Yeast Starter Question

[Otto Von Blotto]

It sounds like it's fermenting if there is gas being released, so it should be alright. I don't get krausens on my starters but they are on a stir plate so that would explain it. Usually I just get a ring of bubbles around the edge of the mixture.

 

You should be able to smell any problems though. Normally starters tend to smell quite bready/yeasty, as opposed to the remnants of a batch of beer which often smell different. I decant the beer off my starters and it does smell a little funky, but the yeast itself always smells fine. That one batch I had the mould in, the starter for that definitely smelt bad, although I didn't realise it at the time because I'd never done one before. I just thought it was the spent beer.

[Canadian Eh!L]

Hey lusty

 

I'm not sure about your starter being infected. You'll have to taste it to find that out. What I do believe is that you can't get great results with a 2 litre starter if you don't step it up from a smaller volume first. Think of it like an under pitch in your brew. If you think your cell count is low to start with then you should start with 1 litre or less and step it up at 500ml at a time.

 

I hope this helps

[Otto Von Blotto]

Which is exactly why I just decided today to make a small pint sized starter for a jar of yeast I harvested from the previous starter. I only ended up with about 10-12mL of yeast (was only a 200mL jar), and I wasn't too keen on pitching that into a 2.5L starter. Basically all I'm doing with this mini one is growing some more cells and putting the whole lot into a pint jar, and storing that until I am ready to make a starter for my next batch, which will probably be in a couple of weeks time. It should hopefully end up with a similar amount had I had a pint jar for the original harvest.

[Beerlust]

Hi Chad & thanks for your input here, it is appreciated.

I'm not sure about your starter being infected. You'll have to taste it to find that out. What I do believe is that you can't get great results with a 2 litre starter if you don't step it up from a smaller volume first. Think of it like an under pitch in your brew. If you think your cell count is low to start with then you should start with 1 litre or less and step it up at 500ml at a time.

 

I hope this helps

What you said makes some sense to me' date=' but there is a facet of stepping up I admit, I don't fully understand.

 

I've actually let the starter fully ferment out. Today it has begun to clear with the yeast dropping out of suspension.

 

In regards to stepping up starters, I admit I do find this a little confusing on the merit of it. I admit to being a complete novice here though, so bare with me. [img']innocent[/img]

 

A starter (to me at least) is a way of determining yeast viability & a means to step up cell counts (right? ) If you restrict the amount of fermentables, surely the cell count can only increase by so much each time through the stepping up procedure, that would only equal the same amount of fermentable material used at the same stage (through multiple stepping) attained with a larger starter to begin with.

 

I'm probably missing something here, but right now, I don't know or understand what that is. All I know is that there is a crap load of yeast at the end of a full 20+ litre fermentation that equates to approx. 4 times that of what was pitched. The problem I'm having a hard time understanding is how a multiple stage stepping up routine using the same amount of fermentable material as what would be used in one starter of full volume (say 2 litres), can possibly create a larger cell count prior to pitching in the main brew wort (20+ litres).

 

Cheers,

 

Lusty.

[livebynight]

Does anyone have any advice on yeast starter vs. non-starter debates? Since i have done some reading on starters due to trying to reinvigorate a yeast past its used by date, i noticed that starters increase the cell count. So does a higher cell count mean a 'clearer' beer? Or slightly better tasting? Or just means fermentation will begin/complete quicker with more cells?

[Canadian Eh!L]

Hey Lusty

There is some good info out there on the subject of "why step up a yeast starter?" As a Google search. Basically, it comes down to a matter of sanitation and mutation of the yeast cells due to being over worked. I'm Not really a man that is wordy enough to give a good explanation to your question. On the matter of sanitation though it it easy to see that you would like to keep the starter volume small to give your yeast a chance to be the dominant yeast in the solution. It doesn't matter how hard you try try to be sanitary there will always be contamination so by keeping the starter small and stepping it up you give your yeast a better chance to be the top dog.

