What I Don't Understand About Slanting

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Just rang my local chemist ( they are a compounding chemist - old school style) and they have 100ml bottle of glycerol for $5.95. They get in what every quantity you want of chemicals. As a side note they will also get lactic acid in - not cheap at $34 / 100ml.

They are located at Ashgrove for the people in Brisbane. I'm sure there are others as this is first I made a call to.

 

[jonocarroll]

Have a peek in the cake (decorating) sections at the supermarket. I reckon that's where I've seen it.

 

[Nevalicious]

Glycerin from Priceline Pharmacy (TTP for those in SA) was only $3.99 for 100ml! Bargain

 

[Thirsty Boy]

According to a 2006 BYO Magazine article, the WL yeasts are now shipped out with an average cell count of 100 billion, a lot more than what I thought to be around 35 billion. With a 20% decrease per month this would still mean there's about 26 billion cells, not far off the previous count. Not bad figures to consider if buying old stock. Also not too far off the previously shipped 35 billion.

I almost bought one of these USB microscopes so me and a mate could look at the cell count on stored yeasts, but many reviews say that they are rubbish, and not even close to the stated specs of 400x. as well as the picture quality being poor. Would a conventional microscope be adequate to view yeast cells, and at least visually estimate cell count? Im very interested to observe the decline in viability with recycled cropped samples, and compare to newly purchased vials.

If brewers are to take samples from an active ferment for storage purposes, isn't this going to be a new generation of healthy cells with a high count per microgram (or whatever the standard measure might be), or will hop & grain debris significantly diminish the count? Mutation aside, Im still unclear as to why you cant just keep culturing crude fresh samples in a series of starters every couple of months to perpetually maintain a yeast bank. Although I guess if you do this often enough to keep your samples viable, the cost of DME and the time involved would be greater than just buying a new vial of reliable clean yeast.

It's not the cell count that is the issue - there's a hell of a lot less cells than 35billion on a slant. It's the storage and dying off process that is the issue. The properties of the yeast change as cells mutate from generation to generation, and the yeast does not maintain its brewing properties. Cells going bung, happens a lot more in stressed and dying samples and for the most part, yeast stored under liquid are stressed and dying samples. - If you culture up, harvest and re-culture from samples that have been allowed to degrade, this drift becomes rapid enough so you may well notice strain drift in as little as a couple of generations.

You probably don't want to waste your money on a microscope for counting yeast.... If you're curious, for sure. But for counting - well, a decent haemocytometer is not exactly a cheap thing and at any rate, cell counting with the stain you are likely to use (meth blue) is notoriously unreliable at cell viabilities below 80-90% - so nun less you are pretty sure that you have 80-90% live cells in your sample anyway, then you are very unlikely to be able to get an accurate cell count. And if you have 80-90% viability... You're pretty good to go anyway.

 

[Bribie G]

Glycerine should be in the vitamins section at Woolies / Coles / IGA along with the Hydrogen Peroxide, liquid paraffin etc. I've just stocked up on test tubes with lids and a rack, and I'll definitely do some frozen ones first before I get into the slants, it just seems so much less stuffing around.

One thing that hasn't been mentioned so far, glycerine has a very sweet cloying flavour although it's quite edible in small quantities (glycerine and honey as used by grandma) - would it taint the beer? so if making a starter from a tube I suppose I should get a good bit of yeast bred up, let it sink then pour off the liquid to get rid of the glycerine?

 

[Thirsty Boy]

i never tasted it in any of the beers I made from yeast stored under glycerol Bribie - hardly definitive I know, but you are only talking a fw ml of the stuff after all.

and if it concerned you - you could culture up in the same way you would from a slant. Shake up tube, red hot loop into the glycerol/yeast mixture, loop into 10-15ml of wort. Go. Then its lid back onto the sample and back into the freezer.

 

[Nevalicious]

i never tasted it in any of the beers I made from yeast stored under glycerol Bribie - hardly definitive I know, but you are only talking a fw ml of the stuff after all.

and if it concerned you - you could culture up in the same way you would from a slant. Shake up tube, red hot loop into the glycerol/yeast mixture, loop into 10-15ml of wort. Go. Then its lid back onto the sample and back into the freezer.

Thats an interesting method...

