Emerging Technologies in Meat Processing E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Serie: IFST Advances in Food Science
- Sprache: Englisch
Meat is a global product, which is traded between regions, countries and continents. The onus is on producers, manufacturers, transporters and retailers to ensure that an ever-demanding consumer receives a top quality product that is free from contamination. With such a dynamic product and market place, new innovative ways to process, package and assess meat products are being developed. With ever increasing competition and tighter cost margins, industry has shown willingness to engage in seeking novel innovative ways of processing, packaging and assessing meat products while maintaining quality and safety attributes.
This book provides a comprehensive overview on the application of novel processing techniques. It represents a standard reference book on novel processing, packaging and assessment methods of meat and meat products. It is part of the IFST Advances in Food Science book series.
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Veröffentlichungsjahr: 2016
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Table of Contents
Cover
Title Page
Copyright
About the IFST Advances in Food Science Book Series
List of contributors
Chapter 1: Emerging technologies in meat processing
1.1 Context and challenges
1.2 Book objective
1.3 Book structure
1.4 Conclusion
Part I: Novel processing techniques
Chapter 2: Irradiation of meat and meat products
2.1 Summary
2.2 Theory of irradiation of foods
2.3 Irradiation equipment
2.4 Future role for irradiation in the preservation of foods
References
Chapter 3: High-pressure processing of meat and meat products
3.1 Introduction
3.2 Theory of high-pressure preservation and decontamination of foods
3.3 High-pressure applications
3.4 High-pressure equipment
3.5 Future role for high pressure in the preservation and decontamination of foods
References
Chapter 4: Electroprocessing of meat and meat products
4.1 Introduction to electroprocessing technologies
4.2 Non-thermal electroprocessing of meat
4.3 Thermal electroprocessing (i.e. electroheating) of meat
4.4 Future of electroprocessing of meat
4.5 Equipment suppliers
Acknowledgements
References
Chapter 5: Application of infrared and light-based technologies to meat and meat products
5.1 Introduction
5.2 Theory of UV, IR, and high-intensity light pulse preservation of foods
5.3 Infrared radiation
5.4 Ultraviolet radiation
5.5 High-intensity light pulses
5.6 Future role for UV, IR, and high-intensity light pulses in the preservation of foods
References
Chapter 6: Ultrasound processing applications in the meat industry
6.1 Introduction
6.2 Fundamentals of ultrasound processing
6.3 Ultrasound processing equipment
6.4 Ultrasound for decontamination of meat
6.5 Applications of ultrasound in meat processing
6.6 Concluding remarks
References
Chapter 7: Application of hydrodynamic shock wave processing associated with meat and processed meat products
7.1 Introduction
7.2 Applicability of hydrodynamic shock waves on meat and meat products
7.3 Approaches to the generation of hydrodynamic shock waves, and the theory and mode of action relative to muscle food applications
7.4 Advantages and disadvantages of hydrodynamic shock wave
7.5 Case studies: hydrodynamic shock wave treatment of meat products
7.6 Developmental advances in hydrodynamic shock wave equipment
7.7 Brief overview of available hydrodynamic shock wave equipment and manufacturers of hydrodynamic shock wave equipment
References
Chapter 8: Robotics in meat processing
8.1 Introduction
8.2 Application of robotics in meat processing
8.3 Mechatronic and robotic systems in the food industry
8.4 Case studies
8.5 Future role for robotics in the processing of meat and meat products
References
Part II: Novel Packaging and meat functionality
Chapter 9: Packaging systems and materials used for meat products with particular emphasis on the use of oxygen scavenging systems
9.1 Introduction
9.2 Case-ready packaging
9.3 Theory of MAP/oxygen scavenging technology for meat products
9.4 Future role for novel packaging systems in the preservation of meat
References
Chapter 10: Smart packaging solutions encompassing nanotechnology
10.1 Introduction
10.2 Smart packaging
10.3 Conclusion
References
Chapter 11: Probiotic functionality in meat
11.1 Introduction
11.2 Ecology of gastrointestinal tract (GIT)
11.3 Identification of potential microorganisms
11.4 Selection of probiotics
11.5 Probiotic meat products
11.6 Functionality of probiotics
11.7 Disease prevention by probiotics
11.8 Role of probiotics in function food development
11.9 Conclusion
References
Part III: Assessment techniques for meat quality and safety
Chapter 12: Rapid methods for microbial analysis of meat and meat products
12.1 Introduction
12.2 Theory of high rapid methods
12.3 Rapid method tools
12.4 Future role for rapid methods in foods safety
References
Chapter 13: The use of hyperspectral techniques in evaluating quality and safety of meat and meat products
13.1 Introduction
13.2 Hyperspectral techniques
13.3 Applications in evaluating quality and safety of meat and meat products
13.4 Advantages and disadvantages of hyperspectral techniques in meat applications
13.5 Conclusion
Acknowledgments
References
Chapter 14: Online meat quality and compositional assessment techniques
14.1 Summary
14.2 Introduction
14.3 In vivo methods of carcass evaluation
14.4 Post-mortem compositional analysis
14.5 Conclusions
References
Chapter 15: Meat authenticity
15.1 Introduction
15.2 Theory of authenticity in the meat industry
15.3 Authenticity methods
15.4 Future role for authenticity in food
Reference
Chapter 16: Regulation and legislative issues
16.1 Introduction
16.2 Overview of principles of food regulation
16.3 Food safety regulation within the European Union
16.4 Meat inspection
16.5 Marketing challenges: reports of adverse health effects
16.6 Conclusion
References
Index
End User License Agreement
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Guide
Cover
Table of Contents
Begin Reading
List of Illustrations
Chapter 2: Irradiation of meat and meat products
Figure 2.1 Slugs (small cylinders) of cobalt-60, which are the building blocks of the radiation source rack.
Figure 2.2 Buildup of a typical cobalt source rack from slugs, pencil, and modules.
Figure 2.3 Decay scheme of radionuclide cobalt-60.
Figure 2.4 Depth–dose distribution in a product container irradiated from two sides with a cobalt-60 source. The curve “
a
”' represents the depth–dose distribution when the product is irradiated from one side only (source is at position “
a
”). Similarly, when the source is at position “
b
”, the dose distribution is represented by the curve “
b
”. The total dose due to irradiation from two sides is then shown as the curve “
a
+
b
”. Notice that this total dose is much more uniform than that of single-side irradiation (curves “
a
” and “
b
”).
Figure 2.5 Schematic diagram of a typical panoramic, wet-storage gamma irradiation facility.
