Modern Extraction Techniques: Food and Agricultural Samples (Acs Symposium)

183 Pages·2006·18.8 MB·English

by  Charlotta Turner

Modern Extraction Techniques

926
ACS SYMPOSIUM SERIES
Modern Extraction Techniques
Food and Agricultural Samples
Charlotta Turner, Editor
Uppsala University
Sponsored by the
ACS Division of Agricultural and Food Chemistry
•
American Chemical Society, Washington, DC
Library ofCongressCataloging-in-PublicatioD Data
Modem extraction techniques: food and agricultural samples/ CharlottaTurner, editor;
sponsoredbythe ACS Division ofAgricultural and Food Chemistry.
p. cm.-(ACS symposiumseries; 926)
Includesbibliographicalreferences and index.
ISBN-13: 978-0-8412-3940-1 (alk. paper)
1. Extraction (Chemistry}-Congresses.
I. Turner, Charlotta, 1970-II. American ChemicalSociety. DivisionofAgricultural
and FoodChemistry. III. Series.
TP156.E8M63 2006
660'2842-dc22
2005053077
The paper used in this publication meets the minimum requirements of American
National Standard for Information Sciences-Permanence ofPaper for Printed Library
Materials, ANSI Z39.48-1984.
Copyright©2006 American Chemical Society
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ISBN 10: 0-8412-3940-1
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Foreword
The ACS Symposium Series was first published in 1974 to pro
vide a mechanism for publishing symposia quickly in book form. The
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oped from ACS sponsored symposia based on current scientific re
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ACS Books Department
Preface
This book is based on the symposium entitled "Modern Extraction
Techniques for Food and Agricultural Samples," which was arranged by
the Division of Agricultural and Food Chemistry during the American
Chemical Society's 227th national meeting in Anaheim, California, held
March 28-April2, 2004.
One of the biggest challenges facing the chemical and
pharmaceutical industry today is the need to replace current
environmentally unsustainable and often polluting processes with cleaner
ones. The transition to these new "green" processes will be easier ifthese
technologies are more efficient and less costly than the current ones. In
their book, Green Chemistry: Theory and Practice, Anastas and Warner
(Oxford University Press, 1998) describe the 12 principles of green
chemistry thus:
1. It is better to prevent waste than to treat or clean up waste after it
has been created.
2. Synthetic methods should be designed to maximize the
incorporation of all materials used in the process into the final
product.
3. Wherever practicable, synthetic methods should be designed to
use and generate substances that possess little or no toxicity to
human health and the environment.
4. Chemical products should be designed to effect their desired
function while minimizing their toxicity.
5. The use ofauxiliary substances (e.g., solvents, separation agents,
etc.) should be made unnecessary wherever possible and
innocuous when used.
6. Energy requirements ofchemical processes should be recognized
for their environmental and economic impacts and should be
minimized. Ifpossible, synthetic methods should be conducted at
ambient temperature and pressure.
ix
7. A raw material or feedstock should be renewable rather than
depleting whenever technically and economically practicable.
8. Unnecessary derivatization (use of blocking groups, protection/
deprotection, temporary modification of physical/chemical
processes) should be minimized or avoided if possible, because
such steps require additional reagents and can generate waste.
9. Catalytic reagents (as selective as possible) are superior to
stoichiometric reagents.
10. Chemical products should be designed so that at the end oftheir
function they break down into innocuous degradation products
and do not persist in the environment.
11. Analytical methodologies need to be further developed to allow
for real-time, in-process monitoring and control prior to the
formation ofhazardous substances.
12. Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical
accidents, including releases, explosions, and fires.
Although these principles are mainly for chemical synthesis applications,
they can also be applied to other processes, such as extraction.
The extraction techniques described in this book fulfill many of
Anastas and Warner's principles. For example, the use of supercritical
carbon dioxide (SC-C0 as the sole extraction solvent results in a
2)
nonpolluting process (prevention of waste and safer solvents and
auxiliaries). Other beneficial properties of supercritical CO include fast
2
diffusivity and nearly zero surface tension, which lead to extremely
efficient extractions. In Chapters 2-4, applications of SC-C0 as an
2
extraction solvent are described. Ethanol and water are also
environmentally friendly solvents that can be used as extraction media in
many applications (see Chapters 5-7). Pressurized hot water ("J100-200
°C) in particular is a safe and nonpolluting solvent that has a similar
dielectric constant to polar organic solvents, such as ethanol or acetone.
Hence, pressurized hot water is a viable green alternative to many current
extraction processes that use toxic organic solvents. Similarly,
pressurized hot ethanol is an excellent solvent for the extraction of most
medium polar to nonpolar organic molecules. Some of the techniques,
such as membrane-assisted solvent extraction, described in Chapter 10,
use organic solvents but in much smaller amounts compared to classical
extraction techniques. Other techniques, for instance solid-phase
microextraction and stir-bar sorptive extraction, described in Chapter 11,
use no solvents.
x
Chapters 2-5 and 7 describe an important aspect ofgreen chemistry:
the use ofplants and biomass waste as feedstock for extraction ofvarious
high-value compounds. Hence, instead of chemically synthesizing
pharmaceutical drugs, food-grade antioxidants, or other high-value
compounds of industrial and consumer interest, these compounds are
extracted from renewable natural sources or from industrial wastes or
byproducts using the green solvents and processes described in this book.
This rather novel approach fulfills most of the green chemistry
principles, including prevention ofwaste, atom economy, less hazardous
chemical syntheses, use of renewable feedstocks, and inherently safer
chemistry for accident prevention. More new extraction plants are being
built around the world based on these ecologically sustainable processes.
As the applications described in this book demonstrate, these modem
extraction techniques are not only better for the environment but are also
faster, easier to automate, more sensitive, more selective, and more
robust than classical organic solvent-based extraction techniques. These
qualities are demonstrated in Chapter 8, regarding online coupling of
extraction and analysis techniques, and in Chapter 9, on extraction
methodologies with integrated cleanup steps.
The first chapter gives a short description ofeach ofthe techniques
described in the book. This section is mainly intended for people who are
new to the field. Those already familiar with the various extraction
techniques can go straightto the second chapter.
I would like to acknowledge all the contributing authors. They have
put in a lot of time and effort, which has helped to make this book an
excellent compilation ofdifferent areas ofexpertise. I am also grateful to
the numerous reviewers, who also helped to improve the quality of the
contributions. I would like to thank the American Chemical Society for
publishing this book.
I hope you will enjoy reading the book and that you will find the
information useful for your own activities.
Charlotta Turner
Department ofAnalytical Chemistry
Uppsala University
P.O. Box 599
SE-751 24
Uppsala, Sweden
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Modern Extraction Techniques