Tonight I made a yeast starter for a honey porter I’m getting ready to brew with an estimated original gravity (OG) of 1.054. Yeast starters are important when it comes to high(er) gravity beers, because if you pitch (the term used to add yeast to your unfermented beer) a yeast pack without enough yeast cells in it into a higher gravity beer, you may strain your yeast. Having the proper yeast count is crucial to both a complete and clean fermentation, and will give your beer the best taste, body, clarity/color, and aroma.
In addition to brewing high gravity beers, when else might you use a yeast starter you ask? Well, you might also use a yeast starter when you suspect the overall viability of your yeast pack has diminished, such as when it has an old production date. You may also create a starter when it has been in warm temperatures for longer periods of time (thereby reducing yeast viability). If in doubt, because the process is quick and painless, consider creating a starter. It’s easier to err on the side of caution and create a starter, rather than tossing 5 gallons of work (over the course of a month) down the drain (literally)!
Practically, I have made yeast starters for several high gravity beers: the aforementioned honey porter, India Pale Ales (hereinafter IPA), and I would also consider them for stouts. I’ve also made them when my yeast shipment arrived via FedEX or UPS, and the package is warm and bloated, which tells me it may have been warm for some time. I’ve also created them when I buy yeast at the local homebrew store (LHBS) and the production date is…old. Yeast starters are also very important when brewing bottom fermenting lagers, which require a longer (and colder) period of fermentation.
To create a yeast starter, you are basically fermenting beer at a much smaller level.
So, how is a yeast starter created? I’m going to go over creating a yeast starter using the shake method. I plan on talking about using a stir plate in a future article.
First, here’s what you’ll need:
Your liquid yeast pack
Dry malt extract (DME) – which is cheap and which I keep on hand for just these occasions
A smaller glass container to ferment the starter (a 1 gallon fermenter, pitcher, flask, jar, or similar container)
Sanitizing solution (such as Star San)
** A note on sanitation: Do unto your yeast starter as you would do unto your beer day brew. Use a sanitizing solution (Star San or otherwise) on your glass container, scissors that are used to cut your yeast pack, funnel (if used), and anything else that comes in contact with your cooled wort. Don’t introduce bacteria into the yeast sample you’ll be introducing into your cool, unfermented beer! In addition to cleaning my fermenting device, I also keep a spray bottle of Star San solution to spray scissors, the yeast pack, my hands, my wife’s cats, and anything else that may touch my yeast starter (I am sometimes OCD when it comes to cleanliness and my beer)!
Measurement: Measure 2 cups of water for every 1/2 cup DME. So, if you are going to make a 1 liter starter (approximately 4 cups), you’ll want 1 cup of DME (math comes hard to me, so I thought I would spell it out for you). You can determine the size of the starter you need by plugging in your brew’s estimated original gravity (OG), and the date of production for your yeast pack, on Mr. Malty’s pitching rate calculator. So, if Mr. Malty tells you you’ll need a 1 liter starter, this is how we get to that:
1) Measure out 4 cups of water (not to beat a dead horse, but again – approximately 1 liter).
2) Put the water in a pot, put the pot on a stove, and bring to a boil. Add 1 cup of DME and stir so there are no clumps. Bring the solution back to a boil for 15 minutes. Once you add the DME, be cautious about boil overs (which are no fun to clean up…or…so I hear).
3) After the 15 minute boil, allow the wort to cool and transfer to a small glass device (such a flask, 1 gallon fermenter – which is what I use, or something similar). Continue to allow it to cool to the yeasts pitching temperature (listed on the yeast pack). To speed up the cooling process, you can place the starter container in an ice bath, which should quickly bring it down to the correct temperature.
4) Important step – once the wort has cooled, aerate the wort by shaking it, vigorously, for a minute or two. This creates an abundance of oxygen in the wort (also known as unfermented beer), which is crucial for the yeast to begin fermentation and to rapidly reproduce – which is the whole point of this exersize. Once the wort is well aerated, pitch the entire packet of yeast into the wort.
** If you have a liquid yeast pack with nutrients (a smack pack) – make sure you have already activated the nutrient pack (by breaking it), which can be added with the yeast to the starter. You will generally see the pack expand/bloat as the yeast begins to activate. If you have a refrigerated yeast pack, make sure you have given it a few hours to warm up. Just as you don’t want to pitch the yeast into really hot wort and shock the yeast cells, you don’t want to pitch refrigerated yeast into hot wort.
5) Cover the opening of the container with foil (it keeps the wort sanitary while allowing it to breath). Paranoia Alert: Don’t forget to spray the side of foil that will face the inside of your container with sanitizer! If you don’t have a stir plate, shake the starter as often as you can (every hour or so as able). The yeast will reproduce on their own, but the more you agitate the better the rate of reproduction. Also, keep the temperature of the starter at the very high end of the yeast pitch range, to promote a vigorous fermentation.
6) Depending on the size of your starter, the yeast will be ready to pitch after 18-36 hours. Beyond that, refrigerate until you plan to use it. Depending on the type of yeast and starter size, at the end of your fermentation period, you may see a base layer of yeast on the bottom of your device (like the off white color base in the picture to the left – which is after 36 hours of shaking and fermenting).
7) Optional, if you have a larger yeast starter (probably 2L or bigger), you may want to decant some of the liquid off your starter. This keeps some of the water volume out of your already measured wort. To do this, I find it’s easiest to cold crash the yeast starter, which causes most of the yeast to go out of suspension and settle in the bottom of the glass fermenting device. You can do that by putting the yeast starter in the refrigerator overnight (which you may do anyway if you don’t plan to brew right away). After that, you can slowly and carefully pour the water off the top of the yeast cake. Leave some liquid so that as the yeast starter warms up, you can use the liquid to slur the yeast off the bottom and back into suspension prior to pitching into your wort.
By creating a yeast starter, you will ensure you don’t stress the yeast cells, and that you will have a vigorous and clean fermentation that will contribute to great tasting beer!
For more information on creating a starter check out Beer Geek Nation’s excellent YouTube video on creating a yeast starter here. You can also read the FAQ section on Mr. Malty (as well as using the pitch rate calculator) here.