Greg Hughes Dried Yeasts are not suitable for reuse

[The Baron]

What are peoples thoughts on this as I know we call his book the bible but it is the opinion of one person who is revered in the brewing fraternity. It is a bold statement on page 33 of the bible and much as I use this book as a base line and have learnt so much from it I do find that in my mind this is a untrue statement - what are peoples thoughts on this and please keep on topic is not a dried versus liquid yeast topic. I only now use dried yeast and have pitched some maybe 2 or 3 times max as it is easy and does save a few pence and have never had a problem also which are the best dried yeasts to use more than once?

 

[Sadfield]

IMO the great advantage of dry yeast is its viability and ease of dosing the pitch rate correctly. Having the correct cell count of healthy yeast. Once you start reusing, you are no better off than with liquid yeast, where there is a greater selection of yeasts. And, It only takes an extra couple of reuses to negate the cost difference of liquid vs dry.

The best dry (or liquid) yeast to reuse? The one you like.

 

[Leon103]

The cost of dried is so little I see the effort to reuse isn't worthwhile

 

[The Baron]

I agree with reuse if a lot of effort is used i.e washing etc but I only store some slurry in a sterile bottle and fridge for a couple of weeks max if I am going to brew in the next 2 weeks etc. I do not generally reuse that often and only if brewing a suitable beer in the next couple of weeks it was just such a sweeping statement in the bible knowing people do use dried yeasts several times

 

[IainM]

Greg Hughes is wrong.

 

[MyQul]

The cost of dried is so little I see the effort to reuse isn't worthwhile

I would say, that depends how skint you are. Its like my thread about real wort starter. Yes I could go out and buy some LME or DME for a few quid but the price difference is quite a bit, so wanting to watch the pennies I use real wort starters. Some people can afford to easily buy an new pack of yeast every batch (In fact if you read some of the American forums some people use a new WYeast/Whitelabs pack every batch , even two!) some people cant. I even reuse CML yeasts.

Sorry Baron, wondered off topic (didnt take long did it ). Brewing knowledge and technology is always evolving. I think perhaps when GH wrote his book when some people advocated not reusing dry yeast as once upon a time drying and packaging were not as good as they are now

 

[IainM]

... or if you're making an obscene Imperial Stout and can't justify buying five packs of US-05, you can just brew a well-aerated mild with one pack and pitch onto the yeast cake. The cost of ingredients for the mild would be less than the extra 4 packs of yeast... so you save money and get another batch of beer out of it.

 

[Sadfield]

I think GH is technically right. Dry yeast are grown in a way that they need little from the wort to get going, but probably aren't that healthy by the time of the second pitch, which would be a mix of dried yeast cells and new cells from the growth stage. The second pitch would less healthy/viable than the first, and it may take three or four repitches to get to a point were all the original cells have died and been replaced by new cells that will synthesise the chemicals themselves in order to ferment. That's my understanding.

Theoretically bad practice. Probably negated by overpitching, which will often explain reports of later pitches, going off like a rocket.

 

[The Baron]

I would say, that depends how skint you are. Its like my thread about real wort starter. Yes I could go out and buy some LME or DME for a few quid but the price difference is quite a bit, so wanting to watch the pennies I use real wort starters. Some people can afford to easily buy an new pack of yeast every batch (In fact if you read some of the American forums some people use a new WYeast/Whitelabs pack every batch , even two!) some people cant. I even reuse CML yeasts.

Sorry Baron, wondered off topic (didnt take long did it ). Brewing knowledge and technology is always evolving. I think perhaps when GH wrote his book some people advocated not reusing dry yeast as once upon a time drying and packaging were not as good as they are now

Thats ok Mqul I do not expect the thread not to mention using other yeasts starters etc as long as explained by yourself it is part of the answer and not a true liquid to dry comparison which has been done many times I was just trying to get opinions re the statement in the book and is truly valid as you say everybody can not afford to buy new everytime and homebrewing is about being resourceful. I as I said only reuse now and then and only by the simple method of trub collection in a sterile bottle and fridge for a few weeks max. Being a Yorkshireman I can not see the point in throwing the yeast down the drain and buying another pack if I am going to brew a similar beer with a short time scale

 

[peebee]

I go with @Sadfield .

Liquid yeasts are fine. You pitch them, they do there job, and at the end you are left with yeast that's pretty much the same as was started with.

Manufacturers of dried yeast have to put a bit more effort into preparing the yeast for a tough process (i.e. the drying). Not all yeast strains tolerate this process. For those that do manufacturers can only be reasonably sure it will behave predictably for one brew. So for the manufacturers it's a no-brainer - don't suggest it can be used for more than one brew. For the users why not take the risk? Eventually a reused yeast will exhibit the reasons why the manufacturer don't want you to do it. And when it happens the manufacturer can say "told you so", and you're left on your own pouring a bad batch down the loo. I'd go with GH and just not take the risk to gain such small return.

