Brewing Science A Multidisciplinary Approach

Michael Mosher · Kenneth Trantham

Brewing

Science: A

Multidisciplinary

Approach

Brewing Science: A Multidisciplinary

Approach

Michael Mosher • Kenneth Trantham

Brewing Science:

A Multidisciplinary

Approach

123

Michael Mosher

Department of Chemistry and Biochemistry

University of Northern Colorado

Greeley, CO

USA

Kenneth Trantham

Department of Physics and Physical Science

University of Nebraska at Kearney

Kearney, NE

USA

ISBN 978-3-319-46393-3 ISBN 978-3-319-46394-0 (eBook)

DOI 10.1007/978-3-319-46394-0

Library of Congress Control Number: 2016952006

© Springer International Publishing Switzerland 2017

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Preface

To the Student

What do your professors do at the end of a day at college? Many, the authors

included, will enjoy a craft brew and discuss the day’s successes and opportunities

for improvement. Thus began the discussion for the beginnings of this book.

“Wouldn’t it be awesome,” we thought, “if we could highlight the science that goes

into brewing? The students would just love a brewing science class!” We spent the

next weeks and months designing and planning a course that would illustrate the

interdisciplinary nature of brewing science.

The result is what you will find here. This text represents the topics that are

taught in our courses on an Introduction to Brewing. These courses are very popular

at our institutions and attended by students from almost every major. We have tried

to write from your perspective and provide not only the processes that you will

encounter in the brewery, but also provide the reasons why those processes are

completed and the science behind them. And we have written the text with no

assumptions as to what courses you have previously taken. As topics are intro￾duced, we also introduce the science behind them starting from the basics. As we

have found, teaching “just in time” provides useful examples for you to use to help

you understand the background and the topic in question.

Every few pages, you will find CHECKPOINT boxes. These are designed to

provide you with a chance to take a break and confirm that you have gathered the

key topics of the discussion to that point. This is also how we have constructed the

images that accompany the discussion. When images and tables appear in the text, it

is important to take a break from reading and examine them in detail. Understand

why each is included in the chapter, and why each is presented in the way it is.

(Some professors, the authors included, find great quiz and test questions by

looking at the figures.)

We sincerely hope that you enjoy your studies of this exciting topic. One thing

you will note from the start, brewing science requires an understanding of a nearly

endless range of topics from biology to chemistry to physics to history to almost

every subject taught on campus. The purpose of the book is not to make you, the

student, a physical chemist or a fluids engineer, but it will give you a sense of what

is possible in the brewery. And, it will provide you with an understanding behind

v

why things are done the way that they are in the brewery. Brewing science can be

very technical, but our hope is that you find the subject just as fascinating as we do.

To the Instructor

The first incarnation of the course described by the topics in this text was directed at

the general studies level. The science discussed in that type of course is descriptive

and general in nature. We found that the class attracted a wide range of majors with

varying interest levels. This class is still taught at the University of Nebraska

Kearney. However, we have found that the class also attracted those with more than

a passing interest in brewing and wanted to dive deeper into the rich science that

surrounds the craft brewing industry. So, we have included the detail that is

appropriate for those courses that do this, such as the course taught at the University

of Northern Colorado.

This text is written from a process-centric approach to uncovering the principles

behind brewing science. Instead of a discussion of brewing from the perspective

of the four main ingredients (water, malt, hops, and yeast), this text is formatted and

written from the viewpoint of the steps taken to manufacture beer (malting, milling,

mashing, boiling, etc.). The topics are focused more on the technical aspects and

design principles of brewing. As the students uncover the process of mashing, they

explore the background chemistry needed to fully develop their understanding. As

we explore wort chilling, we dive into the background in thermodynamics that

explains this process. Thus students learn what they need to know as they need to

know it. We have found this process of “just in time” teaching to be very effective.

It produces opportunities to introduce examples, increase motivation, and set high

bars for achievement.

