Pitching rate discrepancies between manufacturers and other calculators

[Brewnaldo]

My approach is to keep the liquid I pour off from a starter in some Kilner jars to settle out for another week or so in the fridge then discard the clearer supernatant beer and store the residual yeast for the next beer. I'm getting a bit more organised about labelling them now as well. I do have a separation funnel but have rarely used it up till now. I'm going to have a go though with cleaning up the yeast cake from a lager I'm making at the moment to see how well that works.

My next lager is going to use a liquid yeast so I might do the same.... Maybe keep a big jar or the trub and pitch it into my next one.

 

[aolcot]

You can harvest dry yeast you know! Exactly the same as liquid yeast after gen 1.

Yeah I know i can harvest dry yeasts.. If I'm building up starters, I may as well go wet again for the range/choice of yeasts and seeing as there isn't that much difference between some wet/dry yeasts in terms of price now.
Plus from a process point of view and the way I do things, I think I prefer to overbuild/store the excess of a starter, rather than harvest from an active/done fermentation.

 

[Tess Tickle's Brewery]

It depends what you are brewing, both in terms of beer style and original gravity. So lagers and high gravity beers will require more yeast in general and the calculators will take that into account. It's also worth considering whether over or under pitching is going to be a problem, as for beers brewed at warmer ie ale temperatures, a single dry yeast pack will cover a standard 20-30 litre batch. For a lager brewed at cool temperatures then multiple packs are advised or even better use a starter. Last weekend, I added 1 litre from a 3 litre settled starter for a 23 litre batch of lager which was based on a calculator as the pitch rate is more important in such settings. Some other specific yeasts such as Philly Sour are pitch dose dependent, though a single pack again is suitable for a standard home brew batch size, but if brewing a small or larger batch will need to be adjusted by the manufacturer's recommendations.

Anna - as a great lager brewer would you say I've made a mistake here?

I did a starter yesterday for a 22L batch of Festbier. Brewfather told me I needed 2.7L starter but I didn't do a step-up starter. I just made the DME up to the correct gravity and volume, boiled for 15 mins and then cooled the wort and pitched the liquid yeast.

Do you think any of this is wrong? Also what temps is best to keep the starter at? At the moment it's sat at about 14c.

I haven't done that many starters and never a lager one. Going to do it every batch though now.

Is it best to decant off the excess and just pitch the slurry?

By the way it's in a glass demi-john.

 

[DocAnna]

Anna - as a great lager brewer would you say I've made a mistake here?

I did a starter yesterday for a 22L batch of Festbier. Brewfather told me I needed 2.7L starter but I didn't do a step-up starter. I just made the DME up to the correct gravity and volume, boiled for 15 mins and then cooled the wort and pitched the liquid yeast.

Do you think any of this is wrong? Also what temps is best to keep the starter at? At the moment it's sat at about 14c.

I haven't done that many starters and never a lager one. Going to do it every batch though now.

Is it best to decant off the excess and just pitch the slurry?

By the way it's in a glass demi-john.

Hi Tess, thank you for the compliment, though right now based on the two I am conditioning, I'm not so sure.

It sounds like you're on the right track, that's a fairly large starter for a 22 litre batch so is v likely sized right for a lager. Generally you'll ferment a lager starter a lot warmer than the main fermentation, I normally just do so at cool room temperature. It is better for this reason of the temperature, and that the DME isn't the same makeup as your beer, to pour off the supernatant and just pitch the last part. Judging how much is up to you, and how long you've been willing to let it settle out. If you pick up a 1 litre kilner jar from the supermarket, then after sanitising you can use this to keep the middle portion of the pour off - and let it settle out to keep the yeast for next time to pitch into a new starter. (you can pour off the clear liquid from that after a few days too, then keep the rest in a small jar).

You need to leave a little bit of liquid behind enough to swirl and resuspend your yeast for pitching.

One last note, when preparing a starter, you only just need to bring it to a boil momentarily. There's no need to boil for 15min.

 

[Tess Tickle's Brewery]

Perfect, thank you for taking the time to answer all those questions Anna.

 

[dad_of_jon]

Basically which to believe? I'm erring the side of the yeast manufacturers, but they tend to recommend a lower pitching rate compared to some other calculators...in particular looking at a current recipe I'm working on in Brewfather and the Brewfather calculator comes up with 4 packets of yeast and the Lalbrew calculator comes up with 3 packets.

Which to go for? Part of me thinks go with 4 but I don't want to overpitch for the sake of over pitching.

