WTF? A Brewing Tip From Melo
By Mel Thompson
Yeast and s-loads of it! I always make sure, when I buy a vial or smack pack of yeast, that I get the freshest available. They are dated and the more recent the better – more live yeasties. Don’t believe that you can just dump that vial or smack pack into your 5 gallons of wort and always get satisfactory fermentation. Build up that yeast population by making a starter. The proper size of a starter is important for optimum yeast growth. I start with 450 ml of wort to which I add thev packaged yeast for a total starter volume of approximately 500 ml. For the initial starter, I use filtered water with 2 ½ oz of dry malt extract (DME). No matter the size of the starter, I use 2 ½ oz/ 500 ml. So a 2 liter starter would require 10 oz of DME.
If I am making a 10 gallon batch, I make a bigger starter by stepping up the original starter. This requires more time and planning as you will need to let the original 500 ml starter finish (several days) and then “bump” it up with more fresh wort. The rule of thumb is an increase of 4 – 10 fold. So, I would typically transfer the original 500 ml starter to a 2 liter flask or vessel for the second build up. Wallah, you have enough yeast for 10 gallons today and another 10 gallons next weekend figuring 500 ml/5 gallons of wort (more is preferable for a lager). By building my yeast through starters and then harvesting yeast slurry from newly fermented beer when I rack it, I generally get 5+ batches out of a single package of commercial yeast.
As an example of yeast conservation (actually, it’s my Scottish blood), I started my brewing season with a vial of White Labs Ringwood yeast and made 40 gallons of 5 different English ales. I gave some slurry to Bill Newman who made 10 or more gallons and he gave some of his slurry to Pete Ryba and Steve Marler who each made 10+ gallons. The yeast expense, including the cost of the DME for the initial starter, was about 10 cents per gallon. Beers made with that yeast took at least 2 of the 3 medals, and possibly all 3, at the BURP Real Ale competition. Steve Marler couldn’t remember if his winning beer used that yeast or another as he split some batches.
Having flasks of fresh, active yeast in the house is incentive to brew more beer. It can be stored for several weeks in a refrigerator with an airlock if you aren’t going to brew right away. It’s a terrible thing to waste one’s yeast!
After fielding several questions regarding last month’s article on building yeast populations, I think a follow up is needed to make some clarifications and provide some additional information for you inquisitive and “ever striving for excellence” brewers in BURP. Making yeast starters was pretty straight forward. It works and if you have a stir plate, it works even better. A stir plate is a good addition to your brewery, but not absolutely necessary. I, and many other brewers I know, have healthy fermentations without using a stir plate. I use a stir plate now, but brewed successfully for many years without one. Let me become “Mr. Obvious” for a second and remind you that the wort for your starter must be chilled before you pitch that vial of yeast. I make the starter and put it, covered with plastic wrap and aluminum foil, in the freezing compartment of my refrigerator for about an hour and fifteen minutes, or until the wort is about room temperature. If you don’t chill the starter, you will be staring at the vessel for a long time (like eternity) waiting for yeast activity. Then I oxygenate by either shaking the crap out of it or use an O2 stone. I usually resort to the shaking method as it is going on the stir plate where it will get more oxygenation (at least that’s my theory).
If you let the starter ferment for several days and it appears to be clearing with a substantial yeast cake in the bottom, decant off most of the liquid above the yeast sediment. That will allow you to make a bigger volume starter for the next step-up. Some of you indicated that you were reluctant to use yeast from your previous fermentation in a new batch. Don’t be hesitant. Follow good sanitation practices and you should have no problems. I use loads of Starsan and fire all openings before transferring yeast. My typical method is to sanitize a 2 liter flask and after racking the beer from the primary, I pour the yeast sediment into the flask. I insert an airlock and put it in the refrigerator if I’m not going to use it right away. There will be enough yeast for several new batches of a similar style of beer and certainly enough to share with your brewing buddies. How do I know if the yeast is still good? I simply use the smell and sometimes the taste method before I use it. Just like beer, it should not have any off aromas or flavor characteristics. Maybe I’m easily amused, but I find it thrilling to pitch 500-600 ml of thick slurry into a new wort and see it take off like a rocket in an hour or two.
I have also put a new wort on top of the yeast sediment after I’ve racked from the primary. It is the easiest way to reuse yeast, however, I worry more about sanitation though I have not experienced a problem so far. I experimented with some 028 yeast and used it for 8 subsequent generations. The 7th and 8th batches were very sulphury as the yeast appeared to mutate into a yeast with strong lager characteristics. Since then, I limit to 3 or 4 generations before I get new yeast.
The final topic I want to cover before I leave the yeast issue to your own experimentation is that there is an excellent source for acquiring big and healthy yeast slurries for your brewing. That is by befriending your local brewer. We should be doing that anyway and I am not suggesting that you take advantage of someone’s good nature, but what a great source for yeast. The only drawback is that the yeast varieties are somewhat limited. Most breweries use from one to at most three separate yeast strains. Generally, that consists of a fairly neutral all purpose ale yeast, a lager yeast and maybe one or two specialty yeasts for seasonals. If you can get some yeast slugs from you local, there is usually enough to share with your friends. This would leave you to purchase only specialty yeasts for your brewing schedule. Oh, and show your appreciation. Take them a bottle of something special.