Figure 2.6 Direct current electron beam operating principles.
Figure 2.7 Percentage depth–dose curves for a single-side electron irradiation of water.
A
, 1.8 MeV;
B
, 4.7 MeV;
C
, 10.6 MeV.
Figure 2.8 Depth–dose curves for two-side irradiation of a unit-density material with 5 MeV electrons.
Figure 2.9 Forward peaked emission of 5.0 MeV X-rays.
Figure 2.10 Electron beam, gamma ray, and X-ray penetration.
Figure 2.11 Rotation of product on a Palletron
TM
in front of X-ray target.
Chapter 3: High-pressure processing of meat and meat products
Figure 3.1 Diagram of the principle of high-pressure equipment
Figure 3.2 Variation in resistance of various strains of foodborne pathogens
Figure 3.3 Salmonella outbreaks with “strong evidence” and their foodstuff identified origin in the European Union in 2010
Figure 3.4
Campylobacter
outbreaks with “strong evidence” and their foodstuff identified origin in the European Union in 2010
Figure 3.5 Typical inactivation curve obtained following heat or high-pressure treatment.
Figure 3.6 Microbial inactivation curves modeled using Weibull equation:
p
< 1 concave upwards curve;
p
> 1 concave downwards curve;
p
= 1 linear curve with
δ
=
D
of the first-order model.
Figure 3.7 Pressure–temperature contour plot (iso-
D
contour) representing pressure (a) and temperature (b) combinations inducing the same microbial inactivation.
Figure 3.8 Phase diagram of water under pressure
Figure 3.9 Estimation of HPP food global production in 2009 (tons/year)
Figure 3.10 Carbon dioxide temperature–pressure phase diagram
Figure 3.11 Hypothesized mode of action of carbon dioxide in microbial decontamination by HPCD
Figure 3.12 Distribution of industrial high-pressure processing equipment (number of installations) around the world
Chapter 4: Electroprocessing of meat and meat products
Figure 4.1 An illustration of the application differences between ohmic, radio frequency and microwave heating of materials. (a) Frequency (
f
), 50–25,000 Hz (lowest); (b)
f
, 13.6–40.7 MHz (intermediate); (c)
f
, 896–2450 MHz (highest).
Figure 4.2 Relative dielectric loss factor (E″) of 5% aqueous solutions/suspensions of selected ingredients at (a) 27.12 and (b) 2450 MHz (adapted from Lyng (2005)).
Figure 4.3 (a–c) Correlations between dielectric properties (27.12 and 2450 MHz) and electrical conductivities (S/m) of 5% aqueous solutions/suspensions of selected ingredients (adapted from Lyng
et al.
(2005)).
Figure 4.4 An example of a typical temperature profile (surface vs centre) of a meat product placed in a preheated and a non-preheated cooker.
Figure 4.5 A comparison of the yield of conventionally versus electroheated (ohmic or radio frequency heated) meats. F: Frankfurter; WP: White Pudding; PLR: Pork Luncheon Roll; T: Turkey; SH: Shoulder Ham; LH: Leg Ham; B−: Beef (no added ingredients); B+: Beef (added ingredients). ST: Steam; RF: Radio Frequency; OH: Ohmic Heating; LTLT: Low Temperature Long Time; HTST: High Temperature Short Time.
Chapter 6: Ultrasound processing applications in the meat industry
Figure 6.1 The sound spectrum.
Figure 6.2 Acoustic cavitation phenomena.
Figure 6.3 Diffusion kinetics of NaCl from a 200 g/L brine solution into pork loins as a function of different treatments. Solid lines represent the diffusion fitted to the analytical solution of Fick's second law for rectangular geometry.
Figure 6.4 Longitudinal section observed by SEM (150×) of
Longissimus dorsi
muscle of pork meat brined for 120 min in 200 kg NaCl/m
3
solution. CV: impact of cavitation bubble implosion on myofibril.
Figure 6.5 Production of ultrasound-assisted coating of Frankfurter-type sausages (after Heinz, unpublished results).
Chapter 7: Application of hydrodynamic shock wave processing associated with meat and processed meat products
Figure 7.1 (a) Control not ASW processed (Claus, University of Wisconsin-Madison). (b) After ASW processing (Claus, University of Wisconsin-Madison).
Figure 7.2 Porcine femur [drop Femur] Femur bone fracture by ASW.
Figure 7.3 Surface damage after ASW.
Figure 7.4 Muscle tissue separation at the adipose–lean interface after ASW.
Figure 7.5 Beef bottom rounds (non-ASW companion controls, left; ASW processed muscles, right).
Figure 7.6 Chicken breast fillet exterior (top row), interior (bottom row); before ASW (left), after ASW (right).
Figure 7.7 ASW response among beef animals.
Figure 7.8 Marination update, XSW left, control, right
Figure 7.9 Visualization of surface bacteria –
E. coli
(Green Fluorescent Protein labeled)
Figure 7.10 Schematic of DIL's semi-industrial prototype shock wave system.
Figure 7.11 Semi-industrial prototype shock wave system
Figure 7.12 Toroid design
Figure 7.13 Water-filled shock wave generating head.
Figure 7.14 A parabola shaped bowl with shock wave origin occurring at the focus of the parabola.
Figure 7.15 Inner tube meat restraint.
Figure 7.16 Plastic meat retaining ring.
Figure 7.17 Shock wave tunnel development.
Figure 7.18 Principal design of a shock wave processing system
Figure 7.19 Schematic of the TenderClass System
Figure 7.20 Commercial demonstration unit
Figure 7.21 Piston pressure generator
Chapter 8: Robotics in meat processing
Figure 8.1 Schematics of robotic system in the meat industry
Figure 8.2 Manual stunning suitable for halal.
Figure 8.3 Automated pig stunning.
Figure 8.4 Robotic carcass splitting system
Figure 8.5 Spine position detected by ultrasound image
Figure 8.6 Robot used for picking in the meat industry
Figure 8.7 (a) Y-cut – marked in bold black line (b) Brisket cut – flap lifted and shifted back. (c) Belly cut (d) Carcass opening cut – rip down and rear Y-cut followed by complete pelt removal.
Figure 8.8 Layout of MIRINZ shoulder fleecing machine
Figure 8.9 Process and sub-process in lamb slaughtering.
Figure 8.10 Fully automated lamb boning room – RTL Vision
Figure 8.11 Process and sub-processes involved in pig slaughtering.
Figure 8.12 Pig scalding using steam
Figure 8.13 Dehairing machine.