 

There are a lot more detailed explanations out there so check them out for yourself and tell me what you think

[Otto Von Blotto]

I'll try to answer it as best I can, from what I've read about it anyway.

 

Yeast starters aren't purely for growing more yeast cells, their purpose is to grow enough healthy yeast cells to ferment a batch of beer. There's not much point growing 400 billion cells if 75% of them are buggered from being overworked. Stepping up the yeast through a series of starters that get bigger each time ensures they aren't being overworked and by the time you do the biggest starter, the amount of healthy cells should be much greater than if you didn't step up.

 

The optimum inoculation rate is between 25 and 100 million cells per mL of wort, for yeast starters anyway. This is to ensure optimum health and vitality of the cells, as all we're doing is trying to grow them. The rate is less for pitching into a full batch of wort being turned into beer.

 

If I pitched my 30 billion cells harvested a month ago into a 3 litre starter, the inoculation rate is only 7.6 million per mL. Pitching the same yeast into a 500mL starter gives an inoculation rate of 45.6 million per mL. According to Troester's stir plate setting this will net 92 billion cells by the end, a growth factor of 3.02.

 

If I then pitch these 92 billion cells into a 3 litre starter, inoc rate 30.6 million per mL, using the same setting I should end up with 514 billion cells by the end of it (growth factor 4.58), and likely much more healthier ones.

 

If I'd simply pitched the original yeast into 3L, I'd end up with 445 billion cells but a larger proportion of them would likely be either stressed or dead.

 

These numbers are based on the http://yeastcalculator.com/ site. They would appear to indicate that stepping up (in a way) does indeed increase the final cell count compared to just using one big starter. Obviously this was a small starter followed by a big one, but it did increase the cell count. If however, I punch in the original 500mL one followed by a 2.5L one, the cell count is almost exactly the same as one big 3L starter. Either way, building the yeast up in steps like that will most likely ensure a larger count of healthy cells compared to not building it up.

 

I hope that helps a bit

 

Cheers

 

Kelsey

 

 

[Otto Von Blotto]

Does anyone have any advice on yeast starter vs. non-starter debates? Since i have done some reading on starters due to trying to reinvigorate a yeast past its used by date' date=' i noticed that starters increase the cell count. So does a higher cell count mean a 'clearer' beer? Or slightly better tasting? Or just means fermentation will begin/complete quicker with more cells?[/quote']

 

Stepping up as I eluded to in my previous post should help with getting that particular yeast going again.

 

Clearer beer has nothing to do with yeast, at least in the sense of what we're talking about here. Basically a higher healthy cell count ensures a strong fermentation, can be less lag time and a quicker ferment too yes. Also eliminates the risk of producing off flavours from stressed yeast caused by an underpitch. You don't have to pitch at a higher temp and ramp down either, you can simply chill the wort to your preferred fermenting temp and pitch into that. You can also harvest yeast from the starter by overbuilding it, rather than harvesting from the trub in the fermenter. I've just recently started doing this and absolutely love it, way way easier.

 

There are a lot of benefits to making yeast starters. They can also be used as a viability test for yeast you aren't sure about. In saying that, they aren't absolutely necessary to end up with a great tasting beer, plenty of cats make great beer without them, but they do have their advantages.

 

Cheers

 

Kelsey

[Otto Von Blotto]

[Beerlust]

Hi Kelsey.

 

Thanks for going to the trouble of detailing the stepping up procedure & related information. It's all very helpful & I do understand the procedure a little better now.

 

I do have one remaining question that hasn't openly been addressed as yet though.

 

If the starter in both cases is of the same specific gravity used in both a 500ml starter you plan to step up & say a 2 litre starter that you plan to eventually pitch into your main (full) brew wort, then what is it exactly that is "stressing the yeast" in the larger volume starter, that isn't in the smaller starter?

 

Is it simply to do with the ratio of yeast cells you mentioned? i.e. In the smaller starter there are more cells to effectively do less?

