by Bill Coleman by Bill Coleman
Part 2: Bottle-Conditioned Beers
Part 3: Using a Yeast Culturing Kit
Part 4: Culturing Yeast From Bottle-Conditioned Beer With a Kit
When homebrewing, the most important step to creating good beers is to move from dry to liquid yeast. You can use the standard commercially-packaged liquid yeast packages from WYeast, using a new pouch for each batch. You can get even better results, and much more economical ones, by becoming more familiar with yeast-handling.
Yeast is a microorganism; fermenting beer is basically a controlled infection. One of my great pleasures in homebrewing has been to learn by hands-on yeast handling just how powerful beer yeast is; a tiny milimeter-wide point of yeast can grow in only a few days to this size necessary to ferment five gallons of beer!
But I'm jumping ahead. The simplest way to get familiar with yeast handling is by repitching from batch to batch. That was my own first experience with real yeast handling, and it has worked very well. Repitching is simply reusing the yeast in the bottom of a primary fermenter from one batch to the next. It easily compensates for the higher price of liquid yeast, giving you another reason to use liquid. You can easily repitch the same yeast five or six times. Repitching is very simple: when getting ready to wrack your primary fermenter (either for transfer to secondary or for bottling a single-step fermentation), simply prepare a mason jar (two liter size is good) by sanitizing it with a bleach and water solution for at least fifteen minutes. To ease the transfer, you may also want to santize a large funnel at the same time. If you are bottling, cover the fermenter with its lid after you have racked the beer, and get back to it when you have done bottling.
Having racked the beer, you will see at the bottom of your fermenter an intense-smelling mixture of yeast and beer. Carefully pour some of the beer off the top, into a bowl that is handy. This you will throw out when done. Then shake the fermenter, to mix up what is left as much as possible, and simply pour the yeasty sludge from the bottom of the fermenter into the sanitized mason jar, either with or without a funnel, as you choose. Hopefully, you can fit all of it in the jar. You want the yeast to be able to ferment slightly, so put a piece of plastic wrap between the lid and the jar, and tighten the jar enough to stay on firmly, but not totally air-tight. Then keep the jar in your refrigerator.
If you make your next batch of beer within two weeks, then handling the yeast for the next batch is amazingly easy. You will notice at this point that there will be in the jar a level of beer floating over a thicker layer of yeast.
When your wort for the new batch of beer has been cooled to pitching temperature, open the mason jar, take off the plastic wrap, and wipe the lid of the jar with a cotton ball or swab soaked in high-alcohol vodka. With a lighter, flame the lid of the jar, to burn off any bacteria. Be careful not to throw too much vodka around you don't want to burn your hand off! Having sanitized the lid, carefully pour off the beer from the top of the yeast. It might be a good idea to have a bowl handy for this. Then, quickly pour the yeast into the fermenter. You only need about one-half cup of slurry for a regular ale, about one cup for high gravity (over 1065) ales or lagers. If you have a lot more slurry than this in your jar, you may want to measure out the proper quantity in a sanitized measuring cup, and then pitch. If you have less, don't worry; you'll still be starting out your fermentation with a lot more yeast then you had when you pitched the first batch. ( Just remember next time to try to pour more beer off the yeast at the bottom of the fermenter before you and pour it into the jar; that way you will have more slurry next time.) This is the main advantage of repitching yeast; you will start with a lot of yeast, which will result in a quick fermentation, and less possibility of contamination.
This method will work perfectly if you are ready to make a new beer within two weeks. If you waited longer, you have to take another step to insure the vitality of the yeast: rousing it with fresh extract.
Get another mason jar, this one a one-liter size, and fill it with a water-and bleach sanitizing solution. Set it aside. Meanwhile, mix three cups of water and one-third cup of pale dry malt extract in a saucepan, and bring to a boil. Boil it for twenty minutes. Pour the water out of the mason jar, rinse it quickly, and pour in the extract. After the twenty-minute boil, you should have about 250-400 milileters of Sterile wort. Seal it tightly, and let it cool in the refrigerator.
The day before you're ready to make the beer, remove your two mason jars from the refrigerator. Again sanitizing with the alcohol and cotton swabs, carefully pour off the old beer from the yeast, and then pour the cooled extract onto the yeast slurry. Cover the jar with aluminum foil, to allow the gas to escape, and loosely screw on lid. Store in a dark place overnight, at around 70 degrees, swirl the jar around periodically to aerate the yeast.