We hope, as well, that this text will provide you, the instructor, with the greater

detail needed behind each of the processes in the brewery and the insight into the

interrelationships between topics in brewing science. We realize that there are parts

of the book that may be mathematically challenging to a general audience. But, the

language of science is mathematics—and with practice and motivation to be suc￾cessful, the general audience can succeed.

Within each chapter are CHECKPOINT questions that provide key questions

that students should be able to accomplish by studying the material preceding them.

At the end of each chapter are questions that expand upon these in-chapter ques￾tions. The summary section at the end of the chapter is also helpful in directing

students as they move through the text.

Finally, each chapter contains at least one laboratory experiment that can help

explain the material in the chapter. Both of the author’s courses in this subject have

related laboratories that we have noted are extremely useful in developing student

interest and motivation and providing confirmation of topics in the course. Addi￾tional “laboratory experiments” can be obtained by modifying the laboratory tests

found in the American Society of Brewing Chemists Methods of Analysis resource.

vi Preface

It is our sincere hope that you, the instructor, find the information in this text to

be helpful to you and your students irrespective of the level of your introductory

course in brewing science. As a standalone text, or used in conjunction with

handouts and additional readings, the material inside should be helpful to your

students. Whether they are beginning their studies for a Diploma in Brewing from

the Institute of Brewing and Distilling, satisfying a general studies requirement, or

reading for interest, the student is sure to find interest in this topic.

