so it took a little longer than anticipated to cool my wort yesterday in the 95 degree heat we had in LA and I left my rehydrated us05 sitting on the counter inside the house (which was at 75 with the air conditioner on) for maybe an hour and a half before aerating with O2 and pitching. This was yesterday around 430 PM. Checked the fermenter this morning and see a cluster of about a dozen tiny bubbles on the surface. Could be fermentation could not be. Not worried about it I have another packet I can pitch if fermentation doesn't start but my question is how long has anyone ever left rehydrated US 05 out before pitching? The instructions say to put in water and let sit for a half hour then stir for a half hour and pitch so I read that as from the moment the yeast touches the water you should pitch it in an hour.
Don´t worry your yeast will be fine, that extra time won´t hurt it too much, BTW did you cover the yeast during this elapsed time?, air conditioner could make some airborne microbes get into the pot you put your rehhydrated yeast
I agree with Esteban that the delay is not a big issue. Below is some ‘science’ courtesy of Dr. Clayton Cone of Lallemand (Danstar) on this topic: “We recommend that the rehydrated yeast be added to the wort within 30 minutes. We have built into each cell a large amount of glycogen and trehalose that give the yeast a burst of energy to kick off the growth cycle when it is in the wort. It is quickly used up if the yeast is rehydrated for more than 30 minutes. There is no damage done here if it is not immediately add to the wort. You just do not get the added benefit of that sudden burst of energy. We also recommend that you attemperate the rehydrated yeast to with in 15°F of the wort before adding to the wort. Warm yeast into a cold wort will cause many of the yeast to produce petite mutants that will never grow or ferment properly and will cause them to produce H2S. The attemperation can take place over a very brief period by adding, in increments, a small amount of the cooler wort to the rehydrated yeast.” Cheers!
Don't rehydrate US-05 it is a direct pitch yeast. I've seen no difference in beer quality now that I no longer rehydrate US-05.
I agree, but I still will re-hydrate. It's not that big of an issue to do and I'm not a 100% sure it's not better for the yeast in the long run. I just heat a jar up in the microwave the start of brew day, then check temp, add yeast cover when I'm finished whirlpooling the wort.
Just want to point out they give instructions on their website how to rehydrate US-05. Not saying that you have to do it. But they are there for a reason. http://www.fermentis.com/wp-content/uploads/2012/02/SFA_US05.pdf
Agree...kinda like saying, don't make a starter for dried yeast. While it may be unnecessary most all of the time, it's not like it's gonna hurt...just extra time & money if it is unwarranted.
Making a starter for dried yeast can of course hurt. A starter is unnecessary and can become infected. Your increasing the risk of adding unwanted microbes (not matter how small) for no real gain seeing as you already have the yeast cell count you want. Maybe if your dried yeast is old and you're worried about viability but at that point I would just buy new yeast because it is so cheap.
or maybe you don't since you're brewing 15 gallons and don't have easy access to a homebrew shop. Or you're brewing an imperial or you're yeast is old or you're brewing a lager. There are times and places where making a starter can useful even with dried yeast. And not sure what your practices are...but there should basically be zero chance of an infection if you abide by a few basic microbiology techniques that seems to have worked for hundreds of years for folks that work in that field.
I've already noted that the chance of infection can be small. Those examples seem more like a lack or preparedness and planning than anything else. You can provide a scenario in which most things are beneficial if you dig deep enough. Clearly I was responding to the situation the OP was describing . Also aseptic technique began in the late 19th century hardly hundreds of years.
