help me understand the starter!

[joshesmusica]

Ok, so I've been trying to learn what I can about the starter. I feel like I understand the main point to be to multiply viable yeast. Some people are talking about the health of the yeast. One guy even mentioned how he didn't do a starter, but had more than enough yeast cell count, and yet still had no activity in the fermenter. But with that guy for instance, if he didn't have activity in the fermenter, would he really have had activity in the starter?
If a yeast becomes healthy and active in a starter, granted that I add enough yeast cells to my fermenter, shouldn't it have just the same effect in the main wort?

 

[solbes]

I think the answer to your question is in how much sugar is available. Think about how much sugar is available in 2 liters of 1.040 starter wort. Now think about how much sugar there is in 5 gallons of 1.060 wort.

So even if your yeast had marginal health, there should still be plenty of active yeast cells to multiply and get ready to tackle 2 liters of diluted wort. It doesn't take long because in just a couple or few generations of reproduction they are ready to start fermenting.

Taking those same numbers of marginal health yeast cells, if you were to direct pitch into your 5 gallons of brewed wort, they would have to multiply into lots of generations before they could have enough numbers to start chewing through the sugars. Thus the excessive lag time. And extra byproducts created.

Thus this is why making a starter is a good idea for almost any batch. 3 exceptions I can think of: First you pitch slurry from a previous batch of freshly fermented beer. This gives you a lot of active and healty yeast. Only way to fly in really huge ales and big lagers IMO.

Second is if you pitch dry yeast. It is packaged in optimal health and one packet is often good enough for up to 1.060 gravity or so. Two packets will handle almost any ale and most lagers. Rehydrate dry yeast as a best practice.

Third is if you direct pitch 1 vial or pack of liquid yeast into a low gravity session ale. Like 1.040 or lower IMO. No need really for a yeast starter there unless you have older yeast that is not as viable.

 

[ScrewyBrewer]

The purpose of a yeast starter is to increase cell count and to ensure the viability of the yeast cells too. When you pitch your yeast into wort you need to make sure your pitch rate is correct for the gravity of the beer it's expected to ferment, but the cells counted need to be healthy.

 

[Talgrath]

Ok, so I've been trying to learn what I can about the starter. I feel like I understand the main point to be to multiply viable yeast. Some people are talking about the health of the yeast. One guy even mentioned how he didn't do a starter, but had more than enough yeast cell count, and yet still had no activity in the fermenter. But with that guy for instance, if he didn't have activity in the fermenter, would he really have had activity in the starter?
If a yeast becomes healthy and active in a starter, granted that I add enough yeast cells to my fermenter, shouldn't it have just the same effect in the main wort?

All right, let's tackle this one bit at a time.

Yeast health: So, the longer yeast is stored, the fewer "healthy" cells there are. Healthy cells are in stasis, but ready to be awakened by higher temperatures and abundant food (aka wort or starter solution). If you get fairly fresh yeast in a smack pack or dry yeast satchel, it should have enough cells to innoculate 5 gallons of 1.060 of ale (approximately); for the liquid vials I believe it's something like 1.040 instead. There is, however, a catch to the numbers; yeast that has been sitting too long probably has a lot of dead cells, so the time the yeast has been sitting is very important. All yeast products have either a manufactured date or a "best by" date, if you look at the online yeast calculators they all include this because the rate of yeast death when stored in proper conditions is fairly well known. In short, if your yeast is very old (and very old varies depending on the yeast type) then you might need to make a yeast starter even if your yeast should (theoretically) work for beer that you have. In short, try to get fresh yeast and be wary of yeast that has been sitting for two months or more, if it has been sitting that long a starter may be required.

Fermentation didn't start: So, there's a lot of posts like that on this site. 90% of the time the cause of fermentation not starting is either simply a bad yeast smack pack, vial or satchel or that the poster didn't properly pitch their yeast. Even if you vastly underpitch, you will see yeast activity, it's just that you'll get some very funky flavors, so in those instances you are correct that a yeast starter wouldn't help (though it is worth noting that a failed starter would show that the yeast was bad before it was pitched if that is the issue).

The bottom line for starters: If your beer's gravity will be slightly higher than specifications for your purchased yeast (usually 1.060 for an ale using a smack pack or dry yeast satchel) or your yeast is old, a starter is likely required. Otherwise, properly pitch your yeast (either by using a smack pack per instructions or rehydrating dry yeast) and ensure you have fermentable wort and everything should go just great.

 

[m00ps]

It also depends on what fermentation stage the starter is in. I've read that pitching at high krausen will give you the least amount of lag time. But then again, this requires youn to pitch the entire starter volume into your beer...

 

[WoodlandBrew]

The Monod equation for biomass states that the rate of fermentation is directly proportional to the sugar density of the solution. When you have a large biomass growing at a high rate you have active fermentation. So the activity is directly proportional to the amount of yeast and the gravity of the wort.

So to answer your question, if the pitch rate, gravity, and temperature were the same, then you could expect the activity to be similar.

 

[joshesmusica]

all good stuff. thanks everyone.

my next beer is supposed to be OG 1.050. i'll be using whitelabs wlp400. going to buy it today. hoping to do the starter tonight. i was going to buy all of the products for the brew yesterday, but when i emailed the lhbs, they said they didn't have anything. and it completely slipped my mind that the reason why i wanted to buy yesterday was to make the starter. do you think it would be ready for my brew day happening tomorrow? or should i wait til the weekend?
also beersmith says that i should be doing a 4.5 liter starter in order to reach the desired cell counts. and that's going off of a package date of october, but i'm thinking the package date might be a couple months before that. i don't have anything to hold the 4.5 liter (or more depending on the viability) starter except my fermenter. can i just do it in there?

also, what would happen if i tried to combine yeast. I randomly have a packet of us-05. what would happen if i just used both of these yeasts in the same fermenter?