Greeley, USA Michael Mosher

Kearney, USA Kenneth Trantham

Preface vii

Contents

1 Introduction to Brewing Science ............................ 1

1.1 Science and the Brewer ............................... 1

1.1.1 The Scientific Method .......................... 1

1.2 What Is Beer?....................................... 3

1.3 Some Common Conventions ........................... 6

1.3.1 Volume ..................................... 6

1.3.2 Temperature.................................. 9

1.3.3 Weight...................................... 11

1.4 Yes Virginia, Beer Contains Alcohol ..................... 12

1.5 A Short History of Beer in the World .................... 15

1.6 History of Beer in the USA ............................ 21

1.7 The Current Market for Beer ........................... 26

2 Beer Styles .............................................. 35

2.1 Judging Beer........................................ 35

2.1.1 Beer Styles .................................. 36

2.1.2 Conforming to a Style .......................... 36

2.2 Parameters that Classify a Beer Style ..................... 38

2.2.1 Physical Parameters............................ 38

2.3 Common Beer Styles ................................. 44

2.3.1 Lagers ...................................... 44

2.3.2 Ales........................................ 47

2.4 Historical Beer Styles ................................. 51

2.5 How to Sample and Taste Beer ......................... 52

2.5.1 Beer Glasses ................................. 53

2.5.2 Serving Temperature ........................... 55

2.5.3 Sampling and Tasting .......................... 56

3 Molecules and Other Matters............................... 63

3.1 The Atom .......................................... 63

3.1.1 Compounds .................................. 66

3.2 Laws that Govern Atoms, Molecules,

and Ionic Compounds................................. 70

ix

3.3 The World of Carbon-Containing Molecules ............... 74

3.3.1 Basic Functional Groups in Brewing ............... 75

3.3.2 Amino Acid Polymers.......................... 81

3.3.3 Drawing Organic Molecules ..................... 82

3.3.4 Naming Organic Molecules...................... 84

3.4 Reactions of Organic Molecules ......................... 86

3.4.1 Oxidation and Reduction ........................ 87

3.4.2 Condensation Reactions......................... 87

3.4.3 Isomerization Reactions......................... 88

3.4.4 Radical Reactions ............................. 88

3.4.5 Maillard Reactions............................. 90

4 Overview of the Brewing Process............................ 95

4.1 Overview of the Process............................... 95

4.1.1 Agricultural .................................. 96

4.1.2 Malting ..................................... 98

4.1.3 Mashing .................................... 100

4.1.4 Lautering and Sparging ......................... 102

4.1.5 Boiling ..................................... 105

4.1.6 Fermentation ................................. 107

4.1.7 Conditioning and Bottling ....................... 108

4.2 Cleaning and Sterilizing ............................... 109

4.3 Inputs and Outputs ................................... 111

4.3.1 Water....................................... 111

4.3.2 Grains and Malts.............................. 112

4.3.3 Hops ....................................... 116

4.3.4 Yeast ....................................... 118

4.3.5 Finished Product .............................. 119

5 The “Food” for the Brew .................................. 125

5.1 Biology of Barley .................................... 125

5.1.1 The Barley Corn .............................. 126

5.1.2 Barley and the Farmer.......................... 127

5.1.3 Barley Diseases and Pests ....................... 129

5.1.4 Sorting and Grading ........................... 130

5.2 Malting Barley ...................................... 132

5.2.1 Germination of Barley.......................... 132

5.2.2 Equipment Used in Malting...................... 135

5.2.3 Problems Arising from Malting ................... 140

5.3 Maillard Reactions ................................... 141

5.4 Water—The Most Important Ingredient ................... 144

5.4.1 Types of Water ............................... 145

5.4.2 What Makes up Water? ......................... 149

x Contents

6 Mashing ................................................ 157

6.1 Purpose of Mashing .................................. 157

6.2 Equipment Used in Mashing............................ 158

6.2.1 Cereal Cookers ............................... 159

6.2.2 Mash Mixer and Mash Kettles ................... 161

6.2.3 Mash Tun ................................... 164

6.2.4 Processes in Mashing .......................... 165

6.3 Enzymes and What They Are ........................... 165

6.4 Chemistry While Resting .............................. 167

6.4.1 Starch ...................................... 167

6.4.2 Phytase ..................................... 173

6.4.3 Proteases and Peptidases ........................ 174

6.4.4 Glucanase ................................... 175

6.4.5 Alpha-Amylase ............................... 175

6.4.6 Beta-Amylase ................................ 177

6.4.7 Mashout .................................... 178

7 Sparging................................................ 183

7.1 Introduction ........................................ 183

7.2 Fluid Physics: Static Case.............................. 184

7.2.1 Pressure ..................................... 184

7.2.2 Pascal’s Law ................................. 185

7.3 Fluid Physics: Dynamic Case ........................... 190

7.3.1 Conservation of Mass: The Continuity Equation ...... 190

7.3.2 Bernoulli’s Principle and Laminar Flow ............ 192

