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Kolsch New Zealand Pilsner
Kolsch New Zealand Pilsner
Author: Craig Graham
Cold-side oxidation is a process that, for the most part, contributes undesirable flavors to beer. Exposure can happen at several points, such as transferring uncarbonated beer during packaging or when transferring finished beer to bottles and cans. Many describe the flavor effects of oxidized beer as papery or cardboard like, and the overall effect is a muted and unenjoyable experience. Oxidized beer is normally obvious by a change in color to purple or brownish.
We should know! The Brü Club's misadventures with New Zealand Pilsners has become a regular punchline following a fateful Brülosophy review podcast. Not a single review podcast goes by without a mention of purple beers. While the most obvious source of the problem would be oxidation at bottling, the high rate of oxidized beer has caused us to wonder if the yeast used by most members (Lalbrew KÖLN) had a role or if the style was simply much more sensitive to oxidation even with careful packaging.
Both bottles I sent into the review podcast were oxidized (the first review on the episode). I also sent three bottles of my New Zealand Pilsner to the Indiana Homebrew Competition and all three were noted with deficiencies. Two judges said infection and one said oxidation.
Experiment
Experiment
I rather enjoyed the beer off the tap so I decided to brew it again but trying a few different bottling techniques: Decided to do low, because all the bottles I sent in were low fills, and high fills on each technique. I did carb drops from the fermenter, a plastic tap filler from the keg, and filled from the tap.
Recipe
Recipe
Batch Size: 5.5 gal | Boil Time: 30 min | IBU: 36 | SRM: 3.2 | OG: 1.044 | FG: 1.011 | ABV: 4.3%
Fermentables
9 lb (100%) — The Swaen Swaen Pilsner
Hops
14.2 g — Pacific Jade 13% — Boil 30 min
28.3 g — Wakatu (Hallertau Aroma) 7% — Boil 15 min
42.5 g — Nelson Sauvin 12% — Boil 1 min
28.3 g — Wakatu (Hallertau Aroma) 7% — Boil 1 min
Yeast
1 pkg — Lallemand (LalBrew) Koln 75%
More Details
I brewed the beer on my Mash and Boil on October 1st, 2022 using a no sparge BIAB technique. Once the water was heated to strike temp I added the grains and mashed in at 149F for 60 minutes.
Once the mash was complete, I collected the wort and proceeded to boil for for 30 minutes, adding hops at the times listed in the recipe.
When the boil was complete, I chilled the wort then transferred into my Kegland All Rounder and pitched one pouch of Lallemand (LalBrew) Koln at approximately 68 degrees.
Fermentation temperature ranged between 69F and 71F and appeared to be finished in three days but was left in the fermenter for seven days. I typically spund but this time did not to ensure the bottle carbonated samples were not already carbed going into the bottle.
On kegging day, October 8th, I transfered four bottles worth of beer into bottles. Two were high fills and two were low fills. The bottles were left in star-san for about five minutes. I did not purge the bottles as I was filling them. I then added a carb drop to each and capped. The rest of the beer was transferred to a purged keg. The keg was placed on 12 PSI of Co2 while the carb drop bottles were put in a dark part of my pantry.
On November 13th placed eight bottles in star-san. None of the bottles were purged while filling. I filled four with a plastic tap filler.
I then filled four bottles from the tap.
In both cases (bottles filled direct from tap and bottles filled with plastic tap filler), two were low filled and two were high filled.
I placed all 8 bottles in a box and put in the trunk of my car till December 8th mainly because not long after bottling life got crazy and I forgot about them. During that time the outside temperature never exceeded 80F. There were days in the 40s during that time.
I placed one of each bottle in my fridge on December 8th. On December 9th I opened one each of the carb drop high and low fill beers. Both were oxidized as was obvious visually when comparing it to a beer fresh from the keg. I had expected these to be the bes
The next day (December 10th) I tried the tap filler ones with the low fill one showing some oxidation. The high fill one didn't appear or taste oxidized.
Same day I tried the tap filler ones and had similar results.
Discussion
Discussion
While the two tap high-filled bottles didn't show oxidation, the carbonation drop high-fill bottle did. The only real difference I could observe was the amount of "hiss" from the bottles. All four oxidized bottles had loud hisses with the carb drop low fill one being a gusher. The two non-oxidized bottles did not have a loud hiss, but all of them were appropriately carbonated.
Overall, the results were different than I would have suspected with the bottle conditioned beers all being oxidized. Based on these results it is still unclear what might be the primary cause of oxidation in the New Zealand Pilsner, but other good candidates to explore could be the yeast, the hops, or other process factors.
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