[bluesman]

Someday, I'd like to do some blind triangle tastings with a split batch of beer, one using rinsed yeast vs. another batch using un-rinsed yeast slurry,  in an effort to prove to myself the real effect that it may have on the beer flavor. This is the only way to really understand the potential effect that it may have on the finished beer flavor.

My belief is that there may very well be some percieved off-flavor contributions from an un-rinsed slurry, but the only way to really know is to test the theory.

[uthristy]

so uthristy, you never repitch yeast? just curious.

3- 5 times before starting with new yeast.
As I brew often enough I just transfer(keg or 2ndary) and  pitch into the new wort 200-400ml of slurry.
Yeah theres always the risk of possible contamination but its been rare when it does happen, thats why I have gone over to only glass carboys.

Took this pic back in 2007 while making a starter- overkill but thats just my level of biological warfare

[Pawtucket Patriot]

Well, I can think of at least one good reason to do it in my case: keeping rinsed yeast in mason jars won't smell up the mini fridge in which I store my yeast.  My current practice involves just collecting the slurry in a one gallon plastic bag.  This gets messy when pitching to a starter and it really starts to smell after a while.

So your still making a starter? with saved yeast no less? < giggling >

Yes, because I don't always use the same strain so often that I feel comfortable not making a starter. If I'm repitching the same strain within 2-3 weeks, I forego the starter.

You obviously have a process that works well for you. Cheers!

[benamcg]

I am surprised that more people dont rinse yeast.  I would say that as long as you employ Good Lab Practices it is the bee's knees.  A big factor is saved costs: I have definetely cut costs on the 20+ (12 gal.) batches that I have brewed this year. 

Dividing the yeast from a batch I am only on the 6th generation (since each batch makes more yeast than needed for one batch) and have seen no decline in % attenuation.   The yeast I rinsed last night = 83% attenuation.  I keep records on the characteristics of the yeast (time to ferment, volume, etc.) and have observed healthy fermentations and no off flavors. I had originally planned to buy fresh yeast once a year.  I am not sure that I will at this point. 

Since adding a Therminator to my operation (and therefore a strainer/hop sock in the kettle) my Primary is super clean, beer is much clearer, and multiple rinses dont seem necessary.  (i only dry hop in the secondary, too).

Two weeks ago, I made two 12 gal batches in 2 days.  One was straight pitched yeast (pulled out of the fridge, brought to room temp) the other was put in a starter from Beer #1 mash run off.  I didnt notice any differences in the time to ferment (primary) or time it took to become active.  I am not sure that I will be making starters in the future because of this.(unless the yeast is > 1.5 months old.  I think 2 months is longest I have gone before pitching rinsed yeast (no ill effects, just not comfortable going longer).

[a10t2]

A big factor is saved costs: I have definetely cut costs on the 20+ (12 gal.) batches that I have brewed this year.

That doesn't really enter into a rinsing vs. not rinsing debate though. The costs are the same either way.

[blatz]

A big factor is saved costs: I have definetely cut costs on the 20+ (12 gal.) batches that I have brewed this year.

That doesn't really enter into a rinsing vs. not rinsing debate though. The costs are the same either way.

Right - no one said they didn't reuse yeast slurry

[majorvices]

I'm in the "no rinse" camp. Tried it, not really worth the trouble. I'm with Blatz though - I carry very little trub over and dump the trub I do carry over from the conical. That said, I have repitched from Carboys with fine results as well - no rinsing.

One thing to consider is that the more you handle the yeast the more contaminants it picks up. I try to handle my yeast as little as possible.

[Pawtucket Patriot]

Keith, how do commercial brewers manage yeast?  This is a question I've been wondering about for awhile now.  I should probably pick up the Yeast book (although that might be geared toward homebrewers).

[majorvices]

It's actually geared to Pro Brewers a little more than Homebrewers IMO. I collect my yeast in gallon jugs and pitch them usually with a couple days, always within the week. I don't remember what the White/Zani book recommended on the topic. All I know is that from experience what I do works. that said, I only go about 5-6 gens before either growing more or ordering another pitch. I can't say I actually had a problem with any of my beers handling the yeast the way I have. I did pick up some diacetyl (from what probably was an infection) at one point in time but pretty sure that came from not cleaning the ball valves properly.

All of that said, I use conicals almost exclusively so I don't have much problem with trub or hops build-up.

[majorvices]

OTOH, I forgot to mention that using a conical not only allows you to dump the initial trub but also lets you select the middle layer yeast between the dead cells and trub on bottom and less flocculative/dusty yeast on top. Basically that is what the yeast washing technique is supposed to do. Excuse me .... rinsing. 

[Pawtucket Patriot]

So, last night I made a 1L starter with approximately 150 mL of rinsed Thames Valley II slurry for a 5.25 gallon batch of porter.  The yeast was last used on July 10, 2011, and after spending a night on the stirplate, there wasn't even a hint of active fermentation.  I'm über careful about sanitation and yeast handling, so I'm a bit surprised.  One thought I had was that the yeast was still pretty healthy and it blazed through my starter wort really fast.  But when this has happened before, I usually see a ring of yeast residue in the flask, i.e., evidence that the starter has fermented.  

edit: Never mind...after 48 hours, the starter is happily fermenting.  I guess it just took a little longer to get out of bed this time.

[James Lorden]

Depending on how much trub you carry over, I think that another benefit of rinsing yeast is that it makes estimating your pitching rate a little easier since the amount of trub might varry from batch to batch... if you know you have mostly all yeast that could help consistency in pitching rates.