Old yeast fermented my starter. Now can I brew?

[Bisco_Ben]

So I picked up an old packet of the Wyeast Trappist HG a few weeks back for $1. I forget the exact date but it was very old. Now I made a starter on Wednesday and it took until today to completely ferment the 1.8 liter starter. The batch I plan to brew today has an estimated OG of 1.068. My question is, am I ok to use this yeast and brew this batch today? Or do I have to step the starter up again due to the very old yeast? I would love to get this brew going today so any insight would be very much appreciated!

 

[Bisco_Ben]

Also wanted to mention, this is going to be a belgian dubbel. So if I slightly under-pitched, wouldnt that be ok since many people purposely under-pitch belgian strains anyway?

 

[helibrewer]

I've done this before with lager yeast but I did a second step.

 

[richkev]

So, exactly how old are we talking? A couple of months... or longer? I'm curious about how yours turns out since I have some expired yeast in the fridge, also. I was thinking of starting with a 1L starter, and then just stepping it up to a 2L, if it's still viable.

Edit: mine is expired by 2 years. It's a Wyeast smack pack that's been in the fridge hiding. If it turns out to be viable, I'll probably use it on some extra grains lying around. Something to experiment with.

 

[philosofool]

If it took that long to ferment a 1.8L starter, I would step it up. No wait, I would tell myself that I should step it up and then there would be about a coin toss chance that I followed my own advice. I tend to **** things up by rushing them and that's why I have a keg of Buterscotch Porter in my keggerator right now.* (No, the fact that I'm having company for Thanksgiving is not a reason to think that the porter actually finished in 4 days. Hello, diacetyl.)

I know that's probably not what you wanted to hear, but a starter should finish in 1-3 days, and if it doesn't, that tells you something about the cell count of your starter.

In the future, I would recommend revitalizing old yeast with a 800mL starter and then stepping up to a 1.8L starter.

*It's drinkable, but it would have been a lot better with a 2 day rest.

 

[Bisco_Ben]

Thanks for your inputs. I went ahead and brewed without stepping up. I pitched the yeast around 9pm and it was fermenting well by the next morning. I now have had full blowoff and a vigorous looking fermentation. If that is any indicator, I think this is going to be fine. Will update on how it tastes in 6-8 weeks.