The Complete Handbook of Alcoholic Beverages

Chapter 1: Understanding Alcoholic Beverages

The Core Process: Fermentation

At its most basic, an alcoholic beverage is a liquid that contains ethanol produced by the metabolic action of yeast on sugars. The yeast consumes the sugars and excretes ethanol and carbon dioxide as waste products. This process, called fermentation, is a biological constant across all beer, wine, cider, and spirits we consume. The source of the sugar matters more than almost any other factor in determining the character of the final product. Grape juice yields wine, barley-based wort yields beer, apple juice yields cider, and honey yields mead. This is not a stylistic choice made by the producer; it is a foundational recipe constraint. You cannot make wine from barley any more than you can make beer from grapes, because the chemical compounds in those starting materials are what create the distinct flavor esters and acids.

There are two main types of fermentation used in commercial production. The first is top-fermentation, used primarily for ales, where the yeast (typically Saccharomyces cerevisiae) rises to the top of the fermentation vessel during the process. This yeast works best at warmer temperatures, generally between 15°C and 24°C (59°F to 75°F), and it produces a broader range of flavor compounds—esters like isoamyl acetate, which smells like banana, and phenols, which can smell clove-like or smoky. The second is bottom-fermentation, used for lagers, where the yeast (Saccharomyces pastorianus) sinks to the bottom and works best at cooler temperatures, typically between 7°C and