yeast?

[mattrix]

This is about yeast, but not any particular product (beer, wine, cider). I hope this is the correct place for this question, rather than cross-posting to all the sub-forums.
If there is a better place for this, please let me know or go ahead and move it.

Older books always seem to require "proof"ing yeast.

As I understand it,
* put about 100mL of water and invert sugar in an (imperial) pint glass and cover
*when the water is at about 25C add some yeast
*mix and let stand to do its stuff
*Add active yeast to must/wort etc.

Things I am not clear about:
* I'm not too sure how to invert sugar. Something to do with heat and acid?
* How much yeast to use: if it takes off that is enough yeast? if it does not take off add some more? (if it never takes off you are just wasting defunct yeast anyway)
* Is the 'active yeast' the whole lot froth and all?
* what size batch will a pint glass ferment? Presumably there are a lot more yeasties in the glass than a packet of yeast.
* Does the glass need to be kept full?
* How long can you keep the glass going before using it?

Thanks for helping with these beginner questions.

 

[Miraculix]

Why do you want to do this? Side question, why do you want to do this in a way that does not provide any nutrients to the yeast and weakens the yeast?

 

[mattrix]

As I said it used to be standard practice.
Besides it would be nice to know that the yeast works.

How do you make yest nutrients?
I read something about adding nutritional or bread yeast when doing the 'invert'ing.

 

[DBhomebrew]

Replace "proofing yeast" with "vitality starter" and you'll get plenty of current hits.

Active yeast will take over a batch, crowd out undesirable organisms, and start fermentation faster than dormant yeast.

For beer using liquid yeast, starting in wort 1.036-40 is best. Nutrients are seldom needed. Yes, when using a vitality (or SNS, not really the same thing) starter, pitch the whole thing. Liquid, froth, everything.

For dry yeast a starter isn't necessary, but one can hydrate according to package directions in Go-Ferm which is specifically marketed as a hydration nutritive.

 

[mattrix]

Thanks DBhomebrew

Why do they have to rename things?
Change made.

 

[DBhomebrew]

Language evolves. Etymology is fascinating.

 

[Miraculix]

As I said it used to be standard practice.
Besides it would be nice to know that the yeast works.

How do you make yest nutrients?
I read something about adding nutritional or bread yeast when doing the 'invert'ing.

That's no valid reason, it's not done anymore. What is recommended is making a starter with liquid yeast to increase the cell count to the desired amount. Dry yeast can be pitched directly.

A starter is made out of wort, which contains not only sugars but also nutrients. That's why there's no need for any other yeast nutrients. Some people use them but they are entirely optional and from my point of view useless in this case.

Making high quality yeast nutrient is not that easy, the best home-made solution would be indeed to boil bread yeast. I'd buy fermaid o instead.