How the hell did my yeast survive having its sachet soaked in boiling water? O_o

hatrickpatrick

I brewed a UKBrew IPA kit today. For anyone unfamiliar, they're extremely basic 1.6kg kits which give a classic "any 'auld lager" type of taste, but can become incredible IPAs if you dry hop with a significant amount of a nice hop species. The kits come in sealed bags, I've attached a photo under this post.

The yeast for this kit comes in a sachet which is sellotaped to the bottom of the kit. When I brewed it today, I did the usual "stand the bag of malt extract and the bag of sugar upright in a saucepan, and pour boiling water around them so as to loosen the contents" routine. The stupidity on my part was that I totally forgot to take the yeast sachet from the bottom of the malt extract bag before doing this. I'd ordered two kits (I have 100g of Citra pellets so thought I'd split them 50/50 over two separate batches) and I assumed I'd have to use the yeast from the second kit, and for the first time attempt to save it from the trub after bottling to re-use in the next batch. I re-hydrated and pitched the boiled, presumed deceased, yeast from the ill-fated sachet anyway just out of curiosity, to see if any of it would have survived - but the water I poured into the pan was directly from a kettle as soon as it finished boiling and various sources informed me that the fatal temperature for pretty much any yeast strain is far less than 100 C. As I had left the bags to steep in the boiling water for 20 minutes, I presumed there was little hope for that yeast sachet.

To my utter shock, I'm currently (~8 hours later) sitting in my room beside my fermenter - which has been bubbling away since around 10PM, only four hours after I finished the brew and sealed the fermenter. I always oxygenate the sh!t out of my wort so I'm well used to very short lag times, but I'm truly astonished that this yeast survived. The fermentation isn't as vigorous as I'd expect on day one - it's bubbling at a rate more consistent with 2-3 days in when it's calmed down after the usual rapid-fire bubbling I get on the first day, but it's still bubbling every 4 seconds or so.

Dafuq is going on here? It totally defies logic that this yeast could still be alive. The only possible explanation I can think of is that because the base of the bag is slightly inset from the rim of the edges (to make sure you can stand it upright without it falling over) and because I stood it in the saucepan before adding the water, maybe there was a trapped air pocket underneath which prevented the boiling water from getting in? Even so, one would imagine that the temperature of the bag itself which the yeast was sellotaped to would have been enough to transfer into the sachet and kill whatever was inside it.

I boiled and oxi-cleaned the bucket before brewing (I'd left a forgotten litre of my last brew from a few months ago and it had grown some nasties so wanted to be sure) so while I suppose some of whatever infected that could have survived, I really doubt it - and I doubt it would be causing it to bubble this vigorously if that was what was going on.

Anyone have any ideas as to how this is happening? Interested to see what the FG is and whether it turns out ok! Supposing 90% of the yeast cells died and what I'm hearing now is the remainder which survived, presumably they'll still just reproduce to fill the (substantial) available oxygen and it won't make a huge difference in the end?

Interesting incident one way or another, has anything like this happened to any of ye before?

squawker

hatrickpatrick wrote: »

Interesting incident one way or another, has anything like this happened to any of ye before?

yes happened to me a few months ago

didn't seen the yeast attached to the bottom of the bag and plopped it into hot water to soften the wort for a good 15mins

Thought there is no way the yest survived but the Ale turned out fine

Victor

The packet and outer yeast (which likely died) insulated the yeast in the middle.

hatrickpatrick

squawker wrote: »

yes happened to me a few months ago

didn't seen the yeast attached to the bottom of the bag and plopped it into hot water to soften the wort for a good 15mins

Thought there is no way the yest survived but the Ale turned out fine

Fantastic! Hoping for the same!

Victor wrote: »

The packet and outer yeast (which likely died) insulated the yeast in the middle.

