[Whiskers]

Great thread.  I love it when solid science is used to influence process - especially when the process ends up being easier!

In regards to the photo of the flasks with stoppers in the fridge door - one thing I've been doing for the last ten years is using a bit of foil around the top and sides of the stopper.  That way, dust is kept out of the crevice between the glass and rubber.  If there is any dust in there, some of it will likely fall into the culture before you've had a chance to flame the neck. 

[S. cerevisiae]

If there is any dust in there, some of it will likely fall into the culture before you've had a chance to flame the neck.

I clean the area where the stopper meets the flask with an alcohol saturated cotton ball before removing the stopper.  I used to seal the area with Parafilm.

Edit:  One thing that I would like to add is that I keep my brewing refrigerator spotless because I also store my yeast bank in this refrigerator.

[jdpils]

A lot of what S. Cerevisiae has outlined makes sense however when using a carboy or bucket for the primary, rinsing is a very practical way to reuse yeast without needing a starter.  I typically run 3 to 4 batches of beer this way.  In my experience is far more effective in separating trub and dead cells than trying to save and waste extra beer in the carboy.  I also came to the conclusion that storing in water will raise the pH.  So I have begun using lactic acid to drop the pH under 5 and also since my water has 8 ppm calcium I add 1 gm/gallon of calcium chloride.  I syphon off as much beer as appropriate to not transfer too much yeast dump water in stir and pour into a 1 gallon jug.  Fill the jug 85% about and shake.  Then let settle and pour off about 1/2 gallon of the top or middle (depends on yeast) half and store at 35F for 1 week max.  Generally I plan two days prior to brewing as some yeasts require this time to settle   When reusing I allow to warm in the garage while brewing, pour off water, pull about 1/2 gallon of wort through my CF chiller and get the slurry back on a stir plate. This thoroughly mixes the yeast and gets it going.  Then I can just pour in after chilling to the correct temp.  If I have a conical I would collect and pitch but I have not mad the transition yet.

Cheers

[S. cerevisiae]

What makes you believe that rinsing yeast with water is the only way to directly pitch a bottom cropped culture? There is absolutely no justification for rinsing yeast with and storing it under boiled water, none.   Boiled water is not sterile, and rinsing with water adds zero value to the process. However, it does present an infection opportunity while simultaneously removing the culture's force field. Storing yeast under beer is not a waste of beer.  It is a time tested practice that is performed in most of the commercial breweries on the planet.  What you are doing is an infection in the making.  It's not a matter of if you will experience an infection.  It is merely a matter of when you will experience an infection.

By the way, storing a culture under water that is not 100% nutrient and organic matter free results in accelerated glycogen and trehalose depletion.  They only way to remove all traces of nutrients and organic matter from a cropped culture is via centrifuge.

[denny]

A lot of what S. Cerevisiae has outlined makes sense however when using a carboy or bucket for the primary, rinsing is a very practical way to reuse yeast without needing a starter.  I typically run 3 to 4 batches of beer this way.  In my experience is far more effective in separating trub and dead cells than trying to save and waste extra beer in the carboy.  I also came to the conclusion that storing in water will raise the pH.  So I have begun using lactic acid to drop the pH under 5 and also since my water has 8 ppm calcium I add 1 gm/gallon of calcium chloride.  I syphon off as much beer as appropriate to not transfer too much yeast dump water in stir and pour into a 1 gallon jug.  Fill the jug 85% about and shake.  Then let settle and pour off about 1/2 gallon of the top or middle (depends on yeast) half and store at 35F for 1 week max.  Generally I plan two days prior to brewing as some yeasts require this time to settle   When reusing I allow to warm in the garage while brewing, pour off water, pull about 1/2 gallon of wort through my CF chiller and get the slurry back on a stir plate. This thoroughly mixes the yeast and gets it going.  Then I can just pour in after chilling to the correct temp.  If I have a conical I would collect and pitch but I have not mad the transition yet.

Cheers

Well, maybe not....I have repitched yeast that has been rinsed and yeast that has not.  There was no difference in the finished beer.  I reached the conclusion that rinsing is a lot of effort for no appreciable benefit.  Even if you don't consider it a lot of effort, there is still no benefit.  And every time you play with the yeast is another chance to contaminate it.  No, it's not a certainty...but it's a risk there is no reason to take.

[jdpils]

I did not say rinsing is the only way to reuse yeast I stated it is a practical one.  Other than increasing the beer loss and letting settle in the carboy and pouring off the top I would be interested in hearing other options.  I used to just pour off the slurry from the primary into a 1/2 gallon mason jar.  The amount of beer lost was about 3 pints however the slurry was still dirty and I did notice that by the forth pitch I did pick up some off flavors.  By single rinsing and reusing in a short period I do not need a starter as I get about 4 to 16 oz of fairly clean paste. 