Figure 8.14 Interior of dehairing machine
Figure 8.15 Fully automated cutting line.
Figure 8.16 Cuts made on half pig carcass.
Figure 8.17 Middle cutting machine cuts off rib tops and separates the loin and belly automatically.
Chapter 9: Packaging systems and materials used for meat products with particular emphasis on the use of oxygen scavenging systems
Figure 9.1 Examples of commercially available case-ready raw and cooked meat products. (a) Modified atmosphere packaged and (b) skin or vacuum packaged meat products.
Figure 9.2 Tray film sealing selector guide
Figure 9.3 Cross-sectional representation of a nitrite-containing film
Chapter 11: Probiotic functionality in meat
Figure 11.1 Proposed mechanism of viable and nonviable probiotic health effects.
Figure 11.2 Theoretical basis for selection of probiotic microorganism.
Figure 11.3 Basic flowchart of the processing of fermented dry sausage with the addition of probiotic cultures.
Chapter 13: The use of hyperspectral techniques in evaluating quality and safety of meat and meat products
Figure 13.1 Schematic diagram of a line-scan hyperspectral imaging system.
Figure 13.2 A hyperspectral image as a three-dimensional data block covering spatial (
x
,
y
) and spectral (
λ
) information.
Figure 13.3 Schematic of four ways to acquire a hyperspectral image cube (I (
x
,
y
,
λ
)). Scanning directions are shown by arrows. (a) Point scan, (b) line scan, (c) area scan, (d) single shot.
Figure 13.4 Four typical hyperspectral acquisition modes. (a) Reflectance, (b) transmittance, (c) transflection, (d) interactance.
Figure 13.5 Key steps involved in building classification map, which starts from 3-D hypercube of an ST muscle and ends with its classification map. The final classification map shows that the outer borders of ST muscle are misclassified as PM (light grey boundary) and LD (dark grey, mainly on right hand side, and around border) and adjacent fat of muscle is classed as fat (white, front left component).
Chapter 14: Online meat quality and compositional assessment techniques
Figure 14.1 Application of CT scanning in pigs and 3D reconstruction of the carcass relevant parts of the pig
Figure 14.2 Relationship between magnetic resonance imaging (MRI) volume analysis and dissected weights of various tissues (L: left and R: right) from male and female pigs
Figure 14.3 Original and processed MRI images of a ham and a belly after MRI acquisition andafter image processing separating the cuts from the background and segmenting pixels intoclasses corresponding to muscle (1), subcutaneous fat (2), intermuscular fat (3), background(4), intermuscular fat/muscle partial volumes (5), and subcutaneous fat/muscle partialvolumes (6), respectively
Figure 14.4 Two-dimensional (left) and pseudo 3D (right) images from the VBS 2000 (Image courtesy of E+V GmbH, Germany)
Chapter 15: Meat authenticity
Figure 15.1 Principal component analysis of (a) mineral element in pork from organic and conventional farms. (b) Stable isotope in pork from organic and conventional farms. (c) Combine mineral element and stable isotope from organic and conventional farms. □ Organic pork, ▪ Conventional pork.
List of Tables
Chapter 2: Irradiation of meat and meat products
Table 2.1 The characteristics of ionizing radiation sources
Table 2.2 Control effect of food microorganisms by irradiation dose level
Table 2.3 Examples of the effect of increasing the energy, increasing the power, and reducing the dose on economics of X-ray irradiation of foods
Table 2.4 Ionizing radiation sources for food use
Table 2.5 X-ray processing throughput potential
*
Table 2.6 Major irradiation equipment manufacturers
Table 2.7 Gamma irradiation processing service facilities in the world
Table 2.8 Electron beam processing service facilities in the world (selected for beam energy at 5 MeV or higher)
Table 2.9 Approval of food irradiation in the United States
Chapter 3: High-pressure processing of meat and meat products
Table 3.1 Advantages and limitations of high hydrostatic pressure technology in preserving and decontaminating food products
Table 3.2 Main but nonexhaustive commercially available HP-treated products
Table 3.3 Key findings in the area of pressure-shift freezing and pressure-assisted freezing applied to meat products
Table 3.4 Main patents deposited in which high pressure is applied to meat products
Table 3.5 Some available commercial meat products
Table 3.6 Main manufacturers of industrial high-pressure processing equipment
Chapter 4: Electroprocessing of meat and meat products
Table 4.1 Summary of electroprocessing conditions and applications in food processing
Table 4.2 Summary of studies of PEF application in meat up to date
Table 4.3 Industrial scientific and medical (ISM) allocated frequency (
f
) bands
Chapter 5: Application of infrared and light-based technologies to meat and meat products
Table 5.1 UV resistance of
Listeria
strains on food contact and food surfaces
Table 5.2 US FDA CFR 21 179.39 – UV for treatment and processing foods
Chapter 6: Ultrasound processing applications in the meat industry
Table 6.1 Research findings in the application of ultrasound for meat tenderization, in chronology
Chapter 7: Application of hydrodynamic shock wave processing associated with meat and processed meat products
Table 7.1 Warner-Bratzler shear averages (peak force, kgf) for TenderClass System (TCS) processed pork loins
*
Table 7.2 Contact information for companies involved with the development and manufacturing of hydrodynamic shock wave processing equipment
Chapter 8: Robotics in meat processing
Table 8.1 Advantages and disadvantages of automation in meat industry
Chapter 9: Packaging systems and materials used for meat products with particular emphasis on the use of oxygen scavenging systems
Table 9.1 Properties of packaging materials required for use in packaging meat products
Table 9.2 Primary function of various basic materials used in packaging meat products
Table 9.3 Properties of the main gases used in MAP packaging of meat products
Table 9.4 Typical gas mixtures used in MAP of some raw, cooked, cured and processed meat products
Table 9.5 Recommended gas mixtures and gas volume for meat and meat products
Table 9.6 Typical materials used for packaging chilled meat products
Table 9.7 Advantages and disadvantages of modified atmosphere packaging for case-ready meat products
Table 9.8 Benefits of using technologies such as O
2
scavengers in packaged meat products
Chapter 11: Probiotic functionality in meat
Table 11.1 Microorganism species most commonly used as starter cultures in fermented meat products
Table 11.2 Examples of potential utilization of probiotic bacteria in meat products
Chapter 14: Online meat quality and compositional assessment techniques
Table 14.1 Comparison of various carcass evaluation techniques
Table 14.2 Selected examples demonstrating the use of ultrasound for in vivo estimation
Chapter 15: Meat authenticity
Table 15.1 The sTable isotope results for organic and conventional pork
Table 15.2 The multi-element result of organic and conventional pork
Chapter 16: Regulation and legislative issues
Table 16.1 Food legislation – general areas
Emerging Technologies in Meat Processing
Production, Processing and Technology
EDITED BY
Enda J. Cummins
UCD School of Biosystems and Food Engineering, University College Dublin, Ireland
James G. Lyng
UCD School of Agriculture and Food Science, University College Dublin, Ireland
This edition first published 2017
This edition first published 2017 © 2017 by John Wiley & Sons, Ltd
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Library of Congress Cataloging-in-Publication Data
Names: Cummins, Enda John, editor. | Lyng, G. James, editor.
