Although there are a few tutorials out on the web about slants, I thought I'd document how I go about using slants in my brewing. I haven't taken pictures of the process of preparing and inoculating slants yet, so that will be in another post.
People have lots of reasons for using slants, but one of mine is economic- a tube of White Labs yeast or a smack pack of Wyeast can cost over $8, and it's still a good idea to make a starter. By slanting, I can effectively have an almost limitless supply of the yeast strain if I re-culture every 6-8 months, saving $8 per batch of beer, not insignificant.
Plus it's fun, which is why I brew anyway.
Anyway, here goes.
Here are all the items I use for propagating the first stage: slant with yeast (just to the right of the pot), stir bar, dry malt extract, small pot, 1 qt canning jar, thermometer, yeast lab book and pencil! (not pictured- an inoculation loop or a straightened paper clip, and some alcohol in a shot glass- I end just using vodka with fine results)
First step, boil 1/4 c DME with 375 ml water (I measure the water by mass, it's often the easiest way)
Bring to a boil for about 5 minutes (thermometer is handy here to have a feel for when boiling is imminent- boilovers with this sugary liquid are pretty fast and messy.
Transfer to the canning jar, cover with clean foil, and cool in an ice bath to 80 deg F.
Now the delicate part, where cleanliness is most important: getting the yeast from the slant into the prepared, sterile growth media (wort). Working close to a flame (for the updraft), take the inoculation
loop from the vodka, flame the vodka off, remove the foil from the slant and flame the lip. This all should be rehearsed ahead of time, to avoid making mistakes once the slant is open.
Touch the probably-still-very-hot inoculation loop to the agar media in the slant to cool it, and scrape some of the yeast from the slant into the wort.
Re-cover with foil, and place on stir plate for 24 hours. Experiment with the stir plate speed to get as much stirring as you can without throwing the stir bar.
24 hours later, getting ready for the second stage- boil 3/4 c DME with 1500 ml water for the larger starter. Same deal, bring to a boil for 5 minutes, then cool in an ice bath to 80 deg F.
Pitch the first stage starter into the second stage. By this time the yeast have multiplied a lot, and this will be pretty obvious by the turbidity of the first stage.
Place the second stage on the stir plate for another 24-48 hours.
And 24 hours later, we have a krausen on the starter- there is definitely a yeast party going on in there! This is the point at which I have now finished a brewday and pitch the starter into the freshly cooled, aerated wort. Then ferment away!