[S. cerevisiae]

If you had three pints of liquid available for resuspending the culture, and you still achieved a dirty culture, then the problem lies in how you are cropping (more than likely coupled with how you are transferring wort from your kettle to your primary fermentation vessel).  You are not swirling the culture back into suspension, waiting for the heaviest fraction to settle, and then carefully decanting the the thinnest 350ml.  The crop shown below in the 500ml Erlenmeyer flask was cropped directly from a primary fermentation vessel using this technique.  The supernatant (clear liquid that lies above the solids) is beer.  The strain is Whitbread B, which is not the easiest strain to resuspend due to its level of flocculence (i.e., I had to swirl with a purpose in order to break up the clumps and large flocs).  This crop was taken with less than a U.S. quart of liquid left in the fermentation vessel.

[mabrungard]

So I have begun using lactic acid to drop the pH under 5 and also since my water has 8 ppm calcium I add 1 gm/gallon of calcium chloride. 

Aren't we better off dropping the pH to something like 4? Yeast are pretty low pH tolerant, but many other organisms aren't.

Why the calcium chloride addition? Yeast do not need calcium. They need magnesium more than calcium.

[brewinhard]

So I have begun using lactic acid to drop the pH under 5 and also since my water has 8 ppm calcium I add 1 gm/gallon of calcium chloride. 

Aren't we better off dropping the pH to something like 4? Yeast are pretty low pH tolerant, but many other organisms aren't.

Why the calcium chloride addition? Yeast do not need calcium. They need magnesium more than calcium.

If you are storing the yeast under beer as stated above, then the pH of the finished beer should be in the low 4-4.5 range shouldn't it?  Another reason to store under beer and not water.

[klickitat jim]

I used to wash/rinse (whatever) and after getting to where I thought I had really mastered the process, I discovered that it did not help me at all. I scaled all of my recipes to 6 gallon and gave up the rinsing. The only thing I think it gains you is an extra process that adds a significant chance for infection. In my experience you loose way more than you gain. Now I just leave a little beer in the fermenter, swirl and pour to a sanitary container. On brew day I take about 100ml of the slury and make a starter. There might be a couple grams of trub in there, but trub doesn't replicate.

Most of the people I hear supporting rinsing do it because they brew super hoppy beers. Well, since you are dropping $20 on dry hops, seems like you could splurge for a fresh pitch...

[tesgüino]

Most of the people I hear supporting rinsing do it because they brew super hoppy beers. Well, since you are dropping $20 on dry hops, seems like you could splurge for a fresh pitch...

Not in support of rinsing, but the simple answer to that is don't fear the secondary. 



edit:
It's not about the money. I think I get my best beer three or more generation in.

[jdpils]

Lots of great information here.  There is no question that yeast is better stored in beer, however getting a clean crop that can be directly repitched has been very effective for me.  I am going to retry to re-suspend my yeast slurry with the remaining beer and just dump the top third into my final container.  in the past I took the entire slurry.  Taking the top third under any liquid should resolve my issue.  If this get me to a simpler yeast crop and use I will adopt.  However considering the diameter of a carboy I am still going to pour into a 1 gallon or 1/2 gallon wide mouth container.  (If one is worried this causes contamination than one should be concerned about all their sanitation).  It would seem to me a taller vessel will facilitate better separation.  Again my goal is not to bank yeast it is to reuse without having to make a starter within one week.  For rinsing getting the pH down to 4.5 is a goal however our NW water is so soft that once any buffer is exceeded the pH will drop very fast.  Adding a little Mg may be wise too.  Also since the yeast is at the final brew pH about 4.5 with this soft water I doubt it will rise over 5 anyway.  Even if I do not treat my sparge water to 5.5, the final pH of a fully fly sparged batch is still 5.2  Our water is 30 ppm alkalinity measured as CaCO3 and .3 ppm Mg and about 1.3 sulphate the last I asked as this data is no longer published in the consumer water report.

Cheers,

[avanzandt]

I take a different approach. Instead of messing with the stuff after the fermentation I make a 2L starter with 6 oz DME. Then pitch half in the carboy and use the pour the rest into 2 8oz canning jars. Then store it in the fridge. It has worked out fine for me, I have quite a few strains stored up and haven't had any problems.

[RPIScotty]

I take a different approach. Instead of messing with the stuff after the fermentation I make a 2L starter with 6 oz DME. Then pitch half in the carboy and use the pour the rest into 2 8oz canning jars. Then store it in the fridge. It has worked out fine for me, I have quite a few strains stored up and haven't had any problems.

But then you miss out on repitching.


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[S. cerevisiae]

I take a different approach. Instead of messing with the stuff after the fermentation I make a 2L starter with 6 oz DME. Then pitch half in the carboy and use the pour the rest into 2 8oz canning jars. Then store it in the fridge. It has worked out fine for me, I have quite a few strains stored up and haven't had any problems.

You are missing out on the advantages of repitching.  Repitching requires no starter, and a culture tends to perform better on a repitch. 

Liquid cultures are okay for short-term storage, but you will end up with diminished fermentation performance over time.  If you want to keep a more stable yeast bank, you should look into slants.   I maintain all of my cultures on slant.   I have maintained cultures for years on slant, that is, when I remembered to perform periodic subculturing.   The beauty of keeping yeast on slant after going through single-cell isolation on a plate is that slant-to-slant transfers are performed using absolutely sterile media under sterile conditions; hence, the culture remains pure.