Alternatives to conventional food processing RSC green chemistry

Alternatives to Conventional Food Processing


RSC Green Chemistry
Series Editor:
James H Clark, Department of Chemistry, University of York, York, UK
George A Kraus, Department of Chemistry, Iowa State University, Iowa, USA

Titles in the Series:
1: The Future of Glycerol: New Uses of a Versatile Raw Material
2: Alternative Solvents for Green Chemistry
3: Eco-Friendly Synthesis of Fine Chemicals
4: Sustainable Solutions for Modern Economies
5: Chemical Reactions and Processes under Flow Conditions
6: Radical Reactions in Aqueous Media
7: Aqueous Microwave Chemistry
8: The Future of Glycerol: 2nd Edition
9: Transportation Biofuels: Novel Pathways for the production of Ethanol, Biogas and
Biodiesel
10: Alternatives to Conventional Food Processing

How to obtain future titles on publication:
A standing order plan is available for this series. A standing order will bring delivery of
each new volume immediately on publication.

For further information please contact:
Book Sales Department, Royal Society of Chemistry,
Thomas Graham House, Science Park, Milton Road, Cambridge,
CB4 0WF, UK
Telephone: +44 (0)1223 420066, Fax: +44 (0)1223 420247, Email:
Visit our website at />

Alternatives to Conventional
Food Processing
Edited by
Andrew Proctor
Department of Food Science, University of Arkansas, USA


RSC Green Chemistry No. 10
ISBN: 978-1-84973-037-2
ISSN: 1757-7039
A catalogue record for this book is available from the British Library
r Royal Society of Chemistry 2011
All rights reserved
Apart from fair dealing for the purposes of research for non-commercial purposes or for
private study, criticism or review, as permitted under the Copyright, Designs and Patents
Act 1988 and the Copyright and Related Rights Regulations 2003, this publication may not
be reproduced, stored or transmitted, in any form or by any means, without the prior
permission in writing of The Royal Society of Chemistry, or the copyright owner, or in the
case of reproduction in accordance with the terms of licences issued by the Copyright
Licensing Agency in the UK, or in accordance with the terms of the licences issued by the
appropriate Reproduction Rights Organization outside the UK. Enquiries concerning
reproduction outside the terms stated here should be sent to The Royal Society of
Chemistry at the address printed on this page.
The RSC is not responsible for individual opinions expressed in this work.
Published by The Royal Society of Chemistry,
Thomas Graham House, Science Park, Milton Road,
Cambridge CB4 0WF, UK
Registered Charity Number 207890
For further information see our web site at www.rsc.org

Preface
The food industry is a large sector of the international business community,
with food safety and food quality playing a vital role in maintaining profitability. Traditional thermal processing techniques have been effective in
maintaining a safe food supply that is acceptable to consumers. However,
increasing energy costs and the desire to purchase ‘green’ environmentally
responsible products have been a stimulus for the development of alternative
technologies. Furthermore, some products may undergo quality loss at high
temperatures, which can be avoided by many alternative processing methods.
This book is intended to provide food industrialists, professional academics
and graduate students with a review of the major alternative technologies that
could be used to reduce energy costs while maintaining safety and quality. The
introductory chapters provide the reader with an important discussion of the
general principles of green technology underpinning the new technologies and
the legal developments that are influenced by emerging new processing methods. The authors have all made significant contributions to their field and are
well qualified to comment on the value and future significance of green food
processing methods. It is hoped that this book will serve as an introduction for
those interested in gaining an understanding of various ‘green’ alternative food
processing technologies and the their role in the future of the food industry.
Andrew Proctor
University of Arkansas

RSC Green Chemistry No. 10
Alternatives to Conventional Food Processing
Edited by Andrew Proctor
r Royal Society of Chemistry 2011
Published by the Royal Society of Chemistry, www.rsc.org

v

Contents
Chapter 1

Introduction to Green Chemistry
James H. Clark

1

1.1
1.2
1.3

1
5
7
7

Introduction
Resources for Re-manufacturing
Case Studies: Making the Most of Waste
1.3.1 Biofuels – Friend or Foe?
1.3.2 Extraction of Extractable Chemicals from
Biomass
1.4 Conclusion
References
Chapter 2

Comparison of EU and US Law on Sustainable Food
Processing
Michael T. Roberts and Emilie H. Leibovitch
2.1
2.2

