Yeast Rinsing Experiment - Yeast Vs Trub/break

[Wolfy]

Rinsing yeast in water is a useful technique to either remove the trub and break material so the yeast from a yeast-cake can be repitched, or to clean the yest before long-term storage. The technique is easy enough to do, but the biggest question seems to be how to tell the yeast from the break and trub that should be discarded.

This experiment compares a jar of trub and break with a jar of yeast as they both settle over time.

On the left is a jar containing (mostly) only break material and trub, it was harvested after double-dropping one day after fermentation started. I use a CFC so all the cold break ends up in the fermentor, a slotted copper pipe drains from the kettle so there may also be a smaller amount of hot-break but not too much hop-residue.
The jar on the right contains only fresh and healthy easy top cropped yeast.

0 Minutes, both jars freshly shaken:

The trub is more grainy in appearance while the yeast is a homogeneous mixture in suspension.

5 Minutes:

The trub has started to settle a little, and all the yeast is still in suspension.

10 Minutes:

Yeast still in suspension, trub settling more including some compaction at the bottom of the jar that looks a little like the yeast, but the yeast has not compacted at all yet.

15 Minutes:

More settling, about this stage is when you'd be able to leave much of the trub behind but retain all the suspended yeast.

20 Minutes:

Here we see the yeast has just started to settle out at last, while the trub continues to settle well.
Decanting the yeast-suspension from the trub much after this point means you may leave some of the more flocculant yeast behind.

30 Minutes:

The layer of yeast is starting to compact, but much of it is still in suspension.

 

[Wolfy]

40 Minutes:

More settling of both yeast and trub.

50 Minutes:

Same again.

90 Minutes:

... and again

120 Minutes

Even while most of the trub has settled well, much of the yeast is still in suspension.

And one day later when everything has compacted and settled:

The trub still looks more grainy but has settled well to the bottom of the jar, its also a slightly darker colour to the yeast.
The yeast is a clear smooth milky-creamy coloured homogeneous layer on the bottom.

Yeast used for this experiment is "East Midlands 1" from BrewLab and they class it as a 'high' flocculating yeast, so when using different yeast the time it takes to settle might differ a little.
Grain bill for both was 90% Maris Otter with the remaining Crystal and Chocolate and a touch of Wheat malt, so the wort is darker than one would expect from a Pale Ale.

 

[MaltyHops]

Thanks Wolfy - excellent info :icon_cheers:

The trub bottle at the 15min mark - would the settled trub be solid enough
to allow the still suspended yeast to be poured out without stirring up all
the trub? Just being lazy in not wanting to use a syringe or something to
get the yeast out.

So it looks like taking the yeast out just as it starts to settle is good for also
getting the more flocculent yeasts but this is also likely to include some of the
trub material. What then would be the effect of adding break, hops, dead yeast
from previous ferments into a new ferment? I guess there wouldn't be that
much trub material from the previous ferment and increasingly less from even
earlier ferments but in theory there could be some from really early ferments.

I guess the grain/hop/yeast combo will determine how distinct the trub will look
compared to the yeast to help figuring out the best time to separate the yeast.

I used to stick collected trub in the fridge to help the trub/yeast settle quicker
but maybe it would be better to actually keep the sample warm so the yeast
doesn't settle quickly but lets the trub settle?

Once the yeast has been separated, do you replace the beer the yeast is in
with water (presumably boiled and cooled)?

T.

 

[Punkal]

Thanks Wolfy another great addition to AHB...

 

[Hogan]

Well done Wolfy - great pics.

Cheers, Hoges.

 

[Thirsty Boy]

Very nice wolfy, makes it so much easier to understand whats happening when they are both mixed up in the same jar. Cheers

 

[Wolfy]

The trub bottle at the 15min mark - would the settled trub be solid enough to allow the still suspended yeast to be poured out without stirring up all the trub?

Yes, that is the basis of most yeast-washing instructions, including the process outlined by chiller here.
But there will be yeast mixed in with the trub (which will be discarded) and since the trub is still very fluid several rinses are often required.

So it looks like taking the yeast out just as it starts to settle is good for also getting the more flocculent yeasts but this is also likely to include some of the trub material. What then would be the effect of adding break, hops, dead yeast from previous ferments into a new ferment? I guess there wouldn't be that much trub material from the previous ferment and increasingly less from even earlier ferments but in theory there could be some from really early ferments.

Many people directly pitch the yeast cake without washing it and report good results, however, that adds impurities to the new batch and makes it more difficult to estimate the volume of yeast you are pitching.
If you are careful with sanitation, the only disadvantage should be that rinsing discards an amount of viable yeast, but if rinsing a previous batch's yeast-cake there should be an abundance of yeast

I used to stick collected trub in the fridge to help the trub/yeast settle quicker but maybe it would be better to actually keep the sample warm so the yeast doesn't settle quickly but lets the trub settle?

For best/easy results you want the yeast to stay in suspension while all the trub settles out, how best to do that in regard to temperature would probably require more scientific testing than one set of photos.

Once the yeast has been separated, do you replace the beer the yeast is in with water (presumably boiled and cooled)?

The instructions linked above indicate to wash the yeast until the liquid runs clear, and the 'Yeast' book has a small section about storing yeast under distilled water and how that should/could help extend the storage times and yeast health.

Very nice wolfy, makes it so much easier to understand whats happening when they are both mixed up in the same jar. Cheers

That's the idea, but now I have to do a set of pictures of rinsing the yeast-cake in the same set of jars.

 

[MaltyHops]

Thanks again, Wolfy.

T.

 

[corcatraz]

Just what I was looking for thanks Wolfy!

Gunna give the rinsing a go next week.

 

[hobospy]

OK, so first time trying to wash/rinse yeast and I may not have picked the best yeast, WLP029, only classed as a medium flocculating yeast but it seems to compact down quite well ..... I topped my yeast cake up with a litre or two of distilled water but had to go out so chilled all the mason jars of yeast. Took them out today and I'm not seeing the fine layer of the yeast on top and it looks like the trub is in the middle, is this expected for this type of yeast? Or have I done something wrong? Was wondering if I should let everything get to about room temp so I have more chance of the yeast staying in suspension?