Taste Chemistry

632 Pages·1993·93.114 MB·English

by  Robert S. Shallenberger (auth.)

TASTE CHEMISTRY
TASTE CHEMISTRY
by
Robert S. Shallenberger
New York Agricultural Experiment Station
Cornell University
Geneva, New York (USA)
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V
First edition 1993
© 1993 Springer Science+Business Media Dordrecht
Originally published by Chapman & Hall in 1993
Softcover reprint ofthe hardcover Ist edition 1993
Typeset in 1O(12pt Times, by Alden Multimedia, Northampton
ISBN 978-1-4613-6145-9
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The publisher makes no representation, express or implied, with regard to
the accuracy of the information contained in this book and cannot accept any
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A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication data
Shallenberger, R. S.
Taste chemistry ( by Robert S. Shallenberger.
p. em.
Includes bibliographical references and indexes.
ISBN 978-1-4613-6145-9 ISBN 978-1-4615-2666-7 (eBook)
DOI 10.1007/978-1-4615-2666-7
1. Taste-Physio1ogical aspects. 1. Title.
QP456S53 1992 92-11271
612.8'7-dc20 CIP
Dedication
To those who have, and to those who do
To those who would, and to those who will
Pursue the science of'Sweetness and Light.'
Preface
Theobjectofthis text is to examine,and elaborateonthemeaningofthe
established premise that 'taste is a chemical sense.' In particular, the
major effort is directed toward the degree to which chemical principles
apply to phenomena associated with the inductive (recognition) phase of
taste. A second objective is to describe the structure and properties of
compounds with varying taste that allow decisions to be made with
respect to the probable nature of the recognition chemistry for the
different tastes, and the probable nature of the receptor(s) for those
tastes. A final objective is to include appropriate interdisciplinary
observations that have application to solving problems related to the
chemical nature oftaste.
Tasteis themosteasily accessiblechemical structure-biologicalactivity
relationship, and taste chemistry studies, i.e. the chemistry ofsweetness,
saltiness, sourness, and bitterness, have application to general biology,
physiology, and pharmacology. Because it involves sensory perception,
taste is also ofinterest to psychologists, and has application to the food
and agricultural industries. The largest portion of the text is directed
toward sweetness as, due to economic and other factors, the majority of
the scientific studies are concerned with sweetness.
The text begins with a prologue to describe the problems associated
with the study oftaste chemistry. Then, there is an introductory chapter
to serve as an overview ofthe general interdisciplinary knowledge ofthe
subject. It is followed by a chapter on the fundamental chemical
principles that apply to taste induction chemistry.
A series of chapters then present and discuss the structure and
propertiesofcompoundsthatelicitvarious tastes. Theirprimary purpose
is to demonstrate possible relations between structure and taste activity,
particularly sweetness. These relations seem relatively straightforward in
vii
Vlll TASTE CHEMISTRY
some cases, but lead to ambiguity, uncertainty, and contradiction in
others. An example is the oftenconfusing structural identityand taste of
the syn- and anti-oximes, amino acid enantiomers, and peptides. A
second purpose is that, on perusing the text, further possibleinsight into
structure-taste activity relations may occur to the reader, and he/she will
have available sufficient structure-taste relations to afford preliminary
examination ofthose thoughts.
These are followed by a chapter that elaborates upon the common
chemical features associated with each taste, and the next chapter
presents the probable chemical mechanism(s) for them. A penultimate
chapter introduces the role that symmetry, chirality, and topology seem
to have in taste chemistry. The final chapter presents the probable
chemical nature oftaste receptors, and anepilogue contains adiscussion
ofthe extent to which problems associated with comprehension oftaste
seem to be resolved by application ofchemical principles.
A glossary with definitions of stereochemical and other terms is
included,and thedefinitionsarecross-referencedto the text. Theneedfor
the glossary arose with the decision not to digress too far from the taste
chemistry theme because an abstract symmetry or chirality principle
needed to be introduced. Itis hoped that the glossary treatment, plus the
context with which the terms are used in the main body of the text are
sufficient to convey their meaning.
All sections in the text are identified with a number code for cross
referencepurposes. Thepagenumberforeachsectioncan befound in the
textcontentsat thefront ofthebook. Thereisalsoanauthorindexanda
subject index.
ACKNOWLEDGEMENTS
The author thanks the associations, companies, and organizations that
granted permission to reproduce copyright material. They are the
Academic Press, The American Chemical Society and its Division of
