Might be a weird question!

I have brewed, with a friend, 6 batches of beer so far. An IPA, then a Stout, a Saison, a Doppelbock, an Baltic Porter and finally, the same IPA. All grain, always.

Of all these, only twice we had that weird white film over the beer in the carboy, in the second fermentation. It comes with a few white bubbles. there are some lines of that white that are traced, a little bit like a spider web.

Either we got infections in both, or... the dry hopping creates that? Is that possible?

At least I know now that even if it's an infection, I just bottle the beer underneath the pellicle :)

EDIT: Here is the picture

  • possible duplicate of Sanitation & Dry Hopping
    – Scott
    Mar 10, 2014 at 4:33
  • Are you using a muslin bag or introducing something else other than hops to the beer alongside the hops? It would appear that you need to revisit your sanitation practices in order to prevent future infections.
    – Scott
    Mar 10, 2014 at 14:00
  • Yes, I am using a muslin bag, which I boiled for around 15 minutes prior to putting hops in it. All this is clearly a result of bad sanitation somewhere, but I'm not too sure where it could have happened. Mar 10, 2014 at 17:18
  • It could have absolutely nothing to do with the dry hopping. Are you noticing this with a certain set of buckets/lids? Are you racking it to a secondary? Siphons? Hoses? Any of the above could expose it to bacteria if the equipment isn't cleaned and sanitized.
    – Scott
    Mar 10, 2014 at 17:27
  • I might want to make sure that all the materials are cleaned very nicely for the next batch, but that day we brewed 3 batches with the same equipment, and only this one shows signs of infection. The carboy, bucket and lid are almost new. Yep it's in secondary. Mar 11, 2014 at 14:30

4 Answers 4


Dry hopping does not on its own create the conditions you describe, which sound very much like a pellicle.

  • Dry hopping doesn't create the pellicle, but I have noticed that the only time I've ever gotten one in the primary was in dry hopped batches. Fortunately, the beer didn't seem to be affected.
    – GHP
    Mar 10, 2014 at 12:09

If you bottle the beer under the pellicle, make sure you open one every now and then to check for gushers. If you get them, pitch it all--otherwise you may end up with bottle bombs.

Or, put that in a glass carboy and leave it in a closet for a year or two. Maybe it will turn into a good sour. You can always throw it out later.


Yes I think this infection can be cause by hops because I already got the exact same situation. I boiled the muslin bag, but not the hops (I didn't want to lose flavour). It never happened to me before or after, so I don't think it was a cleaning problem.

As I remember, it was smelling really good, like fresh bread! I tried to remove the white film with a spoon, which didn't work well.

Try to bottle it anyway, and with the smell and taste, you will know really fast if it is good or not. In my case, it was one of my best beer ever! But may be I was just lucky.

  • It's so unlikely that the dry hops caused the infection that I think you should consider other causes. Not only do hops have antibacterial properties, but the technique has been used for centuries. If it caused problems that would not be the case. I myself have dry hopped at least a couple hundred batches of homebrew and I've never gotten an infection that could be traced to the hops.
    – Denny Conn
    Mar 25, 2014 at 17:38
  • I would agree with Denny for the most part, but one may wish to question the provenance of the hops used; current year vacuum sealed pellets, fine, two year old flower hops in a ziplock from a buddies skanky freezer, eh, not so certain.
    – Dale
    Mar 28, 2014 at 16:31

Dry hopping has a chance of introducing the bacteria that have formed this film, but does not itself cause it. If the brew is still tasting good, keg it and drink it, so long as you have alcohol in there then no pathogens will be able to replicate. I would not bottle as there is a chance of them going Bang!

Sometimes these accidents can create great sours. I have had a English IPA get a bad lactic case of lacto contamination, and I decided to try something new. I treated it with Brett, as Brett would turn some of the lactic acid into esters. I had to leave it an extra 6 weeks for the Brettanomyces to do its thing, but once it had been left and settled, it was one of the best beers I have ever made.

Well I didn't really make it the Lacto and Brett made it.

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