Food emulsions, fourth edition

tood
tmulsions
Fourth
Edition, Revised and Expanded
edited
by
Stig
E.
Friberg
hive
rsity
of
Missouri- Rolla
Rolla, Missouri
and Clarkson University
Potsdam, New York,
U.S.A.
KIre
Larsson
Camurus Lipid Research
Lund, Sweden
Johan
Sjoblom
Norwegian University
of
Science and Technology
Trondheim, Norway
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
The previous edition of this book was published as Food Emulsions: Third Edition,
Revised and Expanded, edited by Stig E. Friberg and Ka
˚

re Larsson, 1997 (Marcel
Dekker, Inc.), ISBN 0-8247-9983-6.
Although great care has been taken to provide accurate and current information,
neither the author(s) nor the publisher, nor anyone else associated with this
publication, shall be liable for any loss, damage, or liability directly or indirectly
caused or alleged to be caused by this book. The material contained herein is not
intended to provide specific advice or recommendations for any specific situation.
Trademark notice: Product or corporate names may be trademarks or registered
trademarks and are used only for identification and explanation without intent to
infringe.
Library of Congress Cataloging-in-Publication Data
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ISBN: 0-8247-4696-1
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Current printing (last digit):
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PRINTED IN THE UNITED STATES OF AMERICA
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
FOOD SCIENCE AND TECHNOLOGY
A
Series
of
Monographs, Textbooks, and Reference
Books
EDITORIAL BOARD
Senior Editors
Owen
R.
Fennema
University of
W
isconsin-Madison
Y.
H. Hui
Science Technology System
Marcus Karel
Rutgers University (emeritus)
Pieter Walstra
Wageningen University
John
R.

Whitaker
University of California-Davis
Additives
P.
Michael Davidson
University of Tennessee-Knoxville
Dairy science
James L. Steele
University of W isconsin-Madison
Flavor chemistry and sensory analysis
John
H.
Thorngate
111
University
food engineering
Daryl B. Lund
University
of
Wisconsin-Madison
Food lipids and flavors
David
6.
Min
Ohio State University
Food proteins/food chemistry
Rickey Y. Yada
University of [Guelph
Health and disease
Seppo Salminen

University of Turku, Finland
Nutrition and nutraceuticals
Mark Dreher
Mead Johnson Nutritionals
Phase transition/food microstructure
Richard
W.
Hartel
University
of
Processing and preservation
Gustavo
V.
Barbosa-Canovas
Washington
Safety and toxicology
Sanford Miller
University
of
Texas-Austin
of
California-Davis
W
isconsin-Madison
State University-Pullman
1.
Flavor Research: Principles and Techniques,
R.
Teranishi,
1.

Hom-
stein,
P.
Issenberg, and
E.
L.
Wick
2.
Principles of Enzymology for the Food Sciences,
John
R.
Whitaker
3.
Low-Temperature Preservation
of
Foods and Living Matter,
Owen
R.
Fennema, William D. Powrie, and Elmer
H.
Marth
4.
Principles of Food Science
Part
I:
Food Chemistry,
edited by Owen
R.
Fennema
Part

II:
Physical Principles of Food Preservation,
Marcus Karel, Owen
R.
Fennema, and Daryl
B.
Lund
5.
Food Emulsions,
edited by Sfig
E.
friberg
6.
Nutritional and Safety Aspects
of
Food Processing,
edited by Steven
R.
Tannenbaum
7.
Flavor Research: Recent Advances,
edited by
R.
Teranishi, Robert
A.
Flath, and Hiroshi Sugisa wa
8.
Computer-Aided Techniques in Food Technology,
edited by lsrael
SWJY

Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
9. Handbook
of
Tropical Foods,
edited by Harvey
T.
Chan
10. Antimicrobials in Foods,
edited by Alfred Larry Branen and P. Michael
Davidson
11. Food Constituents and Food Residues: Their Chromatographic
Determination,
edited by James F. Lawrence
12. Aspartame: Physiology and Biochemistry,
edited by Lewis
D.
Stegink
and L. J. Filer, Jr.
13. Handbook
of
Vitamins: Nutritional, Biochemical, and Clinical Aspects,
edited by Lawrence J. Machlin
14. Starch Conversion Technology,
edited by
G.
M. A. van Beynum and J.
A. Roels
15. Food Chemistry: Second Edition, Revised and Expanded,
edited by
Owen R. Fennema

16. Sensory Evaluation
of
Food: Statistical Methods and Procedures,
Mi-
chael O'Mahony
17. Alternative Sweeteners,
edited by Lyn O'Brien Nabors and Robert
C.
Gelardi
18. Citrus Fruits and Their Products: Analysis and Technology,
S.
V.
Ting
and Russell
L.
Rouseff
19. Engineering Properties
of
Foods,
edited by M. A. Rao and
S.
S.
H.
Rizvi
20. Umami: A Basic Taste,
edited by Yojiro Kawamura and Morley R.
Kare
21. Food Biotechnology,
edited by Dietrich Knon
22. Food Texture: Instrumental and Sensory Measurement,

edited by
Howard R. Moskowitz
23. Seafoods and Fish Oils in Human Health and Disease,
John
E.
Kinsella
24. Postharvest Physiology
of
Vegetables,
edited by J. Weichmann
25. Handbook
of
Dietary Fiber: An Applied Approach,
Mark L. Dreher
26. Food Toxicology, Parts A and B,
Jose M. Concon
27. Modern Carbohydrate Chemistry,
Roger W. Binkley
28. Trace Minerals in Foods,
edited by Kenneth
T.
Smith
29. Protein Quality and the Effects
of
Processing,
edited by R. Dixon
Phillips and John W. Finley
30. Adulteration of Fruit Juice Beverages,
edited by Steven Nagy, John A.
Attaway, and Martha

