Repitching dry yeast

[Terry_R]

Hi, SOS!!.... Im having a dodgy fermentation. It seemed to start OK but I think for some reason attenuation has been low and I've been stuck on SG of 1030 for over a week. OG was 1060. If I repitch another satchet of safale us-05 yeast into 5g batch will it work and finish the fermentation or will it not survive the alcohol already produce?
Thanks

 

[Covrich]

I would re-hydrate it first, you could even proof it maybe with a little sugar before dumping it in

 

[AdeDunn]

Did you pitch 2 packets to start with at all? I ask, as I know that Mangrove Jacks recommend 2 packets for beers over 1.050 OG in order to reach full attenuation, so could explain your stuck ferment.

 

[stigman]

+1 for Covrich. For 1.060+ gravity's I would always pitch two packets rehydrated, your asking quite a lot from 1 pack.

 

[BeerCat]

Seems odd it stopped that high. Did you have large temperature swings? What was the beer?

 

[Terry_R]

Seems odd it stopped that high. Did you have large temperature swings? What was the beer?

It's and English pale ale. DME and single hopped with east kent goldings. Yeah, temp was a problem with the very cold snap we had, I struggled to keep the temp in my brew cupboard much above 62F. Thats still within range for the yeast though so was hoping that would be OK.

 

[Terry_R]

Did you pitch 2 packets to start with at all? I ask, as I know that Mangrove Jacks recommend 2 packets for beers over 1.050 OG in order to reach full attenuation, so could explain your stuck ferment.

Just 1 packet pitched, sprinkled in dry. Sounds like thats where I've gone wrong. I'll hydrate another packet and drop it in. Thanks.... another lesson learned!

 

[Terry_R]

I would re-hydrate it first, you could even proof it maybe with a little sugar before dumping it in

Thanks. So to do this I boil up some sugar I guess, transfer to a sanitised jug, let it cool to 68F and pitch the yeast into it? How long should I leave the solution before adding it to the FV?

 

[BeerCat]

Balls its gutting when you screw your brew up. We have all done it. A lot of people are using crossmyloof pale ale yeast as its 80p a pack and you could of pitched 3 for the price of us05. Get yourself a brew belt and an inkbird or wire up an stc1000. Will save money in the long run. I have had hardly any spoilt batches since. Good luck with restarting it and let us know if it works.

 

[Drunkula]

Thanks. So to do this I boil up some sugar I guess, transfer to a sanitised jug, let it cool to 68F and pitch the yeast into it? How long should I leave the solution before adding it to the FV?

If you're talking about the already rehydrated yeast then yes, but dry yeast should be hydrated in just water at 35 to 40c. Not reverse osmosis or distilled water, either. After 15 minutes you could add some sugar. The proofing is just to see if it starts working and making bubbles, not for the actual feed.

 

[Terry_R]

If you're talking about the already rehydrated yeast then yes, but dry yeast should be hydrated in just water at 35 to 40c. Not reverse osmosis or distilled water, either. After 15 minutes you could add some sugar. The proofing is just to see if it starts working and making bubbles, not for the actual feed.

Got it, thanks very much

 

[Covrich]

Yes what he said get the boiled water cooled to around 30-35ºc put the dry yeast on top.. wait a few mins then gently stir in with a sanitised spoon.... then you could proof with sugar, it may just wake it up a bit.

 

[Duxuk]

I've heard that rehydrating leaves twice as many active yeast cells as sprinkling. I know it certainly gets going quicker.

 

[Wouter]

I've heard that rehydrating leaves twice as many active yeast cells as sprinkling. I know it certainly gets going quicker.

Interestingly enough, most people who I know who have experimented with it notice little difference.
On the Dutch forums there are some exps posted with split batches, one with dry yeast sprinkled on top and the other with dry yeast rehydrated first.
They basically found that the only difference is that the rehydrated yeasts starts fermenting a little bit sooner, approximately the amount of time it takes to rehydrate.

No difference in FG.
But then again there are a lot of variables to test.

But I do believe they are correct that if you pitch a normal amount of yeast it doesn´t matter much. Maybe if you´re really skint and use low amounts of yeast it matters.

 

[Drunkula]

Interestingly enough, most people who I know who have experimented with it notice little difference.

Do they have microscopes for eyes? And do they do it at the right temperature?

https://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/

In the first few seconds of hydrating the yeast cell walls don't act normally and anything can get through. In a high sugar environment it would be like me waking you up by forcing doughnuts down your throat. Sometimes you'll choke to death.

