Harvested yeast question.

[BitterSweetBrews]

I may be jumping the gun here but I am wondering something.

I was cleaning out my fridge of some old harvested yeasts. I found some Pacman yeast, I originally harvested from a Rogue bottle 3 or 4 years ago. I have some frozen and some I found in the fridge that I harvested from a 3rd gen batch about 21 months ago. I decided to see if it would come alive to use in a batch in a week or two.

I pitched the dregs into a pint starter that was at about 1.030. After 36 hours it appeared to be going great. I was pretty surprised that 2 year old refrigerated yeast was doing so well, so fast. I took the attached picture. Today, I added another pint of 1.040 starter wort.

My question revolves around the smell. It smells sour and not really yeasty. It also tasted tart. I know part of this is because it is concentrated and not really hopped. The first wort was canned and i think had a hop pellet in it. So should I be concerned? Did it take off so fast because it is infected?

 

[tgolanos]

Tart and sour would concern me in my yeast starters. If it were me, I would't use it. Who knows, though - you could have an interesting experiment on your hand.

 

[Gnomebrewer]

I wouldn't use it after that period of time. Just because it becomes active doesn't mean that the yeast are what you want. Tart in that short amount of time suggests some bacterial activity.

 

[BitterSweetBrews]

I wouldn't use it after that period of time. Just because it becomes active doesn't mean that the yeast are what you want. Tart in that short amount of time suggests some bacterial activity.

It has pretty much finished up the starter. I tasted the starter beer and it is not bad (for starter). It isn't sour at all now and smells OK. Not real yeasty, but OK. I think I will try it on a small batch or part of a larger batch for kicks.

 

[BitterSweetBrews]

I brewed Sunday. After crashing and decanting I pitched the starter Sunday night. I started fermenting at 65 and lowered it to 62 after a day. There was a good layer of kreusan after 24 hours. After 48 hours it was really bubbling in the blow off (it never went past the headspace in the fermenter). I checked gravity and it was already 46% attenuated (from 1.055 to 1.036 - I think). So far it tastes pretty good and normal for what I would expect with Citra, Amarillo and El Dorado hops.