Help understand Yeast harvest

[bonk1972]

This is my first yeast harvest ...ive skimmed the foam off the top of wort over 2 days and was wondering if this is all yeast or only the very thin line on top and is this enough for my next brew ...TIA.

 

[Mikeyr]

Thin line on top is yeast

I typically use the yeast after fermentation or farm fresh yeast and split it up rather than top collect. More chance of infection with the later, but perfectly acceptable as long as you're careful.

What you'd need to do from here is arm yourself with more cooled boiled water and another sterilised jar.

Tip the beer off the top of you jar in the photo, add some fresh water, shake it up, let it settle, 30 mins or until most of the rubbish as settled, the yeast will be in suspension in the water. Pour that into your extra clean jar and let that settle. Pour off the liquid, fresh water rinse again if you;re fussy.

Store refrigerated

Your going to need a produce a starter with that much yeast. search "starter" on the site

Lots of info on yeast harvesting as well, just search, some very good youtubes as well.

Best of luck

 

[bonk1972]

Thanks for your help ive all ready added the cooled boiled water so i now shake and wait 30 minutes then pour off into a steryl jar ok thanks.. Would i get more yeast if i harvested the trub after bottling as im not keen on making a starter if i don't have to

 

[Mikeyr]

I get a lot.

Technically you should wash the trub and do the first settle etc to remove junk. If you're not real fussy and you have another brew ready to go of a similar style it's not unheard of just pitch the whole slurry into the new wort ...... otherwise just clean it up the same way. (I can feel the flames rising!)

Worth a bit of youtube watching ...... here's a cracker with the right accent!

Cheers

Mike

 

[Rocker1986]

I always make starters and harvest my yeast from them. So much easier than pissing about washing all the shit out of it from a full batch fermentation. All you need is an Erlenmeyer flask and a mason jar.

 

[Yob]

This is my first yeast harvest ...ive skimmed the foam off the top of wort over 2 days and was wondering if this is all yeast or only the very thin line on top and is this enough for my next brew ...TIA.

that looks really thick mate, id be reducing that to about 1/3 of the trub volume to harvest, its much harder to harvest when its as thick as that.

 

[kaiserben]

What are the downsides if the OP just pitched what's in that jar (after ditching most of the beer from the top)? And is it any different if your skimming the top as opposed to taking from the yeast cake post-ferment?

I ask because I rescued roughly 1/2 a yeast cake after a ferment. I swirled up the bottom of my fermenter, then poured yeast/beer through the fermenter tap into a sanitised mason jar. It's been in my fridge for a bit (will have been 3 weeks by the time I get to use it) and I'm wondering if I should forget it and go buy fresh yeast. (It's WLP029 for a Kolsch, so I suppose healthy ferment is crucial for the style?)

 

[Reman]

Some people do that, it's essentially re-pitching onto a yeast cake, except you've stored it in a bottle for a while instead of using it straight away.

Biggest issue I can see with that is your cell count and viability will probably both be pretty low, that's why most people don't use this method and use a starter instead.

 

[Yob]

3 weeks is fine for fridge stored.. I've direct pitched after months... Sure, not best practice but it fired and finished..

 

[Yob]

What are the downsides if the OP just pitched what's in that jar (after ditching most of the beer from the top)? And is it any different if your skimming the top as opposed to taking from the yeast cake post-ferment?

the downside is also he wouldnt get a grasp of rinsing techniques, nor how much viable yeast is in that slurry, it's likely to be an over pitch but that's not a real concern if brewing a pale ale or IPA for example, but may be with more ester driven styles.

Top cropping is taking the healthiest and most vital / viable of the yeast where collection and using the trub without rinsing can have up to about 5 generations of yeast not to mention all the dead cells, and trub etc...

 

[pablo_h]

What are the downsides if the OP just pitched what's in that jar (after ditching most of the beer from the top)? And is it any different if your skimming the top as opposed to taking from the yeast cake post-ferment?

I ask because I rescued roughly 1/2 a yeast cake after a ferment. I swirled up the bottom of my fermenter, then poured yeast/beer through the fermenter tap into a sanitised mason jar. It's been in my fridge for a bit (will have been 3 weeks by the time I get to use it) and I'm wondering if I should forget it and go buy fresh yeast. (It's WLP029 for a Kolsch, so I suppose healthy ferment is crucial for the style?)

Ale yeast is top fermenting (why they skimmed the krausen for it). The bottom stuff is trub (dead yeast, undesirable flavours, but sure there are some dormant viable yeasts there). But just like collecting yeast from the fermenter at high krausen rather than pitching on old trub, there's no good reason to pitch that much trub into a new brew.
You can, and many do add new wort to a trub. But if that was the intention, why bother with the risk and effort of top skimming in the first place?

 

[Feldon]

I get a lot.

Technically you should wash the trub and do the first settle etc to remove junk. If you're not real fussy and you have another brew ready to go of a similar style it's not unheard of just pitch the whole slurry into the new wort ...... otherwise just clean it up the same way. (I can feel the flames rising!)

Worth a bit of youtube watching ...... here's a cracker with the right accent!

Cheers

Mike

I like that video - well illustrated and straightforward approach.

