re using yeast

Hi all,

I've made a few all grain brews now using safale 04 yeast.
At the end I throw the yeast in the fermentation vessel away. Can I reuse this and if so, can someone give me an idiots guide how to do it :)

Many thanks

Mark

You can reuse yeast. There are two ways to do this. One is better that the other.

1.) (the poorer method) You can collect the yeast trub in a sterile jar after racking your beer out of your primary fermentation vessel, then mix in some sterile water shake, then leave to settle. It settles into layers after a number of hours, then you pour off the top layer into another sterile jar and pop it into the fridge, where it can be stored for a week or so until you brew again. Search for 'yeast washing' on youtube for details.

2.)(The pro method) When your wort begins fermentation it creates a krausen (big foaming head). At the time this first occurs you carefully open the fermenting vessel and skim of the dirty and scummy top layer, using a sterile spoon and discard. Then you pop the lid back on and wait for the foam to reform. You then open the lid again and skim off the top creamy layer. This will be your yeast that you can then save for your next batch (again in a sterile jar in the fridge). Look on youtube for 'skimming yeast' for more details.

I would however say that it is probably best not to bother. You can very good buy dry yeast cheaply and it is cultured in perfect lab conditions, so you get a reliable fermentation. If you harvest your own, then any infection that creeps in will then be passed on batch to batch. Plus your yeast evolves on a fast timescale and will not remain the same beast for long. Having said that it is satisfying to harvest your own yeast, just be super careful with sanitisation when doing so.

If you do wish to harvest your yeast, then I would advise buying new yeast at regular intervals to avoid problems.

Thank you very much

S04 is a good yeast but is a bottom fermenter, this means that you can only collect yeast post ferment really...

Other yeasts you can collect from the top, these are called top fermenting yeasts and can be collected during the fermentation of the beer. Yeasts like WLP001 (US05) and some of the Yorkshire yeasts are top fermenters. However they can be a bugger to clear from finished beer.

A really good yeast that top ferments is Malt Millers West coast yeast...if you are a cheapskate you could try to salvage a yeast from a bottle of Thwaites bottled conditioned beer, this stuff is absolutely ace but a right old faff to capture

Dronfieldbrewer said:

S04 is a good yeast but is a bottom fermenter, this means that you can only collect yeast post ferment really...

Other yeasts you can collect from the top, these are called top fermenting yeasts and can be collected during the fermentation of the beer. Yeasts like WLP001 (US05) and some of the Yorkshire yeasts are top fermenters. However they can be a bugger to clear from finished beer.

A really good yeast that top ferments is Malt Millers West coast yeast...if you are a cheapskate you could try to salvage a yeast from a bottle of Thwaites bottled conditioned beer, this stuff is absolutely ace but a right old faff to capture

Click to expand...

The terms top-fermenting and bottom-fermenting are almost misnomers. With both types of yeast fermentation occurs throughout the wort. Top fermenting apparently tend to have a higher krausen.

Most ale yeasts are top fermenting and a quick search on google showed safale s-04 sold as top fermenting. It is generally lager yeasts that are bottom fermenting.

Skimming yeast from the krausen during fermentation is superior as it is much more pure. Collecting trub after fermentation means collecting a lot of waste products.

I use safale s-04 and it forms a decent krausen so I would've thought yeast could be skimmed from the top.

Like most things you can take yeast reusing as far as you want from simply repitching on the yeast cake or rinsing with sterile water to identify and seperate the creamy live healthy yeast from trub n waste for repitching, to isolating pure colonies for storage and breeding up a pure population as a starter when needed..

http://www.amazon.co.uk/dp/B00C7EYE0Y/?tag=skimlinks_replacement-20

explains it all a lot better than i could ever and while is a technical book is open and accessible to laymen.

James_UK said:

The terms top-fermenting and bottom-fermenting are almost misnomers. With both types of yeast fermentation occurs throughout the wort. Top fermenting apparently tend to have a higher krausen.

Most ale yeasts are top fermenting and a quick search on google showed safale s-04 sold as top fermenting. It is generally lager yeasts that are bottom fermenting.

Skimming yeast from the krausen during fermentation is superior as it is much more pure. Collecting trub after fermentation means collecting a lot of waste products.

I use safale s-04 and it forms a decent krausen so I would've thought yeast could be skimmed from the top.

Click to expand...

If you say so...whenever I have used S04 the krausen was just bubbles along with protien and a bit of trub..no real creamy yeast to speak of..US05 goes the same way for the first bit of fermentation then the krausen changes to a creamy head...This is yeast

Dronfieldbrewer said:

If you say so...whenever I have used S04 the krausen was just bubbles along with protien and a bit of trub..no real creamy yeast to speak of..US05 goes the same way for the first bit of fermentation then the krausen changes to a creamy head...This is yeast

Click to expand...

Well it sounds like US05 over S-04 is the way to go for ease of harvest then. I've never used US05 so I will take your word for it.

Now that Christmas is on the horizon I am brewing once per week. At the start of the next week I put my brew into a secondary F/V, (wilcos barrel). When the new brew is ready I put onto the top of the cooled wort the scooped out yeast from the previous brew and continue to do this if I brew one after another.
I will say the yeast is nothing special just originally a wilco gervin packet yeast. So none of the yeast is saved but placed onto the next brew. Is this practice deemed OK with continuous brewing?

ronnie said:

Now that Christmas is on the horizon I am brewing once per week. At the start of the next week I put my brew into a secondary F/V, (wilcos barrel). When the new brew is ready I put onto the top of the cooled wort the scooped out yeast from the previous brew and continue to do this if I brew one after another.
I will say the yeast is nothing special just originally a wilco gervin packet yeast. So none of the yeast is saved but placed onto the next brew. Is this practice deemed OK with continuous brewing?

Click to expand...

What you are doing will work, and will probably produce decent beer over a few batches, but it is not really good practice as the trub at the bottom of the primary fermenting vessle is not pure yeast.

It is best to skim yeast off the top of a previous batch with a sterile utensil and pop it into a sterile pot in the fridge until you need it (be sure to let it warm up to room temperature before pitching).

To do this:
1.)after you pitch the yeast into the primary wait until a krausen (foamy top) forms.
2.)then skim off the 'dirty' layer from the top of this foamy layer with a sterile utensil and discard it.
3.)replace the lid and wait for the foamy layer to be rebuilt. This time the foamy layer will be clean and creamy. This is what you want.
4.)skim off some of this creamy layer and pop it into a sterile pot and then place that into the fridge.

Of course it is crucial everything is sterile when doing this or else you risk contamination.

Another method is to 'wash' the trub from the primary, but skimming is better. You will find videos of both on youtube.

You will also want to replace your yeast with new bought in yeast regularly as yeast evolves very fast, and therefore will not have the exact same characteristics a year later. Yeast suppliers get around this by culturing vast quantities of a yeast and then freezing it in many small vials, so that periodically they can take a small amount of this and cultivate another massive batch. This way the yeast that they produce from is replaced by the original frozen strain on a regular basis. This basically allows them to 'go back in time' in terms of evolution and the original characteristics are retained.

If you brew a lot and wish to avoid the inconvenience of harvesting yeast. You can buy dried yeast in bulk rather than in sachets, this way it is very cheap indeed.

Hope this helps.

Thanks James that seems reasonable advice.