You've seen them, lurking in the refrigerator case at your homebrew store, next to the hops: shiny envelopes and tiny test tubes containing that mysterious elixir, pure culture liquid yeast.
What's the deal? Your dry yeast works fine. It's easy. It's cheap. It's nearly foolproof. Why would anyone want to mess with yeast in a seemingly expensive and temperamental liquid form?
As it turns out, for quite a few reasons, the most important being taste and control. Most experienced homebrewers will tell you that, all things being equal, beer made with liquid yeast is usually cleaner and tastier than beer made with dry yeast. Beyond taste, however, liquid yeast cultures enable homebrewers to tailor their beer to the flavor profile perfectly appropriate to the target style, be it English ale, Czech pilsner, American lager, Canadian ale, or even Belgian and weizen varieties.
"Certain styles, like British or American pale ale, can be successfully made using dry yeast," says award-winning brewer and homebrew supplier George H. Hummel of Philadelphia. "Other styles, however, such as Bavarian weizen or Belgian ales have unique flavors and esters that can only be achieved using liquid culture."
Dry yeast usually comes in only two varieties, "ale" and "lager" Using dry yeast is like trying to touch up a scratch on your car with generic paint from the hardware store. Sure, it's good paint, but it won't match your car color perfectly. For that you have to spend a little more money and get the exact coded shade from the right manufacturer.
Today's dry yeast is well made. Dry yeasts from reputable firms perform well under homebrewing conditions. But if you really want to control your brew, you need to matriculate to the school of liquid yeast.
Many a brewer made the jump to liquid yeast when attempting to make a true lager. Even if a dry yeast pack is labeled "lager" chances are it is really an ale strain, perhaps one that performs at lower temperatures.
"This is a problem rampant throughout the homebrewing and commercial brewing industries" says Hummel. "More often than not 'lager' or 'ale' is a description of fermenting temperature, not the actual pedigree of the yeast."
Hummel says many commercial brewers use the same yeast for their ales and lagers, just fermenting at high and low temperatures, encouraging the yeast to create a taste profile appropriate to ale and lager styles.
The way to guarantee your yeast is genuinely top- or bottom-fermenting is to use the liquid cultures.
But in homebrewing, as in life, there's no free lunch. Liquid yeasts need special handling. Here's the payoff. Doing just a tiny bit of homework now will yield tons of satisfaction and gallons of great beer later. The benefits truly outweigh the inconvenience. So pop a beer top, relax, and think of how much better your next batch will be...
The liquid cultures are packaged in small test tubes or, in the case of Wyeast, in what are usually referred to as"smack-packs" - a bag within a bag. Sort of like a portion-control ketchup pack inside a one-pot coffee envelope.
Inside one pack is dormant, pure culture yeast. Inside the other is a small dose of sterile wort. When you want to activate the yeast, you break the small bag inside by applying pressure to the outside. This mixes the yeast and wort, safely inside the sealed outer bag.
The yeast then ferments the sterile wort, replicating, increasing in number, and getting stronger. After a day or two at room temperature, the pack swells up with trapped carbon dioxide gas. It really swells, too. You might think the whole thing will explode. But it won't. It's made to take the pressure.
You could pitch this teaspoon or so of actively fermenting yeast directly to your wort. In fact the package directions might tell you to do just that. Many brewers (including yours truly) did it that way on the first batch or two using liquid yeast. But experienced brewers caution against it. A better plan is to make a starter culture--to create a larger volume of active yeast cells for pitching. And making a starter is a must if you plan to use BrewTek, Yeast Culture Kit, or Yeast Lab products, packaged in the test tube without the sterile wort
Using a starter culture will increase the number of viable yeast cells you pitch into your wort, decreasing your chances of infection by encouraging a fast start of fermentation.
To make a culture for your yeast cells, you need to make a "mini-brew" of sterile wort. Experienced brewers make a lot of it at one time. With proper home-canning techniques, your sterile wort will last a long time, so you can make dozens of mason jars filled with the stuff, maybe only a few times a year.
You can head down that road later, if you really get into it. In the beginning you can make small batches of sterile wort easily with equipment you already have lying around the house: beer bottles, caps, aluminum foil and dry malt extract. All you need to do is plan ahead. Your pure culture will need some time to get going in your sterile wort.
Following is the step-by-step, based on a target brew day of Saturday. This method will result in a good 12 ounces of active starter, plenty for the average homebrew situation.
You should start with as much as a gallon of active culture for five gallons of wort. But practical experience among homebrewers has shown positive results with 12 to 16 ounces of active culture for ale. For the slower, cooler lager strains you may want to consider using a large mason jar for your culture or inoculating two large beer bottles of sterile wort to increase the pitching volume to 20 or 30 ounces of culture.