E.
Rhodes
31. Foodborne Bacterial Pathogens,
edited by Michael P. Doyle
32. Legumes: Chemistry, Technology, and Human Nutrition,
edited by
Ruth
H.
Matthews
33. Industrialization of Indigenous Fermented Foods,
edited by Keith H.
Stein kra
us
34. International Food Regulation Handbook: Policy
Science Law,
edited by Roger D. Middlekauff and Philippe Shubik
35. Food Additives,
edited by
A.
Larry Branen, P. Michael Davidson, and
Seppo Salminen
36. Safety
of
Irradiated Foods,
J. F. Diehl
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
37. Omega-3 Fatty Acids in Health and Disease,
edited by Robert
S.
Lees

and Marcus Karel
38.
Food Emulsions: Second Edition, Revised and Expanded,
edited by
Kire Larsson and Stig
E.
Friberg
39. Seafood: Effects of Technology on Nutrition,
George M. Pigoff and
Barbee W. Tucker
40.
Handbook of Vitamins: Second Edition, Revised and Expanded,
edited by Lawrence J. Machlin
41.
Handbook of Cereal Science and Technology,
Klaus
J.
Lorenz and
Karel
Kulp
42.
Food Processing Operations and Scale-Up,
Kenneth J. Valentas,
Leon Levine, and J. Peter Clark
43.
Fish Quality Control by Computer Vision,
edited by L.
F.
Pau and
R.

Olafsson
44.
Volatile Compounds in Foods and Beverages,
edited by Henk Maarse
45.
Instrumental Methods for Quality Assurance in Foods,
edited by
Daniel
Y.
C. Fung and Richard F. Matthews
46.
Listeria,
Listeriosis, and Food Safety,
Elliot T. Ryser and Elmer H.
Marth
47.
Acesulfame-K,
edited by
D.
G. Mayer and
F.
H. Kemper
48.
Alternative Sweeteners: Second Edition, Revised and Expanded,
ed-
ited by Lyn O'Brien Nabors and Robert
C.
Gelardi
49.
Food Extrusion Science and Technology,

edited by Jozef L. Kokini,
Chi-Tang
Ho,
and Mukund
V.
Kame
50.
Surimi Technology,
edited by Tyre C. Lanier and Chong M. Lee
51.
Handbook
of
Food Engineering,
edited by Dennis
R.
Heldman and
Daryl
B.
Lund
52.
Food Analysis by HPLC,
edited by Leo
M.
L. Nollet
53.
Fatty Acids in Foods and Their Health Implications,
edited by Ching
Kuang Chow
54.
Clostridium botulinum:

Ecology and Control in Foods,
edited by
Andreas
H.
W. Hauschild and Karen L. Dodds
55.
Cereals in Breadmaking: A Molecular Colloidal Approach,
Ann-Charlofte Eliasson and Kire Larsson
56. Low-Calorie Foods Handbook,
edited by Aaron
M.
Altschul
57.
Antimicrobials in Foods: Second Edition, Revised and Expanded,
edited by
P.
Michael Davidson and Alfred Larry Branen
58.
Lactic Acid Bacteria,
edited by Seppo Salminen and Affe von Wright
59.
Rice Science and Technology,
edited by Wayne
E.
Marshall and
James
1.
Wadsworth
60. Food Biosensor Analysis,
edited by Gabriele Wagner and George G.

Guilbault
61. Principles of Enzymology for the Food Sciences: Second Edition,
John
R. Whitaker
62. Carbohydrate Polyesters as Fat Substitutes,
edited by Casimir C.
Akoh and
Barry
G.
Swanson
63. Engineering Properties of Foods: Second Edition, Revised and
Expanded,
edited
by
M.
A.
Rao
and
S.
S.
H.
Rizvi
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
64. Handbook
of
Brewing,
edited by William A. Hardwick
65. Analyzing Food for Nutrition Labeling and Hazardous Contaminants,
edited by Ike J. Jeon and William G. lkins
66.

Ingredient Interactions: Effects on Food Quality,
edited by Anilkumar
G. Gaonkar
67. Food Polysaccharides and Their Applications,
edited by Alistair M.
'Stephen
68. Safety
of
Irradiated Foods: Second Edition, Revised and Expanded,
J.
F.
Diehl
69. Nutrition Labeling Handbook,
edited by Ralph Shapiro
70.
Handbook
of
Fruit Science and Technology: Production, Composition,
Storage, and Processing,
edited by D. K, Salunkhe and
S.
S.
Kadam
71. Food Antioxidants: Technological, Toxicological, and Health Perspec-
tives,
edited by
0.
L. Madhavi,
S.
S.

Deshpande, and D.
K.
Salunkhe
72. Freezing Effects on Food Quality,
edited by Lester
E.
Jeremiah
73.
Handbook
of
Indigenous Fermented Foods: Second Edition, Revised
and Expanded,
edited by Keith
H.
Steinkraus
74. Carbohydrates in Food,
edited by Ann-Charlotte Eliasson
75.
Baked Goods Freshness: Technology, Evaluation, and Inhibition
of
Staling,
edited by Ronald E, Hebeda and Henry
F.
Zobel
76. Food Chemistry: Third Edition,
edited by Owen R. Fennema
77. Handbook
of
Food Analysis: Volumes 1 and
2,