Chemical Education, the American Pharmaceutical Association, Walter
deGruyter& Company,TheMacMillanPublishingCompany,McGraw
Hill, Inc., Oxford University Press, Pergamon Press, Inc., The
Psychonomic Society, The Royal Society of Chemistry, Springer
Verlag, and Verlagsgesellschaft mbH.
The author is grateful to colleagues who submitted copies ofreprints,
thoughts, caveats, and copiesofmanuscripts not yet published. Theyare
PREFACE IX
Hans-Dieter Belitz, James N. BeMiller, Gordon G. Birch, James R.
Daniel, Grant E. DuBois, Jan R. Frijters, Dieter Glaser, Murry
Goodman, Leslie Hough, Michael G. Lindley, Frieder Lichtenthaler,
JA. Maga, Mohamed Mathlouthi, Lucio Merlini, Tetsou Suami, P.A.
Temussi, Arnold van der Heijden, Henk van der WeI, and Thomas J.
Venanzi. Hopefully, their valued contributions have neither been
misrepresented nor misinterpreted. My long-time colleague, Terry E.
Acree has been most helpful, and I gratefully acknowledge his
encouragement and interest, but in particular I valued our many
discussions.
The help and encouragement from Grace Fox Parsons (Gracie),
another long time colleague, is fondly acknowledged. I thank Stuart G.
Reevesfordiligentperusalofthemanuscript,andconstructivecomments
on the chemistry and general organization. In particular, help with the
significance of solution recognition reactions versus binding reactions,
from the biochemist's viewpoint, proved to be valuable. Last, but not
least, I thank Mary van Buren, and Jeanne Samimy, of the New York
State Agricultural Experiment Station Library for their help.
Robert S. Shallenberger
Geneva, NY (USA)
Table ofContents
Preface vii
Prologue
1. CHEMICAL NATURE, PSYCHOLOGY, AND
PHYSIOLOGY OF TASTE 5
1.1 GENERAL NATURE OF TASTE 5
1.1.1 The basic tastes 5
1.1.2 Definition ofsweetness, saltiness, sourness, and
bitterness 8
1.1.3 Taste profiles and taste spectra 8
1.1.3.1 Taste profiles 8
1.1.3.2 Taste spectra 9
1.1.3.3 Taste spectra specificationfor basic tastes 10
1.1.4 Morphological receptors for the basic tastes 12
1.1.4.1 Distribution oftastes 12
1.1.4.2 Distribution ofreceptors 12
1.1.4.3 Response oftaste buds to different stimuli 13
1.1.5 Taste 'blindness' 16
1.1.6 Taste blocking and modification 16
1.1.6.1 Taste blocking 17
1.1.6.2 Taste modification 19
1.2 TASTE MEASUREMENT 20
1.2.1 Threshold determinations 21
1.2.2 Comparison tests 23
1.2.3 Scaling procedures 23
1.3 PSYCHOPHYSICAL PRINCIPLES 23
1.3.1 Psychophysical laws 24
xi
xu TASTE CHEMISTRY
1.3.2 Adaptation and cross-adaptation 29
1.3.2.1 Cross-adaptation to saltiness 31
1.3.2.2 Cross-adaptation to sourness 32
1.3.2.3 Cross-adaptation to bitterness 32
1.3.2.4 Cross-adaptation to sweetness 32
1.3.2.5 Effect ofadaptation on other taste qualities 33
1.3.2.6 Mechanism ofadaptation 33
1.3.3. Taste ofmixtures 34
1.4 TRANSDUCTION 35
1.5 OVERVIEW OF THE TASTE OF CHEMICALS 38
1.5.1 Chemicals that taste sweet, salty, sour, and bitter 39
1.5.2 Taste transformations 41
1.5.3 Common chemical sense taste attributes 43
1.6 CHEMICAL INTERRELATIONS AMONG THE
FOUR TASTES 45
2. TASTE CHEMISTRY PRINCIPLES 47
2.1 CHEMICAL EQUIVALENTS 47
2.2 WATER SOLUBILITYAND REACTIONS IN WATER 48
2.3 pH, pK, AND TOTAL ACIDITY 49
2.3.1. Definition ofan acid and base 49
2.3.2 pH 50
2.3.3 pK 51
2.3.4 Total acidity 52
2.4 MASS ACTION AND CHEMICAL EQUILIBRIA 52
2.4.1 Mass action 52
2.4.2 Chemical equilibria 54
2.4.2.1 Chemical activity 55
2.4.2.2 Taste chemicalequilibria 56
2.5 CHEMICAL KINETICS 56
2.5.1 Zero-order reactions 57
2.5.2 First-order reactions 57
2.5.3 Calculation offirst-order velocity constants 59
2.5.4 Calculation offirst-order equilibrium constants 60
2.6 THERMODYNAMICS 61
2.6.1 Enthalpy 61
2.6.2 Entropy 62
2.6.3 Significance offree energy in taste 63
CONTENTS Xlll
2.7 NATURE OF CHEMICAL BONDS AND CHEMICAL
REACTIONS 64
2.7.1 The covalent bond 64
2.7.2 The ionic (electrostatic) bond 65
2.7.3 The hydrogen bond 65
2.7.3.1 Nature ofthe hydrogen bond 65
2.7.3.2 Strength ofthe hydrogen bond 67
2.7.3.3 Inter- andintramolecular hydrogen bonds 68
2.7.3.4 Cooperative hydrogen bonding 68
2.7.4 The hydrophobic bond 69
2.7.5 van der Waals interactions 70
2.7.6 Charge transfer reactions 72
2.7.7 Displacement reactions 72
2.8 INDUCTIVE AND RESONANCE EFFECTS 73
2.9 ISOSTERIC GROUPS 76
2.10 TASTE STRUCTURE-ACTIVITY THEORY 77
2.10.1 Occupancy theory 77
2.10.2 Hit-run theory 79
2.10.3 Rate theory 79
2.10.4 Inhibition 79
2.10.4.1 Competitive inhibition 80
2.10.4.2 Noncompetitive inhibition 81
2.10.4.3 Uncompetitive inhibition 81
2.11 SYMMETRY AND CHIRALITY 82
2.11.1 Principles ofsymmetry 84
2.11.1.1 Rotation 85
2.11.1.2 Reflection 87
2.11.1.3 Rotation-reflection 87
2.11.1.4 Rotation-inversion axes 88
2.11.1.5 Two-dimensional symmetrypoint groups 89
2.11.1.6 Three-dimensional symmetrypointgroups 91
2.11.2 Dissymmetry and asymmetry 93
2.11.3 Chirality 93
2.11.3.1 Demonstration ofchirality 94
2.11.3.2 Classification ofsymmetry andchirality 95
2.11.3.3 The asymmetric carbon atom 96
2.11.3.4 Sources ofchirality in compounds 99
Helical arrays ofatoms 99
Differential labeling 100
Conformationalskewing 100