The yeast companies would prefer to sell more rather than less yeast so if their number is lower than calculators I'd go with that. Having worked in IT for 30+ years its also possible that one of the calculators could have an error in it. but which one is correct? - 40 litres is essentially 2x 21 litres and I only use 1 packet of rehydrated yeast for my 21 litre brews. you can get 21 litres of 12% beer with a single packet of rehydrated yeast that has been stored correctly. Maybe not so likely if stored on a warm shelf in a shop for 6 months near to its BBE date.

 

[hoppyscotty]

Yeah I guess I'm not so cynical to think the yeast companies are trying to push yeast onto you needlessly by fiddling their pitch rate calculators, but there is a risk factor around everything. You can under-pitch yeast and get away with it, but doesn't mean you'll always get away with it. I think dry yeast is a boon as I can't be bothered with a starter, at this level at least. If I were into recovering yeast from trub and building it up then great, or if I were brewing much larger batches commercially then yes as yeast costs become much larger, but I see no point in starters unless you have the ability to count yeast cells to confirm the actual viability of your yeast pitch - I'm always looking for that positive feedback loop. I think the technology of dry yeasts has come on leaps and bounds and most companies don't even suggest you need to or even even go so far as to recommend you DON'T re-hydrate the yeast. For the sake of a few quid I'd rather just pitch that additional packet and err on he side of caution.

 

[Tom Archer.]

As a newbie, slowly getting my head round the subject, pitch rates are an intrigue.

The online and YouTube communities seem to have complete faith in yeast calculators that typically come out with starter to wort volume ratios for ale of around 1:20 to 1:25 coupled to quite a modest expectation of yeast growth in the starter.

But.. looking at the work of Graham Wheeler, who has diligently gathered the recipes from many British breweries and downscaled them, I see a starter to wort ratio of around 1:80, a DME strength that is roughly double that assumed in the yeast calculators, and the confident expectation of building a starter in a single stage from the yeast dregs of a single bottle that may be several months old.

There seems to be a big gulf in approach - unless I'm missing something fundamental here.

Is Mr Wheeler faithfully downscaling actual brewery practice in the UK, or just doing things 'his way' because he is personally happy with the result?

 

[hoppyscotty]

Well hence my comment about it’s all guess work unless you have. The ability to actually count yeast cells. All large scale breweries do th this and won’t leave things to the chance of the guess work of yeast pitch calculators. All calculators make baseline assumptions and their accuracy is entirely dependant on how close to your reality those baseline assumptions are. Calculators like this are only a little bit better than rolling a dice.

Think at my current level i’ll stick with the most dependable and reliable method of dry yeast packets as they degrade far less quickly than liquid yeast so you have a far better idea of what you’ve actually got.

 

[foxy]

Well hence my comment about it’s all guess work unless you have. The ability to actually count yeast cells. All large scale breweries do th this and won’t leave things to the chance of the guess work of yeast pitch calculators. All calculators make baseline assumptions and their accuracy is entirely dependant on how close to your reality those baseline assumptions are. Calculators like this are only a little bit better than rolling a dice.

Think at my current level i’ll stick with the most dependable and reliable method of dry yeast packets as they degrade far less quickly than liquid yeast so you have a far better idea of what you’ve actually got.

There are a few variables to take into account, I would imagine that calculators assume that one has the the mash pH under control, also the temperature control has to be on target to extract the fermentable sugars from the mash also unfermentables do produce some fermentable sugar not enough to make a great deal of difference but I doubt they are taken into consideration in the calculation.
So the mash pH and mash temperature can tip the scales on the amount of fermentable sugars available. Does it matter if you overpitch as a homebrewer I doubt many could tell the difference. Underpitch can cause problems for the yeast struggling to ferment the wort, so for me I would sooner overpitch rather than underpitch.

 

[Tom Archer.]

Thanks for the replies - I've noticed in some advice on brewing with dry yeast the rather casual comment that you might want to pitch two sachets rather than one on stronger beers, which does not suggest that a degree of precision is needed.

There are a multitude of variables in making a brew, and it seems that some are much more critical than others. For my opening forays I think I'll go for a halfway house between the yeast calculators and the Wheeler method, and make a one pint starter for a 36 pint brew - and see how that works out.