 

Before answering that question, consider that I harvested & rinsed roughly enough yeast to probably ferment out 2 full brews & stored this amount. So if I'm understanding all this, I may only have a lowish viability remaining in that yeast, but on the upside I do have a lot of yeast to start with.

 

Apologies if this is becoming a little tedious, but I am finding the conversation both interesting & helpful, & it is beginning to answer quite a number of questions I've had about yeast, starters, & pitching volumes etc.

 

I'm just after some finality, clarity & hopefully some simplicity to help take much of the guesswork out of this whole yeast recycling & re-using process.

 

Cheers,

 

Lusty.

[Canadian Eh!L]

Hi Lusty

If you have a whole heap of yeast harvested like you said (enough for two brews), but the viabli is really low it is basically the same as starting with a very low cell count since most of your cells are dead. I would still go with a smaller starter to begin with.

 

To answer the question about the difference between beginning with a small starter vs. a larger one. It really is a matter of how much you work each individual cell. In a larger starter a mother cell must reproduce many times to increase the cell count which will stress out any mother. In a smaller starter the same mother doesn't have to reproduce as often to chew through the food in the starter before she can rest. When you step up the starter the same mother cell gets back to work but now she has the help of all her daughters to chew through the next step before she can rest again. This is my interpretation of it anyway.

 

[Otto Von Blotto]

Chad has basically answered that pretty well.

 

You can have as much yeast as you like, but if the majority of it is dead, it's the same as having a very small amount of high viability yeast. You've basically got the idea there, that it's the ratio of yeast cells per mL of wort. Using too few cells to do too much will stress them. If you keep it between that 25 and 100 million cells per mL, you will grow much healthier yeast than if you pitch much lower, which is why the stepping up method exists.

 

How long had this yeast been stored before you pitched it into the starter?

[Beerlust]

Thanks again Chad & Kelsey.

 

My feeble little brain (that I'm sure has it's own issues with dead cells to deal with ) has understood your most recent posts very well. Though for a small second or two there, I thought Chad may have confused this subject with the children's bedtime story of Goldilocks & the 3 bears, "...& the Mamma bear said, 'Who's been sleeping in my bed?...'" but then he quickly got back to talking about yeast.

 

OK, so with that side of things understood & out of the way, I wouldn't mind creating some definites to follow etc. I like Kelsey's method of stepping up & splitting a sample from a new packet of fresh yeast, so would like to try maintaining a yeast bank of sorts around this method.

 

I have a 2 litre Erlenmeyer flask & 4x500ml mason jars. What stepping up stagger should I follow with that 500ml portion each time in preparing it for the next brew & allowing for that same 500ml portion to be poured off for storage & re-use prior to pitching that starter into the next brew? A 500ml, then to a litre, then to 2 litres? or simply a 500ml then to 2 litres?

 

At each stage of the stepping up, how long should I leave the starter at that point before stepping it up another level? 2 days? Wait for it to begin clearing & settling out?

 

Is it ok to simply add more wort on top of the previous starter, or does the liquid (unhopped beer) from that earlier starter need to be poured off first?

 

If I wish to maintain a "yeast bank" of sorts, I'm guessing that when a batch of yeast reaches a certain age (as yet unknown to me) it would be advisable to pitch it into a small starter to maintain a good viability level. At what point would you consider this a good idea?

 

If I can get myself into a regular system that I can trust, I know it can only yield good results & help my brewing.

 

Cheers,

 

Lusty.

[Otto Von Blotto]

It really depends on how old it is. If it's only a month or two old, I don't see much need to step it up at all. The viability isn't that low at that point that it needs stepping up, I don't think anyway. It may fall under the 25 million cells per mL of wort, but as long as it's not too far under it should be ok. You could just put it straight into a 2L starter. According to Troester, this (2L size) will produce about double the cells needed for a standard ale batch anyway, so even if 25% of them are dead, the rest will still be more than enough to ferment the batch.

