before pouring it in. Aerating the Wort We have one more step before leaving our brew to ferment. We will aerate our wort, or dissolve oxygen into the wort, by shaking vigorously for at least a minute. The yeast will need this oxygen in this first stage of its life-cycle, the reproductive stage. After the initial reproductive stage, yeast becomes anaerobic, meaning it thrives in an oxygen free environment. Thus, after your beer starts to show visible signs of fermentation, it should never be shaken or splashed. So just before or after adding the yeast and before activity is visible is the only time your wort should be aerated. Once the yeast is added to the fermenter, it starts reproducing, because it now has a huge new food source: 5 gallons of your hombrew! During this reproductive stage there is no visible activity, which is the reason for the lag time between pitching the yeast and visible fermentation. This lag time can range between one and 48 hours, depending on many factors. These factors include: quantity and freshness of the yeast, amount of available dissolved oxygen, temperature of the wort, concentration of sugars in the wort (a stronger beer will take longer to start fermenting), and the type of yeast (lager yeast's generally take longer than ale yeast's).   Now it's time to ferment!   NEXT

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