Using Yeast as Yeast Nutrient

[Gloveski]

Just wondering does anyone else use some of there old Yeast as yeast nutrient . I have some yeast a few months old in the fridge that will need to go back into a dark lager if I reuse. I was wondering if I could just use this a nutrient in the boil ?

 

[fungrel]

Absolutely do. I add it at 15min as I do with yeast nutrient.

 

[Batz]

Have you ever bought yeast nutrient? If so have a smell of it and tell me it does not smell like yeast?

 

[peteru]

Sure. Some brands of yeast nutrient even tell you that the main ingredient is deactivated yeast and that the product complies with The Reinheitsgebot.

But, I wonder if just any old yeast that's been through a 15 minute boil is the optimal nutrient. And, how do you figure out the appropriate dosage?

 

[manticle]

Yes you can. It will help but will be missing a few of the other things you'll get in a commercial beer yeast nutrient, including ammonium phosphates and zinc.

@Batz - mostly I get a massive ammonia whiff when I add mine. The only time brewday smells less than pleasant is when that goes in.

 

[MHB]

Most yeast nutrient (the good ones) have some yeast as part of their ingredient list, it is fully lysed, something that wont happen in a boil.
There is also a lot more of a good nitrogen source (usually DAP) and a bunch of other ingredients.
Here is a good basic link Beer and Brewing.
Its probably more of a concern in starters or propagators than in an all malt wort, but the real stuff is very inexpensive on a brew by brew basis and well worth the investment.
Mark

 

[Lyrebird_Cycles]

This is probably not very important in brewing where the fermentations are much less stressful but in wine we've learnt not to use DAP in early additions.

The reason for this is that yeast has to make transport enzymes for some amino acids in response to their presence but the transport enzymes for ammonium (ammonium permeases) are in a group of transporters that are preferentially up-regulated, so in the presence of mixed nitrogen sources the yeast will preferentially take up the ammonium. This isn't a problem until the yeast gets stressed at the end of fermentation which can limit its ability to switch on new metabolic pathways (such as amino acid transfer). This can lead to a situation where the yeast fails to take up all the amino acids, thus negating much of the point of adding the nutrient in the first place.

Best practice is to use a DAP free nutrient in the first add and DAP only for second and subsequent adds. Since you are very unlikely to need a second add in brewing, best practice would be not to use a DAP containing nutrient.

 

[Gloveski]

Thanks guys for the replies