Yeast Starter And Wort Volume Compensation

[dabre4]

Hi all,

I had a quick search for this but didn't come up with much. I normally brew relatively low gravity beers, and haven't seen the need for making a yeast starter....until now. I'm going to brew an Imperial IPA, and have done all the calculations to figure out the pitching rate I require. My question is, I am meant to make a starter that is 1.8L, if I just throw that straight into my beer won't that be watering it down? Is it common practice to make a beer with a higher OG then the target so that when the yeast starter is added it's back down to the correct OG?

I may be making a mountain out of molehill here, but will be interested to here your thoughts.

Cheers

 

[MeLoveBeer]

Congrats on taking the next step (you'll be stoked with the results that you get with proper yeast prep and management).

Best bet is to make your starter, let it ferment out, crash chill it for a couple of days (to let the yeast drop out), decant all but about an inch of 'beer' off the top, let the slurry return to the temp of your brew, swish it around to get the yeast moving again and then pitch whats left into your fermenter (should mean only an extra 200ml of so of extra volume into your batch)

 

[Lecterfan]

Hopefully you'll get some more informed replies than mine. I had my head turned around with yeast starters over the last few months...mostly since going AG and getting used to Beersmith.

I generally add a 2L starter to my brews (unless repitching slurry almost immediately which I know is not ideal), and I use beersmith to try my best to compenstate for the extra 2L...usually the difference in IBUs is <2 which is easily overcome with a pinch of extra bittering hops. As for flavour and aroma I don't bother adjusting if I am going to dry hop, otherwise I'll add proportionally that little bit extra.

My reasoning may be completely flawed though haha, wouldn't be the first time and won't be the last.

Good luck :icon_cheers:


edit: beaten by melovebeer with a far superior suggestion, but one I ultimately can rarely be bothered doing.

 

[argon]

My question is, I am meant to make a starter that is 1.8L, if I just throw that straight into my beer won't that be watering it down? Is it common practice to make a beer with a higher OG then the target so that when the yeast starter is added it's back down to the correct OG?

For an active starter (that is one that you pitch the full volume into the wort when you see signs of active fermentation) its a reasonable idea to adjust your recipe to account for both the volume and the fermentables that youre added to the starter eg 1.8L starter will have 180g of DME. Pitching an active starter with active healthy yeast will give your wort a little head start in the fermentation process, reducing lag time therefore reducing time for possible infection.

As Warmbeer suggested you can pitch the slurry made from yeast farming. You dont need to adjust recipes, volumes etc, as all you are doing is adding a reasonably insignificant amount to the wort. Doing this is not a starter, its just pitching enough yeast cells to get the job going. Doing this wont reduce lag time, but at least youll be pitching the correct yeast count to your wort, therefore giving your wort exactly what it needs to start the fermentation process.

Either option will be fine personally I swing between either method without prejudice. An active starter does indeed start quicker though.

 

[MeLoveBeer]

An active starter does indeed start quicker though.

Absolutely agree Argon (and most times I would just pitch the whole thing in myself); to be honest even when pitching a decanted starter I've noticed a fairly small lag time anyway, as the yeast doesn't need as long to build up the necessary reserves to take on the wort.

Doog, if the aim of creating the 1.8L starter in this case is to build up the necessary yeast count to support a healthy ferment, then you should be fine either way. Even if you pitch the whole thing in to your brew, I would imagine that it would have minimal impact on your OG or FG (it would take a fair bit of fermented out wort to impact the brew in any large way).

 

[RobW]

Another way if you want say a 2 litre starter is to grow up a 1 litre starter a few days before you brew and store it in the fridge.

On brew day:

Tip the liquid off the top, leave only the yeast behind and let it come to ambient temperature

10 or 15 minutes into the boil (preferably before you start hop additions) run a litre of wort off into another flask and crash chill it to pitching temperature


Add the cooled wort to the yeast, mix and leave at fermenting temperature

Brew as normal, leave the wort at fermentation temp and when the starter is firing pitch the lot into your brew

You need to be confident with your sanitation but in practice it's simple and effective

 

[raven19]

Some good posts above.

If my brew is no chilled, I will (if organised) actually make 'mini' no chills using old water bottles or similar (conjecture over food grade safeness is still rife at the nest! :lol: ). They hold around 300ml, and are great for getting the yeast going if its been stored cold in the fridge for a while - and the wort is the same as the 20L cube, so its win win!

 

[dabre4]

Thanks everyone, good advice all-round. I'm mainly trying to ensure I have the correct amount of yeast to do the job, so I might just chill the starter and decant the excess liquid. Is there any harm in having higher then recommended yeast count/pitching rate? Im thinking if I can decant most of the liquid by chilling, why not make a 2.5L starter, get a higher yeast count, and perhaps have a better chance of good attenuation.

Does anyone think you get a better final result by pitching active yeast, or is it just to reduce the risk of infection?

Cheers

 

[MeLoveBeer]

Is there any harm in having higher then recommended yeast count/pitching rate?

Nah, better too much than not enough....

Does anyone think you get a better final result by pitching active yeast, or is it just to reduce the risk of infection?

