Tips on Yeast Pitching Rates and Creating a Starter (Tips and Tricks #001) -- Contributed by Ryan "House" Clarke

When I pondered what I should put in my first edition of the Tips and Tricks section, the first thing that came to mind was yeast pitching rates. In my first several years of brewing I never made yeast starters or really worked hard at oxygenating my wort, and still made beers that were drinkable and sometimes fairly good. However, they all had that taste what some of my friends referred to as that “homebrew taste”. When I brewed my first batch with a yeast starter the results were dramatic, clean, almost commercial clean tasting beer. Because it has such a big impact on fermentation quality, I think this subject is perfect for the first Tips and Tricks article.

Every batch of beer that is chilled and transferred to the fermenter either in a home or a professional environment is ALWAYS contaminated with unwanted bacteria. Sanitation as always is a must and does reduce the number of unwanted bacterial contamination in the fermentation vessel, but it does NOT get rid of all the bacteria. So the only way to keep this bacteria from multiplying and causing off flavors and aromas in your beer is to give those bacteria as much competition as possible.

That competition comes from the yeast that you pitch. Bacteria eats and thrives in wort just as well as yeast, so the only thing you can do is toss in as many healthy yeast cells as possible to consume the sugars before the bacteria has a chance to thrive. Plus, when yeast starts chugging along, it starts producing its own sanitizer, ethanol (alcohol), to help kill off unwanted bacteria. So yeah, wort needs yeast, and lots of it.

A Homebrewer can buy yeast in basically two different packaged forms: liquid and dry. Liquid yeast is already hydrated and is “ready to pitch” into wort and contains around 100 billion cells per package. Depending on the date of manufacture most of these dormant cells are viable and are ready to chow down on some wort. Liquid yeast is available in many different strains and costs between $6-8 for each “smack pack” or vial.

Dry yeast, has been processed to remove all the water from the dormant yeast cells to extend their shelf life. The upsides to using the dry is that there is up to 5 times more yeast cells and it usually costs less than half of what liquid yeast costs. The downside to dry yeast is that there aren’t as many strains available and it needs to rehydrate before awakening from their dormant stage. If added directly to the wort, this rehydration adds more lag time. I would like to point out though, if you pitch yeast directly from the packaging into the wort, in most cases, the dry yeast will usually show signs of fermentation before the liquid yeast will. This is because the dry yeast package contains many more yeast cells than the liquid yeast. Even though the liquid yeast starts reproducing right away it still has to time to propagate 2-3 fold to catch up to the cell count in the dry yeast package.

Even though 100 and 500 billion yeast cells sounds like a lot, it’s not! Don’t get me wrong here, I’ve made decent beers by just pitching yeast packages directly into the fermenter. But the following advice will greatly improve your chances of making a clean and well attenuated beer.

The most important improvement I made in homebrewing was making starters for every batch of beer. Making a starter increases your yeast cell pitching rate and the yeast is active and ready to go bonkers in your wort dramatically decreasing fermentation lag time. As soon as that starter is pitched into your wort it’s actively budding and propagating and ready to chow down on all that delicious wort.

For ale yeasts for beers that are under 1.060 I recommend a 250-500ml (approx 8-16oz) 1.040 starter. For ales between 1.060 and 1.090 go with a liter. For the really big beers make a big 2 quart starter. There is a formula to help figure this all out, but for brevity’s sake the sizes above should be sufficient. For starters that are bigger than 500ml you might want to consider letting them ferment completely for 2-3 days and when activity ceases put them in the fridge for 24 hours. After a day, you should have a nice yeast cake at the bottom of the vessel with clear liquid on top. Since this liquid is usually pretty sour and off tasting you probably don’t want that in your beer, so it’s a good idea to decant most of this liquid off. Then about 3 hours before brewing take it back out of the fridge and add about 250ml of liquid starter to get the yeast active again. Note: for lagers you want to pitch 2 to 4 times as much yeast as you would for an ale because lagers reproduce much more slowly than ale strains. I usually pitch a decanted 2 liter starter for all my lagers.

Here’s how to make a 1 liter starter. In a small pot add 1 liter of water and 3.4oz by weight of light or extra light DME with a pinch of yeast nutrient. The nutrient is option but highly recommended. Butler sells small bottles and bags of yeast energizer/nutrient. Then bring this to a boil and let boil for 5 minutes. Now if you are not using an Erlenmeyer flask for your starter I would highly recommend that you put a lid on your pot while it boils. The lid will be sanitized while on the boiling pot and then be used to keep falling bacteria out of the liquid when you cool it. It is VERY IMPORTANT not to pour boiling liquid into a growler or any other non-heat tolerant glass vessel, it will break! If you do have a flask you can pour the hot liquid directly in the flask, cover and cool it down in your refrigerator, freezer, or ice bath. Once you have a cool (under 80 degrees) liquid starter add your yeast and cover with sanitized aluminum foil or a stopper with airlock.

This then brings me to aeration / oxygenation. There are two different yeast respiration phases. The first stage is aerobic respiration where it uses oxygen to metabolizes sugars to bud new yeast cells and propagate more yeast cells. Once all of the oxygen is used up, it stops budding, and goes into an anaerobic respiration phase where it metabolizes sugars largely into CO2, ethanol and heat. Since our goal here is to get as many yeast cells in our starter as possible we need to aerate as often as we can. There are several ways to do this, you can shake the baageezuss out of it when ever you see it, or you can give it a dose of pure oxygen and shake periodically, or you can get yourself a magnetic stir plate. The aim is to keep the yeast in suspension in O2 rich starter solution for several days. This will maximize the number of yeast cells produced in your starter.

When you are ready to pitch your yeast into your wort, give your starter a good shake and then pour it into your fermenter. Even with your starter, you still need to get more yeast cells to grow in your wort, so you’ll need to add more O2 to the beer. Oxygenating your wort is vital to getting your cell count up and producing cleanly fermented beer. The most basic method of introducing O2 into wort is to vigorously shake the fermenter for 10-20 minutes. You can probably cut this time down to 5 minutes if you use Dunn’s burley-man method of shaking a carboy around like it’s a morocco. However, if you’re not built like a caber tosser there are some alternatives available. Aeration stones, also called beer stones, can be connected to an air or O2 supply to blow super tiny bubbles into the wort. If you connect a stone to a deep tank aquarium pump it will take about 5-10 minutes to sufficiently aerate. If you upgrade to a regulated oxygen cylinder it will cut the time down to about 30 seconds. By the time the yeast have consumed all the oxygen in the fermenter you should have a large enough population to ferment your beer fast and cleanly.