Starting Yeast

drawing of a conical flask with brown liquidI’m getting to brew a recipe from last year’s American Homebrewer Association’s national competiton – the Underwood’s “Blasphemy at GobblersRoost” (you’ll need an AHA login to view their Homebrewopedia); it’s a sack with buckwheat honey, raisins and oak aged with whiskey.  In getting ready, I’ve been mulling over yeast starters and how I might better prepare yeast to be dropped into the gaping maw (as Pamela Spence called it) of the must.

There are several things to consider in getting your brew to ferment quickly and cleanly, and knowing how to prepare the yeast and then maintain optimal yeast health during fermentation is a lot of information to gather.  Clearly plenty of people read the yeast packaging and follow its directions about rehydration, drop the yeast into the must, and get perfectly acceptable results.  I think we’re all in a little bit of awe of modern brewing yeasts; they’re lab-engineered to be mighty, a far cry from the yeasts we used a hundred years ago.  I’ve had enough sluggish fermentations create harsh flavors that took years to age out to want a little more control to my process.  Yes, I’m patient, but…

Let’s take as given that yeast in the package – even when liquid – is poorly prepared for the sheer biology awaiting it when it’s dropped into a nutrient-rich environment and asked to metabolize, live and die in the millions in your carboy.  Smack packs offer a little support in this regard, since the yeast capsule is broken to release yeast into a nutrient bath in the package.  photo of conical glass flask

A really great article by Ken Schramm on Optimizing Honey Fermentation was published in Zymurgy magazine in 2005.  His process is a bit complicated but I can’t argue with success!

The most basic yeast starter technique I know of is to put honey, fruit juice (apple works well and is fairly neutral), or malt into a jar, wine bottle, or flask.  Dilute honey and malt enough to make it stirrable and easily poured.    Drop your yeast in, stir or slosh to mix, cover lightly (avoiding bad organisms from floating in) and put in a warm place for 12 hours to a day.  I often stir or slosh again several times, to get more oxygen in the mix; as yeast expert M.B. Raines writes,  stirred starter produces significantly more yeast than ones left unmolested.    You should see krauesen, or foam, at the top of the liquid.  When I’m ready to use it, I make sure it’s been left to settle for a while, so most of the yeast falls to the bottom.  I’ll pour off the liquid, and add the yeast into my must.  By now the yeast should have started its metabolic processes up and be reproducing, which is what you want – colonies of brewing yeast in your must are what convert the sugars to alcohol.  (Here’s a printable .pdf of  M.B. Raines’ Yeast Propagation and Maintenance .)

A slightly more complex version goes like this:

1.  Boil together 6 cups of water, 1/4 tsp yeast energizer, 1/4 tsp yeast nutrient, 1 Tb dry malt extract for 5 mins.  2.  Add 1/2 cup honey, cover and cool to room temperature.  Pour into sanitized bottle (approx. 2 liter size) and add yeast.  Shake vigorously for about a minute.  3.  When yeast activity slows (1-3 days), pour off the liquid and add another batch of the starter solution.  You may want to add 1-2 lbs. honey at this point.  4.  When pitching, swirl vigorously before pitching, and have rinse water ready to get all the yeast out of the bottle.

I make more mead than beer, so I use more honey than malt, but you can substitute malt where I say honey here.

Now, adding more equipment yet to the starter phentermine online usa business, you can use a stir plate and flask for your starter.  Assume you have this apparatus (see links below) that keeps the starter liquid moving so that it makes a whirlpool in a 2 liter flask.  This is very healthy for your yeast.  On brew day, turn it off and allow the yeast to settle.  When your wort cools, decant the starter liquid and replace it with some of the cooled wort (remember that if you add wort that’s too hot you can actually kill the yeast).  Put the flask with the yeast and newly added wort back on the stir plate and spin it up so it’s really mixed.  Now you have a lovely slurry to pitch, and you can add all of it plus a little water to rinse out your flask.  By the time you’re ready to pitch it you will probably have some e or foam on the top of the slurry – activity, healthy yeast ready to do its job!

If you want to make your own stir plate, here’s one description.  Stir Starters is a commercial outfit, but they give you a good idea of what a stir plate does and have a nifty little video.

If you’re making a “big beer” or “big mead”, where the goal is to end with a high alcohol content, some folks wonder if they need to start more yeast to begin.  You don’t really need to, but you do need it well nourished, and a kind of yeast that can tolerate higher alcohol levels.  A lot of meads are made with wine yeasts designed to die off at about 12-13% alcohol – same as a bottle of wine.  Read the packaging!

picture of dried yeast such as can be used for brewing
yeast must be awakened

Many brewers will rack a beer off the yeast cake at about 10 days, then make another wort and pour it on top of the first one’s yeast – stir well, make sure you’ve given it good nourishment, and off you go.  Of course, in this age of designer yeasts, do make sure you are using a yeast that works with both recipes.

If you are making a brew that requires special temperatures – lagers come to mind, since they’re fermented cooler than other beers – it’s a good idea to gently bring your yeast starter to within 5-10 degrees F of the wort, so as not to shock your yeast when you add it to the wort.  Yeast can shut down its metabolism just like you do when shocked, and sometimes it doesn’t quite recover like you’d want it to.  It’s a living organism with more similarities to people than we often like to admit.

Now, remember that some yeasts struggle if the significant gravity gets over 1.140, so make sure you have read the yeast package and measure the gravity of your must and know they are well matched.  If you’re not familiar with how to measure significant gravity, it’s a good thing to learn.  The most common tool is a hydrometer, though they make electronic tools too – that’s a topic for a later post, but here’s a pretty good article on how to use a hydrometer.  You can also use an online calculator for starting gravity like Jamil Zainasheff’s.  Honestly I like to do both – I’m not sure I capture all the variables in my kitchen adequately using only a calculator.   That’s more a reflection on my own abilities rather than the calculator’s.

Yeast preparation can take quite a bit of detail and equipment if you let it, but some degree of preparation vastly improves its performance.  Healthy yeast means faster fermentation with fewer stress byproducts making for harsh or unpleasant tastes.  In short – worth it!

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2 Comments

  1. Your yeast prep is very similar to what we do in the lab. We use a starter culture of bacteria to inoculate a larger culture. The starter wakes up the bacteria from their cryogenic sleep and allows them to get going. Once they are growing well then the latge culture won’t shock them.

    • A young engineer friend knew all about stir plates from diluting acids in science class. Science classes have gotten much cooler since I was in school that’s for sure.

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