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This is my 30th or so batch and I've never seen this before.

The best way I can describe it is that it looks like summer in the Arctic and pieces of ice are breaking off the ice caps.

Any idea as to what this is?

The beer is the Extra Special Bitter from Northern Brewer (extract). I used the Wyeast 1968 strain and made a yeast starter. I aerated with an aeration stone. I think I had a temperature problem with this one but can't remember. I either let the temperature spike on the 7th day of fermentation or I let the temperature fall too low on the 3rd day of fermentation (I had a Bitter and an ESB going nearly simultaneously and mixed them up...)


1 Answer 1


Yep, that's definitely an infection. It's likely that either the carboy had some unwanted critters lying in wait, or something got into the wort (e.g. fruit flies, missing the bung). Did you sanitize your carboy before pouring wort into it? Sometimes freak accidents do happen, but the temperature would have nothing to do with the possibility of an infection. That said, it can control the rate at which off flavors are produced and the infection spreads. The warmer it is, the quicker the flavors will generate.

Try sampling it. It won't hurt you. If it tastes alright, you have two options. One is to bottle/keg it and drink it quickly (the colder temperatures will help limit the spread), or if it's noticeably sour by now, let it sit for some time (i.e. months) and come back to it to see if the flavor morphs into something you like. If it tastes like garbage though, it probably won't get any better with time and you may want to consider moving on. Luckily bitters, while hoppy, aren't the hoppiest of styles out there, and it may become a pleasant accidental sour.

  • Interesting. I always do a PBW wash of the carboy followed by StarSan and have never had an infection before (hat I am aware of). I use an airlock with vodka. I think I'll sample it when I get home and follow your advice. Thanks. May 5, 2014 at 19:00
  • You're welcome. We are reaching warmer temperatures around this time of the year, which means there's greater potential for more airborne contaminants to mess with you. One thing to consider is your post-boil chilling time. It's needs to be quick, and it needs to be covered as best as possible. Fruit flies and other contaminants are going to love to fly near/into sweet wort and carry with them whatever bacteria that would harm your beer. The other thing you can control that can limit this is a short lag time in fermentation. Proper aeration, yeast nutrient, and yeast health is vital.
    – Scott
    May 5, 2014 at 19:50

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