 

Basically the idea is to use a calculator to work out how big to make a starter for whatever batch you plan to ferment with it, and then make it about 500-600mL bigger than that, in order to harvest this extra amount into a jar. For example if the calculator suggests a 1.7 litre starter, you'd make it 2.2 litres to harvest the 500mL, leaving the rest for the main batch.

 

That yeastcalculator.com page has provision for working out stepped starters, so have a play around with it even without actually making any starters, and you'll get a bit of an idea of sizes and how many cells are grown etc.

 

I don't think it really matters either way whether you tip the spent wort off or just tip more in ontop of it.

 

That final question is an unknown to me too. I've heard of people successfully getting yeast working again that's been sitting in the fridge for over a year.

 

I don't need to worry too much about stepping up starters because I pretty much always use the same strain, so it never gets stored more than 2 months max, however it is something that interests me so I have done a little bit of research on it, in case I do need to do it at some point.

 

 

An example using the yeast I'm about to harvest today:

 

I start with 92 billion cells. I plan to make a 2.5 litre starter with these for the next batch. Ii'm using Kai Troester's stir plate setting on the calculator. Keep in mind that I'm making it 2.5 litres in order to harvest 500mL of mixed up wort/yeast into a jar, so the size for the actual batch is 2 litres.

 

AT two weeks when I'll be doing that starter, viability is 86%, cell count 79 billion. Pitching into 2.5L at 31.6 million cells per mL wort, netting 431 billion cells. I only need 209 billion for the batch of beer.

 

At one month, the viability is 76%, giving me around 70 billion cells. Pitching into a 2.5 litre starter, inoculation rate is 27.9 million cells per mL wort. This nets 422 billion cells.

 

At two months, viability is 60%, cell count 55.9 billion. Pitching rate into 2.5L is 22 million cells per mL, so not too far under, and not something to be too concerned about. This nets 407 billion cells.

 

Assuming the cells are all evenly mixed through the starter at harvesting time, taking 20% of it should net around 80 billion cells in the jar, give or take. If these are put into a starter again in under 2 months then I reckon you can forego stepping up. I've debated the idea of making 3 litre starters just to get more cells, but it doesn't really net any more in the harvesting jar.

 

I've since read that these calculators are rather conservative with their viability estimates, and that the yeast may in fact not lose viability as quickly as suggested by the calculators. However, in this instance being conservative isn't such a bad thing, because it ensures we end up with adequate healthy cell counts.

 

Maybe once you get out to yeast stored for 3 months or over, doing stepped starters would be beneficial, but going by those numbers I wouldn't worry about stepping up for recently harvested yeast. Just whack it straight into a 2 litre starter or whatever and it should be fine.

[Hairy]

If I wish to maintain a “yeast bank” of sorts

Are you going to become a Banker? I knew it' date=' I just knew it.

 

It explains everything [img']tongue[/img]

[Beerlust]

Thanks a lot Kelsey.

 

The way you've explained that is perfect.

 

I'm still going to pitch this somewhat clumsy starter of mine into a brew today, but this will be the last time I go about preparing yeast for pitching & storing in this manner.

 

Let's hope I have enough viable yeast cells to ferment out the brew.

 

P.S. I can see me referencing that last post of yours quite a few times until it becomes second nature.

 

Cheers,

 

Lusty.

[Otto Von Blotto]

No worries mate.

 

Hopefully it works out, but at least you have a better idea about it all now. Copy and paste that post into a document if you like so it's easier to find.

 

Cheers

 

Kelsey

[Beerlust]

As luck would have it, the starter I pitched yesterday into a version of my Mosaic Amber Ale recipe took off like a rocket! I had obvious signs of fermentation after approx. 7 hours!

 

Excluding some Belle-Saison yeast I used once, that is a new record for my brewhouse. Most of my brews seem to get going around the 12-18 hour mark, so I'm really wrapped about this.

 

Obviously the combination of the starter combined with some proper yeast nutrient in the brew wort is the reason for such a positive outcome.

 

I just checked my records & this yeast has been in storage for 6 months!

