Short question -
Anything wrong with cold packing a yeast starter?
Long version of the question -
I really dislike making starters, but I need to make them as brew 12 gallon batches and lots of those are lagers that I used a 2 gallon starter for.
I have progressed to pressure canning my starters, works great, no boil overs takes about an hour total for 4 jars start to finish ( ½ gallon size jars). If I make a gallon starter I use 2 jars.
A few days ago I noticed I was out of jarred starter and needed 2 jars that day later on so I could pitch the yeast next day and did not have an hour to baby sit the pressure cooker. I then thought about “cold packing” like my mom used to do sometimes. So I boiled some water in my electric brew kettle, which was great cause I did not have to baby sit it and no worry of boil over. Added DME and a few hop pellets to my jars, came back later and added the boiling water to my jars and quickly screwed down the lids, shook the jars to mix the DME and left the jars to cool and they all sealed as expected. I was able to fill all 8 of my jars, not just 4 jars, in minutes, not hours and was still able to work in the yard with no fear of a pressure canner exploding. No more babysitting, Yes !!
So the question is –
See anything wrong with this process?
Are they any nasties that can survive the heat of boiling water left to slowly cool to room temp?
I’m no microbiologist, but I’ve always read and been told that unless you pressure can it you run the risk of botulism. Now, a lot of people will say they’ve been doing it without pressure canning for years and had no problems. But it makes you think they should have added the word "yet A pressure canner will get to 250F which is hot enough to kill botulinum in a few minutes. At 212 (regular boiling method like you propose) it will take 7-11 hours of boiling to kill them. Pressure Canning Starter Wort | The Mad Fermentationist - Homebrewing Blog
That is a scary risk. I think the NB product of pre-canned wort for starters is better insurance for me, or better yet, just boil up some DME each time I make a starter or just pull some wort at the end of the boil and chill and start with that as a starter with a later in the day pitch…
I hate starters too. I suggest using dry yeast. Use 2 packets for 12G or 3 for big beer. I think need for starters is a bit overstated.
Despite the botulism risk, my uncle has been canning his entire life and swears by the cold pack. He and I believe that if botulism presented itself, you would know. You could cold pack a starter without fear of botulism, provided the pH of the wort is below 4.6, which by no accident is the same requirement for packaged beer. https://www.fda.gov/Food/NewsEvents/ConstituentUpdates/ucm228244.htm
But packaged beer is fermented, which lowers the pH to that level. Starter wort is not. How would you know if there was botulism there since you can’t see it or taste it?
My cast out wort on typical beer is around 5ish. Wouldn’t be a problem to reduce this a little further 4.6. I think the risk of botulism is overstated. The same risk occurs every time you drink homebrew. But like I said, dry yeast all the way. There are just too many good options.
I know a guy who got botulism (not from starter wort)…that’s all it takes to make you realize it can happen to anyone who does that kind of stuff. 5 years later and he’s still suffering the effects. I have no desire to take any kind of risk with it. It just isn’t worth it.
Actually there is a way to kill the botulism and make a sterile wort without pressure cooking. It involves boiling, letting the wort cool, then boiling again 3 more times after 12 hour increments. The cysts and catalysts of the microbes start to bloom after 12-24 hours so continued boiling will eventually render the liquid sterile. Not that it makes any real sense to do that for a yeast starter.
The microbiologist in me (PhD in micro) says the likelihood of the DME containing botulinum spores is ridiculously low. The neurobiologist in me (the 17 years since grad school) says botulism toxin is scary as hell. You’ve got a pressure cooker. Why not just use it?
As for the pH thing, I don’t know how much I would trust absolutely that a pH less than 4.6 inhibits growth, even though that is on the World Health Organization website. There was a Nature paper in 1979 showing that the bacteria can grow and produce toxin at a pH less than 4.6 in certain substrates (specifically 3% soy or milk protein). That doesn’t mean they’ll grow in beer, but it also shows that the 4.6 number is not an absolute.
After chilling the wort I usually pick the remaining wort (with some of trub) of the bottom of the brew kettle and let it in a jar (covered with a film) in the fridge. The next day, when the trub has precipitated, I pour the clarified wort in a can and put it in the freezer. When I have to make a starter for the next batch, I boil that wort and add water and/or DME if necessary (in order to get the right OG) and after chilling, pitch the yeast as usual. Is there any risk in this procedure? I mean, any risk related with botulism.