edited by Leo
M.
L.
Nollet
78, Computerized Control Systems in the Food Industry,
edited by Gauri
S.
Mittal
79. Techniques for Analyzing Food Aroma,
edited by Ray Marsili
80. Food Proteins and Their Applications,
edited by Srinivasan Damo-
daran and Alain Paraf
81. Food Emulsions: Third Edition, Revised and Expanded,
edited by Stig
E. Friberg and K5re Larsson
82. Nonthermal Preservation
of
Foods,
Gustavo
V.
Barbosa-Canovas,
Usha R. Pothakamury, Enrique Palou, and Barry G. Swanson
83. Milk and Dairy Product Technology,
Edgar Spreer
84. Applied Dairy Microbiology,
edited by Elmer H. Marth and James L.
Steele
85. Lactic Acid Bacteria: Microbiology and Functional Aspects: Second
Edition, Revised and Expanded,

edited by Seppo Salminen and Atte
von Wright
86. Handbook of Vegetable Science and Technology: Production,
Composition, Storage, and Processing,
edited by D. K. Salunkhe and
S. S.
Kadam
87. Polysaccharide Association Structures in Food,
edited by Reginald
H.
Walter
88. Food Lipids: Chemistry, Nutrition, and Biotechnology,
edited by
Casimir
C.
Akoh and David
B.
Min
89. Spice Science and Technology,
Kenji Hirasa and Mitsuo Takemasa
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
90. Dairy Technology: Principles of Milk Properties and Processes,
P.
Walsfra,
T.
J. Geurfs, A. Noomen,
A.
Jellema, and
M.
A.

J.
S.
van
Boekel
91. Coloring of Food, Drugs, and Cosmetics,
Gisbert Offerstdffer
92.
Listeria,
Listeriosis, and
Food
Safety: Second Edition, Revised and
Expanded,
edited by Elliot
T.
Ryser and Elmer H. Marth
93. Complex Carbohydrates in
Foods, edited by Susan Sungsoo Cho,
Leon Prosky, and Mark Dreher
94.
Handbook of Food Preservation,
edited by
M.
Shafiur Rahman
95.
International Food Safety Handbook: Science, International Regula-
tion, and Control,
edited by Kees van der Heijden, Maged Younes,
Lawrence Fishbein, and Sanford Miller
96.
Fatty Acids in Foods and Their Health Implications: Second Edition,

Revised and Expanded,
edited by Ching Kuang Chow
97.
Seafood Enzymes: Utilization and Influence on Postharvest Seafood
Quality,
edited by Norman
F.
Haard and Benjamin K. Simpson
98.
Safe Handling
of
Foods,
edited by Jeffrey
M.
Farber and €wen C.
D.
Todd
99. Handbook of Cereal Science and Technology: Second Edition, Re-
vised and Expanded,
edited
by
Karel Kulp and Joseph G. Ponte, Jr.
100. Food Analysis by HPLC: Second Edition, Revised and Expanded,
edited by Leo
M.
L. Nollet
101. Surimi and Surimi Seafood,
edited
by
Jae

W.
Park
102. Drug Residues in Foods: Pharmacology,
Food
Safety, and Analysis,
Nickos
A.
8otsoglou and
Dirnitrios
J.
Hetouris
103. Seafood and Freshwater Toxins: Pharmacology, Physiology, and
Detection,
edited by
Luis M.
Botana
104. Handbook of Nutrition and Diet,
Babasaheb
B.
Desai
105.
Nondestructive Food Evaluation: Techniques to Analyze Properties
and Quality,
edited by Sundaram Gunasekaran
106. Green Tea: Health Benefits and Applications,
Yukihiko
Hara
107.
Food
Processing Operations Modeling: Design and Analysis,

edited
by Joseph lrudayaraj
108. Wine Microbiology: Science and Technology,
Claudio Delfini and
Joseph
V.
Formica
109.
Handbook of Microwave Technology for Food Applications,
edited by
Ashim K. Daffa and Ramaswamy
C.
Anantheswaran
1 10. Applied Dairy Microbiology: Second Edition, Revised and Expanded,
edited by Elmer
H.
Marth and James
L.
Steele
11 1. Transport Properties of Foods,
George
D.
Saravacos and Zacharias
B.
Maroulis
1
12. Alternative Sweeteners: Third Edition, Revised and Expanded,
edited
by Lyn O’Brien Nabors
113. Handbook of Dietary Fiber,

edited
by
Susan Sungsoo Cho and Mark
L.
Dreher
114. Control
of
Foodborne Microorganisms,
edited by Vijay
K.
Juneja and
John
N.
Sofos
I
15. Flavor, Fragrance, and Odor Analysis,
edited by Ray Marsili
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
116. Food Additives: Second Edition, Revised and Expanded,
edited by A.
Larry Branen, P. Michael Davidson, Seppo Salminen, and John H.
Thorngate,
111
1 17. Food Lipids: Chemistry, Nutrition, and Biotechnology: Second Edition,
Revised and Expanded,
edited by Casimir C. Akoh and David B. Min
118. Food Protein Analysis: Quantitative Effects on Processing,
R.
K.
Owusu-Apen ten

119. Handbook
of
Food Toxicology,
S.
S.
Deshpande
120. Food Plant Sanitation,
edited by
Y.
H. Hui, Bernard L. Bruinsma, J.
Richard Gorham, Wai-Kit Nip, Phillip
S.
Tong, and Phil Ventresca
121. Physical Chemistry
of
Foods,
Pieter Walstra
122. Handbook
of
Food Enzymology,
edited by John R. Whitaker, Alphons
G. J. Voragen, and Dominic W.
S.
Wong
123. Postharvest Physiology and Pathology
of
Vegetables: Second Edition,
Revised and Expanded,
edited
by