 

[hoppyscotty]

When I started I stuck to 19 litre all grain kits to play nicely with a corny keg and pretty much exclusively these all came with one 11g packet of yeast. I brew many acceptable batches with such kits with no off flavours or problems I could perceive. However once I moved away from the kits and started working up my own recipes and working out pitching rate I found the one packet was not enough according to the own manufacturers pitch rate calculators and more often than not required 1.5 or so packets, so two packets probably about right to account for any degradation of the yeast. So had been underpitching all that time according to the manufacturers calculations. My fermentation is so much better now I’m pitching properly…beer isn’t necessarily noticeably better, but fermentation is so much more consistent and ‘stronger’ if that makes sense.

 

[The-Engineer-That-Brews]

I’d be genuinely interested to know whether any of have ourselves done a split-batch experiment to see if under-or over-pitching makes a perceptible difference to a relatively mainstream style, especially after a decent conditioning time.

I know there are several well-reported “ex-beer-iments” and so on, but I’d be more interested to hear from someone who’s tried it first hand :-)

 

[hoppyscotty]

I suspect you’d have to horribly under pitch to proper ruin your beer. In my case I was only just underpitching and usually make sure to aerate wort well before pitching with a good agitation of the wort with the paddle so it has a good couple of inches of foam on top and always use yeast nutrient so maybe why I haven’t noticed any detrimental affect of underpitching by a few grams I.e probably got away with it by the skin of my teeth. But fermentations are far better now i achieve decent pitch rates.

I have stopped using liquid yeast as I just can’t be sure what I’m starting with and if my starter is sufficient so far easier to use dry yeast. I’ve tasted many a home brew from my local homebrew club that have all sorts of off flavours and issues so I think it is a thing.

Thing with a lot of these ex-beeriments is the skill of brewing isn’t necessarily about making a decent beer once, but can you make that same beer time after time after time so it’s all about removing variability and by underpitching you’re just introducing an element of variability. You might get away with it once, or even ten times but on that eleventh you may get a duff batch.

 

[chthon]

A couple of years ago, I found on another forum someone who worked in a laboratory saying that one could assume for dry yeast, that one sachet contained appr. 200x10E9 cells. Since then, I worked from that and never got bad results.

A couple of weeks ago, I decided to turn this around, and use the Mangrove Jack instructions to calculate how many yeast cells a sachet would contain, calculating back. If a good pitching rate is 750000 cells/ml, and MJ recommends 1 sachet for 23l beer of 1.050, I calculated that, indeed, one sachet contains appr. 210x10E9 yeast cells.

 

[Tom Archer.]

I note John Palmer's observation in 'How to Brew' after identifying the known downsides of under pitching, his doubts that over pitching is an issue of substance. Any modern home brewer following his guidance would therefore be inclined to go big to be safe.

I also note that some of the base calculations seem to have started off as broad, historic 'rules of thumb' using very round numbers, which then found their way onto spreadsheets and got scaled to give a precision that was possibly never demanded.

These two elements seem able (just about..) to cover the wide spread of starter/wort ratios I've noticed.

What remains a little trickier is understanding the discrepancy when it comes to starter yeast volume growth, which is sometimes very large when culturing up from petri dishes, bottle dregs or slopes.

Does it make sense to interpret this as demanding a two stage process, whereby the first stage is an aggressive high build phase, and the second a gentler conditioning phase?

- Or am I getting this completely wrong!

 

[foxy]

I note John Palmer's observation in 'How to Brew' after identifying the known downsides of under pitching, his doubts that over pitching is an issue of substance. Any modern home brewer following his guidance would therefore be inclined to go big to be safe.

I also note that some of the base calculations seem to have started off as broad, historic 'rules of thumb' using very round numbers, which then found their way onto spreadsheets and got scaled to give a precision that was possibly never demanded.

These two elements seem able (just about..) to cover the wide spread of starter/wort ratios I've noticed.

What remains a little trickier is understanding the discrepancy when it comes to starter yeast volume growth, which is sometimes very large when culturing up from petri dishes, bottle dregs or slopes.

Does it make sense to interpret this as demanding a two stage process, whereby the first stage is an aggressive high build phase, and the second a gentler conditioning phase?

- Or am I getting this completely wrong!

Modern day thinking has changed quite a lot especially for high gravity beers, I first read about this in a blog by a master brewer which was called I think The Wandering Brewer. A high gravity wort needs no oxygen dissolved into it (the gravity pushes the oxygen back out) instead the starter is made 4-5 days in advance giving the starter the oxygen for the yeast to rapidly multiply, by the end of the 4th or 5th day there are enough cells to tackle the high gravity beer without injecting any oxygen into the wort. And yes there are two phases the first being the rapid cell multiplication and as the glucose depletes the yeast starts to die off as the beer reaches the FG leaving the remaining yeast to condition the beer.