In order for this to work though Thirsty, you would have to "defrost" the yeast/glycerine mixture to take the sample yes?? Or am I wrong in thinking that this mixture wont harden in the freezer. The reason I ask is, I thought freezing then thawing and so on is no good for yeast viability?? Constant temp should be maintained??

Also, if this would work into 15 odd ml of wort, you would wait for this to ferment out, then step up as usual??

Tyler

 

[Bribie G]

The freezing / thawing damage to cells occurs because the cell walls burst, but apparently the glycerine prevents this from happening. The guys a Alcor maybe use glycerine when they freeze your head.

 

[Nevalicious]

The freezing / thawing damage to cells occurs because the cell walls burst, but apparently the glycerine prevents this from happening. The guys a Alcor maybe use glycerine when they freeze your head.

Planning ahead Bribie???

 

[Thirsty Boy]

Thats an interesting method...

In order for this to work though Thirsty, you would have to "defrost" the yeast/glycerine mixture to take the sample yes?? Or am I wrong in thinking that this mixture wont harden in the freezer. The reason I ask is, I thought freezing then thawing and so on is no good for yeast viability?? Constant temp should be maintained??

Also, if this would work into 15 odd ml of wort, you would wait for this to ferment out, then step up as usual??

Tyler

Yeah, you are right. The yeast is better maintained by keeping a constant temperature. In my samples, they stayed primarily liquid, so it was less freezing than just very cold storage, and at any rate, a freeze thaw cycle is going to be less bad for the life of the sample than using all of it no?

I think you do want them to actually freeze for best storage though (I used to much glycerol) - and even with the glycerol, they will suffer mortality on every freeze/thaw cycle. I wouldn't re-culture from one that had been frozen and thawed, but I reckon it'd be OK to use for stepping up to a starter a few times before you binned it and started from a never thawed out version.

If in doubt - I'd go with using the whole sample though - I'm speculating not speaking from experience or a decent knowledge base.

Once you had inoculated 10-15ml of wort - you give it about a day or so to grow, then step up by 10 fold for ale yeasts and by 5 fold for lager yeasts. Thats going to give you a cell density of about 100,000,000/ml for the "grown" sample and thus a pitching rate of 10,000,000 per ml (or 1,000,000 cells/ml/plato in a 10plato/1.040 starter wort) when you tip it into the next step. Going 10ml -> 100ml - > 1000ml should give you approximately 100billion cells - or the equivalent of a brand spankingly new smack pack. Obviously if you step up by half the volume for lager yeasts, you are doubling the pitching rate - but should end up with roughly the same final number of cells/ml. Or so sayeth Chris White when I cornered him at ANHC anyway

TB

 

[Nevalicious]

Yeah, you are right. The yeast is better maintained by keeping a constant temperature. In my samples, they stayed primarily liquid, so it was less freezing than just very cold storage, and at any rate, a freeze thaw cycle is going to be less bad for the life of the sample than using all of it no?

I think you do want them to actually freeze for best storage though (I used to much glycerol) - and even with the glycerol, they will suffer mortality on every freeze/thaw cycle. I wouldn't re-culture from one that had been frozen and thawed, but I reckon it'd be OK to use for stepping up to a starter a few times before you binned it and started from a never thawed out version.

If in doubt - I'd go with using the whole sample though - I'm speculating not speaking from experience or a decent knowledge base.

Once you had inoculated 10-15ml of wort - you give it about a day or so to grow, then step up by 10 fold for ale yeasts and by 5 fold for lager yeasts. Thats going to give you a cell density of about 100,000,000/ml for the "grown" sample and thus a pitching rate of 10,000,000 per ml (or 1,000,000 cells/ml/plato in a 10plato/1.040 starter wort) when you tip it into the next step. Going 10ml -> 100ml - > 1000ml should give you approximately 100billion cells - or the equivalent of a brand spankingly new smack pack. Obviously if you step up by half the volume for lager yeasts, you are doubling the pitching rate - but should end up with roughly the same final number of cells/ml. Or so sayeth Chris White when I cornered him at ANHC anyway

TB

Thanks Thirsty, this helps alot. I reckon, I might even make up my frozen yeast samples and later down the track when I require a particular strain, even pouring just half out of a vial into a starter and stepping up as required is much more thrifty than just using a $10 yeast in one brew!

Awesome thread...

When my vials of WL's roll up, i'll get things underway!!!

Tyler