 

[IainM]

I think GH is technically right. Dry yeast are grown in a way that they need little from the wort to get going, but probably aren't that healthy by the time of the second pitch, which would be a mix of dried yeast cells and new cells from the growth stage. The second pitch would less healthy/viable than the first, and it may take three or four repitches to get to a point were all the original cells have died and been replaced by new cells that will synthesise the chemicals themselves in order to ferment. That's my understanding.

Theoretically bad practice. Probably negated by overpitching, which will often explain reports of later pitches, going off like a rocket.

Perhaps I'm missing something, but I don't understand the logic here. I get that after fermentation the cells might not be in the best condition, but why would that apply to dry yeast and not liquid yeast? Perhaps there is another reason why dry yeast manufacturers recommend buying a new packet each time.

 

[Clint]

I wonder what that reason could be....??

 

[Sadfield]

Perhaps I'm missing something, but I don't understand the logic here. I get that after fermentation the cells might not be in the best condition, but why would that apply to dry yeast and not liquid yeast? Perhaps there is another reason why dry yeast manufacturers recommend buying a new packet each time.

Doing a bit more research, it appears to be an issue with oxygen in the drying process can cause a genetic mutation in yeast cells switch them from not requiring adenine to requiring adenine. Not sure what role adenine plays, but mutant yeast cells doesn't sound good. I guess this mutation happens when yeast cells bud, so the first pitch of dry yeast would contain the least mutations.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC216451/pdf/jbacter00258-0533.pdf

It also appears that dry yeasts aren't as microbiologically pure as liquid yeasts.

 

[Drunkula]

Somebody told me that they've been using the same S-04 for five years which really blew me away because they don't really do any management, hydrate yeast with sugar and leave it for an hour, and say that rehydrated yeast is liquid yeast. They never use any other types of yeast.

When I think solely of reusing I think about kveik yeast and that wooden ring snakey thing that looks like a half rotted badger's spine I tripped over in Weymouth.

It's like Mumm-Ra the ever living yeast:
https://draftmag.com/kveik-the-hottest-new-centuries-old-beer-yeast-youve-never-heard-of/

 

[IainM]

Doing a bit more research, it appears to be an issue with oxygen in the drying process can cause a genetic mutation in yeast cells switch them from not requiring adenine to requiring adenine. Not sure what role adenine plays, but mutant yeast cells doesn't sound good. I guess this mutation happens when yeast cells bud, so the first pitch of dry yeast would contain the least mutations.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC216451/pdf/jbacter00258-0533.pdf
It also appears that dry yeasts aren't as microbiologically pure as liquid yeasts.

I don't buy it. The mutation rate in the liquid yeast cells was 3 in every 10,000 cells, and the rate for the dried cells was 6 in each 10,000, so double the number of mutants, but double of almost nothing is still almost nothing. Even when they exposed it to high pressure pure oxygen for 20 minutes, it was less than 1 in 200.

The fact is, homebrewers and commercial brewers reuse dried yeast without problem all the time.

 

[BeerCat]

I reuse the slurry of dried yeast It's still the same as far as I can tell. Been using it over 6 months. Saves me a fiver or more a pop. Just bought some new stuff to compare. Interesting thread.

 

[BeerCat]

Somebody told me that they've been using the same S-04 for five years which really blew me away because they don't really do any management, hydrate yeast with sugar and leave it for an hour, and say that rehydrated yeast is liquid yeast. They never use any other types of yeast.

When I think solely of reusing I think about kveik yeast and that wooden ring snakey thing that looks like a half rotted badger's spine I tripped over in Weymouth.

It's like Mumm-Ra the ever living yeast:
https://draftmag.com/kveik-the-hottest-new-centuries-old-beer-yeast-youve-never-heard-of/

Great article. Have you tried any yet?

 

[Sadfield]

The fact is, homebrewers and commercial brewers reuse dried yeast without problem all the time.

This is correct. However, GH's view on suitably is also correct. The two can coexist, depending on your knowledge, experience and standards.

I'll repeat the point I made in my first post. The best dry (or liquid) yeast to reuse? The one you like.

 

[aamcle]

I've done it and will be doing it again in the next week or two.

34/70 for lager then reused it for Honey all and a Mongrel batch, next up is a lager followed by another very hoppy lager. I'll use the yeast from the first batch in the second one.

Aamcle

 

[Cwrw666]

I do it quite often. I find the second fermentation often finishes at a slightly higher FG than the first. But the beer is good so I can't see a problem.
As to dried yeast being so cheap - it's not that cheap. Apparently I did 24 brews last year (gulp) so if I'd have re-used the yeast I'd have saved about £20 or more.
Gervin comes in at just under £2 a packet - about the same cost as the pale malt in most of my brews.