The next day, you should see bubbling on the top of the yeast: this means it is ready to pitch. Again, as long as you sanitize properly, you should have a quick starting-fermentation. I have successfully roused and repitched yeast that was sitting in my refrigerator for eight months. Repitching yeast will allow you to get your money's worth out of more-expensive liquid yeasts, and it will give you consistent results. More important, it will allow you to become comfortable with handling yeasts, which will in turn allow you to progress to the next steps in advanced yeast handling: culturing from bottle-conditioned beers, and maintaining a yeast bank.
Most commercial American beers are filtered and pasteurized, resulting in beer that is yeast-free, clear, and consistent flavor from batch to batch. The brewery-owners are more concerned with the beer tasting the same during the freshness period of the beer, then they are with the best possible flavor they can have. Homebrewers are used to drinking beers that have yeast in them, and know the advantages of yeast in the beer; their beer is a continuously-evolving, living thing, which may age for years, depending on the gravity, at a high degree of quality, and which will taste different from bottle to bottle.
There have been traditional methods of brewing which emphasize unfiltered, unpasteurized beer, which will evolve in the bottle, like homebrew. This is called bottle-conditioning. Some strong English ales, such as Thomas Hardy, are bottle-conditioned; as well, German Weisse beer is often bottle-conditioned, when known as Hefe-Weisse; however, the country with the greatest tradition of bottle-conditioned beers is undoubtedly Belgium. Most of the Belgian beers imported to the United States are bottle-conditioned, with a healthy layer of yeast at the bottom of the bottle.
The Belgian beers that are typically produced in this way tend to be very high in gravity, from 6-10 percent alcohol. They will evolve over a long period, and many taste their best two or three years after bottling. There is no such thing as an expiration date on a beer like this; when the bottle is dated, it is usually when the beer is bottled, not when it will expire. (On the subject of Belgian beers and yeast, there is also, of course, the subject of Lambic beers, which are spontaneously fermented, but now is not the time to be sidetracked into that fascinating topic.)
As homebrewers, we can make two uses of bottled-conditioned beer; we can drink it, and enjoy the intense flavor experience-but we can also use that yeast in our own brewing. The yeast from a bottle of Belgian beer can often be cultured, and used to ferment homebrew in a similar style.
The basic method of doing this is this: first, prepare wort by boiling one-third a cup of malt extract and three cups of water (as noted in last month's article) and place them in a sanitized mason jar. Allow to cool.
You will probably want to put an airlock on the bottle, and you can get a bottle-sized drilled stopper for it at most homebrew stores, which you will sanitize. When you are ready, set up a sanitized work surface, and open the bottle of beer you wish to culture. Wipe the neck of the bottle with high-proof vodka, and flame with a lighter, to sanitize it. Carefully pour off all but the bottom quarter-inch of beer. Try not to disturb the yeast sediment; you will want as much of it as possible. Then pour the previously prepared wort into the bottle. Put the airlock on, and keep in a dark place, at room temperature. Swirl occasionally.
It may take as long as five days for the yeast to be roused. If it takes longer than that, the yeast may have died out. If that happens, you will not want to use it. If it is fermenting well, however, you should be able to ferment a batch of beer with it. Just toss the jar in, flaming the lid, when your batch of beer is ready and at the right temperature.
As simple as this method is, there is a problem with it. Some bottle-conditioned beers also have bacteria in them, and you may not be able to tell what you have until you've fermented out the beer. There is no way of knowing without tasting the beer. I personally had fifty-fifty results with this method; I've made some very good abbey-ale with Chimay yeast cultured straight from the bottle, but I also made some horrendous stuff when attempting to culture straight from a bottle of Liefman's Goudenband.
You will cut down on the possibility of culturing a bacteria if you use an actual yeast culturing kit, which will allow you to plate out on a petri dish exactly what you're working with. This allows you to discard bad yeast or bacteria in the early stages, before it causes you any trouble. A yeast culturing kit will also allow you access to a greater assortment of yeasts available, and will safely allow you to always pitch a sufficient amount of yeast for the type of beer you're making. It's not all the hard, either; I'm still making beer by extract, yet some time ago I switched to a yeast culturing kit. Next month, I'll explain how to use one, and where to get them.
I want to begin this article on a personal note. I started homebrewing nearly two years ago. The catalyst that got me interested enough in beer to want to make my own was the discovery of Belgian beer. Their intense variety of exotic and unique flavors hit home in a way unlike anything else I'd ever had. That was what made me want to brew my own beer; so, as soon as possible, I wanted to be able to recreate Belgian styles.
As noted in last month's article, most Belgian beers are bottle-conditioned; in addition, there are many styles of yeast used by brewers in Belgium. Each of the many varieties (Trappist, Wit, Red, Lambic, etc.) has its own yeast, with individual flavor qualities.
