So why would a homebrewer ever think of getting a microscope? Isn’t it just one more unnecessary expensive gadget? Isn’t it just for the ultra-geeks? Don’t you need to be a microbiologist to know how to use one? The short answer to the last 3 questions is: no. For the long answer to the first question, read on.
In an ideal homebrew environment yeast is always pitched at the correct time and pitching rate, wort oxygenated precisely, temperature controlled perfectly, and perfect beer is created every time. If that’s you, I’m impressed! My world isn’t that perfect.
I had been doing yeast starters and re-pitching yeast for years and thought I knew enough about the importance of yeast health to make great beer. But it wasn’t until a few years ago when I spent a day with a pro brewer who let me look through his microscope that I realized how much I had to learn and I became somewhat obsessed with looking at yeast. By staining and looking at my yeast I found out quickly that I’d been abusing my yeast when I thought all was fine because they still fermented my wort into drinkable beer. I’m always on the quest to improve my beers so getting a microscope has been one of the best homebrewing investments I’ve made.
You know the saying ‘brewers make wort, yeast makes beer’ and while that is true, remember you are the manager of the yeast. Like any good manager, when you can provide your workers what they need, you’ll end up with a superior product.
Many think that the best reason for a homebrewer to have a microscope is for doing yeast counts. While that is helpful, I think the biggest advantage of having a microscope is checking for yeast health and being able to better learn the strengths and weaknesses of a particular yeast strain.
I like to reuse my yeast strains several times not only for economics but because the best beers often come from reusing yeast, if the yeast have been treated well. How do you know you’re treating your yeast well and that it’s ready to ferment your next batch of wort?
Take two samples of yeast off of your collected yeast, one for tasting and one for staining. By tasting, I mean swiping your finger through the thick yeast sample as though you were taking a taste of frosting from a bowl. With practice you’ll know what fresh yeast tastes like and you’ll know when yeast tastes old. Like vegemite without the salt.
So you’ve tasted your yeast and it tastes pretty fresh and clean, but what else can you do to ensure your yeast are at their healthiest and ready to work?
You’ll need to dilute your yeast sample with distilled water then add the stain, methylene blue. As long as you aren’t doing yeast counts the amount of dilution isn’t critical. You don’t need much yeast, a blob the size of a pea is plenty. Dilute the sample and mix well (prior to adding the methylene blue) so it’s not opaque but definitely a bit hazy (like the haziness of a good NE IPA). The amount of methylene blue to add to the sample varies depending on what you read. I go with a 1:10 dilution of methylene blue (0.1%) to diluted yeast sample. The easiest method for looking at your stained yeast is to take a drop of the stained yeast sample and put it on a microscope slide and place a cover glass on top. Looking at this under a microscope will give you information about the health of your yeast by showing which yeasts are dead and which are alive.
In the presence of methylene blue the healthy yeast will metabolize the stain and will not stain blue. Yeast cells that are dead won’t metabolize the stain and will appear blue. Note that young budding yeast will often appear light blue, don’t be alarmed by this, those young yeast are fine.
Note: You should look at the stained yeast soon after staining. After a half hour, even healthy yeast can turn blue.
The yeast you stain will be poisonous so don’t taste it, don’t brew with it and throw it out once you’re done. Keep the methylene blue out of reach of children, pets and anyone in need of adult supervision. Healthy yeast cells are white, most of the blue cells are dead or very stressed.
If your yeast is looking great with no stained cells, great! You’re ready to brew. If more than 10% are stained blue you have a few options:
1) Take some of the yeast (say 20-50cc of yeast slurry) and feed it with a low gravity starter (150g DME with 1.5L water boiled and cooled) let it ferment for a day or so and check on it again.
2) Throw it out and start with something new.
3) Throw all caution to the wind and just brew with it.
It’s your choice, remember we’re homebrewing! Any choice is fine but now you’re making the decision with more information than you ever had before since you’re staining and looking at your yeast.
If you stain and look at your yeast before every brew and keep good notes, you’ll find what makes the yeast happy and healthy. Does your strain do better with more oxygen, higher or lower pitching rate? What about fermentation temperature and original gravity? How is your yeast responding to those variables? What can you change to improve the health of the yeast?
In addition to learning about your yeast strains you may be able to see if you have anything else growing along with your yeast. Though most strains of ale yeast (saccharomyces cerevisiae) look alike, you’ll be able to see that Brettanomyces looks different. While S. cerevisiae is round or sometimes a bit oval, Brettanomyces looks like a fat sausage. Bacteria are much smaller than yeast cells, about a tenth the size of a yeast cell and can be either round (cocci) or rod shaped (bacilli).
Brettanomyces in the photo above look like sausages.
