Rinsing Pro vs Con

Ingredients
1

Why do folks here say water rinsing yeast is ‘bad’?  Can I get references and pros vs cons?

In another thread about hops, I read this comment:

I’ve use a quote from Robert but others have had similar comments. I’ve contemplated this and those other comments that rinsing with water is ’bad’ for the yeast.

However, I see this article Yeast Washing & Yeast Rinsing: What's the Difference? - American Homebrewers Association where the AHA is reprinting instructions on how to rinse (and wash) yeast by using the sterile water method so common around you tube and Homebrew blogs. This article is attributed to Yeast: The Practical Guide to Beer Fermentation by Chris White and Jamil Zainasheff which further compounds the contradiction based on their yeast expertise.

2

I’m confused by Chris and Jamil’s embrace of what otherwise seems a practice made questionable in light of current understanding too.  Here are the risks of rinsing as I understand them.

Replacing the beer yeast is under with water raises pH which increases risk of infection.

Adding water and/or agitation provides oxygen.  This causes the yeast to begin their life cycle, absorbing the oxygen and using up their glycogen reserves.  But now in the absence of wort to consume, they are at risk of either autolysis or starvation.  And when finally pitched, they will lacked the reserves needed to  begin the normal fermentation cycle.

Culture yeast is very precisely adapted, by selection, to this particular life cycle:  once exposed to oxygen, they must proceed all the way through growth, fermentation,  building reserves, and dormancy, then await the signal of oxygenation to start again.  They have lost the genes that allow led them greater adaptability or flexibility to survive an interrupted cycle or to take advantage of food whenever it appears.  Wild yeast (and bacteria) are highly flexible, and can take advantage of situations culture yeast cannot.  So rinsed yeast, when pitched, is at a distinct disadvantage versus any wild yeast or bacteria present, increasing the risk of infection in the batch on top of the fact that the culture yeast, even if they win, won’t necessarily perform at peak.

That last paragraph somewhat explains the mechanism behind the one preceding.  A reference on this, which I posted in another thread a while back, is this. 
https://www.nature.com/articles/d41586-019-00088-y

All in all, yeast wants to live in beer and wait for the next load of fresh wort.  Rinsing deprives it of its ideal conditions,  increases the risk of poor performance and infection,  and is just one more thing to do, when you don’t really need another thing to do.

Yeast rinsing seems to have become standard practice in the 19th century when clean water was seen to purify everything, without current understanding of yeast metabolism.  While there may be something to the notion (Chris and Jamil note it) that rinsing can separate some petite mutants and bacteria,  this should be a relatively minor concern.  If it’s a concern, reculturing is probably more appropriate.

If rinsing is going to be done, it ought to be done right at pitching, not before storage; in this case, it can serve as a means to aerate the yeast just when needed. 
   
For much of this see Kunze, 4.4.4.3.

Again, you’re adding a step, and increasing risk.  Why?  As to why the AHA site, and all the other books, perpetuate outdated advice,  well we’ve been there before on all sorts of subjects…

3

Forgetting about the possibility of contamination while doing it or as a result of doing it, water is hypotonic (lower salt concentration than inside the cell).  The reason the yeast doesn’t rupture due to water influx within a couple of minutes is because it has a cell wall.  While they’re fine in the short term in water (I used distilled deionized water all the time for making dilutions prior to plating when I was in grad school… I was in a yeast lab), it’s not really a great storage medium.

4

Your information seems to make logical sense. In the future, I may simply dump the harvest into a sanitized jar skipping the boiled/cooled water step. Now that I use whole cone hops I am less concerned with green hop sludgy trub in the sample.

Yesterday, I closed transferred beer from my BrewBucket fermenter to keg.  Earlier that morning I boiled water and jars, and cooled them slowly on the countertop then further in the fridge until ready for use. I added three jars of the boiled/cooled water to the now nearly empty fermenter (I did not remove the remaining very small amount of beer), swirled it fairly aggressively to get the yeast harvest into suspension (introducing oxygen no doubt), waited 10 minutes for the chunks to settle into the cone below the spigot level, sanitized the spigot, and drained the suspended yeast thru the spigot into two sanitized jars (alternately filling a third at a time).

I read several sources that instruct to keep the rinsed yeast refrigerated very cold which would keep them dormant. So I placed the two jars in the serving side of a side-by-side.  I use temp controlled freezer side to condition/lager and serve from the fridge side.

Today, I ended up with two jars containing 4 oz each of beautiful creamy yeast covered in 24 oz of watered down beer.

I imagine several homebrewers do exactly what I’ve done with great success. …but given the information you provided, I once again question the AHA as a reliable source of Homebrewing information.

5

I rinsed for years.  Then Denny said he found it didn’t improve his beer in his experience.  So I did a lot of research and learned all the current information.  You’re right, a lot of us rinse, so the detrimental effects may be more theoretical than practical.  It just makes sense not to complicate things when there’s no apparent possible benefit.  Maybe somebody at the AHA or Zymurgy could look into getting an up to date article out there.

6

If you haven’t seen it, check out the thread “Just say ‘no’ to yeast rinsing” by S. Cerevisiae:

https://www.homebrewersassociation.org/forum/index.php?topic=19850.0

7

A very trusted source. Thanks guys!

8

If one is able to, transferring crystal clear wort from kettle to fermenter is ideal.

This is beneficial for two reasons…

  1. Less kettle break material = decreased lipids than oxidize and lead to premature staling.

  2. Allows for harvesting a much “cleaner” yeast sample for repitching. One that is made up of mostly yeast cells
        without hop debris and other material.

By harvesting yeast directly from the primary and storing it under beer, one can safely keep yeast to repitch for the next generation. To “up” the game a bit, if you can transfer “active” yeast along with residual extract remaining into your storage jar then the yeast will benefit even more as they will have some nutrients to slowly feed on as their metabolism slows due to cold storage. This of course can be accomplished through proper spunding techniques.

9

Fantastic read, thanks narcout.  And I must say that the posts ~#65-70 provided exactly the ROTFLMAO session I needed to end my week and start my weekend.

10

This may cause shorts to pucker, but I’ve found science is relative.  YMMV.

11

Literally dead to me.

12

Think about it and get back to me.

13

Just swirled up the remaining beer into the Urkel from a Czech Pils after kegging. I sanitized and used the spigot to fill two sanitized quart jars. I probably could have filled two more but it would just go to waste.