Yeast Technology

459 Pages·1990·10.41 MB·English

by  Gerald Reed

YEAST TECHNOLOGY
YEAST TECHNOLOGY
Second Edition
Gerald Reed
Universal Foods Corporation
Milwaukee, Wisconsin
Tilak W. N agodawithana
Universal Foods Corporation
Milwaukee, Wisconsin
avi
An Book
Published by Van Nostrand Reinhold
New York
To our wives, Helen (in memoriam) and Swarna
AnAVI Book
(AVI is an imprint of Van Nostrand Reinhold)
Copyright © 1991 by Van Nostrand Reinhold
Softcover reprint of the hardcover 1s t edition 1991
Library of Congress Catalog Card Number 90-33144
ISBN 978-94-011-9773-I ISBN 978-94-011-9771-7 (eBook)
DOl 10.1007/978-94-011-9771-7
All rights reserved. No part of this work covered by the copyright hereon
may be reproduced or used in any form by any means-graphic,
electronic, or mechanical, including photocopying, recording, taping, or
information storage and retrieval systems - without written permission
of the publisher.
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Library of Congress Cataloging-in-Publication Data
Reed, Gerald.
Yeast technology/Gerald Reed, Tilak W. Nagodawithana.-2nd ed.
p. cm.
"An AVI book."
Includes bibliographical references.
1. Yeast. 1. Nagodawithana, Tilak W. II. Title.
TP580.R43 1991
664'.68 - dc20 90-33144
CONTENTS
Foreword vn
Preface !x
Introduction 1
Preservation, 2 Nutrition, 3
1 General Classification of Yeast 7
Classification, 10 Impact of Recent Taxonomic
Revision on Industry, 30 Yeasts of Economic
Importance, 31 Culture Collection, 34
2 Yeast Genetics 37
Life Cycle, 38 Techniques Applicable to Yeast Strain
Development,42 Baker's Yeast, 56 Brewer's Yeast, 72
3 Brewer's Yeast 89
General Characteristics of Yeast, 91 Yeast Characteristics
Important for Brewing, 92 Brewing Process, 105
Brewery Contaminants, 121 Biochemistry of
Brewing, 126 Recent Developments, 138
4 Wine Yeasts 151
Ecology, 151 Terminology, 151 Natural Yeasts and
Their Occurrence on Grapes and in Musts, 154
Natural Fermentations, 156 Description of
Species, 157 Selected Pure Culture Yeasts and Active
Dry Wine Yeasts, 159 Preparation of Starter
Cultures, 162 Biochemistry of Wine Fermentation, 165
The Killer Factor, 184 By-products of the Alcoholic
Fermentation and Aroma Compounds, 185
Microbiological Reduction of Acids, 193 Genetic
Manipulation of Wine Yeasts, 198 Microbial Spoilage
vi CONTENTS
of Wines, 199 B6trytis cineria, 201 Biogenic Amines
and Ethyl Carbamate, 202 Technology of Wine
Making, 204 Further Readings, 215
5 Distiller's Yeasts 225
Whisky, 227 Distillates from Sugar-Containing Raw
Materials, 238 Characteristics and Strains of Distiller's
Yeasts, 242 Flavor Compounds, 248 Fermentation
Alcohol as Fuel, 252 Further Readings, 256
6 Baker's Yeast Production 261
Manufacturing Process Outline, 262 Strains, 263
Principles of Aerobic Growth, 264 Raw Materials, 271
Environmental Parameters, 280 Practice of Aerobic
Growth, 284 Further Readings, 309
7 Use of Yeast in Baking 315
Function of Yeast in Baking, 316 Bread Flavor, 334
White Pan Bread Technology, 336 Active Dry Yeast, 359
Further Readings, 362
8 Yeast-Derived Products 369
Flavor Products and Flavor Enhancers, 370 Nutritional
Yeast, 385 Colorants Derived from Yeast, 390
Yeast-Derived Enzymes, 393 Products of
Pharmaceutical and Cosmetic Value, 399
9 Food and Feed Yeast 413
Composition,415 Use of Yeast as a Major Protein
Source,424 Production of Biomass, 426 Further
Readings, 437
10 Use of Yeasts in the Dairy Industry 441
Cheese, 441 Lactose-free Milk, 441 Acidophilus-Yeast
Milk, 442 Kefir,442 Koumiss,444 Desugaring of
Eggs, 444
Index 446
FOREWORD
Yeasts are the active agents responsible for three of our most important
foods - bread, wine, and beer - and for the almost universally used mind/
personality-altering drug, ethanol. Anthropologists have suggested that it
was the production of ethanol that motivated primitive people to settle
down and become farmers. The Earth is thought to be about 4.5 billion
years old. Fossil microorganisms have been found in Earth rock 3.3 to 3.5
billion years old. Microbes have been on Earth for that length of time
carrying out their principal task of recycling organic matter as they still do
today. Yeasts have most likely been on Earth for at least 2 billion years
before humans arrived, and they playa key role in the conversion of sugars
to alcohol and carbon dioxide.
Early humans had no concept of either microorganisms or fermentation,
yet the earliest historical records indicate that by 6000 B.C. they knew how
to make bread, beer, and wine. Earliest humans were foragers who col
lected and ate leaves, tubers, fruits, berries, nuts, and cereal seeds most of
the day much as apes do today in the wild. Crushed fruits readily undergo
natural fermentation by indigenous yeasts, and moist seeds germinate and
develop amylases that produce fermentable sugars. Honey, the first con
centrated sweet known to humans, also spontaneously ferments to alcohol
if it is by chance diluted with rainwater.
Thus, yeasts and other microbes have had a long history of 2 to 3.5
