Help! Harvesting yeast for the first time.

Get advice on making beer from raw ingredients (malt, hops, water and yeast)
Post Reply
Paddington
Piss Artist
Posts: 157
Joined: Tue Nov 14, 2017 8:07 pm

Help! Harvesting yeast for the first time.

Post by Paddington » Mon Nov 20, 2017 11:07 am

I have rinsed and rereinsed trub from a previous brew and have a small amount of yeast coloured substance in a honey jar. I have estimated the quantity to be 20ml. Firstly, is this a reasonable amount? It seems a bit low compared to what 8 have read on forums, blogs etc and secondly, is this enough to repitch a 10 litre brew? I have seen lots of calculators and they all seem to imply using trub which has been less well rinsed, so I can’t make head nor tail of the numbers.

I have a photo but I can’t see how to attach it.

User avatar
Kev888
So far gone I'm on the way back again!
Posts: 7701
Joined: Fri Mar 19, 2010 6:22 pm
Location: Derbyshire, UK

Re: Help! Harvesting yeast for the first time.

Post by Kev888 » Mon Nov 20, 2017 1:29 pm

It partly depends upon the gravity of wort in your next brew, and how viable your slurry is (often estimated from its age). But IMO 20ml would seem too little for 10L 'unless' the slurry is extremely pure, very thick/compacted, very recent, and being pitched into wort of normal or modest gravity. If all of those things apply it may just about be enough, but personally I'd be a bit doubtful.

As you say, rinsing yeast with (sterile) water can indeed help to narrow down how much actual yeast slurry you have, if done properly. However.. if not done properly you may rinse away too much, or even the wrong stuff. As you have so little, I wonder if that may have occurred. Keeping yeast slurry under water is also not as good for its health as keeping it under its native beer, if you rinsed it prior to storage.

So 'unless' you are reasonably confident in your rinsing process it could actually be better to leave it alone and instead estimate its percentage. You've probably found it but the Mr malty calculator lets you move sliders for slurry estimated density and purity, and hovering the cursor over the slider gives a little guidance on how to judge.
Kev

Paddington
Piss Artist
Posts: 157
Joined: Tue Nov 14, 2017 8:07 pm

Re: Help! Harvesting yeast for the first time.

Post by Paddington » Mon Nov 20, 2017 1:37 pm

Thanks, Kev. I may try using a starter and do a 5l brew just as a test. You can’t have too many brew days! If I feel confident, I’ll buy the mrmalty calculator for next time.

User avatar
Kev888
So far gone I'm on the way back again!
Posts: 7701
Joined: Fri Mar 19, 2010 6:22 pm
Location: Derbyshire, UK

Re: Help! Harvesting yeast for the first time.

Post by Kev888 » Mon Nov 20, 2017 2:05 pm

Yes if it is reasonably normal/decent stuff 20ml would be okay for 5L, but a starter would be preferred - letting you assess the yeast's performance. If you made a starter anyway, (and if it worked as expected) then theres no reason why you couldn't make one big enough for 10L should you still wish.

BTW, the Mr Malty calculator is free to use unless you need the mobile (android or iphone) versions.
Kev

User avatar
Meatymc
Drunk as a Skunk
Posts: 836
Joined: Mon Sep 01, 2014 8:36 pm
Location: Northallerton, North Yorkshire

Re: Help! Harvesting yeast for the first time.

Post by Meatymc » Mon Nov 20, 2017 2:12 pm

Make sure you read up on IPA's yeast scavenging method - taking samples from the fermenter roughly 48 hours after pitching. My Worrying start post on the BIAB section is testiment to it working !!!!!

scotsloon
Piss Artist
Posts: 204
Joined: Thu Mar 31, 2011 2:59 pm
Location: Kemnay, Aberdeenshire

Re: Help! Harvesting yeast for the first time.

Post by scotsloon » Mon Nov 20, 2017 2:57 pm

I find that if there is any doubt make up a starter of a Table spoonful of DME in 100ml of boiled/cooled water. If the yeast is viable it will start to ferment on the DME(Dry malt Extract). you can also then add a further T spoonful of DME and another 100ml of water. You can do this again and again if you want to. This will start to multiply the viable yeast so you can think about a starter for a 5Gallon batch.

