I had to post this wonderful piece of information about yeast and yeast starters.  A great great brewer friend of mine, Wade, over at the BKB forums posted a reply to a discussion we were having about yeast starters and cell #s provided in the yeast packages we all typically buy from WhiteLabs and Wyeast.

Wade, a.k.a. 1n1m3g in cyber-land, is currently working on his PhD in the biological sciences arena and works exclusively with yeast for his research.  He and I have talked in the past about yeast; and he really knows his stuff.  When Wade is not working in the lab or being a great father and family man he can be found bumming around with the Boston Wort Processors.  A homebrew club here in the Boston area. (Please consider checking out their upcoming Homebrew Competition)

So please take a minute to read and digest the post I have copied below.  Its a bit long, but it’s amazingly informative.

From Wade:
“OK, OK, i guess I can try to make some sort of contribution to this discussion here.  I think there is a bit of confusion here about the yeast that come in the liquid from the homebrew stores, either smack packs or vials.  There are two key terms everyone should be aware of and the differences between the two.  One is yeast viability and the other is yeast vitality.  Viability is easy to define as it basically describes the overall number of yeast cells that are alive.  If you were able to count the cells under a microscope and then plate out a small, countable number of cells onto an agar plate the viability of the yeast would be the number of cells that actually form a colony as compared to the number of cells you plated.  Vitality, on the other hand, is a more ambiguous term that describes the overall health of those viable cells.  In brewing terms, it could be described as how fast the cells could divide and as well as how efficient they are at fermenting sugars.  Cells will have high vitality if they have sufficient fermentation precursors stored up.  For example, oxygen is required to build up sufficient cell wall components prior to fermentation because during fermentation (in the absence of oxygen) these cell wall components are not synthesized and are depleted upon every cell division until a lower limit threshold is reached and the cells can no longer divide thereby decreasing fermentation efficiencies.  So, even before you pitch your yeast, you can easily have a population of cells with high viability but low vitality if not properly prepared.  For example, the older a vial or smack pack is the lower the viability is as well as the vitality, but I think that vitality drops off much faster than viability over time. 

So back to the question of starters.  Creating a population of cells with high vitality requires that you give the yeast the proper nutrients that prime them for fermentation.  I think this is where Wyeast smack packs are superior to White labs yeast vials.  When you pop the smack pack you release vital nutrients to the yeast so the somewhat dormant yeast greatly increase their vitality.  There is no way to do this for White labs unless you use a starter to wake them up.  A starter is useful for both because depending on the starter technique you use you can greatly increase the total number of viable cells while at the same time increase the overall vitality of the entire population.  The most important component for the starter is oxygen.  Why force the cells to start fermentation in a starter when you are just going to pitch them into an oxygen rich wort, which inhibits fermentation, only to have that oxygen quickly depleted requiring a switch back to fermentation?  If you use a stir plate to add oxygen continuously to the starter you can greatly increase the overall numbers of cells in a smaller volume of starter wort.  These cells will have built a nice ample store of the cell wall components required for proper attenuation of your beer.  If you prefer the more traditional method of a still starter you will be better off if you give the starter a stir twice a day or so to scrub out the built up CO2 and introduce more O2.

I think a better place to add things like yeast nutrient (i.e. Servomyces) would be at pitching or a day or two into the fermentation.  The yeast nutrients add things like metal ions required for enzyme function as well as free nitrogen required to synthesize these enzymes.  Adding this to the fermenting wort of your beer will give the yeast a boost as they use up the limited nutrients that come from the malt.

I use a stir plate for my starters because I don’t use smack packs or vials, but am instead building up my population step by step from literally a single yeast cell.  I need the extra oxygen to get to the proper number of viable cells with the added benefit of also getting high vitality.  Either way, though, if you are using store bought liquid yeast, make sure the package is as close to the manufactured date as possible and if you have the capability, use a starter of any technique (stir plate of otherwise) to increase cell vitality.

Wow, is that enough of an explanation?    Cheers!”

(Standing) BREW ON!

So I am thinking about my first lager session.  I was going to shoot for a Marzen/Oktoberfest style amber lager.  Who knows maybe ready for October!?!?

But I was wavering between using the White Labs Marzen lager yeast or using the White Labs German Lager yeast.  (WLP820 and WLP830, respectively)

I’d like to pick a lager yeast that I can move forward with on subsequent lager beers.  I have heard and read that its best to pick one lager yeast and get comfortable with how it performs, then use it as your standard lager strain.  As opposed to chasing down a different lager yeast for every different lager you do. (Like we do with Ale yeasts).

Anyhow, I am swayed by the marketing of an Oktoberfest yeast called ‘Oktoberfest’ yeast.  However, I am wondering if I might be better served with using a “utility” lager yeast like WLP830, German Lager that I would definitely try out in the future on beers like Dortmunder and Helles.

