THE CHEMISTRY OF BEER The Science in the Suds

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1 THE CHEMISTRY OF BEER The Science in the Suds

3 THE CHEMISTRY OF BEER The Science in the Suds ROGER BARTH, PHD

4 Photography by Marcy Barth. Copyright 2013 by John Wiley & Sons, Inc. All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) , fax (978) , or on the web at Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) , fax (201) , or online at Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) , outside the United States at (317) or fax (317) Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at Library of Congress Cataloging-in-Publication Data: Barth, Roger. The chemistry of beer: the science in the suds / Roger Barth, Ph.D. pages cm Includes index. ISBN (paper) 1. Beer. 2. Beer Analysis. I. Title. TP577.B '.42 dc Printed in the United States of America

5 CONTENTS PREFACE ACKNOWLEDGMENTS ABOUT THE AUTHOR PERIODIC TABLE OF ELEMENTS xi xiii xvii xviii 1 INTRODUCTION Brief History The World of Beer Beer and Chemistry Alcohol and Prohibition Beer Tradition 12 Bibliography 13 Questions 15 2 WHAT IS BEER? Beer Ingredients Beer as Food How Beer Is Made 23 Bibliography 31 Questions 31 v

6 vi CONTENTS 3 CHEMISTRY BASICS Atoms Energy Levels and the Periodic Table Compounds Ionic Bonds Covalent Bonds and Molecules Molecular Shape Polarity and Electronegativity Intermolecular Forces Molecular Kinetics Chemical Reactions and Equations Mixtures 53 Bibliography 53 Questions 53 Appendix to Chapter 3: Measurement in Chemistry 56 Numbers 56 International System 57 Mass Relationships in Compounds 63 Composition of Mixtures 64 Bibliography 66 Questions 67 4 WATER The Water Molecule Acids and Bases ph Ions and Beer Water Treatment 79 Bibliography 85 Questions 86 5 INTRODUCTION TO ORGANIC CHEMISTRY Structural Formulas Functional Groups Using the Functional Group Guide 107 Bibliography 110 Questions 110

7 CONTENTS vii 6 SUGARS AND STARCHES Monosaccharides Chirality Disaccharides Polysaccharides 121 Bibliography 126 Questions MILLING AND MASHING Milling Mashing Enzymes and Proteins Mashing Process Dextrins, Light Beer, and Malt Liquor 146 Bibliography 146 Questions WORT SEPARATION AND BOILING Wort Separation Boiling Hops Hot Break Chilling 158 Bibliography 159 Questions FERMENTATION The Anatomy of Brewing Energy and Bonds Glycolysis Ethanol Synthesis Aerobic and Anaerobic Reactions Higher Alcohols Esters 173 Bibliography 174 Questions 175

8 viii CONTENTS 10 TESTS AND MEASUREMENTS Carbohydrate Content Temperature Color Alcohol Content ph Sensory Analysis 192 Bibliography 192 Questions THE CHEMISTRY OF FLAVOR Anatomy of Flavor Taste Aroma Mouth Feel Flavor Units Flavor Compounds in Beer 202 Bibliography 207 Questions THE CHEMISTRY OF BEER STYLES Beer Style Families Realizing a Style 215 Bibliography 222 Questions FOAM AND HAZE Surfaces Surface Energy Surfactants Haze Foam Foam Issues Nitrogen and Widgets 237 Bibliography 238 Questions 238

9 CONTENTS ix 14 BEER PACKAGING Casks and Kegs Glass Metals Aluminum Bottling and Canning Microbe Reduction 249 Bibliography 249 Questions BEER FLAVOR STABILITY Typical Flavor Changes The Role of Oxygen Staling Prevention 260 Bibliography 262 Questions BREWING AT HOME Safety Issues Full Mash Brewing Full Mash Brewing Procedure Extract Brewing Bottling Starter Brewing Systems Recipes 290 Bibliography 293 Questions 293 GLOSSARY 295 INDEX 317

