Starters: Two Questions

[freisste]

Ok, I've made quite a few batches of beer (2-3 dozen), so my feet are pretty wet but I'm still a noob. I usually make a starter, but I got to thinking while making my latest (for a green flash IPA clone).

1. When I use yeastcalculator.com to determine starter size for the appropriate pitching rate, it gives me the volume(s) I need. In my latest case, it happened to be 1.6L. I have always made the starter and added everything from the smack pack. The liquid in the smack pack adds a little volume. Maybe close to 100ml. I'm not supposed to factor that volume in, am I?

2. I am starting to harvest yeast by making larger than necessary starters. As an example, if I need 150BB cells, I'll use a calculator to determine the starter required to make 250BB cells. Then I'll split it 60/40 and save 100BB cells. As a result, I know my quantity and "production" date, so can I use these values in the viability calculator on yeastcalculator.com? It seems considerably more accurate than determining the slurry volume.

Thanks in advance.

 

[Barley_Bob]

1. The yeast calculator tells you how many cells you're going to need (according to their methodology). But there's no way for you to know how many cells you actually have - they're way to small and numerous for that. So, we use the "liters" measure to approximate how many cells are present based on socially accepted standards for making a stater (1 Liter of 1.04 OG). I have no idea why we measure starters in liters, but my guess is that we do it that way because that's how big Erlenmeyer flasks are and for no better reason. My point is that the actual volume of liquid is almost totally irrelevant. When you make a 1L starter, you don't actually end up with a full liter container of yeast - you simply have an estimated number of cells. You may actually have more or less than that, but we're just estimating.

According to some, an OG of your starter wort less than 1.04 is actually better and can encourage the growth of even more cells. So, when I make my starters, I tend to go a little over on volume of water. I really just don't worry at all about how much water is actually in there, because all that water is going down the drain, and, as a community, we're okay with using an arbitrary measure to keep track of billions of cells. Just as there is a point where you have too little water, there probably is a point where you just have too much water, but I don't know what that is. I would try not to go below 1.02 OG based on other readings, which gives you a huge range to work with. So, don't sweat the little bit in the smack pack. If you did want to get an exact gravity, you would have to factor in the 100ml, but who cares?

2. I use almost this exact same method to split yeast for storage. Although, I don't really worry too much about the date. It's probably better to keep track and do as you suggest, but oh well. If I'm making a really big starter from 1L of saved yeast, or if I know my yeast is really old (more than 6 months), I'll baby it and do a step starter.

 

[JBIII]

Do you use starters for every batch or only batches of a specific O.G.?

 

[Barley_Bob]

I do for two reasons. First, I split my starters so I can save some. So, I do need to grow a fresh batch each time to have some left to put away. Second, it ensures maximum viability in the yeast I do pitch.

There are a lot of other ways to pitch and save yeast, some of which don't require a starter every time.

 

[freisste]

@Bob: thanks for the practical answers. I should have realized the significance (or relative lack thereof) of the 100ml.

@zbill: I do a starter for every batch unless I'm using dry yeast (~1/6 to 1/4 the cost per billion cells compared to liquid) or I'm in a big hurry and buy multiple smack packs. But at $8/ea, multiple smack packs isn't really a reasonable route.

 

[brewprint]

I do what you do as well. Saves a lot of cash and yeast is always on hand.

I too don't worry anymore about how much more volume is from the smack pack, jar of harvested yeast or dme.

Look at all the different calculators for yeast. They all have a different philosophy. Also we don't really know for sure what those smack packs have been through. Did they sit in the warehouse of ups over a long hot weekend? When the store owner opened the package did they sit on the counter while a customer was waited on? That also will affect cell count.

 

[Barley_Bob]

@Bob: thanks for the practical answers. I should have realized the significance (or relative lack thereof) of the 100ml.

Sure thing. I obviously spent a fair amount of time thinking about your question prior to you asking it...