You've pretty much nailed it... less lag time == less chance of infection, however the end result should be much the same (and to be honest I don't think you'll get a whole lot of lag time with either technique).

 

[cubbie]

Some good info here. I generally like to decant the starter and pitch the slurry esp if I am doing a light beer like a kolsch. However I used to always pitch the whole starter and I did on the weekend. I will detail what I did on the weekend and it may help.

I was brewing a triple, had 85% mash efficiency and had roughly a 1.053 pre-boil gravity and 1.069 end of boil gravity. My volumes were 31L pre and 24L post (90min boil). I was planning to decant my starter but during the week I decided to step it up again so it never got to ferment out and on brew day was roaring. Anyway whilst I was cleaning up my brew buddy was emptying the kettle into the fermenter, he started to take in cold break and hops so stopped filling at 19L (I aim for 21L in the fermenter). I was now going to pitch a 2L starter into 19L of wort with a total volume now 21L (my starter is greater than 10% of the volume), plus I am going to add cane sugar during the ferment so needed to work out my gravity contributions.

Firstly how many gravity points will my starter made with light DME add.

Extract SG = (Extract weight) x (Extract ppg) / (Solution Volume) - note this is in pounds and gallons

Starter was made with 200g DME convert this to pounds and (0.44)x(46)/(5.54) = 1.004 or 4 points for gravity contribution

I then had to work out how many points my existing 19L at 1.069 contributed. To do that have a look at MHB's post here

The end result was about 62 gravity points.


In a few days I will add 1kg of cane sugar, using the above equation I calculate that this will add an extra 18 points of gravity.

(2.2)x(46)/(5.54) = 18

Total points in 21L 4 + 62 + 18 = 84 or 1.084


So if you are concerned about how your starter is impacting your gravity you can calculate it.

Just another note on starters, if you are constantly aerating your starter it will be oxidised you may want to avoid putting that in your beer - if you are making a starter aerate it at the start but not constantly (eg with a stir plate). Most people do not use hops in their starter so you need to account for that.

Hope that helps.

 

[goatus]

Question to those smarter than I: If you are no-chilling and fill your cube, and have a couple of litres of wort left in the kettle - can you:

a> crash chill and use as your starter wort instead of using extract (even if its high gravity, or should we be diluting to start the yeast off easy at a lower gravity?)

and

b> if it is the same wort as the rest of the brew (hops and all), there is no point decanting it.. drop the lot in the brew?

Cheers
goatus

 

[cubbie]

Question to those smarter than I: If you are no-chilling and fill your cube, and have a couple of litres of wort left in the kettle - can you:

a> crash chill and use as your starter wort instead of using extract (even if its high gravity, or should we be diluting to start the yeast off easy at a lower gravity?)

and

b> if it is the same wort as the rest of the brew (hops and all), there is no point decanting it.. drop the lot in the brew?

Cheers
goatus

A) You can use it as a starter, although as you indicated a high gravity starter is not ideal (even if brewing a big beer). Ideally you would dilute the starter to something at about 1.040.

B) If you are looking for a starter (rather than just increasing your cell count), then by all means pour the whole lot in. You only want to aerate your starter at the beginning to prevent oxidisation.

 

[MeLoveBeer]

if you are making a starter aerate it at the start but not constantly (eg with a stir plate).

Cubbie, can I why not? All the books (and brewers far more experienced than me) I've ever consulted not only say its okay, but strongly recommend a stir plate for the entire time a starter is being grown (and I've never had a bad experience doing so).

 

[cubbie]

My understanding
A stir plate is used when growing your cell count via continuously introducing oxygen. You will increase your cell growth however the resulting beer (in the starter) will be oxidised. Do you want to introduce that oxidised beer to your wort? Once the yeast growth is finished I you would decant the beer and pitch the slurry into a starter or your wort.

At starter on the other hand is to get the yeast ready for action, you would pitch a starter at high krausen.


That is the theory behind my comment.

Note I do not use a stir plate so other with more experience may want to set me straight on the matter.

 

[goatus]

but you are introducing the whole mixture into airated wort anyway.. so there is gonna be plenty of oxygen in there.. im sure as soon as the yeasties start fermenting the wort and producing CO2 again the oxygen in the starter will be either eaten up by the yeast, or driven out the airlock by the C02. Im pretty sure you only dont want oxygen in your finished beer so it doesnt sit in there and stale your beer.. but im only guessing. Anyone got a copy of that new Yeast book handy? haha.

 

[felten]

Theres a difference betwen aerating your wort before fermentation begins, and during/after fermentation. There's also a difference between oxygen and oxidised. Oxygen gets used up by the yeast while they're in the lag phase for various reasons. But oxidised components of fermented beer can hang around and taste bad.

I'd grab my yeast book and cut+paste a more technical explanation but that would take too long

 

[SanDiegoBrewer]

Most excellent topic and good advise so far! Get White and Zainasheff's YEAST book, that book made me a better brewer and yeast handler and it will blow yer mind if you haven't got it yet! oh and www.mrmalty.com has a nice pitching calculator and yeast starter info