Any experience in our readership with WLP820 vs. WLP830?
Or what do you use instead.

BREW ON!

I am getting prepped for my next brew:  Honey Wheat Ale Recipe

I was reviewing the recipe and I started to think about the yeast strain that I chose.  I think that the clean fermenting California yeast will be fine, but there are a couple of other strains that might be nice.

Wyeast American Wheat 1010 - This strain ferments dry and produces beers that are crisp and low in esters. Ferments in the 58° to 74° range.

White Labs WLP320 - This strain does produce some slight banana and clove flavors.  It is not as clean as the 1010…but it may add some flavors to complement the honey malt.  Ferments in the 65° to 69° range.

I think I am going to stick with the WLP001 but if my local homebrew shop is out of it, I may be in the market for some of these other strains.

After fermentation is over its pretty tempting to reuse the cake of all that good yeast you have.  I like to reuse US-05 (fermentis) because it really seems to perform extremely well on repitch.  It seems to attenuate a little better, flocculate a little better, and it certainly gets an even cleaner flavor.  I tend to collect some slurry on the same day I plan to repitch into a new batch.  So I don’t store the yeast for any appreciable time.

Many brewers really like the idea of collecting yeast slurry from a batch and saving it for a future brew date.   I don’t do this too often because I think the process of handling the yeast, transferring it from container to container, making a new starter and then repitching just seems risky.  The number of steps increase the number of opportunities to contaminate your yeast with foreign microbes.  I ask myself, is it worth a $30-$40 batch of ingredients to save $6-$8 on a new pitch of yeast?  For me it’s not.

Recently, I have read more and more about brewers collecting, storing and repitching successfully.  Certainly, it can be done (as many brewers do it already).  But I think that for the average non-microbiologist type if you get a little lax once with your handling you’ll probably pick up a minor contamination at some point.  The purpose of this post is not to discourage people from experimenting with yeast management at home.   Rather, I wanted to relate my perceived risk to cost ratio and offer a couple easy steps to try and maintain cleanliness.

Maintaining cleanliness:

1. Sanitize more containers than you think you need.  If you are going to collect yeast properly you’ll need to have at least two sanitize containers and some sterilized water.  I would over estimate everything by a factor of 2, so maybe for containers and a liter of boiled and cooled water.  This may seem mundane but its too easy to need another container then half-assed sanitize it because of the worry of time on catching a contaminant.
2. Work in a clean and breeze free area.  Now, don’t think you need to sterilize your entire kitchen to do this.  Just keep your general work area free of dust.  A couple good wipes of the counters with sanitizer would be a good idea.  Keep doors and windows closed to minimize airflow.  Try and do your work when your 4 year old isn’t going to be running by every 5 minutes.  These things stir up dust which can get into your samples.
3. Create an updraft with an alcohol lamp.  You can even use a candle or something, but if you are working with small containers just working near an open flame will keep the air moving in an upward direction, which in turn keeps things from falling into your samples.  If you want to really get fancy you can do a google search for aseptic techniques and how to “flame” an open container (not always good practice if you use mostly plastic).
4. If you suspect you have contaminated your yeast, then don’t bother saving it.  You’ll have to taste the beer you just made before even trying to save the yeast.  You’ll need to train your palette to be more in tune with subtle off flavors.  Regardless, it may be impossible tell at such an early stage.
5. Good yeast collection starts before you even put the first beer in the fermentor.  Most of us do a great job of cleaning and sanitizing the inside of our fermentors, but what about the outside.  There are a lot of weird lips and edges on the opening of the bucket below where the lid attaches.  At least a carboy is a little smoother.  But these areas and the outside of the lid need to be cleaned before a finished beer gets opened.  When you pry open the lid of your fermentor any dust and contaminants on the surface can get kicked up and into you beer…or yeast cake.  So be aware while you are racking the beer out you are sucking air into the fermentor.  If the lip of your fermentor or the air around you get contaminated your likelihood is veyr high that it will also get into the beer and then on the yeast cake.  That alone is something that is very hard to control (a little easier with a conical) and one of the reasons I don’t bother.

I am sure I’ll get a lot of “Oh you are worrying” too much.  Maybe I am paranoid as a guy that does this type of stuff at work regularly and works really hard to minimize contamination.  It’s still a matter of personal choice.  I think its great for people who do it regularly and I encourage anyone interested in that part of the hobby to give it a try.  For me however, I don’t get to brew as often as I like.  So when I do brew, I don’t want to lose a batch to a potentially contaminated yeast source.

BREW ON!

I simply ask: what is your favorite yeast?

I think it’s no secret that I use a lot of S-04 from Fermentis.  I tend to brew alot of English style ales, so the S-04 works for me.  I really enjoy its flocculating power and its flavor.

I will admit though, that I have not fully explored the wide range of English origin yeast available though White Labs and Wyeast.  I hope to start testing some of those strains out in some of my favorite English brews (Ordinary Bitter, English Dark Mild and Oatmeal Stout).

