Brand new home brewer here, just started my first batch last night and I'm afraid I might have already made a mistake. I started priming my yeast in a side bowl a few mins before my boil finished and didn't take into account the time to chill the wort, so the yeast ended up sitting around in water for close to 30 mins before I got the wort temp down. Will having the yeast sit in the water for so long mess up the fermentation process or anything like that? Thanks for the help
Room temp water? You'll be okay. I hope the yeast was covered, but if not, in the future that should be part of your sanitation regimen -- keep the air from the wort and yeast as much as you can. For 30 minutes it is hardly likely that a 'bug' in the air could have invaded your yeast starter, but it is a point to consider.
I assume you are talking about re-hydrating dry yeast and also assuming that the initial temperature of the water you put the yeast into was appropriate, around 90°F or so. I have seen recommendations on dry yeast packets range from 10-30 minutes in the warm water before pitching, so I don't think the amount of time should be a problem. And letting it slowly cool closer to the wort temperature you were pitching into while re-hydrating is probably a good thing. I used a packet of Nottingham not too long ago and if I remember correctly it instructs you to re-hydrate for about 30 minutes. I recall the yeast was visibly active before 20 (I could see it through the glass measuring cup) If anything, you did as well and probably better than just pitching it dry into the wort, which is also done and many people will say works just as well (although I prefer to re-hydrate, too).
As others have posted 30 minutes of rehydration is just fine. Below is something that Dr. Clayton Cone (of Danstar) stated which relates to this discussion: “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 within 15F 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!
I think one problem is that Dr. Clayton Cone (whoever that is, and I'm too lazy to look him up) described a process designed to reach a goal not necessarily consistent with making great beer, or with a homebrewer's goals for a particular beer.