You will need:
- The liquid yeast. Check the expiration date before you buy (if you are not buying mailorder.) Get the freshest you can find. If you buy during warmer months, take a small cooler and some ice to the homebrew shop to transport the yeast home. And if you mail-order when it's hot outside, see if your supplier will pack it in ice for you. If not, find another supplier.
- A big beer bottle, 16 or 20-ounce size. My favorite culture bottle had Harp Lager in it. It is strong, squat and fat, and fits easily in my Dutch oven pot.
- Some light dry malt extract (DME).
- Hop pellets.
- A pot big enough to hold the beer bottle, covered with water.
- A smaller saucepan.
- Bottle caps and your capper.
- Sterile cotton or a sanitized airlock.
- A metal funnel.
- Hot-dog tongs.
- A cigarette lighter or Sterno can.
Monday or Tuesday evening: Make the sterile wort and, if you are using the "smack-pack," activate it by breaking the inner pouch.
"Smack-pack" is a misnomer. You don't really want to smack it. A better way is to place it on a firm surface, feel for the internal pack, place both hands directly on top, and apply even pressure. The dinner pack will suddenly let go, and your yeast will start their feeding frenzy and party time.
After you break the inner bubble, shake the whole kit and caboodle to get the wort well oxygenated, encouraging the yeast to make little yeasties.
Place the activated pack in a warm place.
Then cook some wort:
Fill your large pot with water and bring to a boil. Immerse the bottle, a few caps, and a funnel to sterilize. Keep it boiling.
In the saucepan mix two cups water and four tablespoons DME. Bring to a boil, watching carefully. Small-volume worts boil over just like the big ones. Add three or four hop pellets and boil for five to 10 minutes.
Turn off the heat under the saucepan.
With the tongs carefully remove the bottle and funnel from the boiler pot. Empty the water from the bottle, then fill it three-quarters full with hot wort and cap it. It's a good idea to boil more than one cap, because you may drop one trying to cap the hot bottle.
Now return the bottle to the boiling water and let it boil for 10 or 15 minutes. Turn off the heat and let the bottle cool with the water in the pot. This will prevent the bottle from shattering in a draft of cold air.
Your wort is sealed and sterile. Keep it in a dark place until Tuesday or Wednesday, when you will pitch your liquid culture.
Tuesday or Wednesday evening:
If you used the smack-pack, it should be swollen, indicating healthy fermentation. Now is the time to get the starter going. Wipe down the work area with bleach solution or rubbing alcohol. Shake the sterile wort bottle vigorously for a moment to aerate.
Have the cigarette lighter ready. The next steps should be completed as quickly as possible: Sanitize your yeast pack or tube in weak bleach solution and rinse well. Uncap the wort bottle and "flame" the neck to kill any bacteria or wild yeast hanging around the outside of the glass. With clean scissors snip the corner from the yeast pack and pour the contents into the bottle, or carefully pour in the contents of the test tube.
Plug the bottle with sterile cotton or fix the airlock. Never, ever cap a bottle of fermenting wort!
Put this inoculated wort in a warm, dark place. The yeast will start the party, fermenting the sterile wort. By Saturday, brew day, you should have a bottle of healthy starter ready to pitch into your five gallons of wort.
If your brew plans get scrapped for any reason, just pop the bottle into the fridge. It will stay healthy for up to two weeks, chilled. Just bring it out to room temperature a few hours before pitching.
Another advantage of using pure culture is that it allows you to recycle yeast from your primary fermenter. Most homebrew experts advise against recycling yeast sediment from a batch pitched with dry yeast. Just pour sediment from your fermenting bucket or carboy into a sterilized bottle or jar. You can pitch this right away or refrigerate it for up to two weeks.
Another reason to learn the starter culture protocol is for retrieving yeast from the bottom of a bottle of homebrew or commercial bottle-conditioned brew, if it's a fresh bottle. In fact, that's how many homebrewers got their yeast in the pre-1978 dark days of underground homebrewing! But don't try to culture sediment from beer made with dry yeast!
If you recycle your sediment, you should get three or four healthy batches from each liquid yeast purchase, so it isn't really all that expensive. But you should buy a brand-new culture every so often to ensure well-behaved yeast of the correct strain for the style you are brewing.
And that's the beauty of liquid yeast. No matter what style you are making, you will find the exact strain you need for the job. The printed literature and computer newsgroups are overflowing with information on yeast management for homebrewers. Learn more and brew better.
Take the plunge into liquid yeast. Your next brew will taste so good, you won't recognize it!