Overpitching Yeast

[Stu's Brews]

Would a starter be cheaper?

Yep. That is one of the reasons I use a starter (the other being it helps ensure the yeast is in good health before pitching).

I use Wyeast smack packs which are usually around £8.99 each. I'd normally need at least two of these to hit my desired pitch rates.

When making a starter I use a touch over 100g of DME, which is about £1.

 

[MrJay83]

I do beers 5-7% and I haven't noticed anything to make me think I'm underpitching and needing to use a starter.
I'd love to do two batches (one with 1 packet and the other with what Brewfather recommends) but don't have the setup for it at the moment to do a proper comparison. One day.

 

[Birdsnestbrewery]

Interesting point about lagers needing a higher pitch rate. I have never brewed a lager. Do the packets of dried lager yeast contain more than packets of ale yeast, or are we simply advised to use more packets?
I suspect I can guess the answer but I might be pleasantly surprised if wrong.

 

[hoppyscotty]

All of which suggests that actually, we're not actually underpitching or indeed overpitching, despite some sources suggesting otherwise.
It's biology, not everything is exact.
Of course there are some who would love us to use two packets instead of one, "just in case"... Just saying

Or that other factors are far more important. Those that might experience problems might be under pitching yeast AND not having fermentation temp control AND not doing any PH management AND not aerating where that is beneficial etc.

I do have a pretty good handle on most if not all those other parameters so on it’s own a bit of under pitching or over pitching might not be detrimental, but on top of a load of others sub-optimal process elements might have an impact.

As for cost, £1.50 on half a packet of yeast is hardly a major additional cost per batch and certainly well worth the hassle and risk of harvesting your own yeast. I could buy a larger packet and weigh out e yeast but again, life is too short.

On the larger scale where you might have to pitch 20 litres or more of yeast starter then it gets a bit more serious both in terms of risking ruining an expensive batch and cost of yeast.

 

[Tom Archer.]

I suspect the window is quite wide

One of the things that stands out from my researches is the way old 'rule of thumb' measures are sometimes translated to spreadsheets and then scaled to three significant digits; giving an impression of a need for precision that was never there in the first place

Notable writers and commentators, such as John Palmer and the guy who styles himself as 'Hendo' on YouTube are quite dismissive about the possible hazards of over-pitching; however big commercial brewers don't count yeast cells for the fun of it, and the chemical theory behind pitch rates does not support the notion that overpitching has zero impact.

When you are brewing commercially, for fussy customers who will complain if their pint of lager tastes at all different when the landlord changes a keg, it becomes one of the many brewing variables that have to be pegged down.

Whether anyone else should lose sleep over it seems doubtful.

 

[Stu's Brews]

Interesting point about lagers needing a higher pitch rate. I have never brewed a lager. Do the packets of dried lager yeast contain more than packets of ale yeast, or are we simply advised to use more packets?
I suspect I can guess the answer but I might be pleasantly surprised if wrong.

Not a dried yeast user so no idea whether you get more yeast in a lager pack to be honest.

The premise is that for a lager you want a clean fermentation so that there are no (or very few) yeast-derived flavours in the final beer. The higher pitch rate helps you achieve that.

Ultimately, a lot of it comes down to personal preference. You can brew a drinkable beer with what would be classified as 'under-pitching' but if you want to have a bit more control over your flavour profile then pitch rate is definitely something to consider.

Obviously not everyone is producing beers for competitions, but something to bear in mind is that the Malt Miller have previously mentioned that one of the common issues they've seen during judging is under-pitching and the subsequent off-flavours that it produces. They have recently done a couple of YouTube videos on yeast as a bit of a follow-up, but must admit I haven't got round to watching them yet so not sure what is specifically covered.

 

[dad_of_jon]

Yeap. A second pack of yeast will add up to a 15% extra cost of my ingredients in a brew.
Seriously starting to think about harvesting but don't think my wife would appreciate it in the fridge

Mrs DOJ gives me grief over my packets of dry yeast. Harvesting is a no go.

As for pitching I have never used 2 packs for my 21litre brews and apart from the first 10 beers I brewed I've always hydrated the yeast. 1 Packet - 12.5% easy peasy lemon squeezee

 

[d.carey]

I'm new to the game but there are some people suggesting the state of dried yeast is not optimal for starters? Something about their reserves?

 

[MrJay83]

Don't Lallemand say not to do it? Pretty sure I read AEB say the same.

 

[MashBag]

Dried yeasts are ok sprinkled (finely not dumped). Tbh you are giving the yeast an unnecessary shock by making a starters.

Under pitching is and does cause flavour problems. Over pitching much less likely
to and there seems to be much more margin for error.

 

[Stu's Brews]

Tbh you are giving the yeast an unnecessary shock by making a starters

I can't wrap my head around why that would be the case for dried yeasts as it certainly isn't true for liquid yeasts.

Even if you aren't trying to propagate more yeast, a starter is beneficial for ensuring you have healthy yeast before you pitch it. That's why Wyeast sell their liquid yeast in 'smack packs', which is essentially a mini-starter.