Jerry
A.
Bartz and Jeffrey K. Brecht
124. Characterization
of
Cereals and Flours: Properties, Analysis, and Ap-
plications,
edited by Gonul KaletunG and Kenneth J. Breslauer
125. International Handbook
of
Foodborne Pathogens,
edited by Marianne
0.
Miliotis and Jeffrey W. Bier
126. Food Process Design,
Zacharias B. Maroulis and George D. Sara-
vacos
127. Handbook
of
Dough Fermentations,
edited by Karel Kulp and Klaus
Lorenz
128. Extraction Optimization in Food Engineering,
edited by Constantina
Tzia and George Liadakis
129. Physical Principles
of
Food Preservation: Second Edition, Revised
and Expanded,
Marcus Karel and Daryl B. Lund

130. Handbook
of
Vegetable Preservation and Processing,
edited by
Y.
H.
Hui, Sue Ghazala, Dee M. Graham,
K.
D. Murrell, and Wai-Kit Nip
131. Handbook
of
Flavor Characterization: Sensory Analysis, Chemistry,
and Physiology,
edited by Kathryn D. Deibler and Jeannine Delwiche
132. Food Emulsions: Fourth Edition, Revised and Expanded,
edited by
Stig
E.
Friberg, K6re Larsson, and Johan Sjoblom
Additional Volumes
in
Preparation
Handbook
of
Frozen Foods,
edited by
Y.
H.
Hui, Paul Cornillon, Isabel
Guerrero Legarrefa, Miang Lim,

K.
D. Murrell, and Wai-Kit Nip
Handbook
of
Food and Beverage Fermentation Technology,
edited by
Y.
H. Hui, Lisbeth M. Goddik, Aase Solvejg Hansen, Jytfe Josephsen,
Wai-Kit Nip, Peggy
S.
Stanfield, and Fidel Toldra
Industrialization
of
Indigenous Fermented Foods: Second Edition, Re-
vised and Expanded,
edited by Keith H. Steinkraus
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Genetic Variation in Taste Sensitivity,
edited by
John
Prescott and
Beverly J. Tepper
Handbook
of
Food Analysis: Second Edition, Revised and Expanded:
Volumes
1,
2,
and 3,
edited by Leo

M.
L.
Nollet
Vitamin
E:
Food
Chemistry, Composition, and Analysis,
Ronald
€itenmiller and
Junsoo
Lee
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Preface to the Fourth Edition
Food Emulsions has now reached its fourth edition and very much reflects
the strength of the original publication. Like the previous editions, this book
realizes the value of the long tradition of diversity and excellence of research
and development within the food emulsion industry. This is exemplified by
Chapter 12 on beverage emulsions (Tan), by Chapter 2 on food emulsifiers
(Krog and Sparsø); by Chapter 4 on proteins and polar lipids (Nylander); by
Chapter 1 on food emulsions in general (Dalgleish), and by Chapter 13 on
dressings and sauces (Ford et al.).
There is probably no other emulsion category for which components
have more influence on the properties of crystalline and liquid crystalline
structures, than lipids—Chapter 3 by Larsson on lipid structures is essential
reading.
The first edition of the book introduced advanced chapters on the
fundamentals of food emulsion properties, and this aspect is a conspicuous
feature of the present book with Chapter 5 on destablilizing mechanisms,
Chapter 6 on emulsion stablility, Chapt er 9 on orthokinetic stability,
Chapter 8 on coalescence mechanism, and Chapter 10 on the characteristics

of double emulsions.
Finally, this edition shows strength in an area not repres ented as
strongly earlier: namely, the different methods of characterization and ana-
lysis of emulsions. Chapter 14 on droplet analysis by Coupland and
McClements, Chapter 7 on surface forces in emulsions by Claesson et al.,
Chapter 11 on rheology of emulsions by Princen, and Chapter 15 on NMR in
food emulsions by Balinov et al. give excellent overviews of these methods.
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Needless to say, this book exceeds the quality of its predessors, and
we take this opportunity to recognize the truly outstanding efforts of our
colleagues.
Stig E. Friberg
Ka
˚
re Larsson
Johan Sjo
¨
blom
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Preface to the Third Edition
The economic and social changes during the last decades have changed the
formulation requirements for emulsion systems in the most drastic manner.
Total cost analysis means that the selection of ingredients is no longer
just a question of cost per pound, but the efforts to stabilize the system must
now be complemented by ‘‘hidden’’ costs for long-term technical or com-
mercial failures—sometimes related only indirectly to stability. Social pres-
sure has meant that new components with little or no nutritional value and
with intermolecular interactions different from traditional components must
be accomodated, leading to phenomena for which the earlier methods pro-
vide no appropriate response.

Taken in total, the consequences of change are that compled food
emulsion systems must be analyzed with proper attention to the colloidal
structures involved. Hence, the effects of the specific properties and inter-
actions of polymers and proteins included in this book and the association
structures of lipids leading to the formation of vesicles have received the
attention they merit.
Stig E. Friberg
Ka
˚
re Larsson
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Contents
Preface to the Fourth Edition
Preface to the Third Edition
Contributors
1. Food Emulsions: Their Structures and Properties
Douglas G. Dalgleish
2. Food Emulsifiers: Their Chemical and Physical Properties
Niels J. Krog and Flemming Vang Sparsø
3. Molecular Organization in Lipids and Emulsions
Ka
˚
re Larsson
4. Interactions Between Proteins and Polar Lipids
Tommy Nylander
5. Droplet Flocculation and Coalescence in Dilute Oil-in-Water
Emulsions
Øystein Sæther, Johan Sjo
¨
blom, and Stanislav S. Dukhin

