yeast temp

I have a 5 gallon batch cold crashing. I plan on transferring it to a keg while I’m brewing.then reuse the yeast for the new batch I’m brewing. Does the yeast need to warm up much before I dump my new cooled wort onto it? It’ll be at around 40 degrees and the wort will be 63 degrees.

It’s probably best practice to pitch it when it’s close to the same temperature of the wort. That being said, I generally take harvested slurry straight from the fridge and dump it in the wort. It still ferments. This is one area where a little bit of “sloppy” technique really makes a pretty minor difference, in my opinion.

I’m guessing it works just because of pitch rate. If you’re pitching twice to 3x what’s needed, and kill half you still have more than enough viable. right?
I treat my slurry like original smack packs or vials, I take them out of the fridge at the start of the brew, and let them come to temp on the counter.

I let them warm up also. I also don’t pitch right away. I put the yeast and the fermenter down the basement or in the chamber and then pitch when they are the same temp. I have thrown them in cold though but not anymore. I never had a problem but why stress the yeast.

I’m with Porkchop on this; I don’t think it matters that much. Sort of like rehydrating vs. sprinkling dry yeast directly onto the surface of the wort, it will ferment fine either way in most cases. If often seems to take multiple factors being off or non-ideal to cause enough of a difference to notice with home brews.

That said, best practice is the not “shock” the yeast and make sure the starter or slurry is within 5C of the wort at time of pitching. Just like best practices is to always rehydrate dry yeast before pitching.

There is evidence that pitching yeast that is cooler than the wort is beneficial. For 15 years and hundreds of batches I have simply taken my yeast out of the fridge and pitched immediately. If it didn’t work I would have changed that a long time ago.