MyQul

Re: Help! Harvesting yeast for the first time.

Post by MyQul » Mon Nov 20, 2017 3:42 pm

I use IPA's yeast scavenging method (loving the name. Up till now I didnt know what it was called) but as I only make 10L brews I use 250ml bottles. Theres definately less than 20ml of yeast in the bottom of the bottles and I put this into 1L of starter work. There's enough yeast in the starter to easily ferment out 10L, so much so I'm thinking of just using 500ml starters for 10L brews

Paddington
Piss Artist
Posts: 157
Joined: Tue Nov 14, 2017 8:07 pm

Re: Help! Harvesting yeast for the first time.

Post by Paddington » Mon Nov 20, 2017 3:44 pm

Thanks. Kev, I've had a look at mrmalty calculator, and that is a big help.

Meatymc - hmm, I'm paranoid about opening my fermenter!!!

scotsloon - sorry to be dim, but once I start multiplying my 20ml in a starter, how do I know when I've got enough for a 10l or bigger batch?

MyQui - thanks, that helps.

Out of interest, I've started brewing 10l brews so I can brew more often to get more experience plus more variety of beer in store.

MyQul

Re: Help! Harvesting yeast for the first time.

Post by MyQul » Mon Nov 20, 2017 4:01 pm

If your paranoid about opening your fermenter; what I do is normally I cover my FV with cling film. When it comes time to 'yeast skavenge' I use a turkey baster and roll back the cling film just enough to slip the TB in. I haven't had any problems so far

User avatar
Meatymc
Drunk as a Skunk
Posts: 836
Joined: Mon Sep 01, 2014 8:36 pm
Location: Northallerton, North Yorkshire

Re: Help! Harvesting yeast for the first time.

Post by Meatymc » Mon Nov 20, 2017 4:02 pm

Paddington - so was I (which you'll find on the related thread) but much more experienced brewers said not to worry and haven't had a problem!

User avatar
Kev888
So far gone I'm on the way back again!
Posts: 7701
Joined: Fri Mar 19, 2010 6:22 pm
Location: Derbyshire, UK

Re: Help! Harvesting yeast for the first time.

Post by Kev888 » Tue Nov 21, 2017 10:43 am

Paddington wrote:
Mon Nov 20, 2017 3:44 pm
once I start multiplying my 20ml in a starter, how do I know when I've got enough for a 10l or bigger batch?
In the absence of microscopes, we typically use estimates of the number of cells likely to exist in a given amount of starter wort. This differs depending on the type of starter (simple, stir-plate etc.) and also different people have slightly different estimates. But as an example, a simple starter of gravity 1.035 may contain up to about 150 million cells per ml.

The number of healthy cells actually wanted depends on both the volume and gravity of the wort to be fermented. Again, opinions differ a bit on the optimum pitching rate, some people like to stress the yeast more in certain styles of beer to give more character. But a safe starting point is around 0.75 million cells per ml per degree plato for ale yeast (1.75 for lager yeast).

Often people just use a given size of starter as a rule of thumb, for example a simple starter of 1.5L per 23L. But you can see from my description that different circumstances may have somewhat different requirements. So if wished you can calculate a more tailored size, or the calculator I mentioned above can help you do so, in the 'liquid yeast' tab. It assumes you are starting with bought yeast packs of 20billion cells each, but you can substitute a similar number of estimated cells from slurry etc.

Generally speaking, the growth targeted in a starter should not be much over 10x. So if you have a tiny number of viable cells to start with (e.g. a very small quantity and/or old yeast) it can be better to first make a little starter (around 1/10th the size you ultimately need) to later pitch into a bigger one - a 'stepped' starter. Conversely if you have a lot of viable yeast you may not want to use them all in the starter as there will be little growth - ideally a minimum of around 5x growth is wanted to ensure lots of new, fresh healthy cells.
Kev

Paddington
Piss Artist
Posts: 157
Joined: Tue Nov 14, 2017 8:07 pm

Re: Help! Harvesting yeast for the first time.

Post by Paddington » Tue Nov 21, 2017 6:52 pm

Thanks again, Kev. In that case, I will step it up to around 750ml and give it a try in a 10 litre brew.

Post Reply