Review – Yeast: The Practical Guide to Beer Fermentation

yeastI was really quite excited when Calum told me about this new book by Chris White (of White Labs) and Jamil Zainasheff (of The Brewing Network). Those of you who know me from the Edinburgh meetings will know that I’m really enthusiastic about yeast (even for a brewer), so as soon as I heard about it, I had to buy it. I’m pleased to say that I was not disappointed, but before you all run out and buy copies, you might want to read this review first…

OK, firstly: who is this book aimed at? The blurb on the back says “brewers at all levels, from beginning homebrewers to production brewers at any sized brewery”… Well, I certainly wouldn’t recommend this book for a beginner. This is a serious book for serious brewers. Whilst there is a lot of material in it that is of interest to home brewers, and there is some specific discussion of home brewing equipment and conditions, it seems to be primarily aimed at small-to-medium sized commercial brewers: people with a real interest in consistency and quality control, but who don’t already have dedicated lab facilities and staff. That doesn’t mean there isn’t a lot we can learn from it, but we need to think carefully about what is appropriate and practical for us. For example, the various problems involved with large commercial cylindroconical fermentors probably won’t interest us much… There’s also a fairly heavy US bias and more discussion of lager-type beers than you would expect in a British book, but at least he mostly uses metric units.

The book is divided into seven chapters, which I’ll consider in turn.

Chapter 1: The Importance of Yeast and Fermentation

Well, we all realise the importance of yeast, right? This short chapter is mainly about the history of yeast, but it also includes a brief overview of the major factors affecting its performance. The main message to take from this chapter is that yeast is every bit as important to your brewing as any other ingredient, if not more so. If you want to make great bear, you need to pay as much attention to the choice, care, and feeding of your yeast as you do to recipe formulation or mashing procedure. That’s certainly a message I agree with!

Chapter 2: Biology, Enzymes and Esters

Whilst Chris repeatedly states that this isn’t a yeast biochemistry book (and it isn’t), this chapter gives a fairly good high-level overview of the various biochemical processes and compounds involved, particularly with regard to how they affect flavour. I’m not entirely convinced about the usefulness of this chapter, but it’s not very long and some of the latter material might be confusing without it, especially if you don’t already have some grounding in biology and chemistry. You might be able to skip it if you really are allergic to chemistry, but if that describes you, then you probably won’t enjoy the rest of book much either.

Chapter 3: How To Choose The Right Yeast

This is where we start getting into real, practical information. It gives a really clear outline of the criteria you should use to select a yeast for a given brew, a system of classification of both ale and lager strains, and the practical considerations around using multiple strains in your brewery. There is also some very interesting discussion of the possible refinements available from using multiple strains in the same brew, the pros and cons of using “native” (wild) yeast, and a section on Brettanomyces (which is apparently becoming quite popular with some of the more adventurous mircobrewers across the Pond).

Chapter 4: Fermentation

Now we’re really getting into the meat! This is one of the longer chapters, and is likely to be the most interesting and useful for most people. Chris goes right through the fermentation process from pitching to conditioning in quite some detail, laying out exactly what is going on at each stage. He also looks closely at the variables introduced by different equipment (I certainly didn’t realise that fermentor size and design could be quite so important) and the impact of fermentation variables (temperature, pitching rate, oxygenation, etc) on the production of various flavour compounds.

Chapter 5: Yeast Growth, Handling and Storage

Pretty much exactly what it says on the tin. This chapter is mainly looking at yeast handling in the brewery rather than in the lab (that’s in the next chapter), but it also includes material on making homebrew-sized starters. It’s mainly about cropping, rinsing, acid-washing and storage at brewery scales though. There’s a fascinating discussion of the differences between top- and bottom-cropping and the practicalities of each in a commercial set up, but it’s maybe not of that much use if you’re not running a fairly large microbrewery or doing a lot of cropping and re-pitching at home. He does also include a section on the proper handing and rehydration of dry yeasts, which probably is of a lot more use to many here.

Chapter 6: Your Own Yeast Lab Made Easy

This is the largest chapter in the book, and I’d have to admit that it’s the one that really got my juices flowing (but then I’m probably a bit wierd…) He covers a wide range of laboratory procedures with an emphasis on quality control and contamination detection – everything from long-term storage of yeast cultures to the isolation and identification of bacterial contaminants is covered, taking in a heck of a lot of ground on the way. Much of this isn’t likely to be of that much direct use to home brewers (it’s more aimed at quality assurance in commercial brewing) but I found it all fascinating nonetheless. However, there is quite a lot to interest the keen home brewer, including how to set up and maintain a yeast library and how to propagate fresh cultures from storage. Some of the tests are also potentially useful – for example, we could all use the simple diacetyl force test to avoid nasty buttery surprises from bottling too early, but I doubt that too many people will be buying microscopes to do proper cell counts and viability tests, or the specialised culture media needed to isolate and identify bacteria, or even running forced ferment tests to determine maximum attenuation. Small commercial brewers could certainly benefit a great deal from this chapter though. One thing which I do think would improve this section would be more information on safety – some of these specialised media and reagents are clearly quite dangerous, but there isn’t really enough information for me to decide just how dangerous… I suppose by not including this sort of information he avoids the problem of people misunderstanding, but I’d like the warning signs to be a bit clearer. I also get the feeling that this chapter is a bit more “cobbled together” than some of the others – it could benefit from better organisation.

Chapter 7: Troubleshooting

A fairly short chapter to round off, this breaks down the main problems you’re likely to encounter into a series of groups (attenuation problems, flavour problems, etc) and looks at the possible causes of each, along with suggestions as to how to identify and resolve the source of the problem. It’s not a simple “if A, do B” troubleshooting guide, as all of the problems discussed have many possible causes. It’s more about encouraging readers to learn how to identify and solve problems themselves than simply giving instructions. It does include a really useful table of common problems and the factors which affect them though.

All in all, I’d say it’s certainly well worth a read for anyone seriously interested in improving the cold side of their brewing. It may challenge some of your preconceptions (“The experienced extract brewer with temperature control and an excellent grasp of fermentation will almost always outshine the all-grain brewer relying on luck for temperature control”!) but that’s certainly no bad thing. I’m already making some modifications to my brewing and yeast propagation practices based on what I’ve learned from this book, and I have to admit to having had some rather esoteric flights of fancy about setting up a proper lab… One day!




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