Introduction
EU and US Law and Policy on Green Food
Processing Issues
2.2.1 European Union
2.2.2 United States
2.3 Sustainability and the Emerging ‘Green Processing’
2.3.1 Historical Development of the Concept of
Sustainability
2.3.2 History of Sustainability Approach in the US
and in the EU
2.3.3 Sustainable Agriculture in the US and in
the EU
2.3.4 Sustainable Food Production in the US and in
the EU
RSC Green Chemistry No. 10
Alternatives to Conventional Food Processing
Edited by Andrew Proctor
r Royal Society of Chemistry 2011
Published by the Royal Society of Chemistry, www.rsc.org

vii

8
8

8

11

11
15
15
25
34
34
37
41
52


viii

Contents

2.4

Chapter 3

Private Standards
2.4.1 Outgrowth of Sustainability Movement
2.4.2 Applicability of Private Standards to the Food
Sector in the EU and the US
2.4.3 Special Legal and Policy Challenges
2.4.4 International Trade Implications
2.5 Conclusion

2.5.1 Food Law Regulation in the US and the EU
2.5.2 Sustainability and Green Processing
2.5.3 Private Standards
References

57
57

Advances in Critical Fluid Processing
Jerry W. King, Keerthi Srinivas and Dongfang Zhang

93

3.1
3.2

93

Introduction
Current Status of Supercritical Fluid Processing
with CO2
3.3 Subcritical Fluids for Food Processing
3.4 Multi-fluid and Unit Operation Processing Options
3.5 Multi-phase Fluids for Sustainable and ‘Green’ Food
Processing
3.6 Continuous Extraction by Coupling Expellers
with Critical Fluids
3.7 Extraction Versus Reaction Using Pressurized Fluids
3.8 Conclusion
References

Chapter 4

59
63
68
71
71
73
74
75

94
97
109
116
122
129
135
136

Supercritical Fluid Pasteurization and Food Safety
Sara Spilimbergo, Michael A. Matthews and Claudio
Cinquemani

145

4.1
4.2
4.3

147
150
150
152
152
153
153
154

4.4

Introduction
Supercritical Fluids and Green Technology
Current Issues in Food Pasteurization
4.3.1 Food Preservation
4.3.2 Nutritional Properties
4.3.3 Innovative Techniques
4.3.4 Packaging Material
4.3.5 Modified Atmosphere Packaging (MAP)
Mechanisms and Biochemistry of Microbial
Deactivation
4.4.1 Pressure: Permeability, Membrane Disruption
and Extraction
4.4.2 Temperature: Permeability and Extraction

155
156
156

ix

Contents

4.4.3
4.4.4

pH: Cell Metabolism and Protein Activity
Fluid Flow and Contacting: Mass Transfer,
Effect of Media and Kinetics of Pasteurization
4.5 Applications of Supercritical Fluids for Food
Preservation
4.5.1 Biofilms
4.5.2 Modeling Approaches for High-pressure
Microorganism Inactivation
4.5.3 Inactivation of Enzymes
4.5.4 Processes Based on Gases Other Than CO2
4.5.5 Subcellular Systems (Phages, Viruses, Proteins,
Prions, Hazardous Macromolecular Substances)
4.5.6 Treatment of Solid Objects
4.5.7 Unsolved Problems to Date
4.5.8 Outlook and Discussion
4.5.9 Materials and Composites of Future Interest
4.6 Commercial Aspects
4.6.1 Equipment for CO2 Technology
4.6.2 Patents
4.6.3 Commercialization
4.6.4 Economic Aspects
4.7 Conclusion

References
Chapter 5

156
157
157
158
160
160
162
163
164
165
166
166
167
167
170
171
171
173
174

Membrane Separations in Food Processing
Koen Dewettinck and Thien Trung Le

184

5.1

185
185

5.2

5.3

5.4

5.5

Types of Membrane Separation Processes
5.1.1 Pressure-driven Membrane Separations
5.1.2 Other Types of Membrane Separation
Processes
Separation Characteristics
5.2.1 Filtration Modes
5.2.2 Membrane Separation Parameters
Concentration Polarization and Membrane Fouling
5.3.1 Concentration Polarization
5.3.2 Membrane Fouling
Membrane Characteristics and Membrane Modules
5.4.1 Membrane Characteristics
5.4.2 Membrane Modules
Enhancement of Membrane Separation
Performance
5.5.1 Optimization of Operational Parameters
5.5.2 Effects of Feed Properties
5.5.3 Membrane Selection and Surface Modification