So does that have an effect on fermentation in terms of how much yeast was still viable going in? I mentioned in the OP that fermentation was slow, it's now picked up considerably and is now bubbling regularly, albeit in "bursts" of clustered bubbles every few seconds as opposed to the constant, rhythmic "pop, pop, pop, pop" I usually get on day one.

If I understand the process correctly, once the wort has been aerated prior to pitching, the yeast spend the first several hours (the silent hours as far as visible activity goes) multiplying like rabbits, using the oxygen as a catalyst - and only switch to consuming the fermentables when there's no oxygen left for them to use. Does this imply that even with a lot of the yeast dying as you've suggested, they'll ultimately still end up reaching the same numbers since those that remain will have kept multiplying until they'd used up all the oxygen?

And even if there's less yeast in there than there usually would be because of this mistake, does that necessarily mean that final gravity will be higher - or will the smaller quantity of yeast simply have more work to do and take a bit longer, but ultimately get to the same end result?

I'm honestly totally shocked that this is happening at all, I was all ready to pitch my second kit's yeast sachet this evening after (I presumed) waiting 24 hours without a single bubble

Victor

hatrickpatrick wrote: »

If I understand the process correctly, once the wort has been aerated prior to pitching, the yeast spend the first several hours (the silent hours as far as visible activity goes) multiplying like rabbits, using the oxygen as a catalyst - and only switch to consuming the fermentables when there's no oxygen left for them to use. Does this imply that even with a lot of the yeast dying as you've suggested, they'll ultimately still end up reaching the same numbers since those that remain will have kept multiplying until they'd used up all the oxygen?

That would be my vague understanding. One other factor to take into account is that by the time you have added the boiling water to all the other material, it is no longer boiling. Also, while boiling may kill organisms, it doesn't necessarily destroy their toxins.

And even if there's less yeast in there than there usually would be because of this mistake, does that necessarily mean that final gravity will be higher - or will the smaller quantity of yeast simply have more work to do and take a bit longer, but ultimately get to the same end result?

I suspect the final result might be a bit unpredictable. Note that the yeast continues to produce alcohol until the alcohol concentration is enough to suppress / kill them. However, any tainting with non-beer yeast may damage the brew.

sharingan

OP: you may encounter some under-pitching effects like yeast stress. It might also underattenuate or struggle to hit your expected FG.

Or you might just get away with it.

BeerNut

sharingan wrote: »

OP: you may encounter some under-pitching effects like yeast stress. It might also underattenuate or struggle to hit your expected FG.

Or you might just get away with it.

I've read that using any single sachet, however treated, is woefully under-pitching, but we all get away with it. There's not much point in getting too technical with a kit beer: there aren't any extra rewards for having your yeast game on-point.

sharingan

BeerNut wrote: »

I've read that using any single sachet, however treated, is woefully under-pitching, but we all get away with it. There's not much point in getting too technical with a kit beer: there aren't any extra rewards for having your yeast game on-point.

True - was answering the OPs question for completeness sake. But yeah, getting precious about yeast management in a kit beer is effort gone into the wrong place.

hatrickpatrick

Bottled this today, by some miracle I got to within 0.01% of my expected final ABV, 4.99% when it was meant to be 5! Turns out yeasts are hardy little feckers :cool: tasted a tiny bit and it was grand, although I find that flat beer tastes so spectacularly different to carbonated beer that it’ll probably improve significantly in the next few weeks

Thanks to everyone here for pitching in (....sorry) with theories and thoughts!

sharingan

Yeast is tough. Well done on getting through to the end and arriving at drinkable beer.

I pitched a lager last march that stalled. I added 2 more pitches of yeast to get it going again, and finally had to resort to using a dry beer enzyme (from WHC Labs) to break down the unfermentables enough to finish the job.

I kegged into a growler to bring to the Copper Coast Brewers meetup a week ago, but the remainder only got packaged this weekend. Thats like 4 months for a job that should have taken 4 weeks, and tied up the fermenter the whole time.

Its good to keep the faith. I now have a quite decent Helles type lager.