6. Structure and Stability of Aerated Food Emulsions
D. T. Wasan, W. Xu, A. Dutta, and A. Nikolov
7. Surface Forces and Emulsion Stability
Per M. Claesson, Eva Blomberg, and Evgeni Poptoshev
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
8. Coalescence Mechanisms in Protein-Stabilized Emulsions
George A. van Aken
9. Orthokinetic Stability of Food Emulsions
Siva A. Vanapalli and John N. Coupland
10. Recent Developments in Double Emulsions for
Food Applications
Nissim Garti and Axel Benichou
11. Structure, Mechanics, and Rheology of Concentra ted
Emulsions and Fluid Foams
H. M. Princen
12. Beverage Emulsions
Chee-Teck Tan
13. Dressings and Sauces
Larry D. Ford, Raju P. Borwankar, David Pechak,
and Bill Schwimmer
14. Analysis of Droplet Characteristics Using Low-Intensity
Ultrasound
John N. Coupland and D. Julian McClements
15. NMR in Studies of Emulsions with Particular Emphasis
on Food Emulsions
Balin Balinov, Francois Mariette, and Olle So
¨
derman
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Contributors

Balin Balinov Department of Physical and Analytical Chemistry,
Amersham Health, Oslo, Norway
Axel Benichou Casali Institute of Applied Chemistry, The Hebrew
University of Jerusalem, Jerusalem, Israel
Eva Blomberg Royal Institute of Technology, Stockholm, Sweden
Raju P. Borwankar Kraft Foods, East Hanover, New Jersey, U.S.A.
Per M. Claesson Royal Institute of Technology, Stockholm, Sweden
John N. Coupland Department of Food Science, The Pennsylvania State
University, University Park, Pennsylvania, U.S.A.
Douglas G. Dalgleish University of Guelph, Guelph, Ontario, Canada
Stanislav S. Dukhin New Jersey Institute of Technology, Newark, New
Jersey, U.S.A.
A. Dutta Illinois Institute of Technology, Chicago, Illinois, U.S.A.
Larry D. Ford Kraft Foods, Memphis, Tenne ssee, U.S.A.
Nissim Gart i Casali Institute of Applied Chemistry, The Hebrew Uni-
versity of Jerusalem, Jerusalem, Israel
Niels J. Krog Danisco, Brabrand, Denmark
Ka
˚
re Larsson Camurus Lipid Research, Lund, Sweden
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Francois Mariette Cemagref, Rennes, France
D. Julian McCleme nts The University of Massachusetts, Amherst,
Massachusetts, U.S.A.
A. Nikolov Illinois Institute of Technology, Chicago, Ill inois, U.S.A.
Tommy Nylander Department of Physical Chemistry, Center for
Chemistry and Chemical Engineering, Lund University, Lund, Sweden
David Pechak Kraft Foods , Glenview, Illinois, U.S.A.
Evgeni Poptoshev Royal Institute of Technology, Stockholm, Sweden
H. M. Princen Consultant, Flemington, New Jersey, U.S. A.

Øystein Sæther Department of Chemical Engineering, Norwegian Univer-
sity of Science and Technology, Trondheim, Norway
Bill Schwimmer Kraft Foods, Glenv iew, Illinois, U.S.A.
Johan Sjo
¨
blom Department of Chemical Engineering, Norwegian
University of Science and Technology, Trondheim, Norway
Olle So
¨
derman Department of Physical Chemistry, University of Lund,
Lund, Sweden
Chee-Teck Tan Consultant, Middletown, New Jersey, U.S.A.
George A. van Aken Wageningen Centre for Food Sciences, Wageningen,
The Netherlands
Siva A. Vanapalli Depart ment of Chemical Engineering, University of
Michigan, Ann Arbor, Michigan, U.S.A.
Flemming Vang Sparsø Danisco, Brabrand, Denmark
D. T. Wasan Illinois Institute of Technology, Chicago, Illinois, U.S.A.
W. Xu Illinois Institute of Technology, Chicago, Illinois, U.S.A.
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
1
Food Emulsions: Their Structures
and Properties
Douglas G. Dalgleish
University of Guelph, Guelph, Ontario, Canada
I. INTRODUCTION
A. General Introduction
The taste and texture of a processed food perceived by the consumer depend
on a variety of fact ors, important among which are the structures formed by
the constituent materials. The molecules which make up the food interact to

create assemblies of molecules which give the struc ture and hence to a large
extent, determine the texture of the particular food. The ingredients are
assembled during processing, and the structure created by the manufacturer
is governed by the controlled application of one or more effects: physical
(e.g., interparticle forces, phase separations), chemical (e.g., formation of
specific covalent bonds between molecules and particles), or biological (e.g.,
fermentation, enzyme action). It is, of course, the aim of the processor to
generate products of predictable properties from materials whose properties
are themselves understood and to do this as economically as possible.
Among the structures and structure-forming units within foods, emul-
sions play a major part. They are known to impart desirable mouthfeel
characteristics to the food, but, in addition, they are key ingredients in
the formation of structures in certa in products, such as whipped toppings
and ice creams, and more complex products, such as processed cheeses.
Therefore, the understanding of the formation, structures, and properties
of emulsions is essential to the creation and stabilization of structures in
foods. Food emulsions are widely used and are familiar to almost everyone.
In addition to the products just mentioned, whole milk and cream are
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
emulsions, as are butter, margarine, spreads, mayonnaises and dressings,
coffee creamers, cream liqueurs, some fruit drinks and whippable toppings.
Many meat products depend on the presence of emulsions for their
properties, as does bread dough, although in both cases the emulsion
structures can be extremely complex.
The formulation and creation of a food structure involving emulsions
is always a compromise, depending on the desired qualities of the food and
the materials which can be used to create these qualities. In addition to the
essential physical functionality of the materials, it is necessary to take into
account nontechnological, but nonetheless important, factors. Foods con-
tain ingredients which are subject to regulation by appropriate agencies. In

