• We have a new forum and it needs your help! Homebrewing Deals is a forum to post whatever deals and specials you find that other homebrewers might value! Includes coupon layering, Craigslist finds, eBay finds, Amazon specials, etc.

Estimating Yeast Cell Counts in Fresh Starter

HomeBrewTalk.com - Beer, Wine, Mead, & Cider Brewing Discussion Community.

Help Support Homebrew Talk:

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
I've just started working on building a yeast bank and I'm having a hard time approximating yeast cell counts.

I took a White Labs vial manuf 09 Jan 13 and made a 3.8L starter. Yeast Calc and Mr Malty tell me that I should have 375m cells afterwards. So I cold crashed and decanted, sworled the mixture like crazy to make it as unform as possible and poured into 8.25 40ml vials. 5 vials went into the fridge, and the other 3.25 went back in to be stepped up for next weekend's brew.

The problem is that I'm comparing them to the Wyeast graphic below and coming up with odd numbers. I should have about 45 billion cells in each vial, but my vials look closer to the middle one (87 billion per vial).



What am I doing wrong? There's no way the picture is correct and I actually made 718 billion cells.
 

theveganbrewer

Well-Known Member
Joined
Sep 23, 2011
Messages
1,917
Reaction score
297
Location
Beaverton
A lot depends on how compact and how fresh. It looks like the WL is estimating 3 billion cells per mL based on a very low non-yeast percentage, no aging, and very dense cells. How dense is yours? How old? How much non-yeast is in there? Fiddle around with those numbers on mr. malty repitch from slurry tab until you feel comfortable with the numbers.

This is from the yeast book author:


If you've brewed more than one batch, I'm sure you've noticed that there is a huge pile of yeast in the fermenter at the end. If (and that is a big 'if') you've got excellent sanitation all the way through the process and have provided proper yeast nutrition (including O2), you have a gold mine of healthy yeast ready to reuse. Of course, you don't want to reuse the whole thing. I know a number of people dump a new batch on top of the yeast cake, but you're not going to get the best beer that way. Yeast do need some growth to result in the right kind of ester profile, etc. While too big a pitch is better than too little, it is pretty easy to figure out how much you need and pitch just that.

There are about 4.5 billion yeast cells in 1 milliliter of yeast solids (solids with no excess liquid). According to Fix, in a slurry, only about 25% of the mass is yeast solids. Of course, if there is a lot of trub in there, you have an even lower percentage of yeast solids. The bad thing is that you can't tell how viable that yeast is, unless you have the equipment to properly test and count it. So this is where it gets a little bit like black magic. There are a number of factors that affect the viability of a given pitch of yeast. How old is the yeast? How stressful was their last fermentation? Have they had the proper environment and nutrients for successful reproduction or are they too scarred and tired to go on?

When the yeast is fresh and healthy off an previous batch, viability is maybe around 90%+. It goes down from there fairly quickly without proper storage and it also really depends on the strain of yeast. Unless you're going to get into testing viability, you're going to need to make some educated guesses and keep good notes on the results. This is where being a yeast psychic really helps. Start in a range of 80 to 90% viability and you probably won't be too far off. Use the Pitching Rate CalculatorTM to help figure out how much of that yeast you need. If your yeast viability is much lower than 90%, you should probably toss the yeast. If you really want to use it, you might consider pitching it in some starter wort to get the still viable cells active. When they're in solution, decant that active part of the starter into another vessel, hopefully leaving the dead cells behind.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
A lot depends on how compact and how fresh. It looks like the WL is estimating 3 billion cells per mL based on a very low non-yeast percentage, no aging, and very dense cells. How dense is yours? How old? How much non-yeast is in there? Fiddle around with those numbers on mr. malty repitch from slurry tab until you feel comfortable with the numbers.
Density? Don't have measurement tools for that.

Age? About 100 billion packaged 09 Jan 13 at White Labs, the other 275 billion a few days old.