 

I'm not out of the woods yet, as there is still the possibility of some off flavours appearing in the final beer, but so far so good.

 

P.S. If I haven't said so already, nice thread on "yeast harvesting from a starter" Kelsey.

 

Cheers,

 

Lusty.

[Otto Von Blotto]

 

 

Nice! Glad it worked out alright. I'd say those are two reasons why it took off pretty quickly. It's one of the good things about yeast starters. Hopefully there aren't any off flavours in the end beer though.

 

Thanks mate, I thought it would be good to share it with everyone. Anything that makes a brewing related process easier and produces an equal or better outcome than "traditional" methods, I'm gonna jump on and encourage everyone else to jump on too.

 

Cheers

 

Kelsey

[antiphile]

Obviously the combination of the starter combined with some proper yeast nutrient in the brew wort is the reason for such a positive outcome.

 

I'm really glad it worked well, Lusty. Yet it's not so obvious to me, though, that yeast nutrient played any significant part in the success. From what I've experienced (and also read), unless the viability of the yeast is seriously compromised, there is more than sufficient nutrition in a straight yeast starter for normal use. The scientific papers (see Google Scholar, for example) do suggest, however, there may be some benefit when reproducing yeast to near its growth limits on an industrial scale.

 

There is also still some argument about the strength of the wort for starters. Most authors (and posters on the various fora) seem to insist on an SG of 1.040 as being ideal. However the published papers suggest a level closer to 1.030 is optimal. (It is a compromise between yeast cell death from "osmotic shock" through the cell wall from too high an SG, and sufficient sugars to enable good reproduction).

 

Just my 2 kopeks.

Phil

[Beerlust]

Thanks for the kind words Kelsey & my rich Russian brewing friend.

 

I admit my knowledge on yeast is not as solid as a number of folk here on the forum, but I'm starting to put more time & effort into this area of my brewing. For the time being I'll welcome any tid bits of discussion & advice offered here on the forum by those more in the know.

There is also still some argument about the strength of the wort for starters. Most authors (and posters on the various fora) seem to insist on an SG of 1.040 as being ideal. However the published papers suggest a level closer to 1.030 is optimal. (It is a compromise between yeast cell death from “osmotic shock” through the cell wall from too high an SG' date=' and sufficient sugars to enable good reproduction).[/quote']

I vaguely remember both yourself & our Canadian cohort notating you were using second & possibly third runnings of similar gravities with good results in your starters. Not sure if you both are still following this practice though.

 

It certainly makes a lot of practical sense to me. Consider it added to the tid bits!

 

Cheers guys,

 

Lusty.

[antiphile]

Hi Lustful

 

I must admit I consider there to be be a (huge) difference between these processes, and if I may, I'd like to take a few paragraphs to explain. IMHO, and I'm just as equally to blame as some others in terms of using the existing accepted "loose" language, I'd prefer to see the terms activation and propogation used as follows:

 

Activation: being the process of preparing the yeast cells to metabolise the sugars in the wort. This could be as simple as opening the packet of dried yeast and sprinking on top. Yet I think it also includes rehydrating the yeast (which will speed up the onset of sugar munching), as well as "priming the yeast" in a weak malt solution (as I like to do with the yeast in the final sparge runnings of between 1.015 and 1.025 SG for a few hours) so they have already started all their biochemical pathways even before they are pitched. I know it sounds trivial that it might only lessen the start of action in the brew by a few hours, but in my opinion, that is the most critical time when the battle between the dominant organisms (i.e. preferred yeast Vs wild yeast & bacteria etc) in the home brewery is won. I also don't have any scientific backing or citations for this, either for or against, but it seems rather intuitive.

 

But activation should be seen entirely differently to propogation, for which there is a lot of evidence.