If you’re doing a mixed fermentation beer perhaps you’ll be pleased to see bacteria and wild yeast mingling with your S. cerevisiae. For the rest of us that sort of mingling means we’ve got some contamination issues. Beyond that, you won’t really know what the contaminants are unless you do some advanced testing which is beyond the scope of this article. We’re just looking at what belongs and what doesn’t.
Unwelcome guests. Blue & white circles are yeast, small rods are bacteria.
First, get yourself a copy of ‘Yeast: The Practical Guide to Beer Fermentation’ by Chris White and Jamil Zainasheff as it is a wealth of information written by experts. Specifics on staining and counting yeast can be found in that book as well as the details on what to look for when buying a microscope.
Since I’m a homebrewer I didn’t want to spend too much on a microscope and found one for under $200 which works fine for my needs. It’s an Omax M82ES.
Now if you have kids or grandkids, even nieces and nephews, you can have your microscope do double duty by using it as a cool science tool. This may be the key to convincing your spouse that this is a ‘must have’ educational tool that can also be used in your homebrewery!
If you’re only interested in staining your yeast and not interested in doing yeast counts you’ll need microscope slides (with cover glass). This is the easy and inexpensive way to go. The microscope slides are multipurpose as they can be used for looking at any number of other cool things under a microscope. So consider them necessary if you’re purchasing your microscope under the guise of it being an educational tool for the kids/grandkids. A set of 100 microscope slides with cover glass costs about $15. Plastic graduated transfer pipettes work like an eye dropper for placing a drop of stained yeast solution onto a microscope slide. A package of 100 disposable plastic transfer pipettes is less than $10.
If you’re interested in doing yeast counts, you’ll need a hemocytometer and cover glass. The hemocytometer has grids for counting yeast. A hemocytometer will set you back about $75-90. The yeast solution needs to be wicked in by capillary action between the hemocytometer and cover glass. Proper dilution and proper wicking is important for accurate yeast counts. You may find that you want to get graduated glass pipettes and a pipette pump to accurately do yeast counts.
A bottle of methylene blue (1%) costs about $15.
Get a box of Kimwipes (they’re lint-free tissues) for less than $5 to dry your cover glass, slides and/or hemocytometer after you’ve washed them.
What about taking pictures of the yeast? It’s easy to do with a smartphone. Oddly enough, I’ve not had success with a regular digital camera but my smartphone does a fine job. Just get things into focus on the microscope and zero in on one of the microscope lenses until the image from the microscope lens takes up the screen. This will take a few tries but you’ll get it. If you keep good brewing notes, having the yeast photos can give you one more piece of information in the quest to improve your beers.
In an ideal homebrew environment yeast is always pitched at the correct time and pitching rate, wort oxygenated precisely, temperature controlled perfectly, and perfect beer is created every time. If that’s you, I’m impressed! My world isn’t that perfect.
I had been doing yeast starters and re-pitching yeast for years and thought I knew enough about the importance of yeast health to make great beer. But it wasn’t until a few years ago when I spent a day with a pro brewer who let me look through his microscope that I realized how much I had to learn and I became somewhat obsessed with looking at yeast. By staining and looking at my yeast I found out quickly that I’d been abusing my yeast when I thought all was fine because they still fermented my wort into drinkable beer. I’m always on the quest to improve my beers so getting a microscope has been one of the best homebrewing investments I’ve made.
Being A Yeast Manager
You know the saying ‘brewers make wort, yeast makes beer’ and while that is true, remember you are the manager of the yeast. Like any good manager, when you can provide your workers what they need, you’ll end up with a superior product.
Many think that the best reason for a homebrewer to have a microscope is for doing yeast counts. While that is helpful, I think the biggest advantage of having a microscope is checking for yeast health and being able to better learn the strengths and weaknesses of a particular yeast strain.
I like to reuse my yeast strains several times not only for economics but because the best beers often come from reusing yeast, if the yeast have been treated well. How do you know you’re treating your yeast well and that it’s ready to ferment your next batch of wort?
First, Taste Your Yeast
Take two samples of yeast off of your collected yeast, one for tasting and one for staining. By tasting, I mean swiping your finger through the thick yeast sample as though you were taking a taste of frosting from a bowl. With practice you’ll know what fresh yeast tastes like and you’ll know when yeast tastes old. Like vegemite without the salt.
So you’ve tasted your yeast and it tastes pretty fresh and clean, but what else can you do to ensure your yeast are at their healthiest and ready to work?
Second, Stain Your Yeast
You’ll need to dilute your yeast sample with distilled water then add the stain, methylene blue. As long as you aren’t doing yeast counts the amount of dilution isn’t critical. You don’t need much yeast, a blob the size of a pea is plenty. Dilute the sample and mix well (prior to adding the methylene blue) so it’s not opaque but definitely a bit hazy (like the haziness of a good NE IPA). The amount of methylene blue to add to the sample varies depending on what you read. I go with a 1:10 dilution of methylene blue (0.1%) to diluted yeast sample. The easiest method for looking at your stained yeast is to take a drop of the stained yeast sample and put it on a microscope slide and place a cover glass on top. Looking at this under a microscope will give you information about the health of your yeast by showing which yeasts are dead and which are alive.