Non-yeast? Well, there's no hop trub to speak of. I suppose there could be some proteins from the DME, but it's impossible to tell if there is and how much.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
I'm starting to think that weighing might be a better answer. You wouldn't have to wait for strong yeast compaction to measure. Notice the picture above has % of yeast solids by volume underneath the

I know the OG was 1.040. I can take the FG with a refractometer, correct for alcohol, and know the true FG. At that point I'd know the weight of an empty vial, the gravity of the spent wort, and the weight of the full vial. It's a pretty simple formula to figure out the ratio of yeast to spent wort from there.

Or, we can try it this way:

Wyeast said:
Slurry can be harvested based on volume or weight. 1L (1 quart) of yeast slurry (40% yeast solids) weighs approximately 1.1 Kg (2.4 lbs.). The following guidelines will deliver the appropriate pitch rates.
The only problem is those figures seem to be based upon harvesting the cream from a conical, so it might not be applicable to me, as I have no trub.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
Just pulled the vials back out of the fridge. We're at about 36 hours cold crash now.

Compaction increased overnight. I'm looking at closer to 12-15 of yeast solids now, which seems closer (75b-93b) but still not quite there. The spent wort clarity is starting to approach that of the picture, though still slightly cloudier.

Trying to determine the ml capacity of the pictured vials. I think they're Wyeast Nutrient, which appears to be a 45ml vial. Sent Wyeast an email for clarification. Many shops are listing them as "1.5 fl oz", or 44ml. If they're 45ml vials, I need to scale my 40ml vials to them. If they're 50ml vials and the rest is for headspace, then I need to scale farther.

Looks like calculating percent solids by weight is really the best option at this point, as it ignores temperature and doesn't require cold crashing 48 hours for optimal compaction.
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
Mr. Malty's slurry estimator has been way off in my experience. Especially the viability by date part
http://woodlandbrew.blogspot.com/2012/11/counting-cells.html

Growth seems to be much more closely related to the amount of sugar than anything else in experiments I have run:
http://woodlandbrew.blogspot.com/2013/01/starter-cell-growth.html

And also in experiments that others have run:
http://braukaiser.com/blog/blog/2012/11/03/estimating-yeast-growth/

Kai's work (above) was adopted by Brewers Friend:
http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

I have recently re-ran my experiments with a different strain and have very similar results. It follows Balling's observation.

You probably do have about 300 billion cells.
3.8L * 9°P * 10 billion cells per liter per degree Plato = 342 billion.

Cell density can vary widely from one strain to the next. WLP004 is 100-200 million cells per ml, while WLP566 is 1000-1500 million cells per ml. The rule of thumb that seems to fit for most slurries is 1 billion cells per ml for yeast from a beer and 2 billion cells per ml for yeast from a starter.

You can really only know with a cell count
http://woodlandbrew.blogspot.com/2012/11/counting-yeast-cells-to-asses-viability.html

Which I would be happy do it for you:
http://woodlandbrew.blogspot.com/p/normal-0-false-false-false-en-us-x-none.html
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
That cell count procedure of yours just made my brain 'splode.

I'd love a cell count, but I don't want to intrude. It's OK for my hobbies to make me OCD and spend my time, but not for them to impose on others. Taste testing and keg floating not withstanding.

Since you think MrMalty and YeastCalc are off, I'd be willing to take a look into other calculation methods. Can you point me in the direction of a guide as to how you estimated 300b cells?
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
Trying to determine the ml capacity of the pictured vials. I think they're Wyeast Nutrient, which appears to be a 45ml vial.
They look like 50ml centrifuge tubes to me. Although, I think the numbers are in cells per milliliter, so the size doesn't really matter.
 

Kaiser

Well-Known Member
Joined
Nov 1, 2005
Messages
3,895
Reaction score
164
Location
Pepperell, MA
Thanks for the mention Steve.

Yes, Mr Malty can be off quite a bit and Jamil and I seem to be getting into a fight over this (check out the beginning of Brew Strong from 12/24/12) I have the strong suspicion that Jamil did not use a series of stirred starters to come up with the growth curve for "stirred" in his calculator. I have no strong evidence for this, though, since he never published his experiments. You should press him on that.

My model as implemented in BF estimates a final cell count of about 650 B cells. but it can easily be 750 B.

Kai
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
Thanks for the mention Steve.