some cases, the use of certain ingredients may be discouraged because of
restrictions imposed by certain religious groups or by public perceptions of
health issues. Furthermore, the processor is constrained by economics and
cannot use expensive materials in product formulations. Last but not least,
the product must be safe from a microbiological point of view; this may
have important consequences because of the need for heat treatments, which
may affect the stability of an emulsion during processing. All of these factors
make the study of the efficient formulation and production of emulsions a
key to the structure and behavior of processed foods.
B. Emulsion Types
An emulsion is a suspension of one phase in another in which it is immis-
cible. One of the phases exists as discrete droplets suspended in the second,
continuous, phase, and there is an interfacial layer between the two phases
which is occupied by some necessary surfactant material. There are three
main types of emulsion which are important, or potentially so, in foods. In
oil-in-water (o/w) emulsions, droplets of oil are suspended in an aqueous
continuous phase. These are the most versatile of the emulsion types; they
exist in many forms (mayonnaises , cream liqueurs, creamers, whip pable
toppings, ice cream mixes), and their properties can be controlled by varying
both the surfactants used and the components present in the aqueous phase.
Water-in-oil (w/o) emulsions are typified by butter, margarines, and
fat-based spreads in general. These depend for their stability more on the
properties of the fat or oil and the surfactant used than in the properties of
the aqueous phase, and because of this, there a re fewer parameters which
can be varied to control their stability. The third of the emulsion types is
water-in-oil-in-water (w/o/w), which is, in effect, an o/w emulsion whose
droplets themselves contain water droplets (i.e., are w/o emulsions). These
are the most difficult emulsions to produce and control, because the water
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
droplets contained in the oil droplets must be stable, as must the oil droplets

contained in the continuous aqueous phase. These emulsions are described
in de tail in Chapter 5 and will not be described further here.
For convenience of description, we may divide o/w food emulsions
into three classes, depending on how they are to be used. The first class
contains emulsions which are end products in themselves. Coffee creamers
and cream liqueurs are relatively simple emulsions whose only requirement
is to remain stable toward creaming and coalescence during their shelf-life
(which, however, may have to be considerable, so that sterility is also impor-
tant). These emulsions present less of a challenge to the processor than do
more complex emulsions; there are a few basic rules of formulation which
allow successful products to be created. The second class of emulsions con-
tains those which can be used as ingredients that participate in forming the
structures of more complex products; that is, other components of the food
(proteins, polysaccharides) form a matrix in which the fat globules are
trapped or with which they interact. Examples are yogurts, processed
cheeses, and other gelled systems containing emulsion droplets which
must interact with other components in the food, but are not destabilized
in the process. Their effect is to alter the rheological pro perties of the gel,
thus creating texture and mouthfeel. In the third class of emulsion, the
droplets are required to create new structures during processing, such as
in ice cream or whipped products (1,2), where the emulsion is destabilized
and further interacts as a means of creating structure in the product. Some
emulsions themselves may also form gels during heating, to create new
structures within foods (3). The requirements for the compositions and
properties of the emulsion droplets are different in these different cases.
However, it is generally necessary for the emulsion droplets to interact
with themselves and/or with the other food components to give the required
structures.
One of the ultimate goals in studying emulsions is to be able to
describe their functionality well enough from first principles to allow the

reduction of the amount of fat in a product without, at the same time,
adversely affecting its texture and organoleptic properties. Similarly, it is
important to anticipate the possibility that emulsions will be used as carriers
of flavors or bioactive materials. To best achieve this, we need to understand
how the fat functions in the original structure and how any material which is
used to replace it should efficiently reproduce all of this function. Ideally, we
would like to be able to define the properties of a product and then to
construct it from a knowledge of the possible ingredients. At the present
time, this is possible for only a few of the simpler systems.
In the text which follows, emphasis has been given to emulsions pre-
pared using milk constituents. This is simply because the milk proteins are
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
by far the most studied of the food proteins (being easily prepared, soluble,
and relatively well behaved once they are in solut ion) and the emulsions
prepared using these materials have a correspondingly voluminous litera-
ture, especially on the subject of ice cream. Reports on the basic properties
of other proteins in emulsions are more fragmentary; this is not to say that
they are unimportant, as the egg-based mayonnaise, to name only one, is a
very widely used product.
II. THE BASIS OF THE BEHAVIOR OF OIL-IN-WATER EMULSIONS
A. General Aspects of Emulsions
Oil and water do not coexist comfortably because of the surface energy
(Gibbs free energy) of the oil–water interface. Because of the interfacial
tension between oil and water, any emulsion will seek to minimize the
interfacial energy by making the interfacial area between oil and water as
small as possible. In the absence of surfactants, this is achieved by coales-
cence of the oil droplets, to give separated layers of oil and water. The
presence of adsorbed surfactant molecules lowers the interfacial tension
between the oil and water phases, so that the driving force for coalescence
is reduced, although never to zero. Many surfactants (e.g., proteins) do not