186
187
187
188
189
189
190
192
192
193
198
198
203
205


x

Contents

5.5.4

Modification of Membrane Module
Configuration
5.5.5 Flow Manipulation
5.5.6 Applications of External-body Forces
5.5.7 Other Techniques
5.5.8 Selection of the Techniques
5.6 Membrane Cleaning and Sanitation
5.7 Comparison between Membrane Separations and

Corresponding Traditional Technologies
5.7.1 General Applications and Technological
Advantages of Membrane Separations
5.7.2 Economic Aspects of Membrane Processing
Applications
5.8 Applications of Membrane Separations in the Food
Industry
5.8.1 Membrane Processes in the Dairy Industry
5.8.2 Membrane Processes in the Brewing Industry
5.8.3 Membrane Processes in the Winemaking
Industry
5.8.4 Membrane Processes in the Production of
Fruit and Vegetable Juices
5.8.5 Membrane Processes in the Sugar Industry
5.8.6 Membrane Processes in the Production of Soy
Ingredients and Products
5.8.7 Other Applications in the Food Industry
5.9 Conclusions and Perspectives
Acknowledgements
References
Chapter 6

205
215
221
226
227
228
229
229

231
232
232
235
236
237
237
238
238
239
240
240

High Hydrostatic Pressure Food Processing
Stephanie Jung, Carole Tonello-Samson and Marie de
Lamballerie

254

6.1

254

6.2

Introduction
6.1.1 Rationale for the Interest in High-pressure
Processing
6.1.2 Brief Description of Processing Steps and
Concept of Adiabatic Heating

6.1.3 Is HPP a Green (Environmentally Friendly)
Technology?
HPP as an Efficient Tool for Food Microbial Safety
and Shelf-life Extension
6.2.1 Food Safety
6.2.2 Shelf-life

254
255
257
258
258
260


xi

Contents

6.3

Pressure-induced Modifications of Physico-chemical
Properties of Food Compounds
6.3.1 Water
6.3.2 Proteins
6.3.3 Lipids
6.3.4 Carbohydrates
6.3.5 Nutritional Compounds
6.4 Quality Attributes of Pressurized Food Products
6.4.1 Textural and Rheological Properties

6.4.2 Functional Properties
6.4.3 Color
6.4.4 Flavor
6.4.5 Allergenicity/Antigenicity
6.5 Pressure-assisted Extraction of Food Components
6.6 Commercial Applications of HPP
6.6.1 Fruit and Vegetable Products
6.6.2 Meat Products
6.6.3 Seafood
6.6.4 Dairy Products
6.7 HPP Industrial Equipment
6.7.1 Design
6.7.2 Size and Output
6.7.3 Investment and Processing Costs
6.8 Final Remarks
References
Chapter 7

262
263
263
266
266
267
267
267
276
277
280
281

281
282
287
288
289
290
290
290
294
295
296
296

Ohmic Heating of Foods
James G. Lyng and Brian M. McKenna

307

7.1
7.2

307
308
308
309
310
311
311

7.3

7.4
7.5

7.6

7.7

Introduction
Basic Principle of Ohmic Heating
7.2.1 The Electrical Circuit
7.2.2 Mechanism of Ohmic Heating
7.2.3 Factors Influencing Heat Generation Rate
Electrical Conductivity of Foods
Microbial Inactivation During Ohmic Heating
Physical and Chemical Changes to Foods During
Ohmic Heating
7.5.1 Nutritional Effects
7.5.2 Protein Coagulation/Denaturation
Non-preserving Thermal Processes
7.6.1 Parboiling
7.6.2 Blanching
7.6.3 Thawing
Ohmic Sterilization

312
312
312
313
313
314

315
317


xii

Contents

7.7.1

Technological Challenges in Validating Ohmic
Sterilization Procedures
7.7.2 Temperature Measurement
7.7.3 Modelling of Ohmic Sterilization
7.7.4 Markers
7.7.5 Conductivity Differences
7.7.6 Solid–Liquid Flow
7.7.7 Commercial Uptake
7.8 Ohmic Dehydration
7.9 Specific Food Products
7.9.1 Meat
7.9.2 Fish
7.9.3 Milk
7.9.4 Fruit and Fruit Juices
7.9.5 Egg
7.9.6 Vegetables
7.10 Economics of Ohmic Processing
7.11 Ohmic Heater Control Options
7.11.1 Control of Electricity Supply During Ohmic
Heating