Yes, Mr Malty can be off quite a bit and Jamil and I seem to be getting into a fight over this (check out the beginning of Brew Strong from 12/24/12) I have the strong suspicion that Jamil did not use a series of stirred starters to come up with the growth curve for "stirred" in his calculator. I have no strong evidence for this, though, since he never published his experiments. You should press him on that.

My model as implemented in BF estimates a final cell count of about 650 B cells. but it can easily be 750 B.

Kai
750b from ~80b vial and 380g of DME? That's quite the growth rate!
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
I'm starting to think that weighing might be a better answer.
The density of yeast is very close to that of water. This allows them to float up and down. So measuring the amount of yeast by weight or density is not very accurate. The protein and other trub material will also skew your numbers.
 

barmyarmy

Well-Known Member
Joined
May 24, 2012
Messages
78
Reaction score
4
Sorry, i did not read all of the posts because they are too long. If all you want is an estimate use the Internet. If you want to know for sure buy a microscope and a grid and count them yourself. Those sites tell you what you need, not what you have.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
Sorry, i did not read all of the posts because they are too long. If all you want is an estimate use the Internet. If you want to know for sure buy a microscope and a grid and count them yourself. Those sites tell you what you need, not what you have.
Estimates are fine. I'm not trying to get super precise with it. But right now we're talking orders of magnitude.

I just want to be able to pull a vial out of the freezer and be able to make a starter of an expected size of out if. In other words, I just want to be able to know how big of a starter to make for a known quantity of a known gravity wort. For example:

Grab a vial that says "45b cells", calculate viability from the freeze date, and determine the starter size needed for 11 gallons of 1.052 wort.
 

Kaiser

Well-Known Member
Joined
Nov 1, 2005
Messages
3,895
Reaction score
164
Location
Pepperell, MA
750b from ~80b vial and 380g of DME? That's quite the growth rate!
That's a growth of about (750-80)B/380g = 1.8 B/g. Yes it's higher than the 1.4-1.6 B/g that I commonly observe but not too much out of line. Note that there is a pretty large error bar on the actual yeast count. I would not be surprised if that error bar is +/- 20%.

Here is a blog post that explains my current stand and theory on this: http://braukaiser.com/blog/blog/2012/11/03/estimating-yeast-growth/

Another finding of mine is that when your initial cell population is small compared to the expected or actual growth, the exact amount matters little. That also means that the actual viability of the cells in that old vial doesn’t matter in your case.

Kai
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
I'd love a cell count, but I don't want to intrude. It's OK for my hobbies to make me OCD and spend my time, but not for them to impose on others. Taste testing and keg floating not withstanding.
It's my pleasure to count cells for others. It give me an idea of the results others are getting. More data points. I might not be doing it for free for ever, but for the time being it's not a problem.
Since you think MrMalty and YeastCalc are off, I'd be willing to take a look into other calculation methods. Can you point me in the direction of a guide as to how you estimated 300b cells?
It's simply 10 billion cells per liter per degree Plato. My experiments were done with manually agitated starters, and 10 billion is a little conservative. Kai's results are probably closer to what you actually got.

Another way to look at this rule of thumb is 1 billion cells for every gram of DME.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
It's my pleasure to count cells for others. It give me an idea of the results others are getting. More data points. I might not be doing it for free for ever, but for the time being it's not a problem.
Ok, well, you've piqued my curiosity enough. I'm all for advancing yeast science! ;)

How much mixture should be sent and to where?
 

Kaiser

Well-Known Member
Joined
Nov 1, 2005
Messages
3,895
Reaction score
164
Location
Pepperell, MA
Thanks for generating great work to cite!
Awesome. It looks like that's the "Going Pro - Wrap Up." Does that sound right?
yes. They happen to talk about me b/c I went to the ANHC with John Palmer. This is before they get into the meat of the show.

Kai

Correction: I listened to the show again, this time a little more careful, and Jamil is not as dismissive of my work as I perceived it earlier. He considers my approach valid and just notes that more data is needed. I'm working on getting more data.
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
...Grab a vial that says "45b cells", calculate viability from the freeze date, and determine the starter size needed for 11 gallons of 1.052 wort.
Getting within a factor of two with an estimator is good. In many cases even that is difficult. "viability by freeze date" sounds like some more experiments to run. Although viability isn't everything!