simply reduce interfacial tension, but actively inhibit coalescence by altering
the viscoelastic properties of the interface. The adsorbed material can also
prevent the close approach of oil droplets by causing the surfaces to have
sufficient charge to repel one another or by creating an extended surface
layer, which also prohibits close approach . Thus, although emulsions tend
to be regarded as thermodynamically unstable, it is possible, by judicious
use of surfactants, to control the kinetics of destabilization and to produce
emulsions with very lengthy shelf lives. Surfactant molecules are amphiphi-
lic; that is, they contain hydrophobic and hydrophilic domains. The former
dissolves in, or interacts with, the hydrophobic surface of the fat or oil,
whereas the latter dissol ves in the aqueous phase. The surfactant therefore
forms a layer on the surfaces of the emulsion droplets. Depending on the
type of surfactant, the adsorbed layer may have a complex structure,
examples of which are described in the following subsections.
The thermodynamic instability leading to coalescence is, however,
only one way in which emulsions can be unstable. Coalescence has the
most drast ic consequences, because it can be reversed only by rehomogeniz-
ing the product, but other mechanisms which are important are creaming
and flocculation. Both of these may promote coales cence and are generally
not to be favored. In creaming, the emulsion droplets do not lose their
identity; they simply redistribute in space and can be returned to their
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
original state by agitation. Flocculation or aggregation arises from a more
permanent physical or chemical interaction between droplets. Flocs are
often not easily redispersed and may, therefore, have a negative effect on
product quality (in soups, sauces, etc.). Because flocs are have a long life-
time, the possibility that rupture of the interfacial layers and coalescence can
occur is enhanced.
The functional behavior of oil-in-water food emulsions is related to
their stability and is controlled by the three parts of the system: the fat or oil

in the interior of the emulsion droplets, the interfacial material between this
lipid material and the continuous aqueous phase, and the aqueous phase
itself. Each of these ‘‘phases’’ may be chemically complex. The lipid may be
partly or wholly crystalline and it may be subject to chemical change such as
lipolysis or oxidation. The interfacial material can be composed of proteins
or of small emulsifiers such as monoglycerides, esters of fatty acids, or
phospholipids, or mixtures of a number of these components. Finally, the
aqueous phase may contain ions, which may interact with and potentially
destabilize the emulsions, or macromolecul es such as polysaccharides, which
may exert either stabilizing or destabilizing effects. Therefore, to understand
the functional properties of the emulsions, it is necessary to understand the
properties of these three parts, individually and collectively.
B. Lipids and Emulsion Functionality
In oil-in-water emulsions, the fat or oil used to form the emulsion affects the
functionality of the emulsion mainly by its de gree of crystallinity, or its
ability to crystallize. Oils which are liquid at the temperature at which
foods are produced and consumed have little effect on the behavior of the
emulsion, because they act essentially as fillers. They can, of course, coalesce
if the fat globules are destabilized and the interfacial layer is sufficiently
weak, but they have little structural significance apart from that. On the
other hand, it is possible for unsaturated liquid oils to undergo oxidation,
and this, in turn, can lead to chemical reactions between the oxidized oil and
a proteinaceous emulsifier (4). The overall effect of the reaction may be to
alter functional properties of the emulsion and the nutritional value of the
food, as well as creating undesirable flavors. The details of how the func-
tional properties of the emulsions are altered by these reactions are not
known, althoug h it is known that the oxidized material is harder to displace
from the interface than the original protein.
Emulsions are nearly always created (e.g., by homogenization) at a
temperature at which all of the fat or oil is in a liquid state, and crystal-

lization then occurs as the pro duct is cooled to the temperature at which it is
stored. Fats and oils which can crystallize in this way can be very important
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
in defining the functionality of the emulsion. By far the best known example
of this is the involvement of partly crystalline fat in the mechanism of partial
coalescence, which stabilizes air bubbles in whipped emulsion products or in
ice creams (1). As the fat crystallizes, the growing crystals star t to break the
interfacial layer of the fat globules (5), and this weakening of the surfaces
allows more efficient destabilization of the emulsion (which in ice cream
mixes has often helped by weakening the interface by small-molecule
surfactants). In addition, the emulsion droplets, because their surfaces are
destabilized, are susceptible to being broken by the attachment to the air–
water interfaces of the air bubbles as the mixture is whipped (6). The semi-
liquid fat cannot wholly coalesce as the interfacial layers are broken,
because of the limited mobility of the crystalline material, but it will partially
coalesce to form a sintered layer around the bubble (7). As long as the
crystals are not melted, the layer will remain intact and stable around the
bubbles. The fat may, of course, be completely crystallized after the partial
coalescence has occurred, but it must be semiliquid for the original phenom-
enon to take place. Fats that are completely solid at the temperature at
which whipping takes place are not efficient at stabilizing the foam.
Equally, fat globule membranes that are too viscoelast ic are too tough to
permit the breakage essential for partial coalescence to occur.
Not all of the lipid components of a food are, howeve r, neutral lipids in
the form of triglycerides. Phospholipids (lecithins) are a second class of lipid
materials that are important in defining the properties of emulsions.
However, in contrast to the fats and oils, which are present in the interiors
of the emulsion droplets, phospholipids are foun d in the interfacial layer (8)
or may even not adsorb at all (9). It should be noted that although the
lecithins are often described as ‘‘emulsifiers,’’ they are not as efficient on

their own as are other small or large molecular emulsifiers. They may, never-
theless, have a moderating effect on the properties of these other materials. It
is also probable that although it is popular to designate a whole range of
phospholipid materials under the heading of ‘‘lecithins,’’ each individual
phospholipid type (with different head groups and fatty acids) will behave
in a way unique to itself. Thus, phosphatidylcholines may behave differently
from phosphatidylethanolamines, and distearyl phosphatidylcholine will
behave differently from dioleyl phosphatidylcholine. Hence, the source and
composition of a lecithin sample will influence its functional properties.
C. The Interfacial Layer
The interfacial layers of many oil-in-water food emulsions contain protein s,
which may be mixed with other surfactant materials (Fig. 1). Proteins are
often present in the raw materials of the food, and the fact that they are
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
excellent emulsifiers enhances their usefulness. The properties of the inter-
facial layers dep end not only on the quantities of materials adsorbed but
also on their prop erties, although we do not completely understand how
the composition and structure of an interfacial layer affect the detailed
properties of an emulsion.
The composition of the interfacial layer is governed mainly by what is
present at the moment the emulsion is formed (10). If proteins are the only
emulsifiers present, they will adsorb to the oil interfaces, generally in pro-
portion to their concentrations in the aqueous phase (11). Certain mixtures
of caseins are anomalous in this respect, because there is preferential
adsorption of b-casein from a mixture of purified a
s
- and b-caseins (12).
Figure 1 Transmission electron micrographs of emulsion systems. (A) and (B)
show milk homogenized using a microfluidizer and centrifuged to separate different
populations of particles. (A) represents the larger fat globules, which float