Title: Emerging technologies in meat processing : production, processing and technology / [edited] by
Enda John Cummins, James G. Lyng.
Description: Chichester, UK ; Hoboken, NJ : John Wiley & Sons, 2017. |
Includes bibliographical references and index.
Identifiers: LCCN 2016025830| ISBN 9781118350683 (cloth) | ISBN 9781118350775
(epub)
Subjects: LCSH: Meat industry and trade–Technological innovations. |
Meat–Quality. | Food–Risk assessment.
Classification: LCC TS1960 .E53 2017 | DDC 664/.9–dc23 LC record available at https://lccn.loc.gov/2016025830
A catalogue record for this book is available from the British Library.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.
Cover image: © sturti/Gettyimages
About the IFST Advances in Food Science Book Series
The Institute of Food Science and Technology (IFST) is the leading qualifying body for food professionals in Europe and the only professional organisation in the UK concerned with all aspects of food science and technology. Its qualifications are internationally recognised as a sign of proficiency and integrity in the industry. Competence, integrity, and serving the public benefit lie at the heart of the IFST philosophy. IFST values the many elements that contribute to the efficient and responsible supply, manufacture and distribution of safe, wholesome, nutritious and affordable foods, with due regard for the environment, animal welfare and the rights of consumers.
IFST Advances in Food Science is a series of books dedicated to the most important and popular topics in food science and technology, highlighting major developments across all sectors of the global food industry. Each volume is a detailed and in-depth edited work, featuring contributions by recognized international experts, and which focuses on new developments in the field. Taken together, the series forms a comprehensive library of the latest food science research and practice, and provides valuable insights into the food processing techniques that are essential to the understanding and development of this rapidly evolving industry.
The IFST Advances series is edited by Dr Brijesh Tiwari, who is Senior Research Officer at Teagasc Food Research Centre in Ireland.
Forthcoming titles in the IFST series
Tropical Roots and Tubers: Production, Processing and Technology
, edited by Harish K. Sharma, Nicolas Y. Njintang, Rekha S. Singhal, Pragati Kaushal
Ultrasound in Food Processing: Recent Advances
, edited by Mar Villamiel, Jose Vicente Garcia-Perez, Antonia Montilla, Juan Andrés Cárcel and Jose Benedito
Herbs and Spices: Processing Technology and Health Benefits
, edited by Mohammad B. Hossain, Nigel P. Brunton and Dilip K Rai
List of contributors
Dong U. Ahn
Department of Animal Science, Iowa State University, Ames, IA, USA
Cristina Arroyo
Institute of Food and Health, UCD, Belfield, Dublin, Ireland
James R. Claus
Department of Animal Sciences, Meat Science and Muscle Biology Laboratory, University of Wisconsin-Madison, USA
Malco Cruz-Romero
Food Packaging Group, School of Food and Nutritional Sciences, University College Cork, Cork, Ireland
Patrick J. Cullen
School of Food Science & Environmental Health, Dublin Institute of Technology, Dublin, Ireland, School of Chemical Engineering, New South Wales University, Sydney, Australia
Enda J. Cummins
UCD School of Biosystems and Food Engineering, Belfield, Dublin, Ireland
Maeve Cushen
UCD School of Biosystems and Food Engineering, Agriculture and Food Science Centre, Belfield, Dublin, Ireland.
Agapi Doulgeraki
Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Michel Federighi
INRA UMR1014 SECALIM, Nantes, France; LUNAM Université, Oniris, Université de Nantes, Nantes, France
Jesús M. Frías
School of Food Science and Environmental Health, Dublin Institute of Technology, Dublin, Ireland
Sandrine Guillou
INRA UMR1014 SECALIM, Nantes, France; LUNAM Université, Oniris, Université de Nantes, Nantes, France
Cheorun Jo
Department of Animal Biotechnology, Seoul National University, Seoul, Republic of Korea; Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
Kompal Joshi
School of Food Science and Environmental Health, Dublin Institute of Technology, Dublin, Ireland
Joseph P. Kerry
School of Food and Nutritional Sciences, University College Cork, Co Cork, Ireland
Muhammad Issa Khan
National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan; Researcher, Department of Animal Biotechnology, Seoul National University, Seoul
Tatiana Koutchma
Guelph Food Research Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
Fiona Lalor
School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland
Marion Lerasle
INRA UMR1014 SECALIM, Nantes, France; LUNAM Université, Oniris, Université de Nantes, Nantes, France
James G. Lyng
Institute of Food and Health, UCD, Dublin, Ireland
N.N. Misra
School of Food Science & Environmental Health, Dublin Institute of Technology, Dublin, Ireland
Ki Chang Nam
Department of Animal Science and Technology, Sunchon National University, Sunchon, Korea
Tomas Norton
Agricultural Engineering Department, Harper-Adams University College, Newport, UK
George-John Nychas
Laboratory of Microbiology and Biotechnology of Food, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Efstathios Panagou
Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
Kumari Shikha Ojha
Teagasc Food Research Centre, Ashtown, Dublin, Ireland
Hélène Simonin
UMR Procédés Alimentaires et Microbiologiques, équipe PMB, AgroSup Dijon, France; Université de Bourgogne, Dijon, France
Da-Wen Sun
Food Refrigeration and Computerised Food Technology (FRCFT), School of Biosystems Engineering, University College Dublin, National University of Ireland, Agriculture & Food Science Centre, Belfield, Dublin, Ireland.
