Liquid yeast, just how good?

[Thumper]

Yes you are encouraging the yeast to grow. The yeast also has the option to "aerobically" respire to produce energy for this purpose, but it oddly prefers the inefficient anaerobic method of producing energy (fermentation) as long as there is plenty of food about (source: probably a Whitelabs information flyer).

Their survival strategy basically involves producing CO2 because it inhibits the growth of most other microorganisms (because most others respire aerobically). But this means they themselves have to respire anaerobically. Ditto alcohol; they evolved the ability to produce alcohol (and to live in it themselves) because other microorganisms don't like it.

 

[Sadfield]

@pms67 The beauty of dry yeast is that its pretty stable, so calculating and dosing the correct amount should be quite easy. This is a great calculator, here, although the settings need to be adjusted for UK ways. A few esters won't do any harm as they tend to add fruitiness which will compliment heavy hopping.

Be kind to your yeast and rehydrate it.

 

[peebee]

... The yeast also has the option to "aerobically" respire to produce energy for this purpose, but it oddly prefers the inefficient anaerobic method of producing energy (fermentation) as long as there is plenty of food about (source: probably a Whitelabs information flyer).

Dug up that source. It's for geeks only: https://www.morebeer.com/articles/how_yeast_use_oxygen. Not from Whitelabs (sorry Tracy Aquilla).


(EDIT:

Their survival strategy basically involves producing CO2 because it inhibits the growth of most other microorganisms (because most others respire aerobically). But this means they themselves have to respire anaerobically. Ditto alcohol; they evolved the ability to produce alcohol (and to live in it themselves) because other microorganisms don't like it.

Thanks. I think the link above supports much of what you say.)

(EDIT2: To save folk having a big read if they don't want it, the relevant section is:

The tendency for fermentation: Brewers’ yeast has a very strong tendency toward fermentation and will respire only when the concentration of fermentable sugars is very low and oxygen is available (1). In beer making, yeast will ferment rather than respire, regardless of the oxygen concentration, because the wort usually supplies an overwhelming abundance of fermentable sugar. The production of ethanol during fermentation may contribute to yeast survival because of its toxicity to other microorganisms.

)

 

[trueblue]

Esters, phenols and Ketones are usually the product of yeast stress and it is well documented that excessive yeast growth or over pitching leads to low ester production. Dry yeast packets are designed for foolproof fermentation, they are supplied with high cell count and packed full of the sterols needed for vigorous growth. In my opinion this is why they can ferment cleaner making a bland beer. Dry yeast is not an inferior product, it's just yeast. They make a bland beer when not handled correctly. Getting the best out of any yeast is a balancing act of controlled abuse. If liquid yeasts were supplied with the same pitchable cell count and nutrients, they would also produce a bland beer.

So you are agreeing it dry yeast produces a more bland beer.

 

[Gunge]

Peebee: the article you linked to above - a little geeky maybe but well worth the read. Thanks! I especially like the bit where it says oxygenation is not really necessary ( cos I don't do it, with no detrimental effects that I know of) and that letting cold-break matter into the FV is Good Thing ( cos all mine ends up there thanks to using a CFC)....

 

[Sadfield]

@trueblue Not if pitched correctly.

A fresh 11.5g satchet of dry ale yeast has the correct cell count for a 5 Gallon batch of wort at 1.058 OG (roughly a 6.3% beer). If your wort is weaker or of lower volume, that one sachet will be over-pitching. This will result in a cleaner ferment. If you wort is stronger or of higher volume, that one sachet will be under-pitching and likely result in a too estery beer.

From a novice perspective, where a whole sachet is pitched, over-pitching is the better option, and so dry yeast manufactures lean towards a higher cell count in the sachets. The yeast isn't different to the liquid yeast, but the cell count is.

From Wyeast

A low pitch rate can lead to:

Excess levels of diacetyl
Increase in higher/fusel alcohol formation
Increase in ester formation
Increase in volatile sulfur compounds
High terminal gravities
Stuck fermentations
Increased risk of infection

High pitch rates can lead to:

Very low ester production
Very fast fermentations
Thin or lacking body/mouthfeel
Autolysis (Yeasty flavors due to lysing of cells)

 

[Ciaran12s]

Yes a stir plate aerates continuously and so it's possible/likely the starter will be oxidised. If it's a small enough volume though (<10% or so of the total volume) it shouldn't have an impact. Even better, you can make the starter a day earlier, then after it is finished, chill and decant the liquid off the top and just pitch the Yeast.

Sorry for my complete lack of knowledge but say I've got a coke bottle full of starter that's been going a couple of days and now chilled in the fridge. I will find a fairly large layer of trub with beer on the top? So pitch the beer and leave all the trub behind and this will have a good quantity of Yeast for the full batch?

I thought I'd a fair idea of the process..... looks like a little further reading is in order.

 

[IainM]

I think you missed my point Trueblue. If S-04 and WY1098 are the same strain, they will share the same genetics. Their genetic makeup will influence the enzymes they produce and how they ferment. If their genetics were different they would be different strains.

I don't think this is quite true. Every time yeast reproduces mutations are introduced, and each cell in the population is unique. The yeasts may have exactly the same repertoire of genes, but these these variations will alter the flux through the various metabolic pathways, for instance by altering the levels at which the enzymes are expressed or by altering the efficiency of the enzymes themselves. Consequently two monoclonal populations derived from different cells of the ancestral Whitebread B population might be quite different, and this is before we even consider the effect of selecting only the cells that survive the drying process.

