Another question about yeast starters/slurry

[bitter_dave]

Ps. Can't you just spritz the tap with sanitizer?

On the rare occasions I've taken a hydrometer sample mid fermentation via the tap I have just rinsed it with starsan on bottling day. Never had a problem doing this. Nice method.

[guypettigrew]

Depends on the tap. My conical uses ball valves. No way would I want to take a sample then leave the ball full of fermenting beer!

Guy

[IPA]

If it's any help, my method is taken from IPA's. I sanitise a jug, then scoop half a litre or so from the top of the fermenting beer, including the krausen.

Tip it into a kilner jar and put it in the 'fridge. It carries on fermenting, even at 4°C. The kilner jar allows exces gas to be released as neccesary.

Super easy.

When it's time for a brew I put about 120g of malt extract into 1 litre of water. Boil it for 10 minutes, cool it to about 20°C, put it on a stir plate. Then the clear liquid is tipped off the yeast sediment. The yeast is swirled round in the small amount of liquid left behind and tipped into the malt extract.

Ready for use a couple of days later.

As nallum says, 'don't overthink it'!

Guy

Thanks Guy - I was just about to ask how much DME to add to the starter.

Start with a 300ml starter and step up with 1000ml.
30 gr of DME for the 300ml and 100 gr for the 1000ml
It is very important get some oxygen into the wort after boiling it. Ideally with a stir plate. If not by shaking it vigorously.
With liquid yeast costing £13 quid a time it is worth buying a stir plate once you are happy with this process.
I no longer use DME. I do a 10 litre mash at 1040 and put it into 6 X 1200 ml and 6x 300 ml plastic ex water bottles and store it in the freezer. Much cheaper than DME.

[guypettigrew]

Start with a 300ml starter and step up with 1000ml.
30 gr of DME for the 300ml and 100 gr for the 1000ml
It is very important get some oxygen into the wort after boiling it. Ideally with a stir plate. If not by shaking it vigorously.
With liquid yeast costing £13 quid a time it is worth buying a stir plate once you are happy with this process.
I no longer use DME. I do a 10 litre mash at 1040 and put it into 6 X 1200 ml and 6x 300 ml plastic ex water bottles and store it in the freezer. Much cheaper than DME.

Fascinating, isn't it? Your method and quantities work, IPA, and so do mine. Nicely demonstrates how absolute precision really isn't needed. Nallum's 'don't overthink it' comment is spot on!

Guy

[cc986]

Start with a 300ml starter and step up with 1000ml.
30 gr of DME for the 300ml and 100 gr for the 1000ml
It is very important get some oxygen into the wort after boiling it. Ideally with a stir plate. If not by shaking it vigorously.
With liquid yeast costing £13 quid a time it is worth buying a stir plate once you are happy with this process.
I no longer use DME. I do a 10 litre mash at 1040 and put it into 6 X 1200 ml and 6x 300 ml plastic ex water bottles and store it in the freezer. Much cheaper than DME.

Fascinating, isn't it? Your method and quantities work, IPA, and so do mine. Nicely demonstrates how absolute precision really isn't needed. Nallum's 'don't overthink it' comment is spot on!

Guy

Thanks IPA and Guy!

This is my second bash at homebrewing. The first was in the 90's when fermentation was all about a cheap packet of yeast from Boots the chemist and plastic buckets covered with a tea towel, then life and working abroad got in the way and I had to stop for a long time. I returned about five years ago, and what I have discovered since then is that a lot of modern homebrewers seem to want to make brewing as difficult as it could possibly be. There have definitely been some good improvements, but this conversation about how many billions of cells of yeast there are in 100ml of slurry (which for me, was kicked off by reading a document by some young craft brewer) is a perfect example of how much nonsense there is, because you have shown that it's completely unnecessary to know that. And that's why I prefer to ask these questions here on JBK instead of all those Facebook groups full of hipster brewers (which I have now left). No offence intended to any hipster brewers!