Here is at ambient:
http://woodlandbrew.blogspot.com/2012/12/yeast-health-when-kept-at-ambient.html

and in the refrigerator:
http://woodlandbrew.blogspot.com/2012/12/refrigeration-effects-on-yeast-viability.html

and in alcohol:
http://woodlandbrew.blogspot.com/2013/01/abv-effects-on-yeast.html

Also keep in mind that these are just my results. Yours might be different. The staining technique used doesn't directly assess viability so keep that in mind too when looking at these.

I think the only thing in you sentence that most brewers will agree with is that for 11 gallons of a 1.052 ale you will want about 400 billion cells.
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
Another finding of mine is that when your initial cell population is small compared to the expected or actual growth, the exact amount matters little. That also means that the actual viability of the cells in that old vial doesn’t matter in your case.
That's what I have seen as well which is pretty exciting for those trying to make starters with unknown yeast.
 

Photopilot

Supporting Member
HBT Supporter
Joined
Jul 9, 2007
Messages
1,198
Reaction score
122
Location
Jackson
Now I am confused, I was hoping that mr malty was my one stop source for yeast info. Now I need to figure out how much yeast I got and how much I need to pitch in the dual batch I am planning this weekend.

IMG_2723.jpg
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
Awesome information.
Thanks for this. I'll read these over. The graphs at least gel with what I consider my own version of common sense.

I think the only thing in you sentence that most brewers will agree with is that for 11 gallons of a 1.052 ale you will want about 400 billion cells.
My head's spinning. So many of these numbers which I took for granted are suddenly so fuzzy.

We can't trust that a smack pack has 100 billion cells. We can't calculate its viability reliably. We can't estimate cell count by weight, volume or otherwise visually.

Even if we were to go nuts and count the yeast vial right before pitching into the start, we can't reliably estimate (+/- 5%) the number of cells grown, even knowing the amount of DME used.

Does this make the idea of a home brewer's yeast bank impractical without the gear to count cells?
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
Now I am confused, I was hoping that mr malty was my one stop source for yeast info. Now I need to figure out how much yeast I got and how much I need to pitch in the dual batch I am planning this weekend.
2 billion cells per milliliter should get you close with that yeast. If those are 8 oz jars then it looks like 200 billion, 150 billion and 100 billion.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
That's what I have seen as well which is pretty exciting for those trying to make starters with unknown yeast.
Hold the phone!

Lets assume I have 40-80b cells in each of my preforms. And I need 400b cells.

I can simply just throw them in, say, 4L of 1.040 DME starter on a stir plate and assume that I'm going to wind up with (minimum) 400b cells? At the 1.5b/g DME quoted, it's closer to 640-680b.

If so, that's some pretty darn easy math.
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
We can't trust that a smack pack has 100 billion cells.
White Labs markets the vials as 75 billion to 150 billion. WYeast probably has a similar number.
We can't calculate its viability reliably.
It can be estimated, but by date alone doesn't seem to be the best way to do it.
We can't estimate cell count by weight, volume or otherwise visually.
Visually by volume is probably the best for most homebrewers. 1 billion per ml of slurry from a beer and 2 billion per ml for yeast from a starter. (after refrigerating for a day or so)
Even if we were to go nuts and count the yeast vial right before pitching into the start, we can't reliably estimate (+/- 5%) the number of cells grown, even knowing the amount of DME used.
Even a cell count is hardly that accurate even if done very carefully.
Does this make the idea of a home brewer's yeast bank impractical without the gear to count cells?
A microscope is the best investment I think I have made in homebrewing, but you certainly don't need one to make great beer or to utilize a yeast bank. Yeast will multiply about ten fold during fermentation. If you are off by a factor of two on your pitch it's not a big deal.
 

WoodlandBrew

Well-Known Member
Joined
Oct 1, 2012
Messages
2,209
Reaction score
260
Location
Malden
I can simply just throw them in, say, 4L of 1.040 DME starter on a stir plate and assume that I'm going to wind up with (minimum) 400b cells? At the 1.5b/g DME quoted, it's closer to 640-680b.

If so, that's some pretty darn easy math.
Yup.

