Rehydrating Yeast

[Carboy]

Hi,

Just after some reassurance/ advice please.

I'm just about to put down a Pale Munich Lager and my LHBS owner sold me S-23 lager yeast with the instruction to rehydrate the yeast in 120ml of boiled water (cooled to 30c 3) and then to add 2 teaspoons of Dex or LDM to give the yeast something to chew on... let it sit for 30 minutes... then pitch into fermenter with wort (no need to to stir).

I normally dry pitch, so I've done some research on AHB and the Web but I can't really find any definitive advise on rehydrating yeast :unsure: .

Any advice/ suggestions gladly accepted, thank you.

Cheers
Carboy :icon_cheers:

 

[MCT]

Try these threads:

http://www.aussiehomebrewer.com/forum/inde...=%2Brehydrating

Some good info there.

 

[Carboy]

Try these threads:

http://www.aussiehomebrewer.com/forum/inde...=%2Brehydrating

Some good info there.

Thanks MCT,

When I did a search of the forum only two threads came up with not much info.

I just had a flick through the links you provided me with, and I found my answer/s from BATZ.

Thanks heaps

Cheers
Carboy :icon_cheers:

 

[RdeVjun]

Fair enough question that.

Dried yeast can be rehydrated with just cooled boiled water to determine if it is viable and healthy. All you do is add it to the water, then sit back and watch. Pitch it when it froths up, if it doesn't, toss it and get a new one. You don't need dex or malt extract for this and they're superfluous as the yeast has its own glycogen reserves stashed away anyway.

If on the other hand you need a starter, say for a high gravity wort, then you will need to firstly rehydrate it and then give it something to eat and then multiply from to tackle the unusual conditions. Hence the malt extract you see in some recipes, here's my method (/shameless plug). Some people would suggest that dex is not a good food for yeast at that stage, I couldn't say as I'm not an expert.

Take- home messages: For a standard strength wort- rehydrate if you're suss on the yeast, or want to check that its a-ok. Pitch direct if you're happy its viable. For high gravity wort, make up a starter.

Liquid yeast are another kettle of fish, putting them in water will tell you nothing, but I don't think that's an issue here.

 

[Carboy]

Fair enough question that.

Dried yeast can be rehydrated with just cooled boiled water to determine if it is viable and healthy. All you do is add it to the water, then sit back and watch. Pitch it when it froths up, if it doesn't, toss it and get a new one. You don't need dex or malt extract for this and they're superfluous as the yeast has its own glycogen reserves stashed away anyway.

If on the other hand you need a starter, say for a high gravity wort, then you will need to firstly rehydrate it and then give it something to eat and then multiply from to tackle the unusual conditions. Hence the malt extract you see in some recipes, here's my method (/shameless plug). Some people would suggest that dex is not a good food for yeast at that stage, I couldn't say as I'm not an expert.

Take- home messages: For a standard strength wort- rehydrate if you're suss on the yeast, or want to check that its a-ok. Pitch direct if you're happy its viable. For high gravity wort, make up a starter.

Liquid yeast are another kettle of fish, putting them in water will tell you nothing, but I don't think that's an issue here.

Thank you RdeVjun

A picture paints a thousand words

 

[flattop]

I would follow the instructions, i have rehydrated a few yeasts and i do use a bit of dex or lme to kick it along.... never hurts as a fresh yeast from the fridge will get a temp shock to be thrown straight in, i take it out of the fridge 20 mins before, let it sit then pitch it into about 20*c water, wait 10m then add a couple of teaspoons of dex....

 

[Carboy]

I would follow the instructions, i have rehydrated a few yeasts and i do use a bit of dex or lme to kick it along.... never hurts as a fresh yeast from the fridge will get a temp shock to be thrown straight in, i take it out of the fridge 20 mins before, let it sit then pitch it into about 20*c water, wait 10m then add a couple of teaspoons of dex....

Hi Flattop,

My yeast has been rehydrating for 20 minutes now but some (about the size of 50 peice) of it is still floating on top of the water, shout I give it a light swirl and then add some Dex or LDM?

Thank you in advance for your reply

Cheers
Carboy :icon_cheers:

 

[LLoyd]

I'm a bit suss about yeast (cos I'm a bit suss about my sanitation) Did a double batch awhile back with two different yeasts. One fired up straight away and one took a couple of days. The slow one got thrown, didn't even taste like a BEER flavoured bandaid!! My theory is that we get some sort of infection in all our brews, but as long as the yeast gets going quick enough it's not noticable. So just cos it makes me feel better I always make sure I've go a big starter that's going nuts before I pitch

 

[flattop]

It's all good, you can decide if you want to feed it a little or just pitch it, if the brew is ready for pitching i would probably pitch it at this stage, if your wort is not at the right temp yet then add a little lme and cover it for a while. Don't worry if it's not foamy on top, i have had some that are and some that aren't

 

[Bremmario]

So reading this, basically, the rehydration of the yeast:

A ) gives the yeast a head start over any bacteria/wild yeast that might infect your wort,

and;

B ) lets you see if the yeast is a dud - how often does this occur in people's experience?

 

[rclemmett]

So reading this, basically, the rehydration of the yeast:

A ) gives the yeast a head start over any bacteria/wild yeast that might infect your wort,

and;

B ) lets you see if the yeast is a dud - how often does this occur in people's experience?

A high concentration of sugar is toxic to dried yeast... When dry yeast is added to liquid it cell walls are very week and anything can pass straight though.

This is not as big a problem when low gravity brewing.