Help! Is my yeast spoiled

[Jkane101]

OK So in preparation for a PM Belgian Quad that I planned on brewing today, I made a half gallon starter using WLP500 3 days ago. Last night I popped it into the refridge thinking I may want to decant off the liquid and just use the yeast. This morning I go to the refridge to grab the starter and I notice that the cap is off...I dont know if I forgot to put it on or if it was jostled off by another family member. Anyway this could have been in the fridge uncovered for 12 hours.
So...do you think its contaminated?
would you use it?

I could run to the lhbs store and grab more WPL500 and pitch it straight into the wort, if I do this how many vivial should I use...2 or 3?

Just as an FYI this baby should have a starting gravity of around 1.098

 

[rsmith179]

Well... according to Mr. Malty's pitch rate calculator, you'll need basically 4 vials if you're going to pitch directly into your primary. Either that, or a 3L starter. With the starter's lid being open for a while, it is very well possible that there might be more than just yeast lurking around in the starter. After you pull it out of the fridge, take a little bit and sample it. Yes, take a small sip and smell it. Does it taste/smell like beer? If so, you should be good to go. If it smells like anything other than beer/yeast, throw it out.

 

[hukdizzle]

Well... according to Mr. Malty's pitch rate calculator, you'll need basically 4 vials if you're going to pitch directly into your primary. Either that, or a 3L starter. With the starter's lid being open for a while, it is very well possible that there might be more than just yeast lurking around in the starter. After you pull it out of the fridge, take a little bit and sample it. Yes, take a small sip and smell it. Does it taste/smell like beer? If so, you should be good to go. If it smells like anything other than beer/yeast, throw it out.

This advice may not be particularly correct due to the fact that starters will taste like ass due to being severely oxidized and most of the time fermented outside of the temp range needed. Being that this starter was in the fridge and not in an open area, your starter is more than likely going to be just fine due to the cold and small confined space.

Do you have a stirplate? If you do you could just cap off your wort and let it chill for 12-18 hours and then pitch it with a new starter. It generally takes about 12-18 hours on a stirplate to reach maximum bloom on yeast starters so if you could do that I would recommend that.

 

[rsmith179]

I guess I'll just agree to disagree dizzle. I would NEVER leave my starter in a fridge without the cap on. Maybe slightly loose to allow for escaping CO2, but never open. Yeah, I'll agree with you on the fact that a starter will not taste much like beer, but I will not agree that a "cold and confined space" does not harbor bacteria.

From, Bacteria in the Refrigerator | Mold & Bacteria Laboratories :

"Bacteria such as some Coliforms, Pseudomonas sp., Vibrio sp. and Listeria sp. and moulds such as Penicillium and Cladosporium sp. are all known to survive low temperatures..."