The Science of Beer
Mark Denny is an avid home brewer, has a Ph.D. in theoretical physics and has written popular science books on topics such as machines that changed the world, making sense of radar, the science of power generation, making sense of bird migration, the science of sailing, the science of ballistics, the science behind weather forecasts, the science of navigation, how life works, and making the most of the antrhopocene era. He currently is a professor of biology at Stanford University. In Froth!: The Science of Beer Mark Denny takes on the science of beer. He covers the evolution of beer, how to make good beer at home, yeast population dynamics, brewing dynamics, bubbles, and fluid flow. The book is what you might talk about if you sat down next to a scientist in a bar when the scientist is well into his third or fourth pint. Denny is entertaining but not always accurate and he gets a little sloppy in places. His history chapter is shallow, somewhat fanciful at times, dwells too long on the distinction between beer and ale and flies over the development of beer in the US at too high an altitude. He also introduces too many needless abbreviations - like MB for mega-brewer - they are cute but confusing. His chapter on home brewing lacks meat and gives bad advice. He starts with tap water which may or may not be good advice. His is chlorinated. It the water is treated with chlorine, boiling the water can drive the chlorines off. If the water is treated with chloramine you need to use 1 Camden tablet per 20 gallons of water to neutralize the chloramine (Camden tablets will also work for chlorine). If you do not do this, the water will cause off flavors. Some tap water and some well water is unsuitable for brewing all beer and others may be unsuitable for certain kinds of beer - you need to get water test data from your water supplier. His section on mashing is a little simplified and does not deal enough with sparging. If you sparge too hot you are going to wash astringent flavors off the barely husks and get bad beer. On page 109 he makes an astounding statement for a scientist professing knowledge of brewing: "...mashing at the higher [temperature] range will yield beers with higher alcohol content and more body than beers brewed at the lower end of the range..." Actually, mashing at higher temperatures produces more alpha-amylase creating more unfermentable sugars resulting in a lower alcohol, fuller-bodied beer. Denny ignores the need for rapid cooling of the wort after the boil. Rapid cooling causes solids to form and fall out of solution, slows the production of dimethyl sulfide (cooked corn flavors and aromas) and slows the production of unwanted yeasts and bacteria. Pitching dry packets of yeast, like Denny advocates, might work OK, but making a yeast starter is a much better path for a vigorous start to your fermentation and prevention of off flavors. Denny states that when you hydrometer readings are below 1.010 you are ready to bottle but this depends on the original recipe. Lagers can have a final gravity well below 1.010 and if you follow his advice and bottle at that point, your bottles may explode. The pictures are black and white and are not always very useful and he includes a picture of a beer in an unclean glass. If you know enough about brewing to spot what is wrong, there is some useful information in this book. Denny is an amusing writer and makes the science discussion understandable. The book is a lot like having a beer with a scientist who knows a little bit about brewing and a lot about certain parts of brewing. I liked it but I wouldn't recommend it, although if you are studying for the Beer Judge Certification Program exam, you can learn a lot trying to find all the mistakes in this book.