One thing I do disagree with though is this: he says that when it comes time to take a jar of washed yeast out of the fridge to pitch into a new batch of wort you should let the yeast first come up to room temperature (see about the 11:30 mark in the video). His reasoning is to prevent "shock to the yeast" by chucking fridge temp (~4C) yeast slurry into relatively warm wort. I understand his reasoning because gentle changes in temp are regarded as better practice than sudden shocks which can cause the yeast to over or under-produce various biochemicals.

However, from reading various bits and pieces on yeast and how they recover from dormancy (eg. as a result of drying or low temperature storage) it seems it is now considered best practice to pitch the cold washed yeast directly from the fridge into the wort. To do otherwise might result in major yeast carnage.

The reason for this is the yeast, as they go into dormancy (eg. due to drying, low temp, or lack of food), produce large amounts of sugars. These are stored internally within the cell walls of the yeast as a future energy reserve for when the yeast will eventually exit dormancy when the external environment becomes less hostile (eg. wetter, warmer, or more food about).

Glycogen is an important sugar that is stored. But another one is trehalose - a molecule of which is made by the bonding of two glucose molecules together. Trehalose is thought to form a supporting gel-like substance in the dormant yeast cells which protects its organelles from getting damaged when the cell distorts due to dehydration, and protection from osmotic pressure when its moved from a dilute environment (eg. a jar of water) to a more concentrated environment (eg. fresh wort).

By letting the jar of washed yeast come up to room temp before pitching, the yeast cells exit dormancy (wake up) and become biologically active again, and this requires an immediate need for energy. It was long thought that it was the sugar glycogen that was first used by the yeast for energy as they came out of dormancy. But it is now understood that the yeast consume the trehalose first - and in doing so the yeast become very vulnerable to the osmotic potential of wort very quickly.

So if you leave the washed yeast to come up to room temp for hours, when you pitch it into the wort much of the yeast's reserves of the protective trehalose are gone and many of the yeast cells will be torn apart by the wort that can invade the cells by osmotic pressure.

This also has implications for those who chose to rehydrate dry yeast before pitching. If you are going to do it you have to do it properly or yeast will die on pitching. I think dry yeast makers say rehydrated yeast must be pitched within 30 minutes or so (while there is still enough trehalose remaining in the yeast cells to protect the yeast).

My 2 cents, but for an expert opinion, this is an old post by Dr Clayton Cone of Danstar Yeast in response to a question about cold pitching of yeast:

I have not seen any studies done using this protocol. If I had to take a guess it would be centered around the Trehalose content in the yeast cell. Trehalose seems to be an all around stress related factor. Almost immediately upon the cold storage of the yeast, trehalose begins to build up to help the yeast to adapt to its new environment. Upon pitching this stress factor assists the yeast to adapt to its new environment; warmer temperature and higher osmotic pressure. If the pitching yeast is allowed to warm up for any appreciable time before pitching the carbohydrate reserve, trehalose being one of them will be quickly used up as an energy source. The yeast would then take a longer time adapting to its new environment in the wort thus increasing the lag phase.

Something similar happens when using Active Dry Yeast. The factory builds into each yeast cell an abundance of the stress factor; trehalose. Our recommendations is to rehydrate the yeast in warm water and pitch into the wort (or must) within 30 minutes, because the yeast will begin to metabolize its carbohydrate reserve including trehalose immediately upon reactivation and weaken the yeast if it is not in the presence of a new supply of energy. It will have also used up the stress factor that would have assisted it in adapting to the new osmotic environment. I am sure that there is more to the explanation than I have given.

http://www.danstaryeast.com/articles/pitching-temperature-and-nutrients

 

[kaiserben]

Kinda related to my earlier questions about saving & storing a yeast cake, I've planned ahead to make a Bock. My erlenmeyer flask simply isn't big enough to easily get to as many cells as I will need, so I decided to make a Helles first then use the cake for the Bock.

My steps were as follows:

Bought WLP830 yeast.
YeastCalc suggests the Helles requires 411bn viable cells.
I made a 2.7L starter from the yeast that was 43% viable on stir plate to get me to 423bn viable cells.
Chill starter and discard spent wort.
Pitch resulting starter into 23L of Helles wort, which, treating it as another starter step, YeastCalc estimated would give me 1398bn viable cells.

And from there, for the next batch (Bock) I'll require about 600bn viable cells (and I'd rather pitch a bit over that).
I'm assuming some of those 1398bn cells will die off in the 4 weeks before I access that cake for the Bock batch.

What's the best way of handling this last part? Timing it right means I'll have the option of pitching the Bock wort directly on to the yeast cake from the Helles. But should I worry about discarding dead cells? Washing? Etc.

 

[kaiserben]

So - should I pitch my bock wort directly on to a yeast cake? Or try to harvest and hope I get in the right ballpark of over 600bn viable cells.

EDIT: I think what I'll do is wash/harvest as much of the cake as I can and see how much yeast remains after washing. I'll estimate how many viable cells I reckon I have (hopefully I'll have more than enough). I'll store the resulting jars of yeast in fridge for about 3 days before I'll need to pitch them.

 

[Reman]

I would just pitch on the cake, it's just like you've done an extra big starter. There will be plenty enough viable yeast to do a bock.