 

Propogation: is (what I like to consider) the multiplication of yeast cells outside of the FV for the sole purpose of increasing viable yeast cell counts (as opposed to the aim of fermenting a beer). This is where yeast multiplies for around 12 hours using dissolved oxygen in the liquid, and then for a further 24 hours approx (in some circumstances up to 36 hours) without oxygen (which is called anaerobic reproduction). The last phase then entails the yeast making glycogen stores (a form of glucose), before going to sleep.

 

Of course, if you get the timing close before the start of dormancy, you can pitch activated yeast from the propogation process, but I don't think its helpful to confuse these two separate aims at this stage. I'm sure it's clear as raw sewage, but I've never been one to explain things so others can understand!

[Otto Von Blotto]

I'm guessing that the yeast would have been pretty low in viability since it had been stored for 6 months. So perhaps the nutrient did contribute a bit to it working well in the batch now.

 

As for gravities, according to yeastcalculator.com, my normal mixture of 100g DME per litre of water results in a gravity about 1037. And going by the measurements on the 2 litre flask, it's probably less. I measured out 500mL for that one I just did this week, and when I tipped it in to the flask it was way below the 500mL line on the flask. I haven't tested the 3 litre flask yet so not sure how accurate it is. But at least for those ones I've done in the 2 litre flask, it would seem the gravity has been lower for these starters. Perhaps this is why my harvested amounts seem lower than I've been expecting.

 

At the end of the day though, if I'm growing cell counts around 450 billion from a 2 litre starter, when I only need about 210 billion for my usual strength ale batches, I'm not too worried about a few of them being killed off by a gravity that may be a tad high.

[Beerlust]

Thank you gentleman. From my standpoint, it's great reading,....honestly.

 

I asked a question a few posts back about time frames between stepping. I feel antiphile has answered this for me very well among the information he has conveyed. (Much appreciated by the way)

At each stage of the stepping up' date=' how long should I leave the starter at that point before stepping it up another level? 2 days? Wait for it to begin clearing & settling out? [img']unsure[/img]

Propogation: is (what I like to consider) the multiplication of yeast cells outside of the FV for the sole purpose of increasing viable yeast cell counts (as opposed to the aim of fermenting a beer). This is where yeast multiplies for around 12 hours using dissolved oxygen in the liquid' date=' and then for a further 24 hours approx (in some circumstances up to 36 hours) without oxygen (which is called anaerobic reproduction).[/quote']

Have I understood this correctly? (It does seem to fit)

At the end of the day though' date=' if I'm growing cell counts around 450 billion from a 2 litre starter, when I only need about 210 billion for my usual strength ale batches, I'm not too worried about a few of them being killed off by a gravity that may be a tad high. [/quote']

I already assumed this, but thought it worth highlighting given those that are probably following your very good procedure for portioning off fresh yeast from the starter. Accept that "one size does not fit all" here (as you say) particularly when brewing higher gravity brews & in some cases lower temperature fermented brews where you may require a higher yeast cell count or higher alcohol tolerant yeast before pitching it into your brew.

If I wish to maintain a “yeast bank” of sorts

Are you going to become a Banker? I knew it' date=' I just knew it.

 

It explains everything [img']tongue[/img]

I've already been a banker of sorts since joining this forum. I've grown to bank on you for many things oh follicular one.

 

Acknowledging consistency & performance over a duration, there's no-one else that I'd bank on ahead of your good self!

 

 

Cheers, thanks, & good brewing guys,

 

Lusty.

[Otto Von Blotto]

I already assumed this' date=' but thought it worth highlighting given those that are probably following your very good procedure for portioning off fresh yeast from the starter. Accept that "one size does not fit all" here (as you say) particularly when brewing higher gravity brews & in some cases lower temperature fermented brews where you may require a higher yeast cell count or higher alcohol tolerant yeast before pitching it into your brew. [img']wink[/img]

 

Yep, exactly. Hence why I do have a 5 litre flask for when I do lager yeast starters, as they do need to be bigger. Takes seemingly forever to bring the damn thing to the boil on the stove though!

 

(I only mention lager yeast for myself, because I don't brew high gravity beers, but yes these are another one that will need a bigger starter)