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This article is an excerpt of the book, The Professional Barista's Handbook by Scott Rao. It covers the fundamental knowledge that every successful barista must know, and does so in a succinct and thorough manner. My thanks to Scott for agreeing to share the introductory chapter. —Dan Kehn
When I began in the coffee business fourteen years ago, I read every book I could find about coffee. After reading all of those books, however, I felt as if I hadn't learned much about how to make great coffee. My coffee library was chock-full of colorful descriptions of brewing styles, growing regions, and recipes, with a few almost-unreadable scientific books mixed in. I would have traded in all of those books for one serious, practical book with relevant information about making great coffee in a café.
Fourteen years later, I still haven't found that book. I know many other professionals as well as some obsessive nonprofessionals would like to find that same book I've been looking for. This book is my attempt to give it to them.
There will be many opportunities throughout this book to test and practice different methods of making coffee. To get the most out of the recommended techniques it is useful to have the following equipment on hand.
A "shot" of espresso can mean something different from barista to barista and country to country. For the purposes of this book a shot of espresso will be broadly defined as having the following parameters:
These standards are not recommendations; they are simply meant to reflect common, current practices. Please refer to the appendix for a more comprehensive list of coffee, tea, espresso, and water quality standards.
Note: It is traditional to measure shot size volumetrically, but it is far more useful to measure shots by mass. Volumetric measurements can be misleading due to variations in crema quantity; different amounts of crema can distort one's perception of how much liquid espresso is in a shot.
Extraction is the removal of mass from the grounds. Extracted substances are either soluble or insoluble. In drip coffee and espresso, "solubles" are solids and gases dissolved in the brewing liquid. Soluble solids contribute to taste and brew strength while soluble gases, or volatile aromatics, contribute to aroma.
In drip coffee, "insolubles" are solids and oils held in suspension. Insoluble solids are made up primarily of large protein molecules and fragments of coffee fiber. Insoluble solids and oils combine to form brew colloids. These contribute to aroma, body, and taste and alter flavor by trapping and later releasing soluble solids and gases and by buffering acidity.
In espresso, insolubles are held in either a suspension or an emulsion. The suspended solids are primarily coffee bean cell wall fragments that contribute to body but not flavor. The emulsion is a dispersion of tiny oil droplets surrounded by liquid; these oils contribute to aroma, body, and taste and also act to decrease the perception of bitterness of an espresso by coating the tongue (an espresso tastes more bitter when made into an Americano because the addition of hot water dilutes the oil content, which prevents the oils from completely coating the tongue).