Brijesh K. Tiwari
Department of Food Biosciences, Teagasc Food Research Centre, Dublin, Ireland; Manchester Food Research Centre, Manchester Metropolitan University, Manchester, UK; Teagasc Food Research Centre, Ashtown, Dublin, Ireland
Ubaid-ur-Rahman
National Institute of Food Science and Technology, University of Agriculture, Faisalabad, Pakistan
Patrick Wall
School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland
Di Wu
Food Refrigeration and Computerised Food Technology (FRCFT), School of Biosystems Engineering, University College Dublin, National University of Ireland, Agriculture and Food Science Centre, Belfield, Dublin, Ireland
Yan Zhao
Institute of Quality Standard & Testing Technology for Agro Products, Key Laboratory of Agro product Quality and Safety, Chinese Academy of Agriculture Sciences, Beijing, China; Key Laboratory of Agro-product Quality and Safety, Ministry of Agriculture, Beijing, China
Chapter 1Emerging technologies in meat processing
Enda J. Cummins1 & James G. Lyng2
1Biosystems and Food Engineering, UCD, Dublin, Ireland
2Institute of Food and Health, UCD, Dublin, Ireland
1.1 Context and challenges
Meat is a global product, which is traded between regions, countries and continents. The onus is on producers, manufacturers, transporters and retailers to ensure an ever-demanding consumer receives a top-quality product that is free from contamination. With such a dynamic product and market place, new innovative ways to process, package and assess meat products are being developed. In some instances, industry uptake of new technologies is stifled by a lack of knowledge about these new technologies and their impact on product quality and safety. With ever-increasing competition and tighter cost margins, industry has shown willingness to engage in seeking novel innovative ways of processing, packaging and assessing meat products while maintaining quality and safety attributes. Several new technologies have emerged with regard to meat processing, packaging and quality assessment, which have the potential to improve production efficiency while maintaining meat safety and quality. A number of novel thermal and non-thermal technologies designed to achieve microbial safety while minimising the effects on its nutritional and quality attributes have also become available.
Minimising changes in quality and safety during processing is a considerable challenge for food processors and technologists. Thus, there is a requirement for detailed industrially relevant information concerning emerging technologies in meat product manufacture. In addition, industrial adoption of novel processing techniques is in its infancy. Applications of new and innovative technologies and resulting effects to those food products either individually or in combination are always of great interest to academic, industrial, nutrition and health professionals.
1.2 Book objective
The primary objective of this book on Emerging Technologies in Meat Processing is to provide a comprehensive overview of the application of novel processing techniques as applied to the meat industry. The book evaluates recent advances on how meat is produced, processed and stored and is a benchmark reference book on novel processing, packaging and assessment methods of meat and meat products.
1.3 Book structure
Meat processors have a major responsibility to consumers when it comes to producing quality, nutritious and particularly safe foods. Conventional methods of meat processing and preservation (e.g. heat processing, low-temperature preservation or dehydration) have been used for hundreds of years. However, the last century has witnessed a dramatic increase in the development of new technologies, which have, in many cases, been hyped as replacements for conventional methods. However, in spite of much excitement relating to their discovery and potential, the anticipated uptake by industry has not occurred. In many cases, alternative technologies are still expensive in terms of capital outlay and are therefore not attractive options for processors, although they are generally becoming cheaper as time progresses. The reason for the lack of uptake most likely runs deeper than financial, as in many cases the alternatives are more economic or produce a higher quality product than conventional methods so that processors could recoup the initial capital outlay in reduced running costs or by charging higher prices for a premium quality product. It is most likely that the biggest obstacle these technologies face is a lack of basic understanding of their potential and, more importantly, when it comes to preservation, an unwillingness to trust the alternative methods compared to the tried and tested conventional methods. This book does not set out to try and convince food processors to drop conventional methods and replace them with alternatives. Instead, in Part 1, it sets to review alternative or novel processing techniques reinforcing the positive aspects of each operation and also discussing areas of weakness. Part 2 sets out an overview of alternative packaging solutions and meat functionality, clearly listing advantages and disadvantages and providing the reader with case studies where these technologies have been used. Part 3 reviews advances in assessment techniques for improved meat quality and safety.
Part 1 (processing techniques) consists of a number of chapters on novel processing techniques for the meat industry. Recent developments in irradiation, high-pressure processing, electroprocessing, light-based technologies, ultrasound, robotics and other emerging technologies are discussed with emphasis on operational principles and inherent strengths and weaknesses of the technologies. In Chapter 2, the various sources of ionising radiation are described and distinguished. The mode of action is described and the advantages and disadvantages of irradiation are considered. The chapter finishes with a section outlining the author's view of the future for irradiation. Chapter 3 reviews the history of high preservation, and typical pressures used for meat preservation is put in context. The mode of action of high pressure in meat preservation is discussed, as are its advantages and disadvantages. While a lot has been published, more work needs to be done (e.g. pressure resistance problems, which can be overcome by combining pressure with either mild heat or cold) and the future for high pressure is considered in the final section of this chapter.
Electroprocessing has seen many technological developments in recent years. Chapter 4 begins with the classic categorisation of the different forms of electroheating in terms of the electromagnetic spectrum and then goes on to clearly describe and distinguish the heating mechanism of each. A central portion of the chapter is the presentation of case studies outlining situations where each of the electroheating technologies has been used to preserve products commercially or has undergone research and development to a form, which is suitable for commercial application. Chapter 5 focuses on the application of infrared and light-based technologies to meat and meat products. It has been suggested that magnetic UV, IR and high-intensity light pulses all have potential in meat preservation. Some forms are not always suitable for direct application but still have an important role to play in preservation as they can be used for applications such as sterilising packaging, contact surfaces or air within packaging equipment. These forms of electromagnetic radiation can be used in a number of forms (e.g. near vs far infrared) and the identification of where the various forms fit into the electromagnetic spectrum is achieved using a standardised electromagnetic spectrum diagram. This chapter explores the application, interactions and equipment associated with these light-based technologies in addition to illustrating practical case studies.
Chapter 6 begins where the fundamentals of ultrasonics are outlined and high-intensity versus low-intensity forms of ultrasound are distinguished. This is followed by a section in which ultrasonic equipment and specific industry-relevant case studies are discussed. The use of ultrasound for the decontamination of meat forms a central part of this chapter. It finishes with conclusions regarding the possible future for ultrasonics in meat preservation. Chapter 7 introduces the operational principles of emerging technologies such as the hydrodynamic shock wave, with particular emphasis on applications, mode of operation, advantages and disadvantages of the technology. The chapter concludes with some developmental advances in the technology. Part 1 of the book concludes with Chapter 8 which provides an overview of the use and application of robotics in meat processing. The chapter provides details for product handling and processing with emphasis on inherent strengths and weaknesses. The chapter is illustrated by relevant case studies and provides a reference for currently available robotic equipment. The chapter finishes by providing a synopsis of the likely future role for robotics in meat processing.
