Yeast Starter

[NorsemenRugby58]

Can a yeast starter be too big? I ferment 5 gallon batches in 6.5gallon carboys. I've never really had a problem with the fermentation going through the airlock, or as in my most recent case, blowing the airlock completely off and into my ceiling.

These were my first runs using very large yeast starters. Before, I never used a starter (I would either use slap packs or just dump the dry yeast in and oxygenate).

Also,

I believe one of my American Pale Ales that I was making that fermented through the airlock got infected. The taste is sour, possibly green apple like...however, I do not carb with priming sugar, didnt use any extra fermentables, and it has been kegged for over a week and in the bottles a few days and still very sour.

Thoughts?

 

[SamBrewer]

when you say "Can a yeast starter be too big?" you mean that you are inoculating too much yeast? It's quite impossible to inoculate too much yeast in a homebrewing scale using starter as a yeast propagator; and the reason is simple: it doesn't have any sense to make 2 gal starter for a 5 gal beer...

There is no relationship between using an airlock and infections ( I'm assuming that you sanitize the airlock too ), maybe you have to pay more attention in sanitization in your brewing process

 

[NorsemenRugby58]

yeah, I guess my question is, could I pitch too much yeast after making a yeast starter that itd cause that problem. I think it resulted in my beer becoming infected.

 

[OvaTersley]

This article addresses both of you and your issues, very well.

 

[NorsemenRugby58]

Funny, I don't have reading comprehension problems. Perhaps I did not articulate my question correctly.

Question 1: Can a yeast starter (pitching a lot of yeast) be too big to cause my airlock blowing right off the top of my carboy?

Question 2: If the answer to question 1 is "Yes", do you think this would result in an infected batch?

 

[solbes]

Can the quantity of yeast cause the fermentation to be very vigourous, requiring more head space in the fermentor?

I would say yes. Especially with certain yeast strains. I have blown my bucket twice with 3787 (just 2 days ago on the second one). I pitched a lot of yeast in both cases.

2) Not necessarily. Usually when it blows there is so much activity going on, that even with an open fermenter you have a nice layer of foam and CO2 protecting the beer underneath. My first brew that blew did not get infected. So far I detect no ill smells coming from primary now, 2 days after the "incident".

There is still of course the opportunity for it to become infected being completely open. When I was cleaning up, all of the paper towels going around the opening got the Star San, as did a re-sanitation of the bucket lid.

 

[NorsemenRugby58]

yeah I am thinking that we just had poor sanitation. we were using the low foam star san, which I discovered requires more than regular star san. Since I have never had an infected batch before this, I don't really take into account sanitation...meaning I don't really think of it going through brew day or remember any details about what I did for that brew day other than the low foam. I probably didnt sani well enough, sani the airlock....but one of my questions was answered.

I wont be pitching that big a yeast starter in the future. Never had a problem with the airlock blowing off or getting bubbled through before, and I dont like the mess it makes. Thanks!

 

[erikpete18]

To (re)answer your questions, yes, it is possible to overpitch yeast and that can lead to off-flavors. If you're not already, check out the MrMalty starter calculator and use it to figure out how much starter to make. Over-pitching is gonna be better than under-pitching, but if you can get close to the suggested levels you'll be fine.

Overpitching won't necessarily result in fermenting out of the bucket, but more yeast can lead to a quicker fermentation which could lead to higher temps, which can lead to quicker fermentations, etc., until everything is coming out of the airlock. These high temps can lead to off-flavors unless you've got some good temp control. Fermenting that fast isn't necessarily a bad thing if you've got some form of temp control and a blow-off tube rigged up, it lets you know that your yeast is good and healthy, but you've got to pay closer attention to it.

As far as your off-flavor, it sounds like you are describing acetaldehyde. While it can be caused by an infection, it is also normally a byproduct of fermentation that is eventually cleared out by the yeast. How long did you ferment this batch, and how long did you age it on the yeast cake after it was done? Its possible that while you were done fermenting the yeast were still cleaning up for some reason when you moved it off. A good way to tell is to let those bottles and keg sit for a little while longer. Whatever yeast is left will clean up anything and it should improve. If on the other hand its an infection, presumably the infection should continue to worsen. Try them again in a few weeks and let them age a bit, and see if that improves things at all.

 

[NordeastBrewer77]

Funny, I don't have reading comprehension problems. Perhaps I did not articulate my question correctly.

Question 1: Can a yeast starter (pitching a lot of yeast) be too big to cause my airlock blowing right off the top of my carboy?

Question 2: If the answer to question 1 is "Yes", do you think this would result in an infected batch?

1) no. but an active fermentation can cause the bung to blow out like that. try using a blow off tube.

2) no, no it wouldn't