Rinsing Yeast (in Pictures)

Share your experiences of using brewing yeast.
Wolfy

Rinsing Yeast (in Pictures)

Post by Wolfy » Mon Jun 06, 2011 6:37 pm

Rinsing yeast is a technique used to 'wash' the yeast/trub slurry found on the bottom of the fermentor after the beer has been removed. The 'cleaned' yeast can be pitched directly into a new batch of beer, or saved for later re-use. I've used the term 'rinsing' (as used in the recently published 'Yeast' book) to differentiate between 'washing' the yeast in water to remove trub and debris from 'acid-washing', a process used to to eliminate biological contaminants.

This process was described very well by chiller in this AHB forum thread some years ago, but as an additional starting point, there are some photos in the Yeast Rinsing Experiment which show the difference between yeast and trub.

While the process of yeast rinsing is dependent on the yeast-strain, wort composition and what (if any) fininings were used, the basic process relies on the fact that the yeasty-trub will form three distinct layers when left to settle:
Image
Here you can see the fermentor-dregs of a dark UK-style ale. The top clear layer of left-over beer, the creamy-yeasty middle layer, and then the trub (protiens, break material and other debris) on the bottom. The process of rinsing the yeast aims to retain only the middle layer of yeast and discard the other two layers, especially the trub and debris.

I wash my yeast in (~400ml) glass pickle jars, they can be easily heat-sterilized (in a pressure cooker or boiled in a large pot) and boiling water can be tipped directly into them to enhance the sanitation procedures. Ideally sterile distilled water should be used for yeast washing, however I use plain boiled and cooled tap-water (here in Melbourne the water is very soft and contains few minerals, but if you live in an area with hard water it may be a good idea to use treated or even bottled water). When working with yeast try to keep the equipment and procedures as clean and sterile as possible, and if possible keep the temperature constant, don't shock the yeast by tipping in water too cold or hot. I try to pre-boil the water and seal the jars a day or two in advance so that the yeast and the water will be the same temperature.

Here is the trub in the bottom of the fermetor after a recently brewed Australian Ale (using Coopers re-cultured yeast):
Image

Add a jar full of cooled-boiled water (approx 400ml) and shake/swirl and mix it around and it should look like this:
Image

Let the yeasty-liquid-trub settle for 10 to 15mins, and then the first step of the rinsing process is to decant the majority of the liquid into the rinsing-jars, but leaving behind any large bits of gunk, break material, hop or other debris:
Image

Depending how much beer was left behind, how much yeast and how much trub you have, you should easily be able to fill 1 or 2 jars. Generally yeast rinsed from one jar is enough to pitch into a new batch of beer, but I also wanted to save some for later re-use, so I ended up with 2 jars full of yeasty-trub and the left overs in the fermentor shown above:
Image
Last edited by Wolfy on Mon Jun 06, 2011 6:40 pm, edited 2 times in total.

Wolfy

Re: Rinsing Yeast (in Pictures)

Post by Wolfy » Mon Jun 06, 2011 6:38 pm

Now we need to be patient and watch what happens, after about 10 to 30mins you should start to see three distinct layers in the jar, clear water/beer ontop, a creamy layer of suspended yeast in the middle and with the trub and break material falling to the bottom of the jar.
The time it takes, and exactly what it looks like depends on the yeast, the wort, the grain, finnings and many other factors, so if you are not familiar with the process or the yeast it can be a good idea to let the jars sit for a number of hours (even a day) and watch as the trub and yeast settle out over time. However, the longer you let it sit the clearer the layers will become, but once the yeast starts to settle out of suspension it is harder to separate (so if you let it settle out to observe, simply shake it up so you can start the process again).
Image

We want to keep the middle layer since that contains our yeast in suspension. If you do not leave it long enough you will still have trub mixed in, but if you leave it too long the more floculant yeast will have settled out. The process is a bit of trial-and-error, but by careful observation it's not too hard.

