Why 1L starter vs 2L?

[BroomVikin]

After maybe a dozen yeast starters it occurred to me today that I might have been doing something wrong. I know that with a bigger beer I should always go with a bigger starter. Typically my bigger starter would be 1 vial of yeast into two liters of starter wort rather than one. It occurred though that if I'm decanting all that wort before pitching (which I always do) I'm not sure what the point of 2L is over 1L. Does it simply give the yeast cells more available food to munch on and therefore encourage stronger/ more multiplication? 2L starter doesn't always mean 2 yeast vials does it?

 

[TomRep]

2L indeed gives them more food to eat and multiply. I typically let the starter finish and throw it in the fridge the night before, then decant on brew day. This let's the majority of the yeast floating in suspension fall out, so when you decant, you're not losing much yeast.

 

[bajaedition]

How many gallons are you pitching into
is it a lager or an ale
What is the normal OG

 

[stz]

Double the starter volume and double the potential yeast count right? No, inoculation rate affects the rate of growth. It is not the volume of the starter that is important, but how many cells you add in relation to that volume. This is why people create stepped starters, to take advantage of the sweet spot, but as a healthy vial is already a large pitch into starter volumes and in the home the risk of contamination is greater with multiple steps it is usually wise to just go with the biggest manageable starter (for me this is 2-3L) you need while keeping the following in mind.

At 21C going from 1.036 to 1.008 and assuming your average vial is 100 billion cells then 1.5-2L should give the highest potential yield factor. The yield past this volume starts to tail off, but this does not mean you will still not get a greater number of cells making larger starters. 1L should potentially give 152G (billion) cells, 1.5L 181G, 2L 205G, 4L 276G, 8L 400G, 20L 600G. Growth rates go flat past this point, at an inoculation rate of 4 million cells per ml you exceed the ability of the yeast to multiply during a single fermentation without constant attention to oxygenation and nutrient levels, again usually completely unnecessary and a risk of contamination in the home and you might as well just make a 1.036 beer and pitch the whole cake. You can potentially double those yields with constant aeration.

Also please note this is real thumb in the air type stuff unless you are also performing cell counts to estimate the viability of your slurry and getting an accurate weight per ml of slurry based on your counts. Some knowledge and an attempt to adopt good practice is better than being completely in the dark though, but don't get too caught up in the numbers unless you are playing with extremes.

Before I knew any better I would simply pitch three packages of yeast into beers which I felt were high gravity and it worked out as long as you've got time. Recently though when actually doing the sums I realised I needed 850G cells which was actually quite a lot of slurry and having access to a very basic lab with current cell counts and viability per g for the house strain the correct pitch rate took me 2 points off FG in 3 days.

 

[logdrum]

There are a number of great starter calculators (Brewer's Friend, yeastcalculator.com, Mr Malty) that will guide you through all the relevant maths. I've been making stepped & overbuilt starters for years & have never once had any sort of infection.

 

[DurtyChemist]

As stated above the point of a larger starter is to grow more cells. The volume of beer you're decanting doesn't matter. The amount of food you provide the yeast will grow more cells. Also the inoculation rate is important. When you have a rate of 7 you'll grow a lot of cells. When it's <1 it's almost pointless. This is a big problem with stepped starters. If you make a 1 liter starter, decant then add another 1 L starter wort you won't get double the number of cells because the inoculation rate is much lower.

 

[logdrum]

I don't consider a 1L into a 1L stepped, my understanding is that you have to increase volume, and certainly pay attention to your inoculation rate, I always play around with the inputs on the starter calculators

 

[Jtk78]

As mentioned, use a yeast starter calculator. I will plug my numbers in 2 or 3 of them, compare the results, and decide how big and how much dried malt extract I'll add. Otherwise your kind of relieving yourself in the wind.

 

[jmark]

I use the calculator at BrewUnited.com... http://www.brewunited.com/yeast_calculator.php

The nice thing about this one is that it allows you to calculate stepping up and provides info about inoculation rates etc. I also find the numbers seem to track Beersmith's calculations fairly well, not that that adds or detracts from credibility, just a confirmation data point!

 

[kh54s10]

Both starters will use one package of yeast. 1 liter water with 100 grams of DME (Food) or 2 liters water with 200 grams of DME (more food). When you decant chill first until the "beer" is clear and the yeast have fallen to the bottom then you are just decanting the "beer" (it does have some yeast cells in it) There should be more of a yeast cake on the bottom of the flask with a 2 liter starter. If there isn't you have a different problem.

 

[homebrewdr]

Starter's are rarely actually needed unless youre harvesting your own yeast. Its the equivalent of proofing your yeast when baking.

 

[jmark]

Starter's are rarely actually needed unless youre harvesting your own yeast. Its the equivalent of proofing your yeast when baking.

I think that comment belongs in the "what's your contrarian view" thread

 

[DurtyChemist]

I don't consider a 1L into a 1L stepped, my understanding is that you have to increase volume, and certainly pay attention to your inoculation rate, I always play around with the inputs on the starter calculators

Plenty of people make a 2 step starter like this.

Fresh1L starter, ferment it out, decant, and
Second "step" 1L batch of wort to grow more cells for a lager.

Pitching the second "step" doesn't grow twice the amount of cells because the innoculation rate is so high. It doesn't stop people from thinking they somehow grew twice as many cells compared to just a 1L starter.

 

[logdrum]

Plenty of people make a 2 step starter like this.



Fresh1L starter, ferment it out, decant, and

Second "step" 1L batch of wort to grow more cells for a lager.



Pitching the second "step" doesn't grow twice the amount of cells because the innoculation rate is so high. It doesn't stop people from thinking they somehow grew twice as many cells compared to just a 1L starter.

Really? I agree that that method is not optimal, and have always stepped up my wort volume for that exact reason.

 

[logdrum]

Starter's are rarely actually needed unless youre harvesting your own yeast. Its the equivalent of proofing your yeast when baking.

Um, not at all. Starters are a method of increasing cell counts, proofing yeast for baking simply confirms viability.