Liquid Yeast Quantities

[milestron]

Hey all - just broke my liquid yeast cherry. Picked up a Forbidden fruits smackpack and have started farming it. Basically have boiled up some malt extract and pitched the yeast into a couple of sanitised 2ltr coke bottles with gladwrap around the top. My plan is to split it up into a couple of say 375ml bottles, use 1 for my next brew and keep say 4 or 5 in the fridge.

Anyway my question is - I'm looking at the recipeDB and it will say for example '200ml yeast xxx' - is this qty just the sediment portion after pouring off the fermented malt, or does it mean 'make up a starter to 200ml and then pitch that amount'. It looks as though the quantities vary quite a bit, for example the fly-blown belgium recipe uses 2L Wyeast 1762. Supposedly the activator packs are ready to pitch but when I opened it up it didn't actually look as much as what I was expecting.

 

[manticle]

2L of actual slurry would be way too much for a general sized single batch. The way I've always interpreted it is that if you step up in the correct manner you will be able to estimate the amount of yeast cells contained within. You are aiming for the correct number of cells when you pitch. Therefore once you get up to 2 L of wort that has been fermented out, you will be able to estimate the amount you are pitching. If you wish to use an active starter, then add a bit more and wait till you see any sign of active fermentation (small bubbles when held up to the light is enough).

Hopefully that's correct - that's how I understand it and how I do it and it works the way I would like it to work.

 

[milestron]

Ahh right yeh 2L did seem a bit crazy. I just googled and found the mr malty repitching calculator (http://www.mrmalty.com/calc/repitch.html if anyone's interested) so I think I'll plug the recipes into that. A 1065 OG beer (like the Flyblown) gives 134 ml which seems alot more reasonable

 

[proudscum]

thanks for the link it will come in very handy soon....

 

[J Grimmer]

A couple of Questions:

1. Can you over pitch the yeast and if so what happens.

2. How long can you keep a liquid yeast in the fridge?

 

[black_labb]

over pitching isnt really a worry. you will get more sediment and it may take a bit longer to settle. if you are doing a beer that has flavours coming from the yeast overpitching may result in fewer of the flavours. if you pitch a bit warm it may take off too quick from the excess yeast making it ferment quicker and making more heat.

for most beers id keep on the side of over rather than underpitching, but its not too much of a concern unless you are doing a high gravity beer.

 

[np1962]

over pitching isnt really a worry. you will get more sediment and it may take a bit longer to settle. if you are doing a beer that has flavours coming from the yeast overpitching may result in fewer of the flavours. if you pitch a bit warm it may take off too quick from the excess yeast making it ferment quicker and making more heat.

for most beers id keep on the side of over rather than underpitching, but its not too much of a concern unless you are doing a high gravity beer.

Your thoughts on over or under pitching seem to be opposite to those of Dave Logsdon, founder of Wyeast.
He says
I try to stay within 20% of my ideal pitch rate and I prefer to slightly under pitch rather than over pitch. This causes more cell growth, more esters, and better yeast health. Over pitching causes other problems with beer flavor, such as a lack of esters. Changes in the flavor profile are noticeable when the pitch rates are as little as 20% over the recommended amount.

Nige