Czech Premium Pale Lager 2018

Today I'm brewing my third Czech Premium Pale Lager. The first attempt at this style won a gold medal while the second didn't fare as well.  Comments on the second version indicated the judges thought it had a brett infection. Given how many sour/wild beers I brew, this is entirely possible and I thought I was also able to taste a little funk, especially after a few months in the bottle. I don't believe that brett and bugs are the bogeyman that a lot of people make them out to be, but it goes to show that you need to be careful. In my case, I believe it was picked up in my counter-pressure filler, so I've changed my sanitation procedure by incorporating a pasteurization step every time I use it (140F recirculation while submerged in the same 140F water for about 20 min; heated by my sous vide cooker).

So back to the Czech Pils/Bohemian Pils/Czech Premium Pale Lager. I'm gaining an appreciation for lighter, more delicately flavored beers. I tend to gravitate towards big bold flavors in beer (and food) but there's definitely a time and place for easy drinking beers. The key to brewing this style is very soft water, so I start with distilled water and use minimal salt additions.. Here's the recipe as I'm brewing it today:

8.0# 11 oz Weyermann Floor Malted Bohemian Pilsner
9 oz Briess Carapils
34g Czech Saaz 4% AA (60 min)
41g Czech Saaz 4% AA (30 min)
20.5g Czech Saaz 4% AA (10 min)
20.5g Czech Saaz 4% AA (0 min)
Imperial Yeast L28 Urkel
0.5 Whirlfloc
0.5t Yeast Nutrient

Mash at 154F for 90 mins, 90 minute boil, chill to 44F, aerate well and pitch yeast. Raise temp to 50F over 48 hours. Raise temps to 64F for the diacetyl rest. Cold crash after a couple days.

Water Recipe
10 gallons distilled water
0.55g Epsom Salt
0.33g Calcium Chloride
0.44g Baking Soda
0.44g Chalk

Brewing Notes
No issues in this brew session. I was working on some other projects at the same time, including putting up a trellis and getting started on my first attempt at homemade pastrami. I had to run to the store at one point and had to enlist my son to do the 30 minute addition. OG came in at 13.9P (1.055).

Update 8/5/2018

This beer went in the keg today along with some gelatine for fining.

Update 9/25/2018
So...this beer has a little bit of a problem. It tastes great right off the tap, but once it starts to warm up it's apparent there's some acetaldehyde. It comes across much more in the aroma than the flavor, but regardless, it's not good.

As for the cause, it's often related to one of three things:

1. Poor yeast health - Acetaldehyde is naturally produced during fermentation. Towards the end of fermentation, the yeast converts it to ethanol. If yeast health is compromised, they may not be able to finish converting it.
2. Transferring too soon - Even if the yeast is healthy, if you pull the beer off the yeast cake too early, it can result in acetaldehyde.
3. Oxygen exposure - I've read that O2 exposure post-fermentation can result in ethanol being converted back to acetaldehyde.

In this case, I suspect that oxygen exposure is probably the culprit.