Starter sizes with slants

[Cain Harland]

I'm trying to figure out what size flasks to buy and having a hard time finding any kind of definitive answer for what size steps to build up the starter in. I will be using the whole slant not just scraping a bit off and steeping up to somewhere between 2L and 5L depending on the beer, lets just say 4L for the sake of this discussion which seems about right for most of my brews.

With single colony from a plate 10ml seems to be an appropriate first step and a lot of folks seem to be doing this with slants too but a slant contains a lot more cells than a single colony so that seems like too little, other folks seem to be stepping straight up to 750 ml or 1L on a stirplate which seems like way to much to me, even if the yeast could happily propagate that much its an infection risk.Starting with a small quantity of sterile canned wort seems like a good idea and I have some 25ml brown poison bottles I bought when I was going to freeze rather than slant so I will use them for the wort.

Does the following seem reasonable? 25ml sterile canned wort > 400ml on stir plate > 4L (2x 2L)on stir plate

Or would it be better to go:  25ml sterile canned wort >200ml on stir plate > 1L on stir plate > 4L (2x 2L)on stir plate

Or: 50ml sterile canned wort > 500ml on stir plate > 4L (2x 2L)on stir plate

[Peter Smith]

Read this link on starter sizing,  go for bigger flasks then you think you need  as the hot break will go all over your oven gas hob otherwise

https://www.maltosefalcons.com/tech/yeast-propagation-and-maintenan...

[Cain Harland]

That's probably a good reason to spend the extra few bucks and get the 3L instead of another 2L which would also give me a bit more scope for bigger beers or just putting a bit more starter away for next time.

Yeah its a great article heaps of good info but doesn't provide many definitive answers and (as most article I've found) treats slants and single colonies form plates as being more or less the same thing. My point/question is that they contain very different numbers of cells so require a different amount of wort for optimal dilution. Is 10ml right for a slant or a single colony? And whats right for the other?

This below leaves plenty of room for interpretation but leaves us with the 4x to 10x rule I've seen elsewhere

"Although a 100-fold dilution or step-up seems reasonable for yeast propagation, most breweries (or at least what is taught by brewing schools) advocate even smaller dilutions.  The Siebel Institute recommends that yeast be stepped up in 8-fold increments, the British Brewing schools recommend 10-fold increments, and the German Brewing schools recommend 4-fold increments"

Then this that may support the first step up being a lot larger eg my 25ml (or 10ml) to 400ml step. Or maybe thats wishful thinking as there aren't enough steps after it.

"I should also point out, however that most breweries start with a 10 ml culture and step-up to 500 ml or 1 liter initially and that it is only in the later stages that the step-up size is reduced"

[Cain Harland]

Here is another article by Chris White in BYO. He talks about using 1 hoop from a slant in 10ml then stepping up to 500ml  which seems to be the final product. I have no reason to use just 1 hoop rather than whole slant as it will only be a back up to harvesting starters and by time I need to use the slant it will be past or nearing its best by and time to re slant.