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Acid Washing Yeast

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Gout

Bentleigh Brau Haus
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Now that i have a pH meter i am interested in trying "Acid washing" my yeast starters.

can anyone explain how to do it, eg pH and what acid? citric , phos?
how long , and how

then why, what bugs does it kill, what does it not kill?

and does it effect the yeast ...

thanks
 

chiller

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Hi Ben,

Welcome to world of .......... experimentation :)


Collect a fresh yeast slurry ... about 200ml put in the coldest part of your fridge so that it is as close to 3 --- 4 degrees c.

At the same time adjust 200ml of tap water to pH 1.9 - 2 with phosphoric, lactic or citric or tartaric acid. I use phosphoric acid as my preference.

Use buffer 4 to check your meter is correct before adjusting the water ph.

When the pH of the water is correct mix the slurry and water well and return to the fridge [covered of course.]

Every 15 minutes for the next 60 minutes agitate the mixture.

Leave it sit for a futher 20 minutes and then pitch it into a starter or a ready to go brew. Leave any trub in the container.

Yeast can tolerate the acid for about 90 - 120 minutes but cannot be stored in the acid mix.

You may notice the yeast behaves slightly differently .... it may not flocculate as well as previous. This normally returns to normal after the first starter or brew.


Yeast are pretty tough so have a go.


Steve.
 

Gout

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thanks chiller, at what point do you acid wash a yeast, eg after the first use? or.. after a few brews etc

thanks
I am thinking of brewing tomorrow a english ale, and the yeast is from a smack pak then built up in a starter so should be ok.

but some others are older so i thought it might be worth trying

what does the acid kill? and what dont it kill. (wont kill yeast so i gather there is some baddies that survive there acidic bath)
 

chiller

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Ben said:
thanks chiller, at what point do you acid wash a yeast, eg after the first use? or.. after a few brews etc

thanks
I am thinking of brewing tomorrow a english ale, and the yeast is from a smack pak then built up in a starter so should be ok.

but some others are older so i thought it might be worth trying

what does the acid kill? and what dont it kill. (wont kill yeast so i gather there is some baddies that survive there acidic bath)
If I acid wash I will do it with any yeast I'm unsure of the origon ... another brewer, after 3-4 pitchings in my own set up.

It will reduce the numbers of bacteria to very low levels but won't kill wild yeast.

It is not a substitute for good sanitation. It will clean up the yeast and free the fom the trub but in a conversation with Dave Logsden from Wyeast he did stress that the acid washing doesn't affect all yeast in the same way. So you will need to keep some notes.


You don't need it for fresh starters, only use it every 3 - 4 pitchings. If you get a bad infection dump the yeast regardless.

Steve
 

Gout

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great thanks

i gather with a microscope you and inspect your yeastys and see if there is much "infection" building up??

I am basicly breading yeast blind, untill you taste the beer (and there is so many things that influnce that also)

thanks steve
 
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