Process: Brewing with English Yeast Strains

I've ended up taking a few weeks off from brewing this month, and since J and I are headed up to Toronto next week, it will probably be at least a fortnight before I brew again.  I have a couple of tasting note posts scheduled for while I'm away, but it will be a a bit longer before I have any interesting brew days to write about.

Part of the reason for this is that I'm in between pitches of yeast, and it didn't seem worthwhile to grow one up when I knew I'd be travelling.  Why should that make a difference?  Well, I realized that it all comes down to the way I brew when I'm using English yeast, and I thought it would be fun to write a quick post about my process.  Maybe its uninteresting for others, but I for one quite like hearing people discuss how they go about their brewing.

When I'm doing English beers (and some Belgian ones), my ideal process is to grow up a pitch of a top-cropping strain, and then brew with it once a week until its gone through at least three or four generations.  This only works when I know that I'll be able to brew regularly over a several weeks (so in the summer, and maybe at the start of a school semester).  When I have this kind of space, I brew each weekend, cropping mid-week for the next batch, and keeping this going as long as I need to.

Its fun to be able to trace the lineage of a particular pitch of yeast that's gone through this cycle.  For example, early this summer I grew up a pitch of Wyeast 1469 from a slant.  It was first pitched into this pale mild, and cropped a few days later; after that I brewed two bitters back to back on subsequent weekends, pitching from one to the next  (I haven't written about these yet); the yeast from the last bitter was pitched into Old World's Mantra; some of the yeast cropped from there was pitched into the Keeping Porter, while the rest was grown up on a stir-plate and pitched into Stingo, along with more yeast cropped from the Keeping Porter.

So you can see that the original gravity of the beers increases steadily, with early beers acting as starters to ensure I have healthy yeast.  Since I'm top-cropping, I don't worry too much about the colour or hopping rates in the beer I'm cropping from, as the yeast that I skim off is almost completely free of trub (it may be coated in hop oils, but I haven't had any trouble with this).

I haven't done this consistently enough with particular strains to have any information about how flavours vary between pitches, though I have noticed that attenuation will often increase steadily over several generations.  One thing that has probably been very inconsistent up to now is the pitching rate across batches: I try to pitch roughly the same volume of slurry by eye in beers of the same gravity, but without taking cell-counts or actually measuring it out I suspect I am often over-pitching (remember this is thick, fresh, and healthy slurry).

That should change in future: a fellow home-brewer who runs one of the labs on campus recently told me that his old school was selling some microscopes, so I asked him to pick one up for me.  Once I get the hang of using it, I'll be able to do cell counts for the slurry I'm repitching.  It will be interesting to see what these show about the cell numbers and viability in top-cropped yeast, especially compared to the washed yeast I use in my saisons.

I'm curious as to whether other home brewers think about their process in the same way.  Part of the fun for me is thinking out a series of beers for a particular yeast.  I can tell you now that the next strains I grow up after our trip will be Wyeast 1028 and 1318 (I'm not sure which I'll do first)---and I have a pretty good idea of the sequence of beers I'll brew with each, which is to say that I have at least four beers in mind, and a couple more possibilities that I could work into the sequence if I think I'll have time. (E.g. 1028 goes Ordinary Bitter, Bitter, Summer Ale, IPA, and maybe a stock ale at the end.)

A final note: this is very different from the way I use saison yeasts.  Since these are rarely good top-croppers, and often fairly poor at flocculating, I usually harvest them from one of the clean Better Bottles that I use as bright tanks / secondary fermentation vessels.  In the right context, this process has its advantages too: it means I can wait longer in between brews, and keep a single pitch going over many months.  Obviously brewing with mixed cultures works differently too.