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hydrating US-05

Started by Motorbikeman, February 16, 2016, 06:16:12 pm

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February 16, 2016, 06:16:12 pm Last Edit: February 16, 2016, 06:55:08 pm by Motorbikeman

Planning a brew later this week.   

I have read that rehydrating dried yeast can give better results.    I have never done this before. 

How does this make it better?   

Will it be just fine pitching at 20 degrees. Or should I go cooler? 


The theory behind rehydrating is that it's better to do it in water than in your wort as the sugars in the wort inhibit the amount of water the yeast cells can draw in.

Pitching at 20 degrees is fine.

Leann ull

Just follow instructions in the packet different manufacturers recommend different procedures.


I used to rehydrate US-05 but I haven't bothered for a while. It doesn't make a detectable difference. My numbers are still hit all the same and I detect no difference in flavour.
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Quote from: Motorbikeman on February 16, 2016, 06:16:12 pm
How does this make it better?   

Faster start, which means quicker pH drop, alcohol production etc. Less chance of nasties creeping in.
But the main reason is that it's good for general yeast health, resulting in a cleaner ferment and better flavour.

Leann ull

Sprinkling on the foam has same effect and isn't that what that producer recommends?


No, not according to this:

From my own experience, the rehydrated dried yeast does take off quicker, so that's why I keep doing it.

Most of the brewing boffins (Jamil et al) recommend also recommend rehydrating dried yeast, as pitching directly into wort reduces its viability.

Leann ull

What's on the back of the packet?


My rule of thumb is, if the packet says 'Sprinkle contents directly onto wort', and the batch is 19L or less, I do what it says.
If, I'm pushing the batch to 22-23L and the yeast is close to sell by date I'd then consider rehydrating.

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Quote from: CH on February 17, 2016, 01:17:39 pm
What's on the back of the packet?

I dunno. It surely doesn't contradict what's on their website, does it??  ???

Leann ull

Doses for pro v HB batches
Can somebody post a pic?


I'm pretty sure Notty packets instruct brewers to sprinkle, but the pro brewers (buying in large volumes) are instructed to always rehydrate. Always thought this was weird.

Thought Fermentis were different, but open to correction if someone can post a piccie.




Liquid yeast doesn't come with a lot of active cells, so a starter is needed to build them up. Dried yeast comes with a lot of potential active cells, so to get the best out of it you may need to rehydrate. Dry yeast doesn't like sugar solution in which to do this, so if you were to drop the dry yeast straight in the fermenter you could lose some 40% of potential cells. By rehydrating in water before hand, you lose only a fraction of that. To rehydrate, cool 10 times the yeast weight of pre-boiled water to about 30 degrees, and add the yeast (all sterile and loosely covered of course). Don't pour in to your fv unless within 5 degrees of the wort.


Can post a pic later, but I used us-05 on Sunday night. Instructions on pack said sprinkle onto wort.