 

[Sadfield]

I don't think this is quite true. Every time yeast reproduces mutations are introduced, and each cell in the population is unique. The yeasts may have exactly the same repertoire of genes, but these these variations will alter the flux through the various metabolic pathways, for instance by altering the levels at which the enzymes are expressed or by altering the efficiency of the enzymes themselves. Consequently two monoclonal populations derived from different cells of the ancestral Whitebread B population might be quite different, and this is before we even consider the effect of selecting only the cells that survive the drying process.

Fair point. Considering all strains though, do you think that would lead to all dried yeast to mutate to a point where it ferments with less esters? Or would the result be more random and therefore fair to say that dry yeast producing bland beers is not a result of the drying process?

"Inspiration is the impact of a fact on a well-prepared mind" Louis Pasteur

 

[strange-steve]

Sorry for my complete lack of knowledge but say I've got a coke bottle full of starter that's been going a couple of days and now chilled in the fridge. I will find a fairly large layer of trub with beer on the top? So pitch the beer and leave all the trub behind and this will have a good quantity of Yeast for the full batch?

I thought I'd a fair idea of the process..... looks like a little further reading is in order.

Other way round. When you chill it in the fridge the yeast will drop out of suspension, and so you'll have a layer of yeast on the bottom of the bottle and a layer of beer on top. Carefully pour the beer off and dump it down the drain, then swirl up the yeast layer and pitch it into your waiting wort.

 

[Ciaran12s]

Other way round. When you chill it in the fridge the yeast will drop out of suspension, and so you'll have a layer of yeast on the bottom of the bottle and a layer of beer on top. Carefully pour the beer off and dump it down the drain, then swirl up the yeast layer and pitch it into your waiting wort.

Right I'm with you. That's what I'd thought, I must have misread something. Thanks for clearing that up for me! I may well have dumped the starter and pitched the oxidized beer haha

Edit- just re-read your post. It was me misreading.

 

[Thumper]

I don't think this is quite true. Every time yeast reproduces mutations are introduced, and each cell in the population is unique. The yeasts may have exactly the same repertoire of genes, but these these variations will alter the flux through the various metabolic pathways, for instance by altering the levels at which the enzymes are expressed or by altering the efficiency of the enzymes themselves. Consequently two monoclonal populations derived from different cells of the ancestral Whitebread B population might be quite different, and this is before we even consider the effect of selecting only the cells that survive the drying process.

By definition, if they have mutated then their genome is different, so they won't all have the same genes. What you have is basically a miniature version of the species problem: how different do they have to be, and by what measure, to be considered a different strain?

 

[MyQul]

Great idea Steve - does it keep OK for a week or so like that?

I've done something similar to Steve's idea of using the first runnings as starter (at least I think that is what he said). I've just taken a litre of wort out before I pitch the yeast and freeze it. When it comes to using it I just thaw it out and boil it for 5 mins or so to re-sanitise it. Then cool it down and put my yeast into it.
I've never tested the it's limits but I suspect it would last months.

 

[Ciaran12s]

@myqul did you post a thread along the lines of "making a starter without a stir plate" ? I'm sure I seen one here a while back and I'm sure it was your thread but I couldn't find by searching or trawling through the grains, hop, yeast water section.

 

[MyQul]

@myqul did you post a thread along the lines of "making a starter without a stir plate" ? I'm sure I seen one here a while back and I'm sure it was your thread but I couldn't find by searching or trawling through the grains, hop, yeast water section.

No. I posted a 'how to culture up yeast from bottle conditioned beers', thread

 

[Ciaran12s]

That's the one yeah. Thanks

 

[strange-steve]

What you need is the shaken-not-stirred method, aka the James Bond method. See here, top post.

 

[trueblue]

By definition, if they have mutated then their genome is different, so they won't all have the same genes. What you have is basically a miniature version of the species problem: how different do they have to be, and by what measure, to be considered a different strain?

The brewery I mentioned earlier acquired their yeast in the 1970's from a local brewery who had been using the same yeast as I said for over 100 years. Another micro several miles away have been running with the same yeast for 5 or 6 years. All the yeasts have changed so much all the brewery's have registered their yeast with the National collection of yeast cultures and are considered there own, Whitbread B is just the parent.

 

[MyQul]

That's the one yeah. Thanks

Here it is

http://www.thehomebrewforum.co.uk/showthread.php?t=53567

But as steve say's, if you simply want to make a starter, the shaken not stirred/james bond method is what you want (I use this for my starters, as I dont have a stir plate)

 

[MyQul]

The brewery I mentioned earlier acquired their yeast in the 1970's from a local brewery who had been using the same yeast as I said for over 100 years. Another micro several miles away have been running with the same yeast for 5 or 6 years. All the yeasts have changed so much all the brewery's have registered their yeast with the National collection of yeast cultures and are considered there own, Whitbread B is just the parent.

I use the Gales yeast as my 'house strain' (when I'm not using a clean dried yeast for stuff like pseudo lagers), from what I've discovered on the internet, this is also has the Whitbread B, strain as the parent