 

[MashBag]

Yeast go though an acclimatisation to their substrate. It is a shock..... when we want them to have a happy, easy, warm, well fed, unstressed life.

Starters create another shock. Pitch the yeast. If it fails repitch... And dead yeast cells are yeast nutrition. Imo don't try to solve a problem you don't have. When was the last time you had a fresh dried yeast that didn't start?

 

[Stu's Brews]

Yeast go though an acclimatisation to their substrate. It is a shock..... when we want them to have a happy, easy, warm, well fed, unstressed life.

Starters create another shock. Pitch the yeast. If it fails repitch... And dead yeast cells are yeast nutrition. Imo don't try to solve a problem you don't have. When was the last time you had a fresh dried yeast that didn't start?

Never as I use liquid yeast, hence my question, as I genuinely don't know why it could be worse to use a starter for dried yeast.

I was just looking at the Safale US-05 info on the MaltMiller and it recommends either direct pitching or 30 minutes of rehydration so presumably there is some truth in it. I just can't figure out how dried and liquid yeasts behave significantly differently with regard to starters.

Interestingly, the recommended pitch rate for US-05 is 0.5-0.8g/l so for a 20l batch one packet should be sufficient. I'd hazard a guess that is why most dried yeast users don't have major issues with under-pitching, even though it technically may not be enough to achieve the 'ideal' pitch rate for a style.

A pack of Wyeast liquid yeast has 100 billion cells of yeast, however you normally need about double that and due to the nature of liquid yeast not all 100 billion will be fit and healthy unless you get a very fresh pack. Therefore, probably much more critical to pay attention to pitch rates with liquid yeast as there is more risk of a significant under-pitch, which would match to my prior experiences with it.

Caveat that is all based on a sample size of one dried and one liquid yeast so could be different for different brands.

 

[whistlerface]

I pitched 2 packets of MJ M31 Tripel yeast on my last tripel brew. It went from 1.079 to 1.005 which was a lower FG than planned. I'm thinking of experimenting with 1 packet on the next brew with the possible risk of a stuck ferment if it goes wrong. I read that Westmalle only pitch just over 0.25 million cells/mL/°P which isn't much.

 

[Stu's Brews]

I pitched 2 packets of MJ M31 Tripel yeast on my last tripel brew. It went from 1.079 to 1.005 which was a lower FG than planned. I'm thinking of experimenting with 1 packet on the next brew with the possible risk of a stuck ferment if it goes wrong. I read that Westmalle only pitch just over 0.25 million cells/mL/°P which isn't much.

You may want to check you mash temperature as well though. It's unlikely that over-pitching would cause over-attenuation as the yeast can only eat whatever sugar is available.

More likely you were slightly lower than intended on your mash temperature, which created a more fermentable wort and with a healthy amount of yeast it was able to work it's way through all of those sugars.

 

[Justin Dean]

I follow Brewfather as starter calculation with one packet and whatever litres of wort from liquid or spray malt on stirrer. Always works fine. Yeast is expensive so a starter makes it cheaper particularly if using spraymalt

 

[whistlerface]

You may want to check you mash temperature as well though. It's unlikely that over-pitching would cause over-attenuation as the yeast can only eat whatever sugar is available.

More likely you were slightly lower than intended on your mash temperature, which created a more fermentable wort and with a healthy amount of yeast it was able to work it's way through all of those sugars.

I mashed at 67c so I'm not sure what happened to cause such a low fg, the mash temp wasnt overly low. I guess it's no biggie as it turned out dry and tasting great anyway. Will brew it again and see how it turns out the second time.

 

[Stu's Brews]

I mashed at 67c so I'm not sure what happened to cause such a low fg, the mash temp wasnt overly low. I guess it's no biggie as it turned out dry and tasting great anyway. Will brew it again and see how it turns out the second time.

Sorry, what I meant was are you sure it was actually 67c and not something more like 64-65c? Not uncommon for the mash to actually be a couple of degrees cooler than intended depending on where your temperature probe is located and what you set as your initial strike temperature.

 

[MrJay83]

Sorry, what I meant was are you sure it was actually 67c and not something more like 64-65c? Not uncommon for the mash to actually be a couple of degrees cooler than intended depending on where your temperature probe is located and what you set as your initial strike temperature.

I've tested the temp a few times in my BZ with just water and it's been fine. 6kg of grain with 20l of water creates a different situation all together. I go 4C+ for my strike (before the basket is added) and 2C+ for mash (sometimes drop it to 1C+) and everything works well.
I'll bet that nearly every BZ is a bit different to the user.

 

[hoppyscotty]

Bz’’s are not great at managing a consistent temp over the height of the grist column. It’s a tall and thin grist column which is not the ideal shape for a mash tin. The temp sensor is at the bottom so the column can be a different temp at the top with a gradient. I always run an overflow during mash as I find I get a more consistent temp as if there is a gradient you are diluting the warmer wort at the bottom with cooler wort from the top.