So, it became clear to me quickly that I was going to have to learn as much about yeast as possible if I wanted to duplicate any of these styles. Had my favorite beers been German, I would probably be intensely studying malt (and might be doing full-grain beers by now). Had I been an exceptionally big fan of English Ales, I might well be a hop-expert by now. As my particular favorite was Belgian beer, I made yeast the object of my study.
Early on, when you're still making single step batches from prepared kits, in a plastic fermenter, and studying literature on advanced brewing, you may get very intimidated by some literature you will come across, especially about yeast. You may, for instance (as I did), read about laboratory-level sterilization, maintaining an oxygen-free space to culture in, using a pressure-cooker to create sterile wort, spending hundreds of dollars to buy yeast slants from laboratories in Germany, and so on. These techniques, I'm sure, will allow you to have clean, strong, fermentations-resulting in great beer.
BUT THEY ARE NOT NECESSARY! You need to do none of those things to have clean fermentations. If you've homebrewed long enough to make a few batches, you already know how to sanitize your working environment; and, if you've read previous articles in this series, you already know how to prepare "sterile" wort. Aside from this, you just have to be careful. As noted in last month's article, I am still fermenting using malt extract, two to three-gallon boils, and plastic primary fermenters. To date, I don't even have a wort chiller. I am not a high-tech brewer. Yet I culture the yeast for every batch I make now, because I can see a vast improvement in quality with just a little extra cost and effort.
Late last year, I finally purchased the Brewers Resource Yeast Culturing Kit (the advanced one, which I believe either will soon be, or already is, offered by Hop, Skip and Brew). Besides being an excellent kit, it includes a clear and well-written set of instructions from Maribeth Raines, Ph.D. Much of what I have had to say in these articles is informed by the book, as well as my own experiences. Also, I might mention that the latest issues of both Zymurgy (Volume 17, Number 12) and Brewing Techniques (Volume 2, Number 3) have articles about yeast culturing, which have informed my discussion here. Yeast culturing is in the air, no pun intended.
The Advanced Brewers Resource Kit (and don't let the "advanced" intimidate you; it's actually easier to use, in the end, than the more basic kit, as it provides things you're going to need soon anyway) includes yeast cultures on agar slants, Super Starters (growth material basically, wort, yeast nutrient, and perhaps hops in a liquid form in a screw cap plastic tube), Super Wort (growth material in powder form), a butane lighter to sterilize the immediate work area, a sterile loop, and a flask to grow your yeast in, among other supplies.
I want to outline, in a basic way, how to prepare a culture from a slant for pitching into a five-gallon batch of beer with the kit. About four or five days before you're ready to make the beer, you prepare your work area by spraying it down with rubbing alcohol, using a spray bottle. I work on a counter in the kitchen, and my immediate work area consists of a cookie sheet, which I am able to clean more thoroughly than the counter top itself.
When the alcohol has dried, you set up the butane lighter, holding it in place with a clamp, and get your Super Starter and yeast slant from the refrigerator, where they are kept. Turn on the lighter, and start the flame. Loosen the caps of the slant and the Super Starter, without opening them. Then, hold the sterile loop in the flame until it's red hot, open the slant, cool the loop against the slant wall, dip it into the yeast. Remove the loop full of yeast, and keep it within a couple of inches of the flame. Quickly cover the slant, pick up the Super Starter , open it, and dip the loop in, depositing the yeast. Again, quickly cover it. When you open and close both the yeast slant and the Super Starter tube, wave the mouth of the containers against the flame to sterilize them. Burn off any remaining yeast on the loop by re-inserting it into the flame.
The yeast slant goes back in the refrigerator for future use, and the Super Starter tube goes into a dark spot, at room temperature (this is assuming your room temperature is not much above 85 , which may be hard to manage in the middle of this brutal summer), to begin fermentation. Meanwhile, prepare for the next step of fermentation. Boil cup of Super Wort and three cups of water for twenty minutes, and put it into the flask, which has been sanitized with bleach and water. Cover the flask with a square of aluminum foil, also sanitized, and place it in the refrigerator to cool.
Periodically check to see how the Super Starter is fermenting. When you do, tighten the cap and shake the tube to aerate it, then unscrew the cap slightly. In one to two days, you should see visible sediment in the flask. When you do, it's time to pitch to the flask of Super Wort .
You should again spray down your work area. Again using the flame to sanitize the mouths of the Super Starter and the flask, transfer the yeast to the glass flask, and recover with aluminum foil. As you did with the Super Starter , keep the flask in a dark, room-temperature area, swirling occasionally.
You do not need an oxygen-free area to prepare pitching yeast. You are trying to increase yeast cells, in preparation for fermenting a five-gallon batch. This period of fermentation is aerobic, and so requires oxygen, though obviously you want to keep competing bacteria out. You will keep your flask container of fermenting wort covered with aluminum foil, but you do not need an airlock.
