My SMaSH lager with Isaria 1924 malt recently manifested ridiculous amounts of protein precipitate - it looks like a snow globe in the glass! Luckily, I’m near the end of the keg, so it’s not too much wasted beer.
I’ve never experienced this before in my homebrew, and going by my notes I didn’t change anything with procedure. BrewTanB in the mash and kettle, Whirlfloc in the kettle, closed transfer into the keg, beer brewed at the end of September, keg kept cold, etc. I’ve kept other beers for as long or longer, so that’s not a major change here either (the beer is not even four months old!).
My guess is that I either got really unlucky with this batch and some weird quirk hit the beer, or perhaps the malt had some characteristic that led to this. I really liked the flavor of this malt, so I’ll probably give it a try again (and might see if this precipitate manifests in the second batch), but am curious is anyone else has had similar outcomes. Unfortunately, I don’t have data about the particular lot of malt.
I don’t have an analysis of the lot itself, although a general spec sheet is available via Weyermann. The Kolbach index range is somewhat broad (31 to 43), and it’s listed as of “medium” enzyme activity….but Munich, etc., also share this characteristic. I noted a lower than expected efficiency (~64% vs. my usual 68-70% for full-volume mash at this type of gravity) during my batch, so your comment makes me wonder if I didn’t have a slightly undermodified lot. My mash was at 154 degrees for 60 minutes, so I should have had full conversion in any other circumstance.
I had in my brew notes to consider a longer mash rest or decoction mash next time…which is what I’ll probably do. I really do like the flavors this malt brings, so am willing to give it another shot.
Great suggestion - yeah, I’m grasping at straws, too! This was just so far out of my experience….my only other encounters with this have been in commercial beers that sat in the can too long.
Is it possible that it may be caused from your fining agent used in the keg at time of kegging? I ask this because you stated the keg is near the end. I know you didn’t state that you used a fining agent at time of kegging.
Nope - not a bad suggestion, but the keg is securely in my keezer, only with other kegs, and the keezer is pretty stationary and out of the realm of bumping/shaking.
Like you, I have never seen protein-precipitate present this way. Were you able to assess the texture of these flakes? Are they soft and mushy? Do they disappear when the beer warms up? Could there be stuff caked in either the serving line or the dip tube?
Protein in beer by itself doesn’t really form much haze, let alone very discrete particles/clumps.
Looks like flakes of ice…but I assume you have determined that it’s not ice. I once had a slushy pour that looked somewhat like this, as my kegerator was too cold.
What is the pH of this beer now? Anything anomalous happen with the pH during brewing (if measurements were taken)?
Do you have the opportunity to look at the precipitate under a microscope? If this happened with one of my beers, that would be by my first stop.
If you can, once the keg kicks and you have opened it, report back what you see. Cheers!
I bought some Isaria malt in February and brewed a Landbier in October using 1/2 Isaria, 1/2 Barke Vienna. No precipitation problems with my finished beer, and looking at your process the main difference with mine was that I did a multi-step single decoction mash. I have a hard time believing that your mash caused the problem, but damned if I can think of a cause for this. One solution might be a shorter dip tube on the next one and pretend this never happened, haha.
It tastes perfectly fine (although off-putting with the flakes)….maybe a touch oxidized, but I can’t tell if that’s really or just my suggestibility with the visual flaw.
Yeah, I am thinking a different mashing regimen is probably the ticket.
I have a floating dip-tube, which makes it all the weirder! I plan to pull the keg over the weekend to see if it’s not just weird buildup in the line, but a quick visual in the keezer says otherwise.
FWIW, I recalled that I’ve seen this in commercial beers as well as my own. Doesn’t get us any closer to figuring out what and why, but it does mean that it can happen.
Yes! I had it happen most recently in a can of Munich Helles-style lager from Costco (produced by Deschutes Brewery); very similar, with lots of white flakes in the beer upon the pour. The can was older, but not ancient (although Costco doesn’t refrigerate their beer when out for sale, either, which is a bummer).