People not noticing a difference doesn't mean there isn't a difference. Rehydrating is so easy compared to the rest of the processes you do making beer that not doing it is wantonly ignorant unless you've got enough yeast to cover the losses or deliberately want the by-products of stressing the yeast.

 

[Wouter]

Do they have microscopes for eyes? And do they do it at the right temperature?

https://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/

In the first few seconds of hydrating the yeast cell walls don't act normally and anything can get through. In a high sugar environment it would be like me waking you up by forcing doughnuts down your throat. Sometimes you'll choke to death.

People not noticing a difference doesn't mean there isn't a difference. Rehydrating is so easy compared to the rest of the processes you do making beer that not doing it is wantonly ignorant unless you've got enough yeast to cover the losses or deliberately want the by-products of stressing the yeast.

I agree, quite difficult to really see whats happening at a microscopic level.
But you can compare taste, gravity and the time it took. If the resulting beer is completely the same I'd dare say that you can draw some conclusions. Even if the microscope gives you the impression that most yeast is dead then the fermentation shouldn't work. And yet, it clearly does for a lot of folks. Some critique could be given of your link as well. They look at microscope but do not follow the fermentation afterwards.

I'm not saying that rehydrating is nonsense by the way. I just find it fascinating that a lot of people (including myself quite often) just toss in the yeast and this works just fine.
My gut tells me, that it is especially important if your stressing your yeast anyway.

 

[Drunkula]

The just fine thing is just fine but for me it doesn't mean that you systematically should then avoid rehydrating yeast. It would be great to have enough brewday data to plot graphs of the amount of yeast pitched, the type, whether there was a problem like a stuck ferment, if the yeast was hydrated and what the hydration temperature was.

If it turns out you could avoid one out of every 20 stuck ferments because of rehydrating then I'd definitely do it. It's such a tiny step.

 

[Wouter]

The just fine thing is just fine but for me it doesn't mean that you systematically should then avoid rehydrating yeast. It would be great to have enough brewday data to plot graphs of the amount of yeast pitched, the type, whether there was a problem like a stuck ferment, if the yeast was hydrated and what the hydration temperature was.

If it turns out you could avoid one out of every 20 stuck ferments because of rehydrating then I'd definitely do it. It's such a tiny step.

Yeah I agree. But at the same time there is no need to panic if you choose to toss in some yeast without hydrating.

Yeah the problem with homebrew data is that not many people are very precise. Or if they are they simply don't have the time or capacity to test things.
Whose to say that certain yeast strains don't react badly to rehydrating. Or if the production process of the manufacturer is relevant.

Though on the subject of stuck fermentations. From all the questions I have seen so far about stuck fermentations its almost always the same. You ask "How much yeast did you pitch, and how old is it?". And then you calculate the amount of cells through Mr. Malty or something and the conclusion is "You have like pitched half of what is recommended".
Did you know professional brewers pitch about 10X what is recommended by the yeast manufacturers?

 

[-Bezza-]

John Palmer has the following comments:

Dry yeast should be re-hydrated in water before pitching. Often the concentration of sugars in wort is high enough that the yeast can not draw enough water across the cell membranes to restart their metabolism.

Lallemand/Danstar does not recommend proofing after rehydration of their yeast because they have optimized their yeast's nutrional reserves for quick starting in the main wort. Proofing expends some of those reserves.

As a case of best practice, by rehydrating your yeast, at least your able to prove it's alive rather than worrying if things aren't bubbling after 2 hours.

 

[AdeDunn]

I'd definitely re-hydrate, in fact I always do. I've observed a much shorter lag phase when re-hydrating vs not. I wouldn't proof dry yeast though, especially not with simple sugars. I've read plenty of books saying the same as Bezza, that they contain nutritional reserves etc that get used up. In fact in one book (might have been Brew by James Morton) the author reckoned that making a "starter" with dried yeast, rather than just rehydrating, often leads to a smaller cell count at pitching than you get rehydrating then pitching...

All of my books (I have quite a few now) recommend over-pitching in everything except wheat beers, where they recommend under-pitching in order to deliberately stress the yeast for flavour. That said, I once made the mistake of over-pitching using CML real ale yeast.... Turns out you really don't need 2 packets in a beer with a perfectly normal OG.... lmao It practically tried to climb out of the bucket....

A tip I picked up in my brief time brewing is to keep a supply of the various dried yeasts I use in the fridge. You've always got it to hand should you need it that way.