Infection questions

[Oneiroi]

Hi Guys,

I'm sure you get this a lot, but I couldn't find the specific answers I was looking for.

Just brewed my 3rd batch. All grain, BIAB, decided to go back to basics to work on the processes so a single malt, single hop pale ale. Anyway....

Went to bottle yesterday and there was a fine layer of what looked like white dust across the top of the beer. There was a bunch of hop leaves (transfered from the boil kettle) + a hop bag from dryhopping floating around the surface so it was hard to see if there was any larger lumps or strands but it looked like just dust. (Unfortunately I didn't think to take any photo's)

The beer smelled fine and tasted ok, so I primed and bottled it and stuck it in a dark cupboard at about 18c.

My 3 questions are:

1. I have been assuming the white dust was the start of a pellicle from infection. Could anything else have caused it?

2. Do all infections spoil beer, or do some not affect taste/smell?

3. Could I in theory of moved the beer to a kettle and heated to say 65c/149f for half an hour to kill any infection without boiling off the alchohol. Then added some fresh yeast with the priming sugar and bottled. What would be the negative effects if I did this?


Some more info incase it helps:

3 galons went into the fermenter at 1.052.
Pitched 1 satchet of rehydraded Safale-04 - active fermentation/krausen after ~12hrs
7 days in primary at 18c/65f - f.g 1.012
Added 2oz whole leaf centennial in nylon bag
7 more days in primary at 18c/65f
Noticed Infection!
Bottled

 

[Ashevillain]

If the beer smells and tastes fine it is most likely fine, even if there are wild yeasts/bacteria inside. Most unwanted yeast/bacteria is going to create unpleasant flavors. In theory i think reboiling the wort would be a wasted effort if the beer is fine. A pellicle is only a sign of oxygen in the fermenting container, if there is considerable headspace that will lend itself to pellicle formation. Pellicle formation is common with brett, lacto, acetobacter, and other wild yeasts, but cannot a direct indicator to any particular microbe, and can occur with saccharomyces in some cases. You mainly want to know that it wasn't mold, check out these wikis from milkthefunk. http://www.milkthefunk.com/wiki/Pellicle http://www.milkthefunk.com/wiki/Mold

There are some pretty good picture references in here to determine your pellicle wasnt mold, but IMO sounds like your good to go. Also fun fact, if you do end up with a batch that has some off flavors due to suspected infection, try adding brett. Infection doesn't always mean the beer is unsafe. I just had an IPA that got infected and had some butyric acid which smells and tastes cheesy, brett can convert butyric acid into a ethyl butrate, a tropical fruit aroma/flavor. It can convert many other things that may be considered off flavors as well.

 

[mredge73]

Most posts like this are false alarms, this one looks the same.

1 The "dust" could be anything, most likely going to be oils or something that came off of your dry hops.
Infections usually form early as alcohol is toxic to pretty much everything; new infections this late in the process are rare.

2 Mold/Mildew is pretty nasty and can ruin a batch, but a wild yeast will just change the flavor profile a little.
Acetic acid bacteria will convert alcohol to vinegar, you can use your beer to tenderize meat if that happens.

3 I would watch the FG for the next couple of days and see if it is still moving. If not, proceed with your normal bottling routine.
I would also toss the batch before I would pasteurize it. Trust your tongue/nose; if everything taste right then it is probably fine.

 

[Oneiroi]

Thanks both for your replies, all the info I was looking for and obviously lots to learn.

There was a ton of headspace in the fermenter so that might be something to think about I guess as well as cleaning processes, though hopefully it will just have been something off the dry hops as suggested.

Good to know I didn't do the wrong thing by not pasteurising too.


Beers bottled for 4 days now and no sign of any growth inside the bottle, though I guess that's not saying much.

I guess its all part of the learning process