7.11.2 Control of the Extent of Pasteurization/
Cooking
7.11.3 Packaging for Ohmic Processing
7.12 Modelling
7.12.1 General Heating Theory
7.12.2 Model Development
7.12.3 Prediction of Temperature Profiles in Liquid
Foods
7.12.4 Prediction of Temperature Profiles in Liquid
Foods Containing Particulates
7.12.5 Modelling the Fouling Behaviour of Ohmic
Heaters
7.12.6 Other Factors
References
Chapter 8

Aqueous Enzymatic Oil Extraction from Seeds, Fruits and
Other Oil-rich Plant Materials
Robert A. Moreau
8.1
8.2
8.3

Introduction
Conventional Extraction of Plant Oils Via Pressing
and/or Hexane Extraction
Some Anatomical Differences Between Oil-rich Fruits
and Oil-rich Seeds

317

317
317
318
318
318
318
319
320
320
321
323
324
325
326
327
328
328
329
329
330
330
330
331
331
333
333
334

341

341
343
345


xiii

Contents

8.4

Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Oil-rich Fruits such as Olives,
Avocados and Palm
8.5 Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Corn Germ
8.6 Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Soybeans
8.7 Aqueous and Aqueous Enzymatic Methods
to Extract Oil from Rice Bran
8.8 Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Peanuts
8.9 Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Rapeseed and Canola
8.10 Aqueous and Aqueous Enzymatic Methods
to Extract Oil from Sunflower
8.11 Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Coconuts
8.12 Aqueous and Aqueous Enzymatic Methods to
Extract Oil from Other Oil-rich Plant

Materials
8.13 Aqueous Microemulsion Methods to Extract Oil
from Peanuts, Sunflower, Canola/Rapeseed and
Corn Germ
8.14 Conclusions
Disclaimer
References
Chapter 9

347
350
355
355
355
355
357
357

358

359
359
361
361

High-intensity Pulsed Light Food Processing
Carmen I. Moraru

367

9.1

367
367

9.2

9.3

Fundamentals of Pulsed Light Technology
9.1.1 Components of Pulsed Light Systems
9.1.2 Spectral and Energetic Characteristics of
Pulsed Light
Microbial Inactivation Using Pulsed Light
9.2.1 Mechanisms of Inactivation
9.2.2 Factors That Affect Microbial Inactivation By
Pulsed Light
9.2.3 Microbial Inactivation Kinetics in Pulsed
Light Treatment
Applications of Pulsed Light Treatment
9.3.1 Pulsed Light Treatment of Liquids
9.3.2 Pulsed Light Treatment of Surfaces
9.3.3 Other Applications of Pulsed Light
Treatment

369
371
371
372
376

377
377
378
380


xiv

Contents

9.4 Commercial Pulsed Light Systems
9.5 Conclusions
References
Chapter 10 Ultrasonic Food Processing
Timothy J. Mason, Larysa Paniwnyk, Farid Chemat and
Maryline Abert Vian
10.1
10.2

Introduction
Fundamentals of Ultrasound for Food
Processing
10.2.1 Power Ultrasound in Liquid Systems
10.2.2 Power Ultrasound in Gaseous Systems
10.3 Applications of Ultrasound in Food Processing
10.3.1 Filtration
10.3.2 Defoaming
10.3.3 Degassing
10.3.4 Depolymerization
10.3.5 Cooking

10.3.6 Demoulding and Extrusion
10.3.7 Cutting
10.3.8 Freezing and Crystallization
10.3.9 Defrosting/Thawing
10.3.10 Drying
10.3.11 Tenderizing Meat Products
10.3.12 Brining, Pickling and Marinating
10.3.13 Sterilization/Pasteurization
10.3.14 Extraction
10.3.15 Emulsification/Homogenization
10.3.16 Miscellaneous Effects
10.4 Conclusion
References
Chapter 11 Microwave Food Processing
Sandrine Perino-Issartier, Jean-Franc¸ois Maingonnat and
Farid Chemat
11.1
11.2

11.3
11.4

Introduction
Theory
11.2.1 Microwave Heat Transfer
11.2.2 Instrumentation
11.2.3 Interaction of Microwave Energy with
Biological Material
Drying
Thawing and Tempering