One to three days later, you are ready to pitch. If you're making a lager, or a high-gravity ale, you will need to prepare another flask of wort, and repeat the last step, pitching to the larger flask, so that you double your quantity of starter.
Using this method, you will have quick, clean fermentations. Another advantage to the Brewers Resource Kit is the amazing variety of yeasts they have available on slants. Four different English ales, several abbey ales, two German weisse beers, a saison, various lagers, a Belgian wheat beer; and many more. Sticking strictly to the Yeast slants available from Brewers Resource, you can easily go through twenty different strains of yeast, with different flavor profiles, without repeating yourself.
You can also use the kit to culture yeast from bottle-conditioned beer, in a much safer and more reliable way then discussed last month. How to do this is the subject of the last article in this series, in the next issue.
The last chapter of series returns to subject of Part 2, using the yeast from bottle-conditioned beer to ferment homebrew. This time, we are using tools acquired in the Yeast Culturing Kit, the subject of Part 3, to create a cleaner and safer source of yeast to brew with.
The Brewers Resource Yeast Culturing Kit, described in some detail in the previous chapter, includes petri dishes, and this important addition allows for better culturing from a bottle. The petri dishes consist of a wort medium mixed with agar.
When attempting to culture the yeast from a bottle-conditioned beer, you take several steps. First, prepare your sanitized working area. Then the bottle is opened, and the beer is poured off. After this, you flame the neck of the bottle, as before, and pour about a teaspoon of slurry from the bottom of the bottle into one of the Super Starter tubes that I discussed in the previous chapter. Just as in using a yeast culture from a slant, you will keep the Super Starter in the dark, at 60 75 , for several days. Leave the tube slightly loose, so air can be expelled. Periodically, you will check on the starter, tightening it, and shaking it to aerate it.
It will take several days to rouse the yeast, as it has been dormant for some time; you may not see much yeast in the flask. If there is no sediment after five days, you can assume the yeast is dead. But if there is a small amount, you can prepare to plate it out.
You will sanitize your work area again, and prepare your flame source. You will need the sterile loop, the Super Starter , and one of the petri dishes. You sterilize the loop in the flame, then open the Super Starter tube, flaming the lid as you do so. Dip the loop in the starter, picking up some yeast cells as you do so. Open the petri dish, and swirl the loop on the agar on the plate in a zig-zag pattern that you follow from a sheet of paper that is under the petri dish. Quickly close the dish, and burn off any remaining yeast on the loop in the flame.
Next, you turn the petri dish lightly, open it again, and swirl the loop against the agar again. You repeat this two more times. The point to this is that you are spreading the yeast that you have placed on the dish farther and farther out. The reason for this will be clear in a moment.
After you have done, place the petri dish in a dark, warm spot for a few days. By the third day, you should have visible yeast on the dish. They look like grayish-white clumps. You can tell how pure the yeast is just by looking at it, and you can tell if there are any bacteria, because it will not look like yeast on a petri dish. It looks like mold, or it has a "furry" appearance. Where you have spread the yeast out, you should have growths from isolated yeast cells, in the form of small "dots" of yeast. These single-cell yeast growths are will be a pure source of yeast.
This it what you will use for your next batch of beer. When they are ready, the yeast cells are retrieved from the petri dish using the sterile loop, again in a sanitized work area, with a flame source. The yeast is placed on a slant for future use and storage, or in a Super Starter for immediately preparing your next batch of beer. I recommend using the slant; if the yeast is worth using once, it will probably be worth using again.
In this way, you get to separate clean yeast cultures without throwing them into five gallons of wort. I'm sure you can see the advantage of this! If the yeast turns out to be no good, there will be no wasted batches, merely some wasted time and a wasted petri dish. Also, the yeast you choose, as it is isolated from a single cell, will be purer, and healthier than anything you could ferment straight from the dregs of the bottle.
The thing that should be remembered is that you will not be able to isolate every yeast in every bottle of bottle-conditioned beer you find. Some will be dead; others will be badly-infected. But using this method, you will get the best results with whatever viable yeast that you are able to find. I have had spectacular results with this method myself; one of my best yeasts, which I now maintain on slants, was cultured in this manner I've fermented fifteen gallons with it so far. I have also failed in several attempts, because the yeast was inadequate; these cultures were disposed of before reaching pitching stage. I always found it worth the effort, and I never made a bad batch from yeast cultured in this manner.
That about does it. With the information you have gotten from this series, I hope that you can see that culturing yeast is not as intimidating or technical as you might have thought, and that it
Reprinted from Malted Barley Appreciation Society Newsletter
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