As long as the pitch rate is reasonable. (less than 100 million per ml) and the gravity is reasonable (6-12°P) It works out just like that.

With data I'm looking at now it seems you can get a little closer by looking at sugar consumed instead of initial sugar content. So with a refractometer you can figure out home many cells you have at any point in the starter's growth.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
Got a reply from Wyeast, which confirms that the tubes are 50ml centrifuge tubes.

These are 50ml centrifuge tubes, with 50ml of slurry added and then allowed to settle.

If that enough info? Let me know.


Jess Caudill
Brewer/Microbiologist
Wyeast Laboratories, Inc.
P.O. Box 146
Odell, OR 97044 USA
Phone: 541-354-1335 Fax: 541-354-3449
[email protected]
www.wyeastlab.com
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
White Labs markets the vials as 75 billion to 150 billion. WYeast probably has a similar number.
Wyeast guarantees 100 billion when packaged. I remember watching a videocast where they said they purposely concentrate or dilute to hit 100 billion on every batch.

Found the videocast.


I've watched this about 3 times now over the past few months, and continually pick up more and more each time I watch it.

Skip to 21:00. It's somewhere in there between 21:0 and 25:15. This is where I was getting many of my assumptions.
 
Last edited by a moderator:

Kaiser

Well-Known Member
Joined
Nov 1, 2005
Messages
3,895
Reaction score
164
Location
Pepperell, MA
As you can tell, this is a discussion I wanted to have for a while now but it takes other home brewers that also question the results of the existing pitching rate calculators. I think these calculators, or any calculator for that matter, do a good job in illustrating the need for a starter. Simply making a starter regardless of actual growth rate will be better for your beer.

When we have the expectation to get reasonably accurate results from these calculators we need to scrutinize them a bit more.

Based on my experience of running my own yeast bank I can say that you can get consistent pitching rates by simply controlling the amount of extract you give the yeast for growing. That means wort volume and wort strength. I also know that slurry densities are pretty constant for a given yeast when growing them in a starter (compared to harvesting). But there are differences between strains and to establish that relationship it helps to have a microscope. For most well flocculating lager yeasts I measured about 3-4 Billion cells per g dense slurry. WLP 001 and similar ale yeasts were closer to 2.5-3 B/g. WLP002, which forms very dense sediment, is closer to 4 B/g

Since initial pitching rate seems to have less impact on actual growth as long as you start out with less than 1 billion cells per gram of extract the actual viability of a vial or smack pack matters little. If the difference between a fresh and an old vial is 40 B cells and you grow 400 B cells, that initial difference accounts for only ~10% of your final yeast count.

I don’t care much about viability. For one it’s difficult to assess the actual viability w/o performing plate counts and secondly if you use your freshly grown yeast within a few days it will be 95+% viable. And there is more to viability than simply dead vs. alive cells. One major factor in the length of the lag phase is how much time it takes the yeast cell to replenish reserves before they can start growing. If I had the choice between 300 B old, starved but alive cells and 150 B cells that are full of reserves and can start growing as soon as they have more nutrients available I’ll take the 150B over the 300B any time even if I might be under pitching by the numbers.

Kai
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
Understood completely. I think. :)

Here's where the rubber meets the road to test the viability of a yeast bank. What is the highest gravity wort that can be inoculated with a starter of no more than 3.8L (1 gal) that began with an estimated 45b cell vial (without stressing past 10:1)? This assumes that a home brewer can reasonably stir plate up 1 gallon of starter (two 2L flasks with FermCap on two plates, or one 1-gallon glass jug on a single plate).

If we assume 1.040 starter, we're at just shy of 380g DME per 3.8L batch. Starting with an estimated 45b cell, that's an estimated finish of 615b cells at 1.5b cells/g DME. Space is not the limiting factor here then, because 10:1 would be 495b finished.

10 gal of 1.060 wort would require a pitch of 417b, so that's our neighborhood. (I used Mr Malty because I'm still trying to wrap my head around inoculation rates in m/ml.) We don't pass 495b cells required until about 1.072.

So unless you're making 10g batches of Barleywine, it seems that one 2L preform tube can inoculate up just about any 10g batch with stressing the yeast past 10:1, assuming you have a minimum 45b cells viable.