I've found that by the time the layers start to form about 1/2 to 2/3 of the jar's contents is the milky-homogenous-yeasty-suspension that we want to keep, the trub and debris on the bottom is usually a darker, grainy layer, with the jars having a thin-clear layer on the top.
By carefully decanting the liquids we should be able to discard the clear top-layer, keep the middle layer which is our yeast in suspension, and discard the bottom layer of trub.
The middle jar is the original one, with the trub remaining on the bottom, the jar on the right contains our top clear layer and the jar on the left is our yeast-in-suspension that we will keep:
Image

The suspended-yeast-layer from the second jar was decanted into a flask ready for re-pitching, the top clear layer discarded and the trub (with some suspended yeast), that will also be discarded, remaining in the original jar:
Image

If we have done it right and/or were lucky, by letting the saved yeast-in-suspension layer settle out, we should have only single layer of nice clean creamy yeast:
Image
But if you find you still have a distinct layer of trub settling more quickly, simply repeat the process again.

The yeast in the flask was left to settle (refrigeration would have sped-up the process, however since I was going to directly re-pitch the yeast I did not want to risk thermal-shocking it, so instead just waited a day for it to settle out at fermentation temps).
Once the yeast has been rinsed and settled to form a thick compact layer of yeast-slurry (if it is viable and healthy) 50 to 100ml should be adequate for pitching into the next batch of beer.

The yeast in the jar, which will be stored for later use was washed several times more, until the liquid remained clear, each time decanting the liquid from the top and giving the yeast time to settle out:
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When the liquid above the yeast is clear, it was split into 3 storage containers (ie: sterilized beer bottles):
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Once they have been capped and labeled the washed yeast should remain viable if stored in the fridge for 6 to 9 months.
Image
The thick layer of yeast on the bottom of the bottles should be adequate to pitch directly into a starter (I step it from 300ml to 1.5L before pitching), however yeast stored this way does not usually remain viable more than about 1 year.

H.L.

Re: Rinsing Yeast (in Pictures)

Post by H.L. » Mon Jun 06, 2011 8:45 pm

Another great post Wolfy. Any tips for washing highly flocculent strains like WLP002? I have found that the yeast flocculates so quickly you don't really get the nice defined layers like in your pics.

Wolfy

Re: Rinsing Yeast (in Pictures)

Post by Wolfy » Tue Jun 07, 2011 2:32 am

H.L., WY1968 (which should be the same as WLP002) was the first liquid yeast I ever purchased and it is still one of my favorites. If you shake it up very well, to break up most of the clumps and flocs, I thought that enough of it stays in suspension long enough (can only take 10 or 15 mins) to decant most of the yeast, even if you will leave behind some with the trub in the jar.

De-Geert

Re: Rinsing Yeast (in Pictures)

Post by De-Geert » Tue Jun 07, 2011 8:24 am

You are making great contributions Wolfy! Thanks for the great explanations and photo's.

Any idea what the effect will be when using gelatin for clarification?

Wolfy

Re: Rinsing Yeast (in Pictures)

Post by Wolfy » Tue Jun 07, 2011 8:59 am

De-Geert wrote:Any idea what the effect will be when using gelatin for clarification?
I did think about that, while I now cold-condition my beer for a few days (without the need to use other finings such as genatin) when I did use it there were often largish clumps of yeasty-gelatin on the bottom of the fermentor. Those heavier globs would obviously sink quickly with the trub, and so you'd likely only be left with the yeast that had not clumped onto the gelatin globules. However what that means, other than you would likely harvest less yeast (if you'd be selecting yeast for having or not having a specific property), I don't know. You'd still harvest ample yeast to re-use or store, but some that stuck to the gelatin would be lost.

De-Geert

Re: Rinsing Yeast (in Pictures)

Post by De-Geert » Tue Jun 07, 2011 9:22 am

I guess I just have to try. :)
Harvesting a little less should not be a problem, because the slurry is most often a lot more than needed.

greenxpaddy

Re: Rinsing Yeast (in Pictures)

Post by greenxpaddy » Tue Jun 07, 2011 11:05 am

Thanks very much for this explanation

I think I have been getting confused with my starters.

I thought the yeast needed to settle out before pitching ideally. Half way through there seems to be a lot of sediment bubbling away. I thought this was the majority of the yeast, even though its top fermenting I thought most of it settled during ferment?. It might be that there is trub even in the starter? The sediment I had on the latest starter was quite brown in places. This concerned me that this was wild yeast infection but this may just have been trub I guess. Is brewers yeast always milky white?