Part 2 of the book deals with novel packaging and meat functionality. Recently the area of meat packaging has seen many new developments. This section reports on these developments and implications for shelf life, meat safety and quality. In particular, developments in novel packaging systems and smart packaging of meats are evaluated. Chapter 9 considers novel packaging solutions for meat products including the use of case-ready packaging with emphasis on modified atmospheric packaging and oxygen scavenging systems. The operational principles are detailed along with advantage and disadvantages of the technologies. The chapter concludes with a synopsis of the likely future role that novel packaging will play in the preservation of meat products. Packaging in the future is likely to be more than just a physical container that provides food with protection from the surrounding environment. Chapter 10 analyses the theory, mode of action and role of smart packaging systems in today's meat industry. The recent developments of nanotechnology in smart packaging systems are also discussed. In Chapter 11, the authors look at functionality in the meat product itself, with a focus on probiotics for meat products.
Rapid detection of pathogens and microbial contaminants is essential for ensuring meat quality and safety. Part 3 of this book looks at developments in rapid methods for microbial analysis. In addition, carcass evaluation technology and assessment of meat quality characteristics using computer vision and spectral techniques are evaluated. The section finishes with an assessment of meat authenticity.
Rapid detection of pathogens and microbial contaminants is essential for ensuring meat quality and safety and forms the basis of Chapter 12. Traditional detection methods have relied on time-consuming media culture methods with isolation. There have been a number of new innovations in methods for the microbiological analysis of meat. An array of rapid methods has been developed to make detection and identification faster, more convenient, more sensitive and more specific than conventional assays. This chapter assesses developments in this field and provide a synopsis of rapid methods of assessment. Chapter 13 focus on the use of hyperspectral techniques in evaluating quality and safety of meat and meat products. Spectral imaging techniques have emerged as techniques capable of detecting microbes in a non-destructive and rapid way. Case studies are reviewed and details on advantages and disadvantages of the technology are discussed.
Chapter 14 looks at carcass evaluation techniques with particular emphasis on in vivo methods (ultrasound, X-ray computed tomography (CT) and nuclear magnetic resonance (NMR)/magnetic resonance imaging (MRI)). Methods available for the prediction of body and carcass composition are evaluated. Methods for predicting composition of carcasses including video image analysis (VIA), total body electrical conductivity (TOBEC) and bioelectrical impedance are discussed. Chapter 15 addresses the issue of meat authenticity. With an ever-expanding, open and globalised market place, meat products can be freely transported around the world. As illustrated in previous public health scares (e.g. dioxins in pork), consumer confidence in the meat industry is reliant on effective safety and authenticity. This chapter looks at recent developments in this field including the use of different authenticity techniques. The book concludes with Chapter 16 which provides an overview of the current role of food regulation practices within the European Union (EU) and internationally. International trade law, with emphasis on international food safety systems and food safety regulation within the EU, is discussed in addition to issues surrounding food marketing. The chapter concludes with a perspective on global trends and marketing challenges.
1.4 Conclusion
Emerging technologies do play an important role and have advantages for both processors and consumers. However, any likely uptake in the short term will be as part of a hurdle or minimal processing strategy in conjunction with conventional methods. The long-term success and uptake of emerging technologies depends on practicing food professionals receiving continued exposure to technological possibilities coupled with the education of new graduates of their potential. This text will serve as a comprehensive reference book for students, educators, researchers and food processors providing an up-to-date insight into emerging technologies for meat manufacture. The range of processes covered provides engineers and scientists working in the meat and food industries with a valuable resource for their work. Given the emphasis on novel technologies, the text is expected to have broad and significant appeal. This book can be a valuable reference book for companies, research institutions and universities active in the areas of meat processing, safety and quality evaluation.
Part INovel processing techniques
Chapter 2Irradiation of meat and meat products
Ki Chang Nam1, Cheorun Jo2 & Dong U. Ahn3
1Department of Animal Science and Technology, Sunchon National University, Sunchon, Korea
2Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
3Department of Animal Science, Iowa State University, Ames, IA, USA
2.1 Summary
The various sources of ionizing radiation are described and distinguished (i.e., isotopes, electron beams, and X-ray radiation). Identification of where the various forms fit into the electromagnetic spectrum is achieved using a standardized electromagnetic spectrum diagram. The mode of actions, advantages, and disadvantages of irradiation and companies that manufactureirradiation equipment are discussed. The distinction between dosage levels (i.e., low, up to 1 kGy; medium, 1–10 kGy; and high, 10–50 kGy) in terms of their effect on meat quality is described and the extent to which irradiation has been accepted by consumers and approved for food use is discussed. The chapter also includes a section outlining the authors' view of the future for irradiation.
2.2 Theory of irradiation of foods
2.2.1 Forms of irradiation
Radiation energies are classified into three categories of electromagnetic radiation (gamma ray, X-ray), charged particle radiation (alpha ray, beta ray, electron beam, photons), and uncharged particles (neutron). Among them, two types of ionizing radiation are basically used for food safety: one is the radiation energy generated from a radionuclide of radioactive source and the other is produced from an accelerator or a nuclear reactor. Gamma rays and X-rays have relatively short wavelengths (high energy) among electromagnetic spectrum including radio waves, microwaves, visible light, ultraviolet, and so on (Satin, 1892). Accelerated electron is a charged particle with high energy. Thus, radiation types that can be applied to meat and meat products are gamma ray, X-ray, and accelerated electron.
The “ionizing” radiation has a power to dislodge electrons from molecules and convert them into electrically charged ions. Gamma ray has a strong enough power to ionize molecules located in a deep position of targeted food and is from a radioactive isotope. Therefore, it should be managed safely. On the other hand, accelerated electrons and X-ray are generated by a machine process. Electron beam is directed to only target food, and the energy efficiency is higher than that of gamma ray. The most predominantly available form of food irradiation is gamma ray or accelerated electrons. Use of X-ray for food irradiation has been tested for commercial utilization as well as in research, but its efficiency is 70–80% of gamma ray and <30% of accelerated electrons (Olson, 1998).
Regardless of radiation sources, the amount of ionizing energy absorbed in target materials is measured as gray (Gy); 1 Gy equals to 1 J/kg. Thus, a dosage of 1 kGy indicates that the irradiated food receives 1000 J/kg of food mass. Generally, minimum dosage is applied to a food to achieve irradiation purpose and to maintain the quality of treated foods (Cleland, 2006).