There seem to be a lot of readers these days chiming in with comments, so I put out this post together to hear what others are doing out there.

It can be your favorite yeast, you most often used yeast, or maybe you have a special yeast for your three favorite styles (e.g. American, German and Belgian yeasts)…

So let’s hear it!

BREW ON!

From several posts ago I whipped up an American Brown Ale in which I chose to blend to strains of dried yeast.  I spoke about the purposes of trying the blend in Yeast Blending post.

Now more than a month later I am prepared to share some results!

My primary goal with blending US-05 with S-04 was to see if the super flocculating S-04 would help to pull out the low flocculating US-05.  US-05 always seems to take more time to clear out, flocculation starting somewhere after day 10 in primary.  S-04 on the other hand tends to finish up and start flocculating within 3-5 days.

In this first pass experiment, I was pleased to witness that the total yeast suspension was falling out of solution very rapidly within 5 days.  By 14 days my final gravity (1.012) was achieved and the beer was basically clear.  I used a glass carboy just for the purpose of monitoring the yeast activity.  The yeast cake was very tight (as you see with S-04), but not as firm as you normally see with S-04 alone.  Perhaps this is a result of the combination with the lower flocculator US-05.

The secondary result is the taste.  I would say that the flavor is stil very English.   The ester profile still seems like the traditional S-04.  I would have thought that the two yeasts would have maybe made a mellower English profile.  The flavor is still good though and I would probably try this blend again when shooting for a well attenuated English styled ale.
Hop flavor did seem a bit diminshed though.  For all the Cascade hops in there I would have expected more bitterness.  But the hop “pop” you get when using US-05 alone isn’t there.  Again, this sort of profiles the English yeast again.  I think the bitterness and flavor gets a little lost with the roasty malts and the ester profile of the S-04.

Head formation and retention seemed to be normal for either yeast.

Overall, then I don’t think that the blend really gave me something in between the US and English profiles.  Perhaps the clean-ness of the US-05 just still lets the S-04 character shine through.  While this is not an extensive test (and I hate making and reading about one time experiments as a definitive answer), I found the results useful.  I will definitely try this experiment again as working with the dried yeasts is easy.  A great test for this “co-flocculation” experiment would be to blend some German Hefe-style yeast with S-04 and see how much of that pulls down.  I would not be looking forward to those flavor combinations though.

If it ever warms up here and I get my garden hose unburied from the snow, I’ll brew up the Cascade Pale Ale to accompany the Brown Ale…with the yeast blend for sure.

BREW ON!

It’s another edition of Fermentation Friday.  This month, it is being hosted by the guys at Rooftop Brew.  The subject for this time around is all about brewer’s yeast.

Mike sez:

Always make a starter… You hear time after time. I (Mike) have recommended it a thousands of times.  Practical experience in the brew-garage has shown that making a starter for yeast is the way to go.  The beer always seems better for it.  Better lag times, better fermentation, better flocculation, better post-ferment properties….and of course better flavor.
All things being equal however, Mike uses dry yeast for most brews.  With a young child at home, there never seems to be enough time to make that starter and babysit it while….when babysitting an actual child.  A starter really isn’t that much work but the pre-planning stage is a time sucker.  The opportunity to brew usually comes after the “make a starter” window has passed.  So dry yeast to the rescue.
Dry yeast is great because it is relatively ready to pitch. The cell count in one 11-14 gram packet is generally high enough to tackle any brew under a 1.055-1.060 OG.  It is recommended to rehydrate the yeast in some plain water prior to pitching, and that is the standard practice in the brew-garage.  If laziness does take over and results in the dreaded direct pitch into the wort, then 2 packets can get pitched dry to make up for the poor yeast performance due to the rehydration effects in the sugar solution (wort).  Usually pitching directly results in a ~40-50% cell viability loss in the packet.
The two favorite yeasts of Mike’s are both Fermentis products.  The US-05 American ale and the S-04 (safale) English Ale yeast.  These are fairly cheap products, easy to use and work even better on repitch from cake! But that’s another post.

BREW ON!

John sez:

I think, in the coming year, I would like to understand the number of yeast cells to gallons of wort cold.  I will probably get to know Mr. Malty’s pitching rate calculator pretty well.  I echo Mike’s statements about making a starter.  I think for me, I would like to get even more precise in what size starter I need to make and just get better equipped to make a starter each and every time.

As for other thoughts about yeast, I use liquid yeast:  White Labs primarily.   I like the variety and I have had good results with their line of yeast strains.  I think homebrewers tend to not focus on yeast as an ingredient.  A lot of attention gets focused on malts and hops.  Don’t get me wrong, they are very important.  The other two main ingredients (water and yeast) are important too.   With more attention paid towards yeast strains and yeast preparation, many homebrewers will be on their way to making not only good beers, but great beers.