7.3.3 Pressure and Hydraulic Head..................... 195

7.3.4 Head and Pump Dynamics ...................... 197

7.3.5 Darcy’s Law and Laminar Flow in Porous Media ..... 205

7.4 Equipment Used in Sparging and Lautering ................ 215

7.4.1 Batch Sparging ............................... 215

7.4.2 Fly Sparging ................................. 216

7.4.3 Mash Filter .................................. 218

7.5 When Do We Stop Sparging?........................... 219

8 Wort Boiling ............................................ 227

8.1 Why Boil the Wort? .................................. 227

8.2 The Equipment of the Boil ............................. 230

8.2.1 Metals and Heating ............................ 231

8.2.2 Corrosion.................................... 234

8.2.3 Methods for Heating ........................... 235

8.2.4 Direct-Fire Vessels ............................ 237

8.2.5 Calandria .................................... 239

8.2.6 Other Heating Systems ......................... 241

8.3 Heat and Temperature................................. 243

8.3.1 Types of Energy .............................. 243

Contents xi

8.4 Heat Capacity and Heat Transfer ........................ 246

8.4.1 Phase Transition: Boiling ....................... 247

8.4.2 Power ...................................... 248

8.5 Hops in the Boil ..................................... 250

8.5.1 The Hop Flower Revisited....................... 250

8.5.2 Hop Oil Constituents........................... 251

8.5.3 Modified Hop Oils ............................ 254

9 Cooling and Fermenting ................................... 263

9.1 Setting the Stage..................................... 263

9.2 Wort Chilling ....................................... 264

9.2.1 Heat Exchangers .............................. 265

9.3 Equipment Used in Fermentation ........................ 272

9.3.1 Refrigeration ................................. 273

9.3.2 Fermenters, CCV, and Round Squares ............. 294

9.4 Yeast ............................................. 299

9.4.1 Yeast Morphology............................. 300

9.4.2 Yeast Metabolism ............................. 302

9.4.3 Products of Yeast ............................. 307

10 Conditioning ............................................ 313

10.1 Why Condition? ..................................... 313

10.1.1 Secondary Fermentation ........................ 314

10.1.2 Warm Conditioning ............................ 315

10.1.3 Other Adjustments............................. 318

10.2 Equipment Used in Conditioning ........................ 322

10.2.1 The Conditioning Tank ......................... 322

10.2.2 Cask Conditioning............................. 323

11 Packaging............................................... 331

11.1 Introduction ........................................ 331

11.2 Carbonation and Other Gases ........................... 331

11.2.1 Pressure Loss in Transferring Liquids .............. 332

11.2.2 Other Gases Used in “Carbonation” ............... 335

11.3 Packaging .......................................... 338

11.3.1 Small Pack .................................. 338

11.3.2 Large Pack .................................. 346

11.4 Pasteurization ....................................... 349

11.4.1 Tunnel Pasteurization .......................... 352

11.4.2 Flash Pasteurization............................ 353

11.4.3 Other Methods of Pasteurization .................. 355

12 Quality Assurance and Quality Control....................... 359

12.1 What Is Quality?..................................... 359

12.2 Quality Control...................................... 360

12.2.1 Safety in the Brewery .......................... 361

xii Contents

12.3 Quality Assurance.................................... 367

12.4 HACCP Analysis .................................... 369

12.5 Sensory Analyses .................................... 371

Appendix A: Math for the Brewer .............................. 379

Appendix B: R134a Refrigerant Data ............................ 391

Index ...................................................... 405

Contents xiii

1 Introduction to Brewing Science

1.1 Science and the Brewer

Master brewers know a lot about the process and the product that they make. In

most cases, they have spent a considerable number of years at their craft, experi￾menting with different malts and grains, different yeasts, and different processes

until they have arrived at what they consider to be the perfect beer. Any courses or

training that the master brewer takes is extremely rigorous, often involving multiple

months or years of intensive study and potentially even an apprenticeship under an

experienced master brewer. Those years of training to master the art of brewing

beer require not only mastery of the processes and recipes, but also an under￾standing of how the science behind the process results in a particular flavor or

product profile.

Many brewers would agree that knowing the science of brewing is important to

the process of brewing beer. Not only does the science govern how hop oils protect

beer from minor spoilage or how barley must be sprouted before it can be used to

make beer, but the general principles used to practice science guide the brewer

everyday. What principle helps a brewer make everyday decisions?

1.1.1 The Scientific Method

The scientific method is a process of thinking about problems. The method is

outlined in Fig. 1.1. Brewers, or anyone for that matter, that use this process

methodically arrive at the answer to a problem or develop a law or theory based on

observations. This is the same way of thinking about the world around us that

scientists use everyday. An example helps guide us to understanding the scientific

method.