381
382
382
387

387
388
388
392
392
392
393
394
395
396
397
399
400
401
402
403
404
405
406
406
407
407
407
415

415
416
416
418
420
421
425


xv

Contents

11.5
11.6
11.7

Blanching
Baking
Continuous Pasteurization and Sterilization of
Liquid Food
11.8 Microwave Extraction Techniques
11.8.1 Microwave-assisted Solvent Extraction
(MASE)
11.8.2 Microwave-assisted Distillation (MAD)
11.8.3 Microwave Hydrodiffusion and Gravity
(MHG)
11.8.4 Main Applications of Microwave-assisted
Extraction

References
Subject Index

428
431
434
437
437
438
440
441
444
459



CHAPTER 1

Introduction to Green Chemistry
JAMES H. CLARK
Green Chemistry Centre of Excellence, University of York, York, UK,
YO10 3HW

1.1 Introduction
This brief chapter provides readers who are unfamiliar with ‘green technology’
with a broad understanding of ‘green principles’ to better appreciate the social,
economic and technical context that necessitate the development of alternative
food processing techniques, that reduce energy requirements and/or organic
‘chemical’ solvent use. Life-cycle analysis is also introduced as a key concept in
evaluating the sustainability of any green technology that uses alternative fuels,

or reduces energy use, relative to established technology. The issue of biofuels is
explored and supercritical extraction briefly discussed as an example of green
transformation.
Developing alternative technologies and products are essential to move the
food industry, and other industries, towards sustainable processing and to
reduce commercial energy use and thereby responsibly preserve local and
global environments. This activity is called Green Chemistry, Green Engineering or Sustainable Design1 and requires input from various scientific,
engineering, technological, environmental, economic and legal disciplines. It is
influenced by multiple drivers which affect the creation of new green technologies, which are outlined in Figure 1.1.2
Green chemistry/technology involves the sustainable manipulation of chemicals and materials to value-added products, and therefore involves both new
processes and products. The principles of green chemistry were first outlined in
RSC Green Chemistry No. 10
Alternatives to Conventional Food Processing
Edited by Andrew Proctor
r Royal Society of Chemistry 2011
Published by the Royal Society of Chemistry, www.rsc.org

1


2

Chapter 1
Poor
reputation
and
low uptake
in education

Increasing

producer
responsibility

Increasing
energy
costs

Unreliability
of
supply

Drivers
for
Change

Costs of
petrochemicals

Negative
reporting

Costs of
storing
hazardous
substances

Costs of
waste
disposal

REACH

Figure 1.1

Drivers for change – and green chemistry.

energy

Non-renewables

waste

REDUCE

cost

Figure 1.2

water

risk

Green chemistry reductions.

the 1990’s.3 However, it can also be considered as simply a means of maximizing the efficient use of resources and achieving cost savings, while minimizing negative human and environmental impact (Figure 1.2).4 Green
chemistry requires new, low environment impact technologies to reduce energy
use, facilitate greater use of catalysis and environmentally benign processing
and avoidance of harmful organic solvents. Furthermore, it also involves
reducing the number of processing steps in industrial manufacturing to obtain
the same products in fewer processing steps with less energy and waste

materials.5
Green engineering thus requires the application of fundamental engineering
concepts and practices to reduce the environmental impact of current manufacturing practices.6 The United States Environmental Protection Agency
describes this as the design, commercialization and use of processes and


3

Introduction to Green Chemistry
SOCIAL

ENVIRONMENTAL

Figure 1.3

ECOLOGY

Triple bottom line for sustainable design.

products that are economically feasible to implement, while minimizing pollution production and human/environmental risk by incorporating the principles of process optimization, life cycle assessment and the environmental
economics of processing.
Sustainable design differs from a conventional approach by including a
consideration of the environmental impact on local and global ecosystems. The
‘three pillars of sustainable development’ have been described as society,
ecology and environment,7 often referred to as the triple bottom line of true
process sustainability (Figure 1.3). This eco-efficient tool developed by the
world’s largest chemical company, BASF, integrates these pillars and quantifies
the most sustainable processes by including the health and safety costs.8 Ecological impacts are evaluated by life cycle assessment by considering land use,
raw material consumption, atmospheric emissions and water-borne pollutants.
The situation is made more complex by resource allocation as described by

