I kegged this beer a couple of days ago and thought I should report back on it progress. You may recall the aim of them experiment is to test the assertion that yeast starters are needed for all beers, or whether a single smack pack can be used for “normal” beers with original gravities (OG) of 1.060 without affecting the final beer.
Do yeast starters decrease lag times? I did not notice any difference in lag times between the two fermenters, probably because they started overnight while I was asleep. By the time I checked the fermenters the next morning (maybe 16 hours after pitching), both had a good inch of kraeusen and were churning away merrily. While it’s possible the fermenter with the starter started more quickly, the fermenter that got the smack pack certinly had an acceptably short lag time.
Do yeast starters decrease the time to completion? Both fermenters had very similar times to completion. I checked them morning and evening every day while they were actively fermenting, and they both seemed to ramp up and taper off at about the same time. One interesting thing is that the fermenter with the starter had a thicker, heavier kraeusen which took longer to fall into the beer after the active ferment stopped. The fermenter with only the smack pack may actually have been ready to rack a day or so ahead of the other because of this.
Do yeast starters give more complete ferments? The OG on both fermenters was the same, of course, since they came from the same kettle. Their final gravities (FG) were also the same, at 1.008. This is an apparent attenuation of 86% which is fairly high for the yeast I used (Wyeast American Ale II).
The only remaining questions seem to be related to the flavor of the final beer, which we won’t know for another week and a half or so. The beer is currently resting in its kegs on dry hops and under pressure. Once it’s carbonated and has had a chance to soak up some aroma, I plan on doing a semi-blind test to see if I or my testers can find any difference.
So far, the results seem to indicate that there is little advantage, if any, to making yeast starters when there are healthy smack packs available and when the beer is not above 1.060. The advantages might be more obvious if the yeast in question were older, or if the beer were very strong. As starters cause extra work and therefore increase my overall level of worry (which Charlie tells us is to be avoided in pursuit of homebrew), my inclination is to skip them unless I am doing something extraordinary.