[Ale Farmer]

I have only my third lager now in the fermenter--a Vienna Lager, and while things seem to be fine at day 4, it took 2 days for any krausen to appear--making me worried that I didn't pitch enough yeast (even though I made a 1 L starter).

This experience has me wondering--more generally--what the flavor consequences are if a lager is underpitched. A quick check at some of my brewing guides didn't give me a clear answer (maybe I missed it)--so I'm turning to you more experienced lager brewers out there for some background on this. Thanks.

[dmtaylor]

With a major underpitch, there's a possibility of acetaldehyde, or green apple, off-flavors due to unusual stresses on the yeast.  This can be mitigated by aging at warm temperatures >70 F prior to packaging, since that is the boiling point temperature for this chemical.

You could also induce additional fruity esters or phenols, again due to stress.  Perhaps sulfur as well.  Aging may or may not help reduce some of these.

If you don't detect anything off, I wouldn't be surprised, either.  You're likely to just luck out and not have any problems.  Hope so.  Now that fermentation has taken off, everything is likely to be just fine.

Cheers.

[majorvices]

Don't stress too much about a 2 day lag for a lager. You like to see fermentation kick off within 24-48 hours so you are in the time window.

[Ale Farmer]

Thanks for the general info. and reassurance about my latest lager--much appreciated.