Pitching the Yeast

Fermentation begins with the pitching of the yeast. "Pitching" is simply a brewer's term meaning to add the yeast to the fermenter. Before pitching, you need to make sure that you've properly cooled and aerated the wort. In some cases, you may need to prepare the yeast well beforehand; for more information, see below or under Preparing the Ingredients. The steps you may want to take to prepare your yeast depend on whether you are using dry or liquid yeast.

Pitching the Yeast for the Beginning Homebrewer

Beginning brewers should now have the beer in their fermenter (probably a plastic bucket fermenter) and have cooled the wort to below about 70 or 80 degrees Fahrenheit. The simplest and easiest way to pitch your yeast is to simply open your yeast container and pour or sprinkle the yeast into the wort. What steps you may want to take before that depend on the type of yeast you are using (dry or liquid) and how fresh you think it is. Be sure to take a hydrometer reading before you pitch.

Before You Pitch

Just before you pitch the yeast, take a sample of your wort and use a hydrometer to measure its specific gravity.

Yeast Starters

Pitching Dry Yeast

One packet of dry yeast is typically enough to inoculate 5 gallons of wort, and a "starter" is not necessary. The dry yeast packet can be pitched directly onto the cooled wort; however, performance can be improved if the yeast is first rehydrated. This is done by pouring the yeast packet into a small amount of boiled/cooled water several hours before you add it to the wort. This adaptive period allows the yeast to get used to the liquid and wake up before it encounters fermentable sugars.

Pitching Liquid Yeast

As explained above, the many varieties of specialized liquid yeast strains make liquid forms very appealing. However, the amount of yeast that is provided in the popular brands' (Wyeast and White Labs) packages is typically inadequate to inoculate 5 gallons of wort. And, since the packages typically cost upwards of $6, it is not financially wise to simply buy 2 packets per 5 gallons, in most cases.

In order to overcome this inadequacy, many brewers make yeast starters for their liquid yeast. The purpose of a yeast starter is to increase the number of viable cells prior to adding the yeast to the wort, thus cutting down on lag time and making for a healthier fermentation. When yeast cells are added to fermentable wort, they begin to reproduce in amazing numbers. As such, pitching the yeast onto sugar prior to adding them to the main beer wort allows the brewer to cheaply increase his yeast cell count. It also allows him/her to get the yeast cells working, so that lag time (the time between pitching the yeast, and the start of fermentation) is minimized.

Yeast Cultures

Yeast Cakes

When a beer is done fermenting, it is typically transferred to a secondary vessel for conditioning and clarifying. Meanwhile, a "yeast cake" is left at the bottom of the primary fermenter. This goopy sludge is made up of a huge amount of viable yeast cells, in addition to protein solids and break material. While some may discard this cake, or "trub", others may harvest it in jars for future use (see washing yeast and freezing yeast ); another option is to pour the cooled wort directly onto it. Given the high yeast cell count, and the viability of those cells, this results in very short lag time and very vigorous fermentation. However, given that some of the byproduct of the previous beer remains in this trub, it is important the the style of the new beer does not clash with the prior style.

Since this method results in such a vigorous fermentation, some brewers opt to pour some of the trub out prior to pouring wort onto it. This allows the initial yeast reproduction period to take place again, which some brewers feel adds desirable qualities to their ales. Others worry about the natural heat that is produced by vigorous fermentation (thus resulting in higher fermentation temps), and also opt to pour a portion of the trub out.

What do I do next?

Once the yeast has been pitched, you are ready to move on to the final step in the beer brewing process: Primary Fermentation.