Proof: The Science of Booze.

Adam Rogers’ book Proof: The Science of Booze delivers handsomely on its title: It’s a book about adult beverages, and it will make you want to go drink some, but it also gives quite a bit of information on the (light) science involved in the production of and flavors behind those libations, especially distilled spirits. While some of the stories around booze manufacturing get too bogged down in operational details, there are also magnificent anecdotes within the book, including the best mystery you’ll ever read where the culprit is a fungus.

Rogers divides the book into eight chapters, each revolving around some essential element of alcohol production – yeast, sugar, fermentation, distillation, aging – or its consumption – smell/taste, body and brain, and the hangover. That gives him the latitude to talk about just about anything he wants that’s related to the manufacture of sauce and suds, including but hardly limited to some deep dives on what we do and don’t know about the science of such beverages.

Alcoholic beverages, especially distilled spirits – often called “hard liquors,” produced by putting some alcohol-containing mixture through a still, leading to whiskey (from fermented grain mash, like that created in beer production), brandy (typically from wine), rum (from fermented molasses or sugar cane), vodka (usually potatoes), and so on – have dozens or even hundreds of aromatic and flavor compounds, some of which still aren’t identified, that give them their distinctive tastes and smells. When you sip an aged spirit, often whiskey but applicable to rum and brandy as well, you may pick up “notes” much like you’d identify in good wines or coffees; those notes are specific chemicals or combinations of chemicals formed during the aging process, sometimes on their own and sometimes due to the interactions between the spirit and the wooden (sometimes charred wooden) casks in which they’re housed.

Rogers explores this angle, and many others, with visits to artisanal producers of these various beverages, moving his writing lens from wide shot to close-up and back, extrapolating from individual producers’ experiences to discuss larger points that he can back up (sometimes) with science. He talks about the obsessions distillers have with the shapes of their stills, even trying to reproduce flaws in old stills when it comes time to replace them with new ones. He talks to a barrel maker – apparently this is about as dying as a dying art can be without being, you know, dead – about the specifics of manufacture and the demands of clients. He gets into the lactones formed during the aging of whiskey in wood barrels, a subject so critical it’s even been the topic of academic research. He also compares production of alcoholic beverages from eastern and western cultures; where Europeans relied heavily on Saccharomyces cerevisiae, Japanese beverages such as sake and shōchū come from a mold called koji (Aspergillus oryzae).

Speaking of molds and fungi, the best passage in Proof is, by far, the mystery of the whiskey fungus, practically a detective story about one man’s quest to identify a specific organism growing on buildings near a particular whiskey distillery. The distilling term “angel’s share” refers to the portion of a distilled spirit lost to evaporation during the aging process, usually water but sometimes a mixture of water and ethanol, the latter of which attracts certain fungi that will be found growing on surfaces where the evaporated alcohol may condense. The story Rogers tells is told in greater scientific detail in this free Mycologia journal article – you probably still have that back issue at home – which describes the mycologists’ development of a new genus to encompass these molds, including Baudoinia compniacensis, now identified as the “angel’s share fungus.” Rogers infuses the story with a bit more drama than the journal piece does, of course.

Rogers even gets involved in the debate over wine ratings, where the American Association of Wine Economists (led in part by the perfectly-named economist Richard Quandt) is among the leaders in arguing that the judgment of wine experts like Robert Parker is too subjective to have any value. Quandt and Orley Ashenfelter, who also appears in Ian Ayres’ book Super Crunchers, are in effect the leading sabermetricians of oenology, whereas Parker is … I don’t know, Old Scout or something. Quandt even wrote his own manifesto comparable to Percentage Baseball or early Bill James Abstracts, called “On Wine Bullshit“. Rogers takes a somewhat middle road here, pointing out that truly objective wine measures are impossible until we’ve identified all of the molecules responsible for their flavors and aromas, but I thought he sided with the quants – as will many of you, I’d wager.

As only a casual drinker but one who greatly enjoys a well-aged rum and a well-mixed cocktail, I found Proof (which I listened to as an audiobook) both entertaining and informative, aside from the occasional tangent into manufacturing minutiae. I wish he’d spent a little more time on spirits beyond whiskey, but brandy gets a fair shake and I may merely be expressing my pro-rum bias. If you tipple, you’ll enjoy this book.