Lacto bottling

[radpotato]

Hi all,

A few months ago I made an old ale, which I then left for a full 6 weeks in primary before bottling. When I came to bottle (around 10 weeks ago) the beer was clearly infected with what looked like lacto, although the infection wasn't all that developed and the beer, while sour, was just about palatable. I decided to ride it out to see what would happen, from a 35L initial batch size I got around 30L of beer which was primed with 150g of brewing sugar, I guess the wastage was a little high which meant it might have been slightly over-primed.

I tried one last night and it turns out the beer is actually now quite nice - the sourness from the infection is only slight and works quite well with the residual sweetness from the old ale (a fair bit of crystal, roasted barley and treacle used). But every bottle is a gusher.

If the beer was sitting around for that long in the primary then I'd have thought it had fermented out, any thoughts on why the bottles are gushers? I've never purposefully used lacto or other bacteria before (and this is my first infected batch); is it possible that the infection got hold late on (I brew at a communal brewery so can't say for sure that someone else accidentally infected the beer). Or, will lacto cause enough CO2 just from the brewing sugar to make them gushers, in which case, how do you prime and bottle intentionally infected beer?

Cheers!

 

[millsbrew]

Before you bottled, did you take gravity readings? I'm just getting into sours, but lacto or pedio won't usually make bottle bombs unless you drastically over prime. My guess is the yeast wasn't done yet and you over primed. Rule of thumb is to make sure you have hit your final gravity with 2 readings at least a week apart.

 

[radpotato]

Because of where I brew being out of the way I don't normally take readings, rather I leave the beer to sit for quite a while and then do a simple comparison between what my recipe predicts and what I see in the reading; it's not caused any issues so far. The FG for this was 1.015, which seemed a little low given the high roasted malt content (and OG was 1.082). At the time I put this down to the lacto having dropped the gravity below what the yeast alone would manage (recipe predicted 1.026).

 

[tennesseean_87]

Ignore what a recipe predicts for fg. It should have been done after weeks if you had a good starter and aerated and everything.

You could try putting bottles in the fridge, get them cold, then open and immediately cap them (new caps) one by one. That will hopefully release pressure and even out the carb level a bit. This might not works if they gush violently immediately upon opening.