The comparative characteristics of ionizing radiation sources used for food irradiation are shown in Table 2.1. The effectiveness of irradiation varies based on the type of radiation sources used, the radiation intensity, and the targeted microbes (Kwon, 2010). Following are the relative advantages and disadvantages of the three forms of food irradiation.
Table 2.1 The characteristics of ionizing radiation sources
Gamma ray
Electron beam
X-ray
Energy type
Electromagnetic
Charged particle
Electromagnetic
Energy volt (MeV)
1.17 + 1.33
∼10
∼5
Energy efficiency
Low (∼30%)
High (∼85%)
Low (∼10%)
Penetration capability
Deep (60–80 cm)
Low (8–10 cm)
Deep
Source control
Continuous
Switch (on/off)
Switch (on/off)
Source: From Kwon (2010). Adopted with permission by Korea Food Safety Research Institute.
2.2.1.1 Gamma ray
Gamma ray is the most widely used form for food irradiation and is normally emitted from the spontaneous disintegration of radionuclide, that is, radioactive isotope. Gamma ray is classified as photons and does not have mass despite its very high energy levels (Satin, 1892). Gamma ray is higher frequency photons than either ultraviolet or X-ray and can penetrate into a target food to a depth of 60–80 cm (Olson, 1998). Thus, gamma ray is appropriate for “poststerilization” of packaged foods, and the concern about recontamination of final products is minimal (Loaharanu, Kava, and Choi, 2007). The approved source of gamma ray for food irradiation is cobalt-60 and cesium-137 by the US FDA and by the International Standards for Food Irradiation (Olson, 1998). Co-60 emits two gamma rays simultaneously with energies of 1.17 and 1.33 MeV and has a half-life of 5.26 years with activity decay by 12.35% per year (Kwon, 2010). Co-60 is mainly used to sterilize various medical devices and to control pathogens in foods. Co-60 is encapsulated in a thin stainless steel cylinder (called a pencil). Since the Co-60 in the pencils will not contact with the irradiated food, it does not become radioactive. However, Cs-137 is seldom used because large amounts of source are not readily available (Cleland, 2006).
2.2.1.2 Electron beam
The electron beam is a high-energy stream of electrons generated by an electron accelerator that has a similar structure to television tubes. Electron beam has totally different mechanisms from the gamma ray. Electrons can be accelerated up to 10 MeV, which is about eight times higher than the energy level of gamma ray (Olson, 1998). The machine to produce electron beam can be easily controlled by its on/off switch system because it does not use any radioactive sources. However, electron beam has similar effectiveness to eradicate microorganisms in irradiated meats (Kwon, 2010). Electron beam has advantages in terms of ease of process control, irradiation speed, accuracy, energy efficiency, and consumer acceptance compared with the gamma ray, and the application of electron beam is eagerly tried in many developed countries (WHO, 1988). The only disadvantage of electron beam is its limited penetration capability. As electrons have a small mass and slow down quickly as they enter a product, electrons (10 MeV) can penetrate to a depth of only 3.81 cm in meat. Thus, it can be applied for the surface sterilization of meat or thin meat products (WHO, 1988). To overcome the short penetration capability, simultaneous use of two beams positioned oppositely is normally used.
2.2.1.3 X-ray
X-ray radiation facility can be regarded as a more powerful version of the machines that can be easily found in hospitals. X-ray is produced by collision of the high-energy electrons with a metal (tungsten) target without using any radioactive materials (Brynjolfsson, 1989). X-ray is developed to overcome the low penetration capability of electron beam. The penetration capability of X-ray, however, is lower than the gamma ray, and the facility can be freely switched on and off. X-ray is considered as a new technology with advantages of gamma ray and electron beam, but X-ray has relatively low energy efficiency.
Selection of an irradiation source can be determined by treatment goal (pasteurization, sterilization, insecticide, or growth control), characteristics of target food (thickness and density of target material, contamination degree, moisture content, deteriorated rate, density, packaging, or surface sterilization), energy characteristics (penetration capability, energy efficiency, or source control), minimum dose, dose uniformity, processing rate, and economics (Cleland, 2006).
2.2.2 Mode of action
The microorganisms in foods are highly susceptible to irradiation. When ionizing energy passes through a food, some of the atoms or molecules in the food absorb the energy and become reactive ions, free radicals, or damaged (Woods and Pikaev, 1994). Free radicals are highly reactive and destroy cellular components (Olson, 1998). This type of radiation is called ionizing radiation and is used to destroy insects, pathogenic bacteria, and parasites in meats.
The most direct target of ionization energy is DNA molecules. An exposure of bacterial cells to 0.1 kGy irradiation resulted in 2.8% DNA damage, whereas 0.14% of the enzymes and 0.005% of amino acids were altered with the same dose (Diehl, 1995). The loss of replication ability of cells is caused by damaged DNA. Even small changes in the DNA of a bacterial cell can result in the death of the bacteria. Breaking bonds in the DNA results in the loss of a cell's ability to replicate. The biological mechanisms of ionizing radiation can be explained by a direct theory and an indirect theory (Grecz, Rowley, and Matsuyama, 1983). Radiation destroys microorganisms by inactivation of genetic material in living cells either by its direct effects on DNA or through the production of radicals or ions that attack DNA indirectly (WHO, 1994).
According to the direct theory, some molecules in cells or food components are more sensitive to the action of the ionizing energy than others. DNA is the most critical target of irradiation although other cellular components may also be affected. The direct effect of irradiation on nucleic acid is either ionization or excitation. DNA molecules, especially the base part of DNA, are highly susceptible to ionizing radiation resulting in cleavage of phosphodiester bonds of DNA double helix. The damaged DNA causes the loss of a cell's ability to replicate and eventually lead the cell to death, but some can be repaired by DNA polymerase or ligase (Kwon, 2010). Depending on the repairing capacity, radiation susceptibility of each microorganism is also different.
Indirect theory is that radiolytic products (ions or free radicals) of water molecules induce chemical changes in essential compounds or the structure necessary for maintaining life (Smith and Pillai, 2004). Especially, hydroxyl radical (·OH) is known to have 90% damage rate to DNA molecules. Ionizing radiation can also affect cell membrane, resulting in an additional impact on the resistance and susceptibility of cells to irradiation (Kwon, 2010). The susceptibility of bacteria to irradiation is influenced by environmental factors such as temperature, atmosphere gas, water activity, pH, food components, and growth step of microorganisms. Indirect effects of irradiation on DNA include excitation of water molecules, which then diffuse to the medium and contact with chromosomal materials (Moseley, 1989).
