As important as yeast are to brewing beer, they are still often a mystery to both beginning and experienced homebrewers. Brewers know that making yeast starters and fermenting at proper temperatures will produce better beer, but may not know why yeast are happier under these conditions. Yeast: The Practical Guide to Beer Fermentation walks us through some of the mystery, and shows us how we can better use yeast to produce the flavors that we want in our beer.
The authors, Chris White and Jamil Zainasheff, are rock stars in the homebrewing community. Chris White has a Ph.D in biochemistry and started White Labs, a popular yeast producer for both homebrewers and professional brewers, in 1995. Jamil Zainasheff is one of the most awarded homebrewers by the American Homebrewing Association, taking home the top Ninkasi Award in both 2004 and 2007. Jamil hosts regular podcasts on The Brewing Network, including the Brew Strong show and The Jamil Show. He opened his own commercial brewery, Heretic Brewing Company, in the spring of 2011.
Given the background of the authors, it's not surprising that Yeast seems to be written for both the professional brewery lab technician and the homebrewer. Topics ranging from the history of yeast research to yeast health and storage always contain an application for brewers, whether they're making small batches at home or 100 barrels of beer a week. In some ways, Yeast reads like a high school science book. Diagrams of cells structures show up early, while later chapters include descriptions of how to count yeast cells under a microscope. This level of detail might initially seem unnecessary for someone who brews five gallons of beer every few weeks, but the authors do a good job of applying the scientific theories to help you improve the character of your homebrew.
The chapter on how to pick the right yeast strain for a recipe is one of the book's most inspired. Choosing to do away with conventional descriptions like "Belgian", "American or "English", the book encourages us to look at the characteristics such as the esters, phenol production, and attenuation. This helps brewers to think outside the box when designing recipes, and perhaps select a strain of yeast that may not initially be the most obvious choice. It also presents situations where it might be appropriate to use multiple strains of yeast to achieve a desired result. A barley wine fermentation, for example, might start off with an English yeast strain to form fruity esters, and then integrate American yeast half way through fermentation to produce a drier finish than the English strain alone would achieve.
Those familiar with Zainasheff's podcasts won't be surprised to find an extensive commentary on the importance of pitching the right quantity of yeast, along with optimal oxygen concentration and fermentation temperatures. This is a message that he is well known for, and he even hosts an online calculator that determines the appropriate sized yeast starter needed for a given beer. Yeast goes into detail about how to step up yeast growth starting from single cell colonies and going all the way up to the amount of yeast you would need for a large-scale commercial brewery.
The information on how to reuse and store yeast will be useful for many homebrewers. Yeast is a living organism, so it doesn't "go bad" immediately after fermentation. Instead beer brewers can capture used yeast in a sanitary way, store it in the refrigerator, and use it for future brewing projects. White and Zainasheff go into detail on how to collect the best yeast for reuse and how long the preserved yeast will remain viable under different storage conditions.
The book also contains some information that will only be useful to the most scientifically oriented homebrewer or professional brewer. The chapter entitled "Your own yeast lab made easy" convinced me that maintaining a yeast lab is decidedly not easy. It includes methods for testing beer for infections and other quality control issues. The level of detail is certainly beyond what any homebrewer needs to know to brew great beer.
Yeast is a great source of information for brewers who want to step up their brewing and fermentation to a more advanced level. While a little technical at some points, it takes a little bit of the mystery out of fermentation and serves as an excellent reference on how to coax yeast to produce the flavors you want in your beer.