I am asking this because we have a situation where a perfectly good pilsner suddenly dramatically changed after it was bottled into a hazy, oxidized, hoppy mess. It was for a beer competition where they were gracious enough to give us one of the extra bottles after the fact. The change was so dramatic that many of us are wondering if they accidentally switched our beer with someone else's pale ale. The beer does not taste infected or soured, it just tastes and looks completely different. The beautiful clear straw yellow turned into a rose tinted gray haze. The light hoppiness turned into an intense fruit-forward hop aroma. The mineral and slight buttery background notes completely faded away. It just tasted more like a pale ale than a pilsner.

Anyway, we're trying to get to the bottom of this. This beer was fermented in a closed system and transferred into the serving keg in a closed system. When we bottled it, we purged the bottles with CO2. We also capped it with an oxygen barrier cap. So theoretically, it has never been exposed to oxygen. It was also filtered when transferred to the serving keg so we are also puzzled how it could become cloudy again. Could there be some mishandling of the bottles after the fact that could cause this? Can a beer become oxidized after it's been bottled? Like if it's left in a warm room or outside for long periods of time? We dropped off our beer directly with them for the competition but it was 2 weeks before judgement day.

  • 1
    That sucks. Yeah, oxidation can certainly happen after bottling. Crowns and seals aren't always perfect which can cause air ingress/egress as pressure inside the bottle changes with ambient temperature. The gray color does sound like oxidation. Any "wet cardboard" aroma? I have a pilsner in a corny keg which has been sitting at room temp for three months. Every few weeks I close-transfer a gallon into a smaller serving keg and chill it to 35F. It doesn't seem adversely affected by the temp changes. How about your water (wondering about Chloramines)? How does your filtering work?
    – HomeBrew
    Commented Oct 19, 2022 at 9:13
  • @HomeBrew, we did not detect any wet cardboard but one of the judges describe a papery flavor so it's probably there. Chloramines are a non issue because we buy RO/DI water and customize the mineral composition. The filter is a one micron water filter that gets sanitized and purged with CO2 before filtering. After reading your comment, we are now thinking that bad storage conditions are the likely culprit, we'll likely be waiting till the last minute to submit beer to future competitions, especially if they are as delicate as a pilsner.
    – daniella
    Commented Oct 20, 2022 at 16:14
  • The thing that has really puzzled me is how a filtered beer can become cloudy again. My husband has suggested chill haze but we're not totally convinced since filtering can resolve that also.
    – daniella
    Commented Oct 20, 2022 at 16:19

1 Answer 1


Yes- it can.

Chasing down oxidation after you've covered the basics is hard. Oxidation is typically perceived as starting once the beer is fermented... but that's not entirely true.

However the difference you're describing appears a bit extreme given the time and causes me to be a bit suspect. Do you still have this keg? Can you try to replicate the bottling and mishandling?

Most homebrew competitions are done by volunteers doing their best, and they're not always as organized as you might suspect. It is completely plausible that bottles could get mixed... but I wouldn't start throwing that around until you've tried to really confirm it.

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    I totally agree with you. Starting this post was the first step in trying to figure out where the problem originated. We brew this beer quite frequently as my husband has very particular tastes which has resulted in what I think is some of the best pilsner style homebrew I have ever had. Last night we brewed another batch for another competition and plan to bottle a dozen bottles and store them in various environments to pin down whether storage can really cause this dramatic change.
    – daniella
    Commented Oct 20, 2022 at 17:45
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    I want to point out that we've been involved in all aspects of various beer competitions, I know all too well, it's a volunteer run situation and since judges and entrants are barred from sorting bottles for judgement day, it usually means less experienced volunteers are frantically sorting hundreds of bottles. I agree too, that I wouldn't want to accuse anyone of mixing up bottles until we were absolutely sure that was the case.
    – daniella
    Commented Oct 20, 2022 at 17:49

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