during centrifugation (scale bar ¼300 nm). (B) shows the sedimenting fraction
from the same milk, where very small fat globules are complexed with protein
particles (scale bar ¼200 nm). (C) shows an emulsion made with soybean oil and
sodium caseinate, with only thin protein layers around the fat droplets (scale
bar ¼200 nm).
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
However, this preferential adsorption does not seem to occur in emulsions
made with sodium caseinate, where the caseins adsorb approximately
according to their ratios in the original caseinate (11). Why this should be
is not clear, although it may be a c onsequence of the different aggregated
states of the caseins in solution (13). It is possible also that the concentration
of casein in the emulsion is important (14).
Small-molecule surfactants have important effects on the composition
of the interfacial layer. Depending on their nature, they may completely
displace adsorbed protein, as in the case of water-soluble surfactants
added after the formation of the interface (15), or partially displace the
protein, as found for oil-soluble surfactants, which must be added before
the interface is formed (16). The effects of these surfactants may not be
confined to simply displacing the proteins; there is evidence for binding to
proteins (17) or a complex displacement reaction, which has been observed
by atomic force microscopy (18). Between the small-molecule surfactants
and proteins in size, there are peptides derived from the proteolytic break-
down of protein molecules. These are also capable of stabilizing emulsions,
although it appears that larger peptides are more effective at this than
smaller ones (19,20). Controlled proteolysis of proteins used as emulsifiers
can give increases in their emulsifying efficiency; this has been observed for
whey proteins (9,21) and soy proteins (22,23).
The direct or competitive adsorption processes during the formation
and storage of an emulsion are, of course, time and path dependent, a
subject on which there is little information. This leads to difficulties when

interpreting the properties of emulsions produced in laboratory conditions,
where it is often the case that ingredients are mixed one at a time, with the
normal industrial situation, where many ingredients are mixed and pro-
cessed at one time. Evidence of time dependence is manifest in the formation
of networks of adsorbed whey proteins on the surfaces of emulsion droplets
as the emulsion is aged (24). The formation of disulfide linkages be tween
adsorbed proteins is probably responsible for the stability of that
adsorbed layer, which is extremely difficult to displace (25). Strong rigid
interfacial layers can also be created by deliberate enzymatic cross-linking
of adsorbed proteins, the best known example of which is the use of
transglutaminase (26).
Details of the structures of the adsorbed layers will be discussed in
Section VI. Briefly, a number of methods has been used to estimate the
dimensions of adsorbed protein monolayers, among them are dynamic
light scattering (27), ellipsometry (28,29), and neutron reflecta nce (30).
The results show that adsorbed layers of protein may be thick compared
to molecular dimensions. By forming a hydrodynamically thick layer and
because they are generally charged, adsorbed proteins can stabilize emulsion
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
droplets by both steric repulsion and electrostatic (charge-repulsion)
mechanisms.
Many, if not all, adsorbed proteins exist in conformations that are
different from their native states (31–33). This is a result of the tendency
of hydrophobic parts of the molecules to be adsorbed to the hydrophobic
interface, with a consequent distortion or disruption of their secondary or
tertiary structures (34). As a result, the properties of the emulsion are not
necessarily the same as those of the parent protein. A more drastic manip-
ulation of the adsorbed layer is possible—by the action of proteolytic
enzymes on the adsorbed proteins. Although it would be difficult to
control on an industrial scale, the partial breakdown of adsorbed casein

by trypsin can considerably enhance the stability of the emulsion toward
Ca
2þ
(35).
D. The Continuous Phase
If the emulsion droplets are to contribute to the struc ture of a food , they
must interact in some way with the other components which are present.
Interactions can occur between the droplets themselves, leading to gelation
or flocculation, but other reactions are possible. If the components of the
food which are in the aqueous phase tend to form gels, then the emulsion
droplets may act in the simplest case as filler particles (i.e., they take up
space but do not interact physically or chemically with the gel) (36). On the
other hand, the interfacial layer of the emulsion droplets may be capable of
interacting with the aqueous-phase components as they gel (37); one obvious
example of this is the gelation of whey protein-based emulsions during
heating, where the protein in the aqueous phase interacts strongly with
the adsorbed whey protein of the emulsion droplet surfaces (38).
Similarly, in the acid gelation of milk, which is part of the manufacture of
yogurt, the globules of milk fat are homogenized and end up with an inter-
facial layer that is composed mainly of disrupted casein micelles (39). This
allows the droplets to interact with free casein micelles as the acidification
proceeds. In yogurt, the interfacial layer remains intact after gelation, but in
the related product, cream cheese, the protein–fat emulsion gel is further
worked, with the result that the interfacial layers are partially broken down,
to give a different structure to the final product.
Interactions between emulsion droplets and macrom olecules in solu-
tion can be aided by the presence of certain ions, of which calcium is the
most important. The presence of these ions may cause flocculation of the
emulsions, or gel formation may be enhanced. A general increase in ionic
strength can destabilize the emulsions (40), but calcium may form more

specific bridges between emulsion droplets and materials in solution (41).
Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.