 

[tg123]

My purpose of a yeast starter is so i can split it and save some for the next batch.

 

[WoodlandBrew]

If both strains grow equally then the result would be some characteristics of each, but one could also dominate over the other. Pitching two packages of yeast would be another way to get your cell count up.

I've found the viability by date to be overly conservative. If the yeast has been stored well there should be very little cell death over the course of several months. See here for details:

http://www.woodlandbrew.com/2012/12/refrigeration-effects-on-yeast-viability.html

The popular cell growth calculators are based on cell count after a 48 hour period. If you allow them to run to completion the yield will be about 1 Billion cells per gram of extract independent of the aeration method.

You might also consider using the first few days of fermentation in place of a starter. Instead of increasing the number of cells needed for the wort, the amount of wort can be reduced to the appropriate volume for the number of cells you have.
details here:
http://www.woodlandbrew.com/2012/12/no-more-wasteful-yeast-starters.html

 

[joshesmusica]

Thanks for that idea. That is truly genius!

 

[joshesmusica]

So if I'm using the above technique when should I be pouring on the second half of wort? Brewed yesterday evening, and on the fermenting half I've got airlock activity and some krausen this morning (about 14 hours after pitching yeast).

 

[beerme70]

I've never gotten to involved in the cell count. I know that the more cells, the better. My last batch of lager, Beersmith recommended something like 600 billion cells, requiring a 6 liter starter. I used around 1 lb of light DME for a one gallon starter. Not using a stir plate or anything, I pitched it when it was at high krausen, and fermentation in the primary started rolling after about 1 hour. I know a lot of people use a starter for the purpose of procreating yeast for higher populations, but I look at it as getting the yeast at the height of activity.

 

[WoodlandBrew]

Generally you'll want to add the second batch of wort at the 24 hour mark. If you have a good amount of krausen that means there is high yeast activity which is a good indicator that you can add the additional wort.
See this fermentation calculator for details:
http://www.woodlandbrew.com/2014/05/fermentation-model.html

(you can play with the numbers in the spreadsheet to match your fermentation)

 

[RM-MN]

I've never gotten to involved in the cell count. I know that the more cells, the better. My last batch of lager, Beersmith recommended something like 600 billion cells, requiring a 6 liter starter. I used around 1 lb of light DME for a one gallon starter. Not using a stir plate or anything, I pitched it when it was at high krausen, and fermentation in the primary started rolling after about 1 hour. I know a lot of people use a starter for the purpose of procreating yeast for higher populations, but I look at it as getting the yeast at the height of activity.

It isn't always true that the more yeast cells is better. Getting a huge amount of yeast cells can make you a bland beer. Sometime you need the cell replication to produce the esters for the beer flavor.

 

[Talgrath]

I've never gotten to involved in the cell count. I know that the more cells, the better. My last batch of lager, Beersmith recommended something like 600 billion cells, requiring a 6 liter starter. I used around 1 lb of light DME for a one gallon starter. Not using a stir plate or anything, I pitched it when it was at high krausen, and fermentation in the primary started rolling after about 1 hour. I know a lot of people use a starter for the purpose of procreating yeast for higher populations, but I look at it as getting the yeast at the height of activity.

So not quite true. There is a concept of "underpitching", meaning too few cells to ferment your wort without "excessive" ester production; most people are more concerned about underpitching because it can cause some "off flavors", particularly estery flavors and if you badly underpitch your beer won't fully ferment. However, if your beer gets much of its flavor characteristics from yeast, overpitching can be a major issue; most of the flavors from yeast come from yeast reproduction over multiple generations, if your yeasty beer has too much yeast they won't reproduce very much before they run out of food. So, in some instances people might deliberately slightly underpitch to increase the flavors from yeast, I do this on my saison, for example or they might deliberately overpitch slightly for a more "clean" taste; but usually you want to strike a balance and pitch at recommended levels for the gravity and volume of the beer you are making.

As for what you're talking about regarding "peak of activity", there's really not any difference between pitching from a starter or pitching from a properly rehydrated dry yeast or a smack pack or a vial; yeast works at a fairly fast pace like most micro-organisms compared to us.

 

[beerme70]

I have worked hard to understand all the aspects of beer production, but getting all the little nuances of understanding yeast has been quite an undertaking. I have been fortunate to produce rather splendid tasting beer, getting nothing but praises from some very stingy critics (coworkers). I need to try to work harder to get a better understanding of the miracle of those tiny little organisms.

 

[joshesmusica]

I have worked hard to understand all the aspects of beer production, but getting all the little nuances of understanding yeast has been quite an undertaking. I have been fortunate to produce rather splendid tasting beer, getting nothing but praises from some very stingy critics (coworkers). I need to try to work harder to get a better understanding of the miracle of those tiny little organisms.

Yes from what I've been reading, that is one of the most important aspects to consistently brewing great beers.

 

[Talgrath]

Yeast is arguably the most difficult thing to hit exactly right, sometimes you made a small mistake and you don't even realize it. Sanitization and proper pitching are the only real ways to keep things relatively consistent.