If you’re like many brewers, you have a favorite recipe you just keep coming back to, one you brew frequently and almost identically each time. Although you probably don’t want to change your favorite recipe just to change it, you might find that tried-and-true brew could benefit from a change in yeast. If you’ve always used dry yeast, one of the several dozen liquid yeast strains available at your local homebrew supply shop might provide the extra something you’re looking for in that favorite recipe. 

Until a few years ago, the amateur brewer had only a few choices in selecting brewing yeast, all of them  dehydrated, packaged, and primarily ale yeasts. Besides the drawback of the fairly small selection, the handling in manufacturing and preparation subjected the yeast to the risk of contamination. Dry yeast packets are never entirely pure; they always contain at least some wild yeast. 

Over the years, the variety of dry yeast has expanded a bit and the strains are more pure than they once were. Dry yeast is still readily available and very inexpensive. Liquid yeast begins from a culture grown from a single cell under controlled conditions, and contaminants are controlled to far lower levels than with dried yeast. Manufac­turers package the yeast in a liquid nutrient sealed in foil pouches or plastic vials. The most widely available liquid yeast is sealed in a  breakable plastic bag surrounding a smaller foil pouch containing sterile wort — sometimes called a “smack-pack.” Liquid yeast packaged in vials is loaded directly into the container with a small amount of liquid nutrient cover. 

A new product on the market is “pitchable” yeast. The term pitchable doesn’t refer to a property of the yeast but simply means it’s packaged in enough quantity that you can pitch it directly into your wort without first making a starter. Some pitchable yeast packages provide 10 or 20 times the volume found in smack packs. Pitchable yeast starts much faster than a standard packet or vial of liquid yeast pitched without a starter. Still, pitchable yeast packets provide roughly a fifth of the yeast needed for a five-gallon batch, according to typical commercial pitching rates.

Dozens of yeast varieties are now available, cultured from yeast sources around the world. Because the strain of yeast selected for your beer has such a big influence on the final product, it’s very satisfying to know you made a choice that is perfectly matched to your beer style. Homebrew suppliers have complete information about what varieties of yeast are on the market.

Get Started With Starters

A true story: One pair of brewers had a typical surprise when they first used liquid yeast — the long time it took for fermentation to begin after pitching directly from the foil bag. The odds couldn’t have been more stacked. First, they were brewing a Scottish ale, and they had cooled both the yeast package and the wort to just under 60° F. Second, the starting gravity was nearly 1.070, a hearty brew to say the least. And third, they didn’t know about starters. With all this going against the yeast, it took three days for any noticeable fermentation. 

This experience has been repeated many times by brewers unfamiliar with the volume of yeast recommended per unit volume of wort (called the yeast pitching rate). Although recommendations vary, pitching rates based on accepted commercial brewing practice are far larger than those used by many amateur brewers and come close to one-half fluid ounce of yeast solids per gallon of wort. It’s impossible to know how close this rate is to ideal; the difference in the number of yeast cells in two half-ounce measures of yeast starter could differ by a factor of 100 or more. A rule of thumb: for five gallons of wort of average gravity (say 1.050), use at least one-quarter cup of settled yeast.

By contrast, the volume of yeast in a typical liquid yeast foil pouch is about one-half teaspoon or less, and even the pitchable yeast packages contain only an ounce or so of settled yeast. This means that the yeast you buy in these packages must be bulked up in a starter to get close to the recommended pitching rates for even a five-gallon batch. Increase the volume by 30 to 50 times for the smack-packs, and by three to five times for a vial of pitchable yeast.

Starters are easy to make using a clean saucepan with a clean lid. First, bring just more than two quarts of water to a boil, adding about 1 cup of extract as the water gets hot. Boil for at least 15 minutes, then cover the pan with the lid and cool in the kitchen sink in an ice bath. Using a sterile thermometer, cool the wort until it reaches 70° F and pour it into a sanitized half-gallon glass jug. Seal the jug with a sanitized screw-on cap or rubber stopper and shake vigorously to aerate the wort. Remove the stopper or cap, and pitch the yeast from the smack-pack or vial and fit a sanitized air lock and stopper assembly into the mouth of the jug.

Let the fermentation finish; the yeast froth should rise and fall. The bubbles in the air lock should be at least a minute apart. Wait for the yeast to settle out, then pour off the spent wort and replace it with a fresh batch of wort. This process can be repeated as often as needed to ensure that a large, well-fed population of yeast is ready on brew day. If you have a week or more before brew day, you’ll have plenty of yeast to pitch and even some left over. What remains in the jug can be fed and maintained until the next brew session.

Some brewers prefer to pitch the starter when it is at the peak of activity instead of waiting for the yeast to settle. There are probably hundreds of arguments for both methods, but if you’re like many brewers, the choice is seldom yours; you brew when you can. That means you pitch the yeast in whatever condition it happens to be. As a rule, the best fermentations happen when the starter has been nurtured for at least one week. The single most influential factor seems to be sheer volume, and very little else matters. 

Handling Liquid Yeast

Keep liquid yeast refrigerated until you’re ready to use it. To start the foil smack-pack, lay the package across the palm of one hand or on a hard, solid surface, and with your other hand in a fist, press down on the package or hit it gently to break the inner wort pouch. With the foil pouch held between the palms of your hands, force the liquid inside the package from end to end to mix the yeast with the nutrient. Finally, leave the package in a 65° to 75° F location until it appears to be almost fully swollen. Sanitize the outside of the foil package, trim one upper corner off with the scissors, and pour the solution into your prepared starter wort. 

For liquid yeast sold in plastic vials, let the yeast come to room temperature prior to pitching. Shake the vial occasionally to keep the yeast in suspension, and when your starter wort is prepared and in your starter jug, sanitize the top of the vial and pitch the yeast.

After the yeast has been pitched into the starter jug and you’ve put an air lock on the jug, swirl the contents around to agitate the yeast, being careful not to lose the air lock to rough handling. It’s okay to repeat the agitation frequently (several times a day, if you want) until you can see fermentation begin. 

Liquid Yeast Strains

Because there are so many strains of liquid yeast available now, with more appearing in store refrigerators each year, you can match yeasts to almost any style of beer or mead you choose. Manufacturers publish specification sheets on their yeast strains, and generally your brewing supply shop will have a copy. These spec sheets contain general information such as beer style recommendations, preferred fermentation temperatures, flocculation behavior, and flavor characteristics. These data sheets, along with the experiences of your fellow brewers, will help you select the yeast to try next.

Although your shop may not carry dozens of strains, many shops now carry the most popular ones that work well for brewing a wide variety of adult beverages. Some strains are considered much cleaner than others, leaving very little behind in the way of flavor-producing by-products in your beer. Others are well known for rapid settling in the secondary fermentation, producing an almost crystal-clear beer without the need for filtration. Ask your homebrew retailer for suggestions. 

By choosing good general-purpose yeasts, using a starter, and practicing sanitary brewing, you can use a single package of liquid yeast to make several batches of beer continuing for several months or more. This can make the use of liquid yeast very economical, in spite of the higher cost per package when compared with dry yeast. Why not make your next batch a liquid yeast brew?