Does this math check out?
 

Kaiser

Well-Known Member
Joined
Nov 1, 2005
Messages
3,895
Reaction score
164
Location
Pepperell, MA
So unless you're making 10g batches of Barleywine, it seems that one 2L preform tube can inoculate up just about any 10g batch with stressing the yeast past 10:1, assuming you have a minimum 45b cells viable.
I'd say that is correct for ales. I brew 5 gal batches and have been fine with just a 2 L flask for most of my lager yeast propagations as well.

A 5L flask is nicer b/c a 2 l starter gets a nicer vortex in the larger flask.

Kai
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
I'd say that is correct for ales. I brew 5 gal batches and have been fine with just a 2 L flask for most of my lager yeast propagations as well.

A 5L flask is nicer b/c a 2 l starter gets a nicer vortex in the larger flask.

Kai
While a 5L flask would be nice, it seems a bit comically large for most users here. And also, much more expensive than two smaller flasks.

I personally use 1 gallon cider jugs for the moment being. They're a pain in the butt to get the stir bar to stick because of the concave bottom, but they work. At least, they do now that I use grade 50 neodyium magnets. No way they'd work with even entry-level neodynium magnets, let alone ceramic magnets.
 

Kaiser

Well-Known Member
Joined
Nov 1, 2005
Messages
3,895
Reaction score
164
Location
Pepperell, MA
I don't believe in anti foam agents, so I do like the head space that the 5 L flask gives me. Mine was only $40 at MoreBeer. The 2 L ones cost about $20 each.

Kai
 

Coff

Well-Known Member
Joined
Aug 19, 2010
Messages
1,525
Reaction score
190
Location
Philadelphia
Yea this has been an awesome thread to follow. I dont have anything to add but I am learning alot.
 
OP
thadius856

thadius856

Well-Known Member
Lifetime Supporter
Joined
Dec 17, 2012
Messages
2,265
Reaction score
811
Location
Marysville
I don't believe in anti foam agents, so I do like the head space that the 5 L flask gives me. Mine was only $40 at MoreBeer. The 2 L ones cost about $20 each.

Kai
You don't believe in them? I assure you, they exist. ;)

I've seen the 5L flask you're referring to. NB sells it, too. Terrible reviews there of it cracking under the lightest use conditions. So I avoided it.

If I was going to buy flasks (I will, eventually), I'd go for the Pyrex or Kimax brand ones. They're the only two brands I've seen that offer the rough service flasks, usually with "heavy duty" or "thick" in the title description. They're noticeably thicker all around in the pictures.

Those are close to $25-30 for a 2L and $80-100 for a 5L.

I'll get there, eventually. Just better places to put my equipment money at the moment.
 

Paulgs3

Well-Known Member
Joined
May 1, 2010
Messages
434
Reaction score
18
Location
Hamburg
http://www.teknova.com/YPD-AGAR-PLATES-100MM-p/y1000.htm

Make serial dilutions, 1 ml of yeast into 9 ml of diluent (boiled water, uninoculated media, whatever you are using to grow your yeast...). This is a 1 to 10 dilution.

Take one ml of that and put into another 9 ml. We are now at a 1 to 100. You want to do this nine times so you have nine dilutions total in front of you. To explain what is going on, if you originally had 100 cells in 1 ml, a 1:10 dilution now gives you 10 cells per ml, a 1:100 dilution now gives you 1 cell per ml. You are shooting for 100 billion cells cells, so I would dilute out to one billion which is 9 1:10 dilutions.

Take one ml of the last dilution and pour it onto the agar plate. Its a rather large size to put on a plate but it should make spreading easy. Stick it somewhere warm for a good 24 hours.

Count the colonies, each colony will represent 1 billion cells per ml. To find out total cells, multiple the number of colonies counted by 40 ml which is the volume of your stock. That will give you an idea of where you are based on the principle of one cell = one colony.

If you count 10 cells, multiply by 40 and we get 400. You have 400 billion cells in your sample.
 

novaris

New Member
Joined
Dec 8, 2012
Messages
3
Reaction score
0
this has been a great thread to help get my head around storing and using yeast. Thanks for sharing the results of experiments.
 
2

Latest posts

Top