To Slant or not to Slant

Bad yeast is no joke. Nothing can be a bigger let-down than popping that thingy in the wyeast bag, waiting for an hour while you brew up your wort, then you go to pitch and - dammit! - the date on that yeast was last year, not last month! Now you're SOL for that batch.

Why do we rely on companies like wyeast for such an important ingredient? Because they make a good product, for sure. And its convenient (I guess, assuming you can get the strain you need locally, on your lunch-break, and you know your supplier keeps fresh stock, and its not summer when the shipment got cooked in the back of a hot truck). Mostly we do it I think because we don't know how to grow yeast ourselves.

Some homebrewers will say you need slants and a lab to culture yeast. What are slants? These are slants. As fun as that looks, I say why bother. Yeast has everything it needs to survive in a bottle of homebrew. Otherwise, how could we bottle-condition beer? We all know that yeast needs sugar to multiply and grow. But all yeast needs to survive is the right temperature. All that is in a wyeast pack is some yeast, separated from some nutrient solution. You pop that thingy to mix the two, the yeast gets going, multiplies, and produces gas to make that pack, as Jon says, turgid, and then you have a couple million yeast cells to give your primary fermentation a strong start.

So the secret is in the nutrient solution, AKA the starter. Assuming you have a source of at least a small amount of yeast, whether from a bottle-conditioned homebrew or a slant or dried yeast or wild yeast in the air or whatever, you make up a starter to get a high enough population to innoculate the primary. For the amount of starter you need, about 6 oz, you make the starter up the night before. The starter is simply sanitized weak wort.

So here is a way to do it, simply:

• Put a tablespoon of malt extract (preferably similar to your intended brew) in a half-cup of boiling water. Let cool to about 100deg.
• Crack open a bottle-conditioned homebrew and pour about 2/3 out (if you pour that down the drain I am going to beat you, pour it in a glass for consumption, you dolt). Give the remainder in the bottle a good swirl, pour in your starter solution, and top with an airlock. Let sit in room temp about 24 hrs, give a good whiff to find out if it was contaminated with bacteria, and if not then pitch.

How simple is that?! You would be surprised, I think, to find out how long yeast stays viable in a bottle of homebrew. If its particularly old, you may want to start 48 hours in advance. Time is the essential ingreedient here, as yeast population can double every hour under the right conditions. What you need is a large population, so what you must give it is the right conditions and time.

Even if you keep your brew in kegs, you could keep some yeast on hand by siphoning out some of the trub during transfer from your primary into a bottle, and then store it well (i.e. cool). To create a stockpile of yeast strains then, you simply need to keep a bunch of bottles labeled and cool. Surely, this inconvenience is outweighed by the risk of a bad yeast pack, or even paying $5 for a good yeast pack?

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UPDATE 1:
Yet, all is not as simple as is made out here. Yeast can mutate, an unfortunate (in this case) side-effect of evolution. It sounds like 4 generations is the limit. We must find out what constitutes a generation, because strictly speaking if the yeast doubles in population every hour we get a new generation every hour. THIS layman's site is an excellent reference, as is THIS site (for professionals).

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PROPOSAL:
Nothing beats a little experimentation to put conflicting opinions to rest, and the references we have found to date definitely give conflicting opinions about the mutation rate of yeast and the effect on beer taste. SO we should take one of our standbys, bitter or stout, and make five 1-gallon microbatches, using sediment from the primary to pitch 4 of them and a fresh wyeast pack for the 5. Repeat this process over 5 batches, for a total of 25 gallons of samples. Then taste-test. This in theory will develop 4 separate strains of yeast by the last batch, and if our hypothesis holds up (that the yeast will mutate past 3 batches into a totally different taste arena) then we will be able to taste 5 different beers by the last batch, with the wyeast batches being the "control".