Repitching yeast slurry

[bitter_dave]

What is the jbk view(s) on repitching yeast slurry into a wort?

I'm in the unusual position (for me) whereby I am brewing on the same day as bottling the previous batch.

I made 15 litres of mild and going to make a pale ale of about the same quantity. In both cases modest gravities (low 40s). Used lallemand London.

Can I just collect a bit of slurry and pitch it in the next batch? If so, how much should be used? Or is that risking off flavours etc?

[Jocky]

You can just repitch slurry - the amount depends upon freshness, the new wort gravity and the yeast you are using, but I'd say for starting gravity up to 1.055 half a pint is plenty into 5 gallons.

When you're done bottling just leave a tiny bit of beer on top of the yeast, swirl it up to get yeast into solution, then pour it into a sanitised glass. You can then clean out your fermenter ready for the fresh wort.

You will need to aerate your wort as normal. I would also recommend adding some yeast nutrient to the wort just in case it's a bit tired out.

Ideally you don't want hops in there too (if you dry hopped the previous batch), but a little is not going to cause any problems.

[Eric]

At the end of a decent fermentation from a plentiful pitch, there will be four to five times the initial quantity of yeast. I mostly top crop, but for slurry, which contains more dead cells and other debris, I skim the deposit with a flame sanitised spoon and into a sanitised jar. This assumes that during the preceding cooling period, active yeast will drop out and form the top layer.

It is amazing how much a small amount of yeast nutrient improves subsequent fermentations.

[bitter_dave]

Thank you Jocky / Eric, I follow your advice.

I have some Wilkos yeast nutrient knocking about that I've never used:

https://www.wilko.com/en-uk/wilko-yeast ... /p/0022654

Do you think this will be ok? It refers to winemaking but I can't see why it should not help beer as well. My local homebrew shop has youngs yeast nutrient, but I suspect it is the same stuff.

[Eric]

A good question. I have used Wilko's in the past and still have some in stock. Recently I managed to get some Yeast Vit, that I know is used by some local commercial breweries and have wanted for some time. However, it looks more like Wilko's than described in Murphy's Technical Information Sheet. However, their advice differs from Wilko's and I do as Murphy suggest and drop some on the yeast as it warms to pitching temperature and it would appear to significantly reduce lag.

I never thought Wilko's product ever had a detrimental influence while the Yeast Vit dosage is vastly smaller.

[bitter_dave]

Excellent, thanks for that advice Eric.

[charliemartin]

That dosage is extremely small. Only 5g per hectolitre. Can that amount really make a difference to fermentation?

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[Eric]

That dosage is extremely small. Only 5g per hectolitre. Can that amount really make a difference to fermentation?

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Yes, it is, but 95% of that volume is water. Homebrewers might typically pitch 11g of yeast including nutrients needed into 23 litres, say 45g in a hectolitre, but this is just of the essential nutrient part. I can say it stirs activity when pitched directly onto wet yeast. By similar comparison, a teaspoonful per gallon for Young's wine nutrient seems excessive. Most nutrition for beer comes from grain, but, as example, yeast need zinc and there is little, if any, in grains and many water supplies, while RO water usually has none.
Try it.

[MashBag]

You can just repitch slurry - the amount depends upon freshness, the new wort gravity and the yeast you are using, but I'd say for starting gravity up to 1.055 half a pint is plenty into 5 gallons.

When you're done bottling just leave a tiny bit of beer on top of the yeast, swirl it up to get yeast into solution, then pour it into a sanitised glass. You can then clean out your fermenter ready for the fresh wort.

You will need to aerate your wort as normal. I would also recommend adding some yeast nutrient to the wort just in case it's a bit tired out.

Ideally you don't want hops in there too (if you dry hopped the previous batch), but a little is not going to cause any problems.

Nice post Jocky . I stopped short of posting "you could just drop the new mash in the existing fermenter" after bottling.

Dead yeast is considered to be nutrient.

What did you think was "a bit tired out"?