Depending on the irradiation dose, food can be either pasteurized to reduce or eliminate pathogens or sterilized except for some viruses (Crawford and Ruff, 1996). Less than 10 kGy of irradiation can kill insects and larvae and destroy pathogenic bacteria and parasites. Very low doses (up to 1 kGy) of radiation can kill at least 99.9% of Salmonella in poultry and an even higher percentage of Escherichia coli O157:H7 in ground beef (Olson, 1998). Spore-forming bacteria can be controlled by the combination of high dose of irradiation and heat treatment. Irradiation is not effective to control virus that is resistant to irradiation (Dickson, 2001).
Irradiation can dramatically improve the safety of meat products by killing pathogenic bacteria contaminated. Relatively low doses (<10 kGy) of irradiation can increase the shelf life of meat products in cold chain and is called “radurization” or “radiopasteurization” (Table 2.2). Most of the meat and meat products can be irradiated using the effect of radurization because cold chain has been well equipped in meat industry and meat products are stored in refrigerated temperature. Radicidation is killing asporogenous bacteria and foodborne bacteria contaminated in meat, and radappertization is used to eradicate microorganisms except virus completely using more than 10 kGy of radiation doses (WHO, 1994). Depending on the contamination degree, high doses of 10–50 kGy are required (Loaharanu, Kava, and Choi, 2007).
Table 2.2 Control effect of food microorganisms by irradiation dose level
Irradiation effect
Dose (kGy)
Purpose
Examples
Radurization
1–5
Decrease in putrefaction bacteria, Increase in the shelf life of cold chain foods
Fresh meat, processed meat products, poultry meat
Radicidation
2–10
Killing nonspore pathogenic bacteria, food-poisoning bacteria
Meat, poultry meat
Radappertization
1–50
Killing all bacteria including spore-forming bacteria (
Bacillus
and
Clostridium
)
Canned, germ-free for patient, astronaut food
Source: From Kwon (2010). Adopted with permission by Korea Food Safety Research Institute.
2.2.3 Advantages and disadvantages of irradiation
Meat irradiation is a process that provides several important benefits for consumers as well as industry. It improves the safety of fresh meats by reducing or eliminating foodborne pathogens and extends the shelf life of the products (Thayer, 1994; Murano, 1995). Consumers and regulatory agencies have become increasingly aware of the dangers of pathogenic microorganisms to human health, and this has led to a greater willingness to consider irradiation treatment of meat. FDA and USDA had approved the use of irradiation on red meats at the maximum absorbed dose of 4.5 and 7.0 kGy for refrigerated and frozen meats, respectively, in 1999 (USDA, 1999). Poultry meat was approved in 1990 at a dosage between 1.5 and 3.0 kGy to control pathogenic bacteria. Irradiation can also provide numerous advantages to meat processors including increased hygienic quality, extended shelf life, and reduction in chemical and toxic residues by reducing the use of nitrite or other chemical preservatives (Lebepe et al., 1990; Radomyski et al., 1994; Murano et al., 1995).
The radiolytic products in irradiated foods are neither unique nor toxicologically significant in the quantities found (Thayer, 1994). However, the interactions of radiolytic products and meat components can deteriorate meat quality. Water is the major component of meat, and the content ranges from 60% to 75% in meat and meat products. When pure water is irradiated, a number of radiolytic products are formed (Swallow, 1984).
Among the radiolytic products, hydroxyl radical is a powerful oxidizing agent whereas the hydrated electron is a strong reducing agent (Diehl, 1995). When the primary electrons from a radiation source collide with an electron in the medium, the energy is transferred to the electron in the medium. This causes the ejection of secondary electron and generates a charged radical. Therefore, despite many advantages on meat safety, irradiation can accelerate oxidative chemical changes in meats.
Water-soluble vitamins react with the radiolytic products of water, whereas fat-soluble vitamins react with free radicals formed by the radiolysis of lipids. Thiamine is the most radiation-sensitive but other B vitamins are resistant to irradiation-induced destruction (Woods and Pikaev, 1994). Vitamin C acts as an antioxidant against irradiation-induced changes and is converted to dehydroascorbic acid by ionizing radiation, but its reactivity remains the same as the native form. Vitamins A and E are the only fat-soluble vitamins affected by irradiation (WHO, 1994). α-Tocopherol is the most radiation-sensitive fat-soluble vitamin (Olson, 1998), but can act as an antioxidant against irradiation-induced changes.
Irradiation accelerates lipid oxidation, especially in aerobically packaged meats, and produces characteristic irradiation off-odors. In the presence of oxygen, irradiation of unsaturated fatty acids accelerates autoxidative changes and produces a number of oxygen-containing products such as hydroperoxides and carbonyl compounds (Nawar et al., 1996). Irradiation at 1.5–10 kGy dosage increased 2-thiobarbituric acid reactive substances (TBARS) values in turkey breast muscles when aerobically packaged in oxygen-permeable bags (Hampson et al., 1996; Ahn et al., 2001). Lipid oxidation in meat, however, was not influenced by irradiation with vacuum packaging (Ahn et al., 1999). The lipid oxidation of frozen-stored irradiated meat was different from those of refrigerated storage, which can be explained by the limited mobility of free radicals in frozen state (Nam et al., 2002).
Several off-odor volatile compounds were newly generated or increased in meat after irradiation. In general, aromatic and sulfur-containing amino acids are the most susceptible amino acids to irradiation (Patterson and Stevenson 1995; Ahn et al., 2001). Jo, Lee, and Ahn (1999) showed that 1-heptene content in volatiles was positively related to irradiation dose. Du et al. (2001) showed that the production of alkenes and alkanes is associated with irradiation. Irradiation-induced fatty acid degradation may be similar to lipid oxidation, especially when oxygen is available. Several sulfur compounds were newly generated or increased in meat after irradiation: dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide were among the most prominent sulfur compounds responsible for irradiation off-odor in meat (Ahn et al., 2000). Sulfur compounds formed by radiolysis of sulfur-containing amino acids might be the major contributors for irradiation odor since sulfur compounds have very low threshold for odor detection (Ahn, 2002; Ahn and Lee, 2009).
Gamma irradiation converted the brown metmyoglobin to a red pigment, which is similar but not identical to oxymyoglobin (Satterlee, Wilhelm, and Barnhart, 1971). Irradiated chicken breasts had a definite change from the usual brown or purple color to a more vivid pink or red color in oxygen-permeable film (Millar et al., 1995). Irradiated pork loin muscles had increased redness, and the increased pink color was very stable during refrigerated storage in even aerobic packaging conditions (Ahn et al