the food versus fuel debate, or as more correctly stated the food verses fuel
versus feed versus chemicals issue, which stimulated discussion regarding the
use of agricultural land. However, this debate is often oversimplified, as will
now be considered.9,10 As oil reserves are used and the demand from a growing
population increases we may experience conflict in the use of resources. The use
of oil imported for chemicals plastic production and transport fuels is nonsustainable and could have a serious negative environmental and societal
impact if a more efficient use of energy and greater use of alternative renewable
fuels from agriculture, and other resources, is not realized. However, the food
versus fuel debate has increased awareness of the direct and indirect cost of crop
production. Therefore, the environmental footprint of corn production for
bioethanol must include the impact of agrichemicals used to manage the land
and the cost of using more land to grow the food crops that the non-food use of
corn has displaced.9,11 However, there is an overall benefit if displacing a largely exported food crop from a region resulted in more locally produced food
being consumed. It is also important to take into account the environmental
benefits of not using petroleum, including the avoidance of environmental
damage at oil extraction sites. This potential for environmental damage will
become greater as efforts are made to obtain less accessible petroleum sources,
such as in deep water marine environments sources in the Gulf of Mexico, the


4

Chapter 1

Non-food
components
of food crops

Non-food biomass

O

H
OH

Food waste

O

OH
O

O

O

O
OH

Chemical intermediates

Chemically-intense consumer goods

Figure 1.4

Routes to biomass-derived chemicals.

Mediterranean Sea and the Canadian tar sands. The environmental cost of oil
use in food production should also include the carbon footprint developed by
food production that uses oil as an energy source at various life cycle stages.

Nevertheless, there may be certain biofuel crops that can grow on land not
suitable for non-food or non-feed crops, and therefore do not compete with
food crops. Jatropha is an example of a biodiesel feedstock which can be grown
on poor quality land. Sugar cane, which is grown in excess of local food needs,
can be used for bioethanol production, thereby reducing oil use and supporting
the local economy. Although sugars are readily converted to bioethanol, there
is a much greater volume of lignocellulose from food and forestry production
and processing which is a potential source of renewable carbon (Figure 1.4).
Lignocellulose represents a second generation biofuel source, but there are
significant technical challenges in cellulose conversion to bioethanol fuel that
are currently being addressed.
Reducing the global environmental burden is not feasible by population
control or by curbing the significant growth in world prosperity, which is
driven largely by emerging economies, such as those of China, India, Brazil
and Russia. However, some reduction in the global burden could be
achieved by a) reduction in resource use i.e. dematerialization; and b) substitution of traditional resources with greener, more sustainable alternatives i.e.
transmaterialization.


5

Introduction to Green Chemistry
Reduced energy
Minimum
auxiliaries

Pre-Manufacturing

Waste Minimisation

Manufacturing

Intensive Processing
to reduce energy

Product Delivery
Low energy in use

Recyclable or
reusable Products

Figure 1.5

Product Use
End-of-life

Reduced/Degradable
Packaging
Safer Chemicals
Biodegradable
Products

Sustainability improvements across the lifecycle.

Dematerialization steps should be included throughout a product’s lifecycle
to increase process efficiency from the pre-manufacturing stage to a product’s
end-of life (Figure 1.5).12 The final stages of a product’s life should include
some recovery of environmental cost through reuse, recycling, or combustion
for energy. For example, ash from combustion may be used as plant mineral
nutrients or as useful products in themselves e.g. carbon and silicate adsorbents. In contrast, many manufacturing processes produce more waste than

product, with the waste product ratio being 4100 for high value chemicals such
as pharmaceuticals.13 Therefore, sustainable production and consumption
based on traditional non-renewable resources is not reasonable.
The need for more efficient use of limited resources is well illustrated by the
use of many mineral resources commonly used in consumer goods. The present
rates of consumption of platinum, germanium, silver and zinc are not sustainable (Figure 1.6).14 An effective way to show the increasing demand on the
worlds resources is to calculate the number of ‘earth-like planets’ necessary to
sustain the lifestyles of various world regions. This was found to be four for the
world’s richest regions and less than one for the most underdeveloped regions,
with a world average of two.15 The global disparity in resource utilization may
play a role in affecting international social stability but may be reduced by
dematerialization and transmaterialization technologies, i.e. ‘one person’s waste
is another person’s profit’.16 The key requirements of this idealized sustainable
production life cycle are shown in Figure 1.7.
Transportation is an important part of lifecycle costs as unless it can be
achieved at very low resource and environmental cost, it is not sustainable and
limits geographical distribution of life-cycle stages.

