SO4 or SO5 yeast

[Cathal O D]

Hi
Im currently fermenting a porter with SO4 yeast and was thinking of pouring my next batch directly onto the yeast cake. I was hoping to do a blond ale. Do you think this would be ok or would it be better to use fresh yeast? If using fresh yeast would SO5 be better for blond ale?

[Cathal O D]

Yea ive seen that wiki. I might do that. Whats the story with using stored yeast? Do you have to make up a starter?  I have some yeast i got from a friend in a test tube and not really sure what to do with it. Is there a wiki?

[Rossa]

A starter would be good. Start with a small one if it is a test tube baby. Maybe 50ml and 5g dme. Step it up after a day or two to 100ml with 10h dme and so on until you have a pitcheable amount....I like a 2l starter. Never fails me. It just takes time...a week or so.

[Cathal O D]

Ok sounds easy enough. Is there any way of ensuring that only yeast grows. Obviously everything nerds to be sterilised but im worried that there may be something else in the test tube.
Ive heard of something that will kill bacteria but leaves yeast alone.

[Will_D]

Ok sounds easy enough. Is there any way of ensuring that only yeast grows. Obviously everything nerds to be sterilised but im worried that there may be something else in the test tube.
Ive heard of something that will kill bacteria but leaves yeast alone.

The technique is called "acid washing"

There should be plenty of info both here, on Beoir and on the www.

Basically it consists of taking the pH of the yeast slurry down to pH 2.2 using food grade Phosphoric acid or FG Citric acid ( Citric much easier to get hold of )

This kills bacteria and wild yeasts but the brewers yeast is resitant at this pH.

Will

[Spud395]

Ok sounds easy enough. Is there any way of ensuring that only yeast grows. Obviously everything nerds to be sterilised but im worried that there may be something else in the test tube.
Ive heard of something that will kill bacteria but leaves yeast alone.

This kills bacteria and wild yeasts but the brewers yeast is resitant at this pH.

Will

Wild yeast is not effected by acid washing and will live to infect another day, it's one of the downfalls of acid washing

[Will_D]

Ok sounds easy enough. Is there any way of ensuring that only yeast grows. Obviously everything nerds to be sterilised but im worried that there may be something else in the test tube.
Ive heard of something that will kill bacteria but leaves yeast alone.

This kills bacteria and wild yeasts but the brewers yeast is resitant at this pH.

Will

Wild yeast is not effected by acid washing and will live to infect another day, it's one of the downfalls of acid washing

I stand corrected: thanks Spud!

Acid washing is a "just in case" option:

Its just less likely in a domestic environment to suffer wild yeats as opposed to bacteria!

Plus I would rather suffer wild yeasts in my beer than massive cultured bacterial nastys! 

Will

[Cathal O D]

With this yeast i got from a friend in a test tube, if i make a strater and grow it up to a pitchable amount, will it be obvious if some bacteria is present? i.e will there be a bad smell or something from the 2L volume?

[Spud395]

Simple answer.....no, not at all.

The best way to crop ale yeast to minimize bacteria is by top cropping.

Really you want to skim the dirty head a day after the ferment kicks off, what you're seeing there is trub, not yeast. This is mostly what will be in that dirty ring after the ferment. Anyway skim and discard this.

With a proper top cropping yeast you will then get a yeast head forming as fermentation starts to slow down and the yeast flocculate to the top. This is the ideal time to crop an ale yeast. Bacteria or trub should not be present in any amount here, this is how some traditional breweries keep a yeast going for hundreds of years. If you leave it longer and the yeast finally drops to the bottom, it will again have trub and bacteria in there.

It is handier to crop at this stage after racking the beer off, as you have no chance of infecting the beer and this is when most homebrewers will crop their yeast.

Chances are there is some level of infection in the yeast you got from your friend. The chance is also that when you pitch enough of that yeast when it's healthy and viable it will dominate any other organism thats mixed in there in small quantities and produce good beer. But I would have to be happy that the brewer I got the yeast from does everything in his power to keep things as right as possible at all times.

Sorry if I went on a bit 

Oh but I do know one brewer who advises to get to know your yeast, look at it, smell it, taste it, use it long enough and you will get to know when it's off

[Cathal O D]

Thanks for that. Im sure he would have been very good with his  sanitisation. Also the yeast in the test tube is about 4 or 5 months old. It has been kept in the fridge the whole  time. Do you think it is still ok?
I might make up a starter and see what happens.........

[Cathal O D]

Cool thanks

[Spud395]

You'll have to make a starter with that, but it's not a biggy.

A simple and cheap way to make a starter is when you have drained your wort from the mashtun to your kettle take a litre out of your kettle. Boil the litre for a few minutes and let it cool, and use it to make your starter.

Then the following evening boil your main wort, cool it, and throw in the starter you just made the day earlier.

How do you store the unboiled wort?

Would you not be afraid you could have a party kick off in the day it's sitting there just being it's sugary self?

[Spud395]

In the kettle. Not really worried as boiling it for 60 or 90 mins will put an end to any party

It'll kil any nastys for sure, but dead nastyness might not taste great either 

I suppose if it works, I'd be scared