[nallum]

Working ‘blind’ based on starter volume, instead of cell number guesstimates, is the simplest way and anyone can do it. No specialised equipment or knowledge required. But it’s surprisingly relevant too. Assuming we’re not under seeding the starter, a starter wort of, say, 300ml, is only going to contain enough key nutrients, e.g., sugars, amino acids and nitrogen compounds, to support a certain amount of yeast growth. And the yeast cells, like all living cells, are highly sophisticated biosensors constantly monitoring their environment and communicating behavioural decisions to each other, cell to cell. The concentration (strength) of chemical signals (nutrient levels, growth factors/population density, etc.) in the wort affects yeast cell behaviour. So in that 300ml there’s always going to be approximately the same amount of biomass (yeast slurry) at the end of the culture. The same applies when stepped up to 1.5L, i.e., 1.5L only contains enough key nutrients and space to support a certain level of yeast biomass production. If we under seed the starter wort, we’ll get more growth. If we over seed it, we’ll get less growth. But, regardless, we’ll end up with approximately the same amount of live yeast biomass in a given volume of starter wort. I’d say add roughly a few millilitres viable yeast slurry to 300ml starter wort. Considering loss of viability over time in storage, the several millilitres yeast slurry in one of Ian’s bottles clearly works. We want to promote yeast growth, though, to rejuvenate the yeast population, so we don’t want to massively over seed and get little growth, e.g., by adding something like 100ml slurry in 300ml starter wort. That’s merely ‘feeding’ the yeast.

The reason we use aerated wort at about 1.040 is at this gravity barley-based wort provides enough key nutrients, especially amino acids and nitrogen compounds, to promote sufficient yeast growth for our purposes. Fermentation. There are tricks to increase biomass, but the costs to benefits are far too low for home brewers to bother. Keeping it simple is more than enough to succeed. Anything beyond simple is misguided mental masturbation.

It’s pretty much ‘bucket biology’ and difficult to get wrong. With a little respect, the yeast do what they do regardless.

[IPA]

Have you ever wondered how your bottled beer is conditioning ?
For many years I used to use a PET bottle for the the first bottle and by squeezing it over a number of days I got a rough idea of how carbonisation was progressing. I now have a far more accurate way of knowing.
One of these. https://www.themaltmiller.co.uk/product ... aning-cap/
And one of these. https://www.themaltmiller.co.uk/product ... tal-gauge/
Fitted to a 500ml PET bottle gives you this.

P1010633.JPG (156.5 KiB) Viewed 2158 times

and this

P1010634.JPG (179 KiB) Viewed 2158 times

Just simply push the button and you will know the pressure in the bottle.

[Eric]

All good advice here, but a small fraction of a gram of a good yeast nutrient can help.

This is a recent harvest from a 28 litre brew fermented using a Brewlab top fermenting yeast. No reason to cell count.

TopCrop.jpg (818.94 KiB) Viewed 2135 times

[PeeBee]

Remarkable! Only today I came across a slide from a presentation that made me think "Could that be applied to yeast slurries?".

Now I haven't attempted to process this yet. I have no idea if it's of any value ... I just present the slide for comment (i.e. Do not shoot the messenger!). And when you find out how I might have come across it, give me time to beat a hasty retreat because you're not going to like it!

"Nallum" has already mentioned one potential problem ... it makes no differentiation 'tween active and inactive (dead) cells. And how "accurate" those calculators are ...

The slide was titled "Measuring the Percentage Solids in a Slurry". Promising start:

Measuring the Percentage Solids of a Slurry.jpg (145.08 KiB) Viewed 2128 times

It will probably require a "Hubbard bottle" to measure the density of a thick slurry ... it's a sort of wide-necked ... nah, I'm not saying it! Going to need the density of the yeast, but should be able to work that out (can easily get the densities of settled out slurry and cleared-ish "beer"). And might need a bit of "IPA's" processing to prepare the samples.

Err ... over to you?

