Thanks for the tip, I had a feeling it might be the stirring. Currently I'm using a steel mash tun and underletting to 100% full then locking down the lid so that there's no headspace, then draining and underletting to full two more times to sparge. No stirring whatsoever. I think next time I'll give it a gentle stir.
I've also been having an issue with temperature equilibration using the underletting method- the strike water is getting pretty cool by the time it reaches the top of the grain bed. I think a gentle stir would fix that as well. At some point
@Overkill is going to finish his crazy automated eHERMS rig and we'll switch to brewing on that, hopefully doing away with all of these issues.
On a sidenote, mind sharing your Kolsch recipe?
No problem, but it's a little process-specific, you'll have to see if you like it.
Here it is; it's about 10 percent too heavy, but I'm trying to compensate for losses in the mash tun, hoses, and so on.
6# Pils malt
6# 2-row
.75 # White Wheat
.75 # Munich Malt
3ml
Hop Shot at 60 minutes (it's for bittering, in lieu of a normal bittering hop)
1 Whirlfloc tablet, 15 minutes
.5 oz Hallertau Hops, 5 min
WLP029, pitched directly with no starter. Yeah. There's a thread on here somewhere about that. I attended a yeast workshop put on by Chris White at the BYO boot camp in March, along w/ my son. White says he wouldn't do starters unless it was a big beer, he'd just pitch a tube of yeast and that would be that.
My son has been doing that, did it with his Kolsch, so I thought, well, why not. Still trying to wrap my head around it.
Anyway, I used 8.25 gallons of strike water, heated to 139 degrees. I always use 1 gallon of tap water (which is pretty mineralized) plus the balance in RO water. I added 2gr gypsum, 4gr Calcium Chloride, 2gr Epsom Salts, 1gr BrewtanB, 1.5 campden tablets (crushed), and 2 ml lactic acid.
I have a RIMS so we did a step mash with the first step at 132, held it there for 10 minutes after underletting (and stirring--you're right, stirring will make temps more homogeneous throughout the mash), then ramped it up to 149, which took 15 minutes or so. Then held it there for an hour. I was just following my son's procedure with the step mash; not sure there's any great value in it, but he has a grainfather so that's what he did. To try to approximate his process I did so as well. My recipe is somewhat different--his has all Pils malt but I've found the LODO stuff makes the Pils flavor go over the top, so I cut it in half with 2-row. I also added the Munich for a bit more complexity.
BTW, that's something else I've tended to do--go a bit longer with the mash. For me, a 60-minute mash would be after underletting and then stirring, starting the timer then. That's arbitrary, of course. I've tended to let it go to maybe 70 or 75 minutes with this, but I'm also doing some refractometer reads to see where I'm at.
OG was 1.055; that's a tad high, I'm still trying to dial all this stuff in. It finished at 1.006 (!) for a final ABV of 6.3%. Lots of flavor but finishes pretty dry. Very interesting.
Anyway, once that's done, into the kettle, simmering boil. Then chill and xfer to the fermenter. Pitch yeast, oxygenate, and wait. I set the temp at 60 degrees for fermentation. It took about 24 hours for any visible sign of activity. Four days after pitching, I sealed it up, then started to raise the temp to 69 degrees. Held it there for 2 days, then back to 60 for 36 hours, then crashed.
So....just writing about this makes me want to go have another one.
