It is hard to believe that all the work the homebrewer does to get the wort ready is really insignificant compared to the job ahead of the yeast when you pitch it to the fermentor.  Once in the wort the yeast will begin to transform the wort into actual beer by converting the sugars in the wort into carbon dioxide and alcohol.  Pitching the yeast is a very simple and easy step in the brewing process after a little prep work and making sure good sanitation practices are followed .

Types of Yeast

Brewing yeast comes in two basic types: dry and liquid.  Both types work well to ferment beer and come in several varieties suited to producing different styles of beer.  Many recipes will specify the type of yeast to use, but the yeast you use to brew your own beer is up to you.  Yeast is another way for the homebrewer to have more control over the characteristics of the finished product. 

Dry Yeast:  Dry yeast is available in sealed plastic packets and is freeze dried before packaging.  The freeze drying helps to suspend the living yeast cells and to help lengthen the shelf life of the yeast.  Most dry yeast packets have a “best if used by” date printed on the packet, but if kept in a dark, cool place dry yeast can stay viable for long periods of time.  Dry yeast is relatively inexpensive and comes in several varieties of both ale and lager yeast. 

Liquid Yeast:  Liquid yeast generally comes in plastic vials or in sealed pouches referred to as “smack packs”. Because the yeast is not freeze dried the cells are not in suspended animation and are more nearly ready to begin converting wort into beer.  Liquid yeast must be kept refrigerated before it is used to keep the yeast cells alive and typically has a shorter shelf life than dry yeast.  Liquid yeast comes in many varieties (many more than dry yeast) and can be used to replicate almost any beer style the homebrewer might desire.  While the many varieties help make liquid yeast a good choice, it is generally more expensive and is best bought close to brewing day and used quickly.  

How to Pitch the Yeast

Once your wort is sufficiently cooled down it must be transferred to the fermentation vessel and be aerated.  This is the first and last time you are going to want to expose your beer to excess oxygen.  The oxygen is very important in helping the yeast reproduce until their numbers are sufficient enough to ferment the wort.  The simplest way to aerate the wort is to pour it vigorously into the fermentation vessel and then slosh it around (if it isn’t too heavy…be careful!).  Some homebrewers aerate their wort by using an aquarium pump equipped with an inline HEPA filter and diffused through an airstone.  Still others pump pure bottled oxygen into their wort.  How you aerate your wort isn’t all the crucial in the beginning, the important part is to give the yeast the oxygen they need to do their job.

Dry Yeast:  Dry yeast can literally be poured in on top of the wort and will usually get started and begin fermentation.  While this method works it is generally better to rehydrate the yeast first.  To rehydrate your dry yeast heat 1 cup of clean water to between 90-105 degrees Fahrenheit and pour it into a sanitized cup, jar or similar container.  Pour the contents of the yeast packet into the warm water and cover it with a sanitized lid or kitchen purpose plastic wrap.  After 15 minutes stir the mixture with a clean and sanitized spoon and then replace the cover.  After another 15 minutes you should see an opaque layer of yeast at the bottom of the container.  At this point the yeast is ready to pitch.  Swirl it around in the container and then carefully pour it into the wort (remember to sanitize a funnel if you use one!).

Liquid Yeast:  One of the advantages of liquid yeast is that it doesn’t have to be rehydrated.  The liquid yeast varieties that come in the plastic vials are already pitchable.  Just let the vial come up to your target fermentation temperature, swirl it around and carefully pour it into the wort.  The liquid yeast that comes in smack packs should be taken out of the refrigerator at least 2-3 hours before time to pitch.  The packs not only contain yeast cells, but also small inner pouch(es) of yeast nutrient.  They are called smack packs because you “smack” them in order to break the inner pouch(es) of nutrient.

This can be kind of tricky the first time you do it.  While you certainly can smack the pack, the Homebrew Garage recommends placing the pack on a flat surface such as s counter top and applying firm, even pressure with your hand or other object.  Once the nutrient pouch(es) is broken allow the pack to sit out at room temperature.  The yeast will begin to invigorate thanks to the nutrient and the pack will swell up.  When the pouch is good and swollen the yeast is ready to pitch.  It is good practice to sanitize the smack pack and the scissors you use to cut it open before you pitch.  You have come too far to risk infecting your brew!