[nallum]

In the context of a yeast slurry, the phrase ‘density’ refers to number of stationary phase cells per ml at the end of a culture. It’s surprisingly fixed (by biology and physics) for a given volume of starter wort. Yeast are self-replicating biological systems. It’s very simple. Pour off liquid above the slurry then, depending on starter size, collect teaspoons or tablespoons of slurry to seed the starter wort. No need for pretentious calculators. Simply bung some in there.

[PeeBee]

In the context of a yeast slurry, the phrase ‘density’ refers to number of stationary phase cells per ml at the end of a culture. It’s surprisingly fixed (by biology and physics) for a given volume of starter wort. ...

That's actually encouraging. The bit I thought I'd be picked up on was density of solids. Which I conveniently passed over. But you've commented it's "surprisingly fixed". A bit of embellishment on that and I reckon you can slap a figure (cells per ml) on that. "Dead cells" I presume are denser (hence they sink quick) so an "operating density range" could be specified? All rough, but as someone who's picked over those "starter calculators" I know there's a huge amount of "approximation" to accommodate a bit of roughness.

I've given up with "Hubbard bottles" BTW. Having seen the price! A fairly large (100ml?) open vial with a glass slide as a top (to negate any meniscus) will be accurate enough.

The calculation looks scary (pretentious?) but it's only the (pretentious?) symbolism they use (e.g. "Dliq", etc.) ... it is only percentage calculated like you're taught in primary school (%=[fraction]/[total]*100) with a little extra 'cos we're after a proportion of the "fraction".


On to the rest of your response! "It's very simple", "collect teaspoons or tablespoons of slurry" ... okay, most of us here know who you are by now, but these statements coming from an otherwise "unknown" are pretty meaningless. A line I wrote on another forum (which you frequent) said:

... The very best solution (but escapes me now-a-days) is a combination of: Experience and Confidence; i.e. no measuring tools at-all ...

Your "anonymity" means you can't use "experience and confidence" as a teaching aid as effectively as you once did. You might try my policy of fighting this un-necessary complication of homebrewing ways - I know you must want to help or else you wouldn't write responses in forums - I try to use the techniques and "solutions" of the "homebrew heroes" to counter the complexity they are introducing. Doing so means immersing yourself in the complexity to come out waving a simple approach using the tangled nonsense the "homebrew heroes" have created. (This wasn't my original reason for soaking myself in complexity ... just I eventually woke up and thought "what the hell am I doing?").

I could obviously do with some help with this ... I've recently got myself slung off the THBF (the "UK" forum) for my efforts!

The best saying I can come up with describing this approach:

"Keep your friends close and your enemies closer." (Sun Tzu)

[nallum]

My best advice is keep it simple and just bung some yeast slurry into starter wort. At a rate of about 1-5% of the starter volume. Where about 1% is for fresher and about 5% for older slurry. Don’t worry about trying to be precise. Just bung it in there. It’s ’bucket biology’. The cell number is kind of redundant information for brewers. A belief system in most cases. If I were doing some research comparing different culturing methods cell counts provide very valuable information as endpoints for comparison.

[MashBag]

+1 slurry.

Just soo easy.

[IPA]

+1 slurry.

Just soo easy.

Not if you want to keep it a while before use.

[nallum]

I top cropped some Verdant IPA about 2 months ago. Not my favourite yeast. Just the freshest English ale yeast slurry I have at the moment. Set up a 200ml starter with a tsp of slurry last night.

IMG_0694.jpeg (2.32 MiB) Viewed 1106 times

The yeast are not as active as they seem in this pic. More a case of being stored under pressure by mistake. No harm done. Lucky the jar didn’t explode, though. I poured off the liquid into another jar so I could take a tsp of yeast slurry. Poured it back on top of the remaining slurry for further storage.

Gave it a good stir with the spoon and left it overnight.

This afternoon, looks like this:

IMG_0697.jpeg (678.2 KiB) Viewed 1106 times

Lots of growth already. I’ll step it up to 1L tomorrow ready to pitch at the weekend.