When Is Yeast Dead?

[dirty mac]

After getting a little bit more experienced I have decided that my next brew I might try the wyeast and do the whole starter thing. OK. Now I understand the whole fresh yeast thing that when you feed it sugars the cells multiply and you end up with more yeast, hence why you can end up with 5 seperate starters. Whats really bugging me is at what point does the yeast just not work anymore? I've heard people just brewing over a yeast cake!! I thought that yeast was dead hence the reason why it went to ground. Is it possible that the yeast can just keep multiplying for ever? Is this why you can cultivate the yeast from commercial coopers beers and how do you know that you have enough????
:blink:
Sorry for all the Q's but before I undertake anything scientific like making a starter I need to understand why I'm doing something.

Please help so I can take the next important step in improving my brews

 

[Fingerlickin_B]

Nah, not dead.

When yeast flocs out (settles) it has just run out of food and gone to sleep.

Dead yeast can break down and create horrible flavours in your beer, but then again "not viable" and "dead" could often mean different things.

That's about all I know...we'll wait for the experts now

PZ.

 

[razz]

Morning Dirty Mac. Yes it is a highly technical process, and there is plenty of data on the net about yeasties. On the question of the yeast just keep on multiplying for ever they don't. What a lot of brewers do is to keep the yeasties at low temps to inhibit their growth and to put them to sleep so to speak. I personally have had great success by racking fresh wort onto yeast cakes. If you use the search fuction you will have a lot of reading. Good luck !

 

[dirty mac]

Morning Dirty Mac. Yes it is a highly technical process, and there is plenty of data on the net about yeasties. On the question of the yeast just keep on multiplying for ever they don't. What a lot of brewers do is to keep the yeasties at low temps to inhibit their growth and to put them to sleep so to speak. I personally have had great success by racking fresh wort onto yeast cakes. If you use the search fuction you will have a lot of reading. Good luck !

See this is what I don't understand. Your not meant to leave the brew on the yeast cake for toolong cause of off flavours, but you can put a new brew on it :huh: Back to my other Q. How much is enough? If you are making 5 starters how do you know you've got enough in each one?

 

[Stuster]

The reason you are not meant to leave the beer on the yeast cake for too long is autolysis. As pointed out by Trough Lolly not long ago, this happens when there is not enough food for the yeast to eat. So using the yeast for another ferment is fine because you providing the yeast with lots of yummy wort to get into.

How much is enough? Well, it's debatable how much exactly, but keeping it simple, making up a 1-2L starter will be fine. You don't need to make up five of those and keep them in the fridge for later brews though. If you are following Batz's directions (airlocked in the common ground forum), you'll see how to do it. Store less in the fridge and when you need to use it, make a starter from that stubby.

 

[DrewCarey82]

After I've made a 2 litre starter I then break it up into 400ml bottles.

Then when I need to make a yeast for a brew I activate the yeast via another starter of 2 litres and pitch the whole kit, kat and kaboodle.

 

[razz]

One thing you will find in your life long brewing hobby is that there is a lot of theory, some of this theory will work well in practise will some is just that, theory and nothing more. If you have good temp control over your fermenter you can leave the finished beer on the yeast cake for several weeks but you need to keep the temp down to inhibit the yeast. I have been doing this for many years. As to your question on how much is enough for starters, a general rule is you need a cup of slurry for each batch. This is general only and it will vary upwards for higher gravity beers. When you split the yeast into 5 you need to store these under boiled and cooled water in the fridge until you want to use one, then you need to step up the culture by making a starter. I still think you need to use the search fuction before you come back to this post. Happy to help.

 

[dirty mac]

Thanx, thats all I probbaly need to get going. It was just hard getting my head around the fact that yeast can just keep scoffing for so long . When we start out brewing its all under the assumption that you pay your $5 for yeast each time to make each brew.

 

[dirty mac]

The reason you are not meant to leave the beer on the yeast cake for too long is autolysis. As pointed out by Trough Lolly not long ago, this happens when there is not enough food for the yeast to eat. So using the yeast for another ferment is fine because you providing the yeast with lots of yummy wort to get into.

How much is enough? Well, it's debatable how much exactly, but keeping it simple, making up a 1-2L starter will be fine. You don't need to make up five of those and keep them in the fridge for later brews though. If you are following Batz's directions (airlocked in the common ground forum), you'll see how to do it. Store less in the fridge and when you need to use it, make a starter from that stubby.

I just read that and am getting my head round it. My biggy is if I've made a 1 L starter with 100g of DME. Each time I step it up do I use 1L and 100g again to expect that double amount of yeast??

 

[Stuster]

You won't necessarily double the number of yeast there by doubling the amount of wort. There are a number of factors involved. Mostly you'd step up by factors of ten, so start with a 200ml wort, then step up to 2L. Starting with Wyeast/White Labs yeast, you're fine making a 2L starter straight off.

Have a read of the two airlocked threads at the top of the Common Ground forum, especially Chiller's Yeast Farming thread. They are both relevant with heaps of info. You may well have more questions after you read those.