11 PREFACE Whether you are a serious brewer or a person who is just interested in beer, the more you know about the scientific basis of beer, its preparation, and its flavors, the more you will appreciate and enjoy the depth and diversity of the world of beer. Although this book is written largely for the general reader, there is material that will be useful to brewers or people who are considering taking up brewing as homebrewers or as professionals. What distinguishes this book from others on the topic is the logic and sequence of the presentation of chemistry concepts, first atoms, then electrons, then chemical bonds, then molecules. Measurement in Chemistry, the Appendix to Chapter 3, includes units of measure, the mole concept, and mass calculations from chemical formulas. Water alkalinity and hardness measurements are dealt with in Chapter 4. Specific gravity tables and hydrometer corrections are presented in Chapter 10. The basics of computing a beer recipe are covered in Chapter 12. Chapter 16 includes some basic homebrewing recipes. Each chapter has references to some of the key primary and secondary literature and questions intended to help you study the material. Questions marked with an asterisk (*) are more challenging and may depend on supplemental material. Although commercial brewing and homebrewing are discussed to help give context to the material, this is not intended to be a complete textbook on brewing, several of which are mentioned in the chapter bibliographies. Nonetheless, it will be very helpful to read this book before one reads one of the brewing textbooks. Many readers will be college students, some of whom are in the process of developing attitudes and practices regarding the use of alcohol. Alcohol is xi

12 xii PREFACE what it is. It has enriched many lives and ruined many lives, making it much like every other aspect of the human experience. It should not be taken lightly. I hope this book will help its readers attain a thoughtful approach to alcohol. Those who are experiencing difficulties with alcohol should seek assistance from college, pastoral, or health counselors. Roger Barth, Ph.D. Department of Chemistry West Chester University West Chester, Pennsylvania

13 ACKNOWLEDGMENTS Many persons provided support and assistance that greatly enhanced the quality of this book. I deeply appreciate their irreplaceable contributions. Of those, I can acknowledge only a few. Justin Ligi of the West Chester University English Department put in many hours of effort assuring that the chemistry could be understood. Mario and Donna Marie Zoccoli, my eagle-eyed copy readers, went over the manuscript multiple times correcting typographical and stylistic errors and making suggestions for improved readability. Fellow chemists Douglas Hauser (Rutgers), David Cichowicz (La Salle), and Joel Ressner (West Chester) made helpful corrections and suggestions to the chemistry of early versions of the manuscript. Joe Frinzi and his staff at the Mill Creek Avenue Brewery of Yuengling Beer Company in Pottsville, Pennsylvania, gave us a detailed tour. Our local experimental malting barley farmers, Bryan Taylor and Matthew Canan, provided insights as well as samples. David Wilson of Alaskan Brewing Company provided insights from his experience with mash filtration. The librarians at West Chester University, particularly Walter Cressler, did outstanding work tracking down references. Anthropologist Diane Freedman of Philadelphia Community College provided many corrections and helpful suggestions for the first chapter. Regrettably, she passed away a few days before the manuscript was submitted. Gary Beauchamp of the Monel Chemical Senses Center provided helpful insights for Chapter 11. Whitney Thompson of Victory Brewing Company in Downingtown, Pennsylvania, conducted us through the brewery and kindly allowed Marcy to take splendid photographs. Larry Horwitz of the Iron Hill Brewery in West Chester, Pennsylvania, got me interested in flavor chemistry. The Carlsberg Brewery in Ashkelon, Israel, gave me special access to their unique museum/visitor center. Anat Meir, Carlsberg s Laboratory Manager, showed me the brew house and xiii

14 xiv ACKNOWLEDGMENTS laboratory of this ultramodern facility. Fellow author Patrick McGovern ( Uncorking the Past ) provided valuable assistance for the first chapter, and Don Russell (Joe Sixpack column in the Philadelphia Daily News) suggested the subtitle of this book. The visual appeal of this book is due to the artistry and skilled work of my talented wife, Marcy Barth. All photographs not credited to a specific source are hers. Her constant support made this project possible. R. B.

17 ABOUT THE AUTHOR Roger Barth was born in New York City. He attended public schools in Levittown, Pennsylvania, and received his bachelor s degree from La Salle College in Philadelphia. He was awarded a doctorate in physical chemistry at the Johns Hopkins University. After working at UOP Inc. in Des Plaines, Illinois, he did postdoctoral work at University of Delaware and at Drexel University. He has been teaching chemistry at West Chester University of Pennsylvania since 1985, and he created the Chemistry of Beer course in xvii

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