A brewer starts with an observation. For example, suppose they notice that a

recently brewed batch of beer tastes a little like buttered popcorn. The brewer would

then develop an educated guess, called a hypothesis, which would attempt to

© Springer International Publishing Switzerland 2017

M. Mosher and K. Trantham, Brewing Science: A Multidisciplinary Approach,

DOI 10.1007/978-3-319-46394-0_1

1

explain the origin or cause of the off-flavor. For example, the brewer may

hypothesize that the temperature of the water used in the process was too hot. Then,

the brewer would perform an experiment to try to eliminate that flavor, in this case

by reducing the temperature in the next batch of beer. After making more obser￾vations (tasting the beer, running laboratory analysis of flavor components, etc.), the

brewer would then compare those results to the original hypothesis. If the obser￾vations did not fit the original hypothesis, the brewer would modify the hypothesis

and return to the brewery to perform another experiment. Then, they would modify

or recreate the hypothesis and test it out in the brewery. This cyclical process would

continue until the hypothesis did not need modification after repeated experiments.

The brewer would have found the answer to the observation and know what to do if

that situation ever arose again. When the hypothesis is proved in such a manner, it

can be called a law or a theory.

A law is a tested and proven hypothesis that explains the initial problem. Laws

do not explain why the problem occurs, but simply what happens if another thing is

done. In our previous example, the brewer may eventually discover that if the

serving tap for the beer was cleaned immediately before use, the off-flavor would

disappear and arrive at a law: Cleaning the beer tap removes the buttered popcorn

flavor in the beer.

A theory, on the other hand, is a tested and proven hypothesis that explains why

something happens. Theories are the most definitive statements that can be made.

They are not just statements that identify the outcome of a particular step in the

brewery. They predict the outcome by providing a detailed explanation of why that

outcome occurs at any level of observation. To a brewer, and any scientist, a theory

is the best statement that one can have about a process. In our example, the brewer

may develop a theory that explains that bacteria in the tap line cause the off-flavor.

Fig. 1.1 The scientific method. A researcher makes observations, develops a hypothesis, and then

tests the hypothesis with carefully designed experiments. This is a cyclical process that eventually

results in a proven hypothesis that can either be called a theory or a law

2 1 Introduction to Brewing Science

We will use this method as we explore issues surrounding brewing science. We

will learn the existing theories about the science and use the scientific method to

suggest additional directions that the brewer could use to advance their under￾standing of the process. Let us start by examining beer and brewing from its origins

to the present day.

CHECKPOINT 1.1

In your own words, what is the difference between a law and a theory?

Why would a brewer likely be satisfied with a law instead of a theory?

1.2 What Is Beer?

The word “beer” has many possible origins. Most likely this word derives from the

Middle English word bere or from the Old English word bēor. The Old High

German word bior may also be the precursor, as could the Middle Dutch word bēr.

As we can see, the word “beer” has roots from Europe at least as early as the Middle

Ages (fifth to fifteenth century). The words from that time that gave us “beer”

referred to a fermented drink made from malted cereals and flavored with a myriad

of different ingredients. In some cases, roots or other starchy plant materials instead

of cereal grains were used to make the drink.

It is clear that beer is vastly different from wine. Beer is brewed, and wine is not.

Brewing is the process of converting starches into fermentable sugars. In other

words, the starch in grains or other materials is converted into sugars, and then,

those sugars are fermented into an alcoholic beverage. Because fermentable sugars

already exist in fruit, a beverage made by adding yeast to fruits is not brewed, but

still results in an alcoholic beverage we know as wine. While both wine and beer

are alcoholic drinks, making beer requires a few more steps.

The people in the early years of brewing did not use the same recipe to make

beer. One group of people used recipes that vastly differed from other groups. Some

used malted barley; others used roots, wheat, rice, and other grains to create the

beverage. Flavoring agents added to the drink were equally as varied in those early

days and in many cases absent from the finished product. Moreover, the alcohol

content in beer was varied. Some early beers (and some beers that are still found

today) had very little alcohol content, while others were quite potent. It all

depended upon the process, the availability of ingredients, and the tastes of the

peoples that made the drink.

The first recorded recipe The first beers were most likely made in Mesopotamia,

the cradle of civilization, well before the eighteenth century BC. We know this

because references to beer parlors were noted in the Code of Hammurabi. This code

1.1 Science and the Brewer 3