1.2 Resources for Remanufacturing
Non-food biomass, agricultural waste, forestry co-products, grasses and other
high volume high turn-over plants are recognized as having the greatest


6

Chapter 1

Figure 1.6

Key elements are running out.

Renewable energy

Renewable resources only

Premanufacturing

Reduce supply chains
Where possible

All auxiliaries
Recoverable and
reusable

Manufacturing

Product
Delivery

Zero inputs in use or
Renewable energy only

Product
Use

End of Life

Any waste must be
Recycled/reused or
Returned to the environment

In a recoverable form

Figure 1.7

A sustainable product life-cycle.

potential as a sustainable carbon source. Such biomass would provide many
organic-based materials and would provide the equivalent to using about 20%
of the world’s oil supply.17–19
Waste management legislation can be of assistance in the transmaterialization or ‘cradle-to-cradle potential of waste use.20 For example, EU legislation
on Waste Electronic and Electrical Equipment (WEEE) require the producer to
take responsibility at the end-of- life.21 This is resulting in logistic development


Introduction to Green Chemistry

7

for WEEE collection and facilitation of collection of scarce inorganic chemicals
from this resource. For example, GSK recycled PET in bottles to improve
waste management for production of recycled soft drink bottles,22 Coca Cola is
building a new factory for processing of waste plastic23 and Hotpoint is producing the backs of washing machines from recycled plastics.24 It is important
that extraction of valuable components has a low environmental impact. A
good example of this is the use of supercritical carbon dioxide to extract liquid
crystal compounds from WEEE.25 LCD displays consist of complex mixture of
organic compounds and their production has a substantial footprint due to the
many steps in manufacture and the waste produced. Therefore, for LC recovery
from WEEE to be environmentally and economically effective, uses need to be
found for more than the organic chemicals that represent a small proportion of
a modern display panel.

The ‘E factor’, devised by Roger Sheldon,26 is a useful first approximation of
the environmental footprint and is expressed as the ratio of waste to product:
E¼

Waste produced throughout manufacturing process
Product

1.3 Case Studies: making the most of waste
1.3.1 Biofuels-Friend or Foe?
Interest in biofuels during the last decade has led to more recent concerns about
using agricultural crops for fuel, due to a belief that this would result in
increasing food prices.
However, there are several reasons why biofuels are attractive alternatives to
fossil fuels.
1. Biofuels are derived from renewable resources; although crop cultivation
and transport consume traditional fossil resources i.e. fertilisers, agricultural chemicals, fuels for agricultural and transport vehicles.17
2. Biofuels can lead to a reduction in carbon emissions and hence climate
change mitigation; Incomplete use of renewable resources at each stages
of the biofuel lifecycle, suggest that carbon dioxide reduction may be less
than anticipated.
3. Biofuels can help to increase farm income and contribute to rural development; many countries are beginning to use land to grow energy crops.
For example, plans to grow sugar cane in Tanzania to reduce their
dependence on foreign oil. Farmers in more prosperous region see energy
crops as an alternative to traditional crops. Co-products from food crops
such as straw and hulls, are being used as fuel products e.g. pelletized
straw for co-firing with coal in electricity power stations.
4. Biofuels can improve energy security; reduced dependence on imported
energy is a priority in many parts of the world.

8

Chapter 1

The ‘biorefinery principle’ will be the means by which fuel, energy and value
added products are obtained from biomass.27at a single integrated site. The
various components and energy will be removed sequentially. Extracted starch,
cellulose and lignin can be processed into various chemicals and materials. In
contrast to the relatively stable composition of petroleum oil, there is compositional variation between species and production seasons. Therefore, there
needs to be flexibility in processing conditions when dealing with various biomass materials. Alternatively, unprocessed biomass can be used in its natural
form or slightly modified to produce useful materials.16,19

1.3.2.