billion years. Humans inherited the microbes along with their foods when
they arrived on Earth probably about a million years ago. It is only about
300 years since Leeuwenhoek discovered "animalcules" and a little more
than 100 years since Pasteur showed the connection between microbes
and fermentation. Since then, knowledge of microbes has accumulated at
an ever-increasing rate, and the present book covering only one group of
microbes - the yeasts - demonstrates the large amount of information cur
rently available on yeast science and yeast technology.
This book is an authoritative, comprehensive condensation of yeast
knowledge. It contains the basic scientific knowledge of yeasts and also
their practical use in the production of bread, wine, beer, and distilled
beverages. There are very good chapters on yeast taxonomy, yeast genetics,
food and feed yeasts, and yeast-derived products. It is truly a comprehen
sive reference on the subject that will be valuable to microbiologists, food
vii
viii FOREWORD
scientists, and others interested in yeast foodlbeverage interactions. It cov~
ers a wide range of yeast technology including nutritional aspects, enzymes
and nucleotides, and the production of flavor~enhancing compounds - all
subjects of great interest to the food industry and to the consumer. The
authors are to be congratulated on a fine addition to the scientific literature.
Keith H. Steinkraus
Cornell University
PREFACE
This book is a broad introduction to the technology of yeast as it is used in
the food and beverage industries. The main features of commercial pro~
cesses are explained and illustrated, but the book is not meant to be an
operating manual. Rather, it will guide the reader through the principles
underlying commercial operations.
Every technology is based on art, science, or a blend of art and science - on
what we commonly call know~how. In yeast technology the transition from
an art to a science has proceeded since publication of the first edition in
1973, due to progress in engineering, yeast genetics, computer applications,
and improvements in analytical techniques. In some instances, scientific
investigations have drastically affected traditional processes; in others,
they have merely provided a rationale for what has been done traditionally.
The first two chapters provide an introduction into the scientific basis of
commercial processes. They deal with the classification, biology, and genet~
ics of yeasts. The following chapters describe the various industries that are
based on the use of yeast, principally baking, brewing, wine making, the
production of distilled beverages, the propagation of food and feed yeasts,
and the production of major yeast~derived products such as yeast extracts
and enzymes.
In addition, the monograph stresses the various scientific and techno~
logical factors common to several industries for which the use of yeast is
basic. It concentrates essential technological information in one handy
volume and provides references for further detailed study. The first edi~
tion of the book has been particularly well received by food technologists
and by chemists, physicists, and engineers interested in the technology of
yeast. We hope that the second edition, which has been completely rewritten,
will be equally well received.
The invaluable help of Mrs. Betty Blue in the preparation of the
manuscript is gratefully acknowledged.
IX
INTRODUCTION
A few definitions are in order. The word ferment means to seethe with
agitation or excitement. It is derived from the Latin fermentum (yeast) or
fermentare (to cause to rise). In its broadest sense fermentation includes all
microbial processes used industrially, as well as fermentations carried out
in the home. It also includes microbial spoilage, as when we speak of
fermented honey or wine turned to vinegar. Food fermentations are the
production of food and beverages. These are the main subjects of this text.
The production of such food ingredients as organic acids, amino acids, and
enzymes will be treated only in outline.
Food fermentations can be usefully divided into alcoholic fermenta
tions carried out by yeasts, acid fermentations carried out by bacteria,
mixed alcoholic/acid fermentations, and fungal (mold) fermentations. It
should be remembered that this division is not clear-cut. For instance, the
production of white bread, rolls, and buns is an alcoholic fermentation.
But sourdough bread and soda crackers are produced by alcoholic/acid
fermentations. Table 1 lists the major food fermentations based on this
classification.
All food fermentations started as natural (spontaneous) fermentations,
that is, fermentation of any raw material by its indigenous microflora.
Examples are the spontaneous alcoholic fermentation of crushed grapes or
the spontaneous "souring" of milk. Such processes can be carried out
successively by mixing a retained portion of the fermented food with fresh
raw material. This food fermentation was the only kind carried out until
the end of the nineteenth century. Even today several industrial processes