Get To Know Your Yeast - Making A Starter

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A typical Saturday brewday for me begins on Monday before sitting down to eat dinner. After picking up the liquid yeast vials needed for my recipe I boil up a batch of yeast starter wort made from extra light dried malt extract and filtered water. My LHBS The Brewers Apprentice stocks Munton's Extra Light DME packaged in convenient one pound plastic bags, they're perfect for making up starter wort on short notice and easy to store on a refrigerator shelf once opened. To make up the wort I use a pretty simple formula of one cup of dried malt extract to two liters of filtered water, it gets me within the 1.030 to 1.040 gravity range every time and it's easy for me to remember. Once you've measured out the water pour it into a small pot and begin heating it up as you stir in the DME making sure to break up any clumps with the back of a long spoon if any form. Let the wort boil for ten or fifteen minutes and prepare an ice bath to cool the finished wort down to pitching temperature then pour the cooled wort into a sanitized Erlenmeyer flask and your done.

I should also point out that the next question that comes to mind, after finding out that the yeast I need is in stock, is how old is the yeast that I'm buying. If you're lucky enough to live within a short driving distance of a LHBS like I am there's a pretty good chance when you drop by in person you'll like the way they store their liquid yeast. If your yeast supplier refrigerates their yeast and their yeast packages aren't too close to the 'Best Used By' dates you should have no problem making a good starter. In really hot weather you can prevent shocking the yeast with too rapid a temperature swing by bringing a small cooler and ice pack with you to transport them home in. I remember being contacted a few years ago by a representative of a formally well known brewing system and ingredient supplier about the deal he would give me on buying vials of liquid yeast that were more than a month past their 'Best Used By' date, in heat of August too no less!

Think temperature and age when buying your liquid yeast because the best yeast to use hasn't been frozen or stored at or above room temperature for any length of time. If you're ordering liquid yeast and having it shipped long distances in either weather extreme make sure the supplier packs the yeast in an insulated container to prevent it from freezing or baking while on its way to you. Temperature extremes and excessively long storage times kill yeast cells and to ferment our beer efficiently we need as many healthy viable cells as possible. That's where the benefits of making a yeast starter, rather than pitching a vial of yeast directly into our beer, can really be appreciated. If after spinning a yeast starter on a stir plate there's hardly any krausen forming after the first twelve hours it's an indication that the yeast you used had a very low cell count and would probably benefit from making a step starter to build up the initial cell count.

To calculate the cell count needed to ferment a beer I first enter the estimated original gravity of the wort my recipe will make and the estimated final gravity. There are plenty of yeast pitching rate calculators out there so pick one that works best for you and stick with it. The calculator will estimate the number of cells needed to ferment the beer according to the gravity, size of the batch and the type of yeast. Nearly all pitching rate calculators double the Ale pitching rate when calculating the cell count for a Lager yeast. There are also hybrid strains of yeast like White Labs WLP810 - San Francisco Lager Yeast that are true Lager strains but fermented at or near Ale temperatures, for these I've used one and a half times the cells used for fermenting an Ale and have gotten excellent results. I use the fairly unscientific method of estimating that each vial of fresh yeast holds 100 billion cells and when spun on a stir plate in a two liter starter wort it yields 220 billion cells. I haven't run into any brewers yet that have been accused of over pitching their fermentations but I have read a lot about those who have inadvertently managed to under pitch their fermentations at some point and I believe that's much more likely to occur.

Vince "Screwy Brewer" Feminella is one of the many bloggers and industry pro's making HomeBrewTalk their home online. For more from Vince please be sure to visit his blog,

If you use Fermcaps or something to prevent foam, you can boil and cool in the flask.
I put water, dme, yeast nutrient, fermcaps and my stir bar into the flask and bring it to a boil. Then i cool it in the sink and then just pitch the yeast and throw it on my stir plate.
No cleaning of funnels, or pots, or anything really.
Also just measure 100 grams of DME per liter of water.
Great article and relevant topic for a new brewer learning that starters are not just for advanced brewers. The article does not get into this but I did wonder about cold crashing and decanting the starter. This in of itself is debated, but assume it is the path I want to take ... here is what I think I know, but steer me toward the light if I am off:
1) Above all ... sanitization is key
2) After active fermentation (24-36 hours) cold crash in the fridge for at least 24 hours (or a couple of days depending on your brew day schedule)
3) On brew day decant by pouring off most of the beer leaving a bit behind to swirl with and then pitch it.
4) I can decant and pitch cold, meaning directly out of the fridge or leave it sit out to reach room temp before decanting and pitching. Either works fine, the choice is just preference.
5) Looping back to #1 above, I am not clear if I need to re-sanitize the neck and rim of the flask before decanting and pitching. If it can't hurt then I assume a few sprays of star san would be advised?
Great article ... thanks for posting.
Nice write up!
Good tool to estimate the cell count pre/post starter is
Based on a 2L starter on a stir plate with 100% viability gives you between 312B to 381B cells (depending on if you trust Kai's or Jamil's estimations).
I usually punch in the numbers at the top for my recipe (OG, batch size, etc), and the do a starter volume based on the number of cells required + 100B cells. This allows me to harvest approx 100B cells (estimated by a taking percentage of starter beer with "known" cell count) and save in the fridge for the next batch, technique borrowed from
@NoahBeach - My question to you is how you know how much is 100B cells when harvesting for the next batch? Also, how many times can you do that?
Great article, but I would like to correct one thing, overpitching is bad, mmkay? If you overpitch your beer won't pick up the proper flavor from yeast reproduction and you'll miss out on complexity, don't do it!
@Talgrath Yes, but it seems that overpitch in the homebrew scale is not an easy feud. You want to try to do it to get to do it. But that's only what I've read :)
You might add what size batch you are doing and the corresponding # vials you start with? What stir plates do you use? How do you keep the ale yeast temps up while stirring? How long do you stir? 5 days?
Thanks for sharing!
@WissahickonBrew I used two vials of WhiteLabs liquid yeast, one vial in each of the two flasks, to build up the cell count for a ten gallon batch of 5% ABV beer. One stirplate is a StirStarter and the other is a DIY stirplate I built myself.
The starter temperatures stay within 70-80F without effort when spun in a typical room temperature area. The krauzen usually peaks and falls in around 48 hours so the starters spin for 2-3 days.
Hope this helps.
From your experience/knowledge is there any adverse affect if I cool my yeast starter to 50 degrees and then pitch it into my wort which is also at 50 degrees?
@RobFlott none at all, in fact doing that would prevent the yeast from being shocked to too rapid a temperature change. Yeast cells prefer gradual temperature changes over rapid temperature swings, it keeps them happy and your beer tasting better.
So I have a question about Yeast Nutrient, say I'm brewing a Honey Ale and instead of yeast nutrient, Can I add a tsp of honey to the boil of the starter and pitch the whole starter if its a 1 liter in my 5.5 gallon batch?
No that won't work. Honey is actually very low in nutrients that yeast need, so you're really just adding sugar. This is why mead makers have to add nutrient to their batches. No nutrient in the honey.