Extraction of Chemicals and Food from Biomass

Isolation of valuable chemicals from biomass could potentially form the initial
processing step of many future biorefineries. Although this already represents
the first stage of all current oil-bearing crop food processing plants (e.g. oilseed
crushing and solvent extraction) and green biorefineries (e.g. green grass
pressing), this concept could be extended to the extraction of high value surface
chemicals from many biomass types. Valuable wax products, for example, have
been extracted from wheat straw using supercritical carbon dioxide,25,28 a green
chemical technology that allows the production of many consumer products
e.g. cosmetics, polishes, nutraceuticals, with no solvent residues. This book
contains two chapters that exhaustively address the use of super-critical carbon
dioxide by the food industry for extraction and pasteurization sterilization,
respectively. The discussion below briefly examines the technology as an
example of green processing.
Carbon dioxide can exist in the solid, liquid or gaseous phase. Furthermore,

if the liquid phase is taken beyond the critical points of temperature and
pressure, a supercritical fluid is formed, which in simple terms can be considered as a dense gas.29
Liquid and supercritical carbon dioxide can be used as an effective extraction
solvent.29 Liquid carbon dioxide behaves like a non-polar solvent, and preferentially dissolves non-polar compounds. This is a very useful property of
carbon dioxide as its solvating power can be easily manipulated by altering
pressure and temperature. Thus non-polar and slightly polar molecules, such as
terpenes, can be soluble in liquid carbon dioxide. Supercritical carbon dioxide
can be a good solvent for many pharmacologically or industrially valuable
molecules, such as the antimalarial compound artemisinin. Even very polar
compounds such as polyphenols can be extracted by supercritical carbon
dioxide at high enough pressures and temperatures.
In a typical supercritical carbon dioxide extraction plant, carbon dioxide is
pumped through columns containing the material to be extracted. What distinguishes liquid and supercritical carbon dioxide from solvents such as hexane
and ethanol is that (i) the carbon dioxide solvent is released as a gas and recycled in the process, so that a solvent-free extract and solvent free extracted
material is produced and (ii) the solvating power of carbon dioxide can be


Introduction to Green Chemistry

9

manipulated readily by temperature, pressure, flow rate and residence time
modification. The extraction can therefore be highly selective, which greatly
reduces the need for further downstream purification and refining.
The remainder of the book discusses the legal context of green food processing and important technologies that are being developed for industrial use
to produce high quality food products. The sustainability, food quality, energy
needs and technical limitations are discussed with an evaluation of how close
each technology is to commercialization, if not already commercialized.

1.4 Concluding Remarks

The modern industrial society is based on the conversion of natural resources
into consumer products by relatively inefficient processing that may have
negative human and environmental consequences. Green chemistry and engineering was established to develop more efficient, environmentally benign
technologies. Some green technologies convert agricultural and food co-products into valuable resources such as biofuels and food and non-food ingredients, to ensure ‘today’s waste will be tomorrow’s resource.30 Other green
technologies are developed to reduce use of energy and organic solvents derived
from fossil fuels. This book addresses the efforts taken by food scientists and
engineers to address this latter objective by processing food with less energy
and solvent costs while maintaining food quality and industry profitability.

References
1. M. A. Abraham, J. H. Clark and N. Winterton, in Green Chemistry
Metrics, ed. A. Lapkin and D. J. C. Constable, Wiley, Chichester, 2008.
2. J. H. Clark, Green Chem., 2006, 8, 17.
3. P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice,
Oxford University, New York, 1998.
4. J. H. Clark, Green Chem., 1999, 1, 1.
5. J. H. Clark and D. J. Macquarrie (eds), Handbook of Green Chemistry and
Technology, Blackwell, Oxford, 2002.
6. (Accessed September 2010).
7. Ecosystems and Human Well-Being, eds. R. Hassan and R. Scholes, Island
Press, Washington, DC, 2007.
8. D. R. Shonnard, A. Kircherer and P. Saling, Environ. Sci. Technol., 2003,
37, 5340.
9. O. Inderwildi and D. King, Energy Environ. Sci., 2009, 2, 343.
10. R. Luque, L. Herrero Davila, J. M. Campelo, J. H. Clark, J. M. Hidalgo,
D. Luna, J. M. Marina and A. M. Romero, Energy Environ. Sci., 2008, 1, 542.
11. W. S. Logan (ed.), Implications of Biofuels Production in the United States,
National Academies Press, Washington, DC, 2008.
12. A. Azapagic, S. Perdan and R. Clift (eds), Sustainable Development in
Practice: Case Studies for Engineers and Scientists, Wiley, Chichester, 2004.