How long is a yeast starter good for after you make it? I made one on Thursday night and was planning on brewing on Friday. Something came up with work so I didn't get to brew Friday. I had an out of town wedding to go to on Saturday and didn't get home until about 5PM today. I have the day off tomorrow but didn't know if the starter was still good to use after about 80 hours of sitting on the countertop.
It will be alright. You'll have less cells due to the time sitting at room temp, but it was growing during the first day or so. Put it in the fridge overnight. If the yeast flocculate well overnight, you can decant and use just (mostly) the yeast.
I think the more important question is why are you doing a starter in the first place? I mean, what are you looking to get out of your starter? If it's a starter for an average gravity beer, and you're just looking to "jump start" the yeast, then it seems counter productive to make a starter 5 days--a full fermentation cycle for an ale--ahead of pitching. I make my starters 12-24 hours before I plan to pitch, in order to have a thriving yeast colony ready to demolish my wort. On the other hand if you're just looking to purely increase cell count, then I could see not being as anal about pitching promptly and going through the refrigerator, decanting, etc.. I recommend having your yeast rip roaring and ready to go when you pitch. For this, I wouldn't pitch anymore than 24 hours after making the starter. It's good to use (barring contamination), but I don't believe you're getting the most out of after multiple days of sitting on the counter.
What if you make a starter and don't brew until 55 hours? I don't have a stir plate and use the shake periodically method. Would you recommend putting it in the fridge 24 hours to brewing or leaving at room temp for 2+ days would yield the same results?
Depends. If it seems done (not much foam when you swirl) and you have at least ~24 hours to go before pitching, I would crash and decant, assuming a very flocculent strain. My rules of thumb... Fast flocculators: 24 hours Medium flocculators: 48 hours Slow flocculators: 72 hours YMMV.
It had high krausen earlier and now a bunch of yeast has flocculated on the bottom, so it would appear to done. Also, no foaming any more when I swirl it. Brewing tomorrow evening so I'll put it in the fridge...thanks!