In the presence of methylene blue the healthy yeast will metabolize the stain and will not stain blue. Yeast cells that are dead won’t metabolize the stain and will appear blue. Note that young budding yeast will often appear light blue, don’t be alarmed by this, those young yeast are fine.
Note: You should look at the stained yeast soon after staining. After a half hour, even healthy yeast can turn blue.
The yeast you stain will be poisonous so don’t taste it, don’t brew with it and throw it out once you’re done. Keep the methylene blue out of reach of children, pets and anyone in need of adult supervision. Healthy yeast cells are white, most of the blue cells are dead or very stressed.
If your yeast is looking great with no stained cells, great! You’re ready to brew. If more than 10% are stained blue you have a few options:
1) Take some of the yeast (say 20-50cc of yeast slurry) and feed it with a low gravity starter (150g DME with 1.5L water boiled and cooled) let it ferment for a day or so and check on it again.
2) Throw it out and start with something new.
3) Throw all caution to the wind and just brew with it.
It’s your choice, remember we’re homebrewing! Any choice is fine but now you’re making the decision with more information than you ever had before since you’re staining and looking at your yeast.
If you stain and look at your yeast before every brew and keep good notes, you’ll find what makes the yeast happy and healthy. Does your strain do better with more oxygen, higher or lower pitching rate? What about fermentation temperature and original gravity? How is your yeast responding to those variables? What can you change to improve the health of the yeast?
Is That Supposed to be There? Well, it Depends on What You’re Brewing.
In addition to learning about your yeast strains you may be able to see if you have anything else growing along with your yeast. Though most strains of ale yeast (saccharomyces cerevisiae) look alike, you’ll be able to see that Brettanomyces looks different. While S. cerevisiae is round or sometimes a bit oval, Brettanomyces looks like a fat sausage. Bacteria are much smaller than yeast cells, about a tenth the size of a yeast cell and can be either round (cocci) or rod shaped (bacilli).
If you’re doing a mixed fermentation beer perhaps you’ll be pleased to see bacteria and wild yeast mingling with your S. cerevisiae. For the rest of us that sort of mingling means we’ve got some contamination issues. Beyond that, you won’t really know what the contaminants are unless you do some advanced testing which is beyond the scope of this article. We’re just looking at what belongs and what doesn’t.
What Do You Really Need to Buy and How Much Will it Cost?
First, get yourself a copy of ‘Yeast: The Practical Guide to Beer Fermentation’ by Chris White and Jamil Zainasheff as it is a wealth of information written by experts. Specifics on staining and counting yeast can be found in that book as well as the details on what to look for when buying a microscope.
Since I’m a homebrewer I didn’t want to spend too much on a microscope and found one for under $200 which works fine for my needs. It’s an Omax M82ES.
Now if you have kids or grandkids, even nieces and nephews, you can have your microscope do double duty by using it as a cool science tool. This may be the key to convincing your spouse that this is a ‘must have’ educational tool that can also be used in your homebrewery!
If you’re only interested in staining your yeast and not interested in doing yeast counts you’ll need microscope slides (with cover glass). This is the easy and inexpensive way to go. The microscope slides are multipurpose as they can be used for looking at any number of other cool things under a microscope. So consider them necessary if you’re purchasing your microscope under the guise of it being an educational tool for the kids/grandkids. A set of 100 microscope slides with cover glass costs about $15. Plastic graduated transfer pipettes work like an eye dropper for placing a drop of stained yeast solution onto a microscope slide. A package of 100 disposable plastic transfer pipettes is less than $10.
If you’re interested in doing yeast counts, you’ll need a hemocytometer and cover glass. The hemocytometer has grids for counting yeast. A hemocytometer will set you back about $75-90. The yeast solution needs to be wicked in by capillary action between the hemocytometer and cover glass. Proper dilution and proper wicking is important for accurate yeast counts. You may find that you want to get graduated glass pipettes and a pipette pump to accurately do yeast counts.
A bottle of methylene blue (1%) costs about $15.
Get a box of Kimwipes (they’re lint-free tissues) for less than $5 to dry your cover glass, slides and/or hemocytometer after you’ve washed them.
Some Basic Equipment for Microscope Fun
What about taking pictures of the yeast? It’s easy to do with a smartphone. Oddly enough, I’ve not had success with a regular digital camera but my smartphone does a fine job. Just get things into focus on the microscope and zero in on one of the microscope lenses until the image from the microscope lens takes up the screen. This will take a few tries but you’ll get it. If you keep good brewing notes, having the yeast photos can give you one more piece of information in the quest to improve your beers.
