Three of the most important things you can do to make the best beer is using proper sanitation techniques, proper yeast pitching rates and controlling your temperature. By now, all of you should be aware of the need for proper sanitation and in a future article, we will discuss temperature control, so this article will discuss how to make a yeast starter to make sure you have enough yeast cells to properly ferment your beer.
Commercial pitching rates for an average strength beer are 10 million cells per milliliter of wort, or 200 billion yeast cells for a 5 gallon batch. The liquid yeast manufactures claim to have between 70 and 140 billion yeast cells, enough to pitch into wort that has an original 1.060 or less. The problem is that as the yeast ages some of the cells start to die and that decreases the number of viable yeast cells. This is why it is a good idea to make a starter with liquid yeast. Dry yeast have substantially more yeast, so a starter is not required. Since most home wine makers use dry yeast, the preparation of a yeast starter is not necessary.
Starter Preparation
To make a yeast starter you will need water, dry malt extract (DME), yeast nutrient and a pot big enough to boil 2-3 quarts of water. The ratio of water to DME is 1 pint of water to ½ cup of DME, or for those that are not metric challenged, like myself, 10 ml of water to 1 g of DME, will yield wort with a specific gravity of 1.040. It is also a good idea to add about a ¼ teaspoon of yeast nutrient. You want to keep the starting gravity around 1.040 because the yeast will ferment and multiply quickly at this level. If the starting gravity is too high it can stress out the yeast.
To make a 1.5 quart yeast starter, add 3 pints or 1500 ml of water to a 3 quart pan, 1.5 cups or 150 g of DME and ¼ teaspoon of yeast nutrient. Bring this to a boil for 10 minutes. Make sure you stir the mixture well to break up any clumps of DME and watch out for a boil over! This can happen very quickly and can make quite a mess on the stove. For the last 2-3 minutes of the boil cover the pot to allow the steam to sanitize the lid. You may need to turn your stove down when you cover the pot.
After the 10 minute boil, you want to cool the wort down quickly so the yeast can be pitched. The best way to do this is fill your sink with water and put the pot in the water. Change out the water a few times to make sure it is cool enough to rapidly lower the temperature of the must. It is a good idea to add ice on the third water exchange to help bring the temperature down below the tap water temperature.
Sanitize, Sanitize, Sanitize
The importance of sanitation can not be stressed enough. From this point on everything that comes into contact with the wort or yeast must be sanitized. A two gallon bucket works very well to sanitize air locks, stoppers, funnels, scissors, pieces of aluminum foil for covering the tops of growlers and even the yeast packets.
Vessel
You can prepare your starter in any number of containers, growlers, beakers, large beer bottles and numerous sizes of jars. I prefer to do my starters in beakers because they work well on stir plates (electric plates that use magnets to stir). I have also had success using growlers on stir plates. A stir plate is not necessary for a yeast starter but will increase the cell count more that just a starter alone, as it agitates the starter and adds more oxygen for the yeast to multiply.
Sanitize your vessel by filling it with the sanitizer of your choice in the proper ratio and allowing the sanitizer do its thing for the allotted time. If you are using a stir plate, now is the time to put your stir bar into the vessel to sanitize it. It is a good idea to have a small magnet near by if you are using stir bars. When it comes time to dump the liquid out of the container, put the magnet on the glass to hold the stir bar in place. This keeps you from dumping the stir bar down the sink.
Yeast Growth
Now that you have your wort prepared, cooled and your equipment is sanitized, it is time to put everything together. Drain your vessel (if using a stir bar, make sure it stays put by using a small magnet) and cover the vessel with a piece of your sanitized aluminum foil. Using you sanitized funnel pour the wort into the growler, even the dregs at the bottom. With the funnel still in place open your yeast package and pour it in. If you are using a smack pack, use the sanitized scissors to cut it open. If you are using White Labs, I find it best to shake the tube to loosen the yeast and re-suspend the yeast. Next, if you are using stir plate, put your sanitized aluminum foil over the opening, crimp it tightly and place the vessel on the stir plate. If you are not using a stir plate, put an air lock and stopper on your vessel. Since there are no hops in the wort, you can leave it to ferment on the counter at room temperature, out of direct sunlight. You ferment the starter at room temperature even if you are using lager yeast, as this step is about yeast growth not making beer.
Pitching
After one to two days, you should notice the liquid starting to clear and the yeast starting to drop out of suspension. You will notice a creamy white layer on the bottom of the vessel. This is the fresh yeast you have just grown. Placing the vessel in a refrigerator overnight will cause the yeast to drop out of suspension much faster. The next day take the yeast out of the refrigerator a few hours before you are ready to pitch. When you are ready to pitch your yeast, pour off most of the liquid above the yeast layer, swirl the yeast to make sure to get all of it off the bottom and then pour directly into your fermentor. A one quart yeast starter will significantly increase the yeast count, shorten the lag time and provide enough healthy yeast for a fast and thorough fermentation.