Wolfy

Re: Rinsing Yeast (in Pictures)

Post by Wolfy » Tue Jun 07, 2011 11:46 am

greenxpaddy, the above process is about washing yeast that has already fermented beer and has been sitting in the fermentor for a week or two, so things will not look the same as what you expect from a starter.
In my experience brewers-yeast is usually a creamy-light-brown colour, when allowed to fully ferment and settle, it should fall to the bottom as a thick sticky creamy layer, sometimes there will be layers or brown patches but most of it is creamy. However, during active-ferment the yeast will often float as a creamy fluffy layer at the top of the starter and it's not uncommon to get some (usually a very small amount) break material and other gunk in your starters, and you can usually observe brown gunk floating on the yeast or sticking to the sides of the starter container. A darker brown colour or can often be dead or unhealthy yeast cells and if you store your yeast (like in the clear bottles pictured above) for some time, you can often see the yeast darken as it slowly dies over time.

My active starters often look like this:
http://i184.photobucket.com/albums/x37/ ... rshake.jpg
http://i184.photobucket.com/albums/x37/ ... arter1.jpg
http://i184.photobucket.com/albums/x37/ ... tarter.jpg
http://i184.photobucket.com/albums/x37/ ... arter8.jpg
And once the yeast settles out:
http://i184.photobucket.com/albums/x37/ ... arter9.jpg
http://i184.photobucket.com/albums/x37/ ... arter7.jpg
http://i184.photobucket.com/albums/x37/ ... cyeast.jpg
And some older washed yeast that has been stored in the fridge:
http://i184.photobucket.com/albums/x37/ ... dyeast.jpg

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Bobba
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Re: Rinsing Yeast (in Pictures)

Post by Bobba » Tue Jun 07, 2011 12:59 pm

Top stuff from our resident yeast expert! Cheers Wolfy =D>
This is extremely useful and you're doing a fantastic job building up some excellent resources!

FV: -
Conditioning: AG34 Randy's Three Nipple Tripel 9.2%, AG39 APA for a mate's wedding
On bottle: AG32 Homegrown Northdown ESB, AG33 Homegrown Cascade Best
On tap: -
Garden: 2x cascade, 2x Farnham whitebine (mathon), 2x northdown, 1x first gold

greenxpaddy

Re: Rinsing Yeast (in Pictures)

Post by greenxpaddy » Tue Jun 07, 2011 2:04 pm

Yes great clarification

I think we new brewers are completely paranoid 8) that everything we are doing is abnormal whereas in all likelihood its all normal

paddy

Wolfy

Re: Rinsing Yeast (in Pictures)

Post by Wolfy » Tue Jun 07, 2011 2:30 pm

greenxpaddy wrote:I think we new brewers are completely paranoid 8) that everything we are doing is abnormal whereas in all likelihood its all normal
Most likely very true, after it's been done a few times, all this stuff becomes easy and straight forward - but, hopefully the photos make that first step an easy one to make.

In terms of a starter made from a Wyeast or WhiteLabs pack, we are pitching a huge quantity of fresh yeast into a small batch of fresh wort (remember that yeast-packs are designed to ferment US5Gallons ~ 19L of wort) so unless something really drastic happened in regard to procedures or sanitation the pack-yeast should quickly and easily out-compete everything else and so it's really hard to get wrong if you keep things clean and within the temperature range the yeast are happy with.

Wolfy

Re: Rinsing Yeast (in Pictures)

Post by Wolfy » Wed Jun 08, 2011 4:32 pm

Here is the process again, just with a different yeast/slurry/beer.

Fermentor dregs:
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Add water, mix, decant into jar:
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Allow to sit for appox 20mins:
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Tip out top-non-yeast layer, decant (and keep) suspended-yeast middle later into second jar (on left), discard trub remaining in original jar (on right):
Image

Allow yeast to settle (one day) and it's ready to repitch (after decanting the clear liquid):
Image

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Re: Rinsing Yeast (in Pictures)

Post by oz11 » Wed Jun 08, 2011 7:51 pm

What a great post! Thank you for the detail and the pictures..given me the confidence to give this a go.

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Re: Rinsing Yeast (in Pictures)

Post by jmc » Wed Jun 08, 2011 8:12 pm

Great post. Really helpful =D>

I'm sure I've been adding back trub in recent brews. :oops:
Pictures make it very clear what to do next time.

BTW: Do you only harvest yeast this way, i.e. do you bother to skim yeast when its most active?
About 36-48 hrs into brew for my WLP002

ATB
John

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