Yeast pitching temp

[hlmbrwng]

I'm a bit confused by some information I have read about pitching temp. I have read, in the same book, that:

1. the temperature of the yeast should be the temperature of the wort or lower
2. one should prepare the yeast, from a dry packet, about halfway through the boil (so with about 30 minutes left)
3. the dry yeast should be hydrated in previously boiled water that is now 95-105 F

My question is this. If the yeast is added to water that is, let's say 95 F, will the temperature of the yeast really get down to, say, 68 F by the time it needs to be pitched? If not on its own, what would one do to decrease the temp of the yeast?

 

[ncboiler]

I'm a bit confused by some information I have read about pitching temp. I have read, in the same book, that:

1. the temperature of the yeast should be the temperature of the wort or lower
2. one should prepare the yeast, from a dry packet, about halfway through the boil (so with about 30 minutes left)
3. the dry yeast should be hydrated in previously boiled water that is now 95-105 F

My question is this. If the yeast is added to water that is, let's say 95 F, will the temperature of the yeast really get down to, say, 68 F by the time it needs to be pitched? If not on its own, what would one do to decrease the temp of the yeast?

You don't use a lot of water to rehydrate yeast, so by the time you pitch it, it will be around room temp. I usually rehydrate near the end of boil because it takes me at least 20 minutes to cool the wort.

 

[lilbova3]

You're using such a small amount of water that it shouldn't take too long to cool it down. I believe it's 10 mL per gram of dry yeast. Double check me though.

They say to make it 30 mins prior because with rehydrating dry yeast you'll sprinkle the yeast into the warm water and let it sit for 15 mins, then stir, then sit another 15 mins. Then it's rehydrated. Whether it's cool enough to pitch or not is a different story. I would only make it 30 minutes before if you can cool your wort down from boiling to pitching temp ASAP. It takes me a lot longer so I make it once I know for sure my wort is at pitching temp.

If it's not I've put some sanitized foil on top of the container that held the yeast and popped it in the fridge for a little to get it closer to 60*ish

 

[hlmbrwng]

I'm glad you mentioned that. That leads me to another question. I am about to do an imperial stout and shooting for about OG of 1.125. I was just going to use 2 packs of US-05 (maybe even a bit extra to get over 400 billion). I typically see 1 cup of water for a pack. What would you do for multiple packs? A cup per packet? Or does it not scale up linearly?

 

[lilbova3]

I added to my previous post above too about timing when to rehydrate. FYI.

I would think it scales linear, if I was doing it that's what I would do but I've never pitched two packets of dry yeast. The important thing to know for a big beer like that make sure you're pitching closer to 1 million cells per mL Plato rather than the standard .75 million cells per mL Plato due to the high gravity. Use the Mr Malty website to figure exactly what you need and how much. Brewersfriend yeast pitching calculator would be good too.

 

[lilbova3]

BTW, I've read that with a beer that big with such a high OG it might be good to supply the beer with oxygen twice. So whether you have an O2 stone or just shake it, make sure to give it a good shake before you pitch (at least two minutes) and another shake about 12-24 hrs into active fermentation. This will help assure yeast health and proper attenuation.

I just did a BIAB stout with an OG of 1.080 and gave it a shake about 12-16 hrs into fermentation so we'll see what happens.

Don't worry about oxidation because the yeast will still be quite active and clean up the oxygen. It's more for their health.

 

[hlmbrwng]

Thanks for the info.

I will be aerating with a wand using pure oxygen. Like you said, I will be doing it twice: once at pitch and once at 18 hours

Any idea how long I should be aerating with pure oxygen? I saw a video showing 30 seconds (Northern Brewer?), but with a bigger beer, should I be doing it a bit longer?

 

[lilbova3]

Probably closer to 60-90 seconds first go around. Second go around I would think not so much.