Food Packaging Technology PDF

FOOD PACKAGING TECHNOLOGY Edited by RICHARD COLES Consultant in Food Packaging, London DEREK MCDOWELL Head of Supply and Packaging Division Loughry College, Northern Ireland and MARK J. KIRWAN C...

FOOD PACKAGING TECHNOLOGY Edited by RICHARD COLES Consultant in Food Packaging, London DEREK MCDOWELL Head of Supply and Packaging Division Loughry College, Northern Ireland and MARK J. KIRWAN Consultant in Packaging Technology London Blackwell Publishing © 2003 by Blackwell Publishing Ltd Trademark Notice: Product or corporate names may be trademarks or registered Editorial Offices: trademarks, and are used only for identification 9600 Garsington Road, Oxford OX4 2DQ and explanation, without intent to infringe. Tel: +44 (0) 1865 776868 108 Cowley Road, Oxford OX4 1JF, UK First published 2003 Tel: +44 (0) 1865 791100 Blackwell Munksgaard, 1 Rosenørns Allè, Library of Congress Cataloging in P.O. 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Pondicherry, India Boca Raton, FL 33431, USA Printed and bound in Great Britain, Orders from the USA and Canada (only) to using acid-free paper by CRC Press LLC MPG Books Ltd, Bodmin, Cornwall USA and Canada only: For further information on ISBN 0–8493–9788–X Blackwell Publishing, visit our website: The right of the Author to be identified as the www.blackwellpublishing.com Author of this Work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Contributors Helen Brown Biochemistry Section Manager, Campden & Chorley- wood Food Research Association, Chipping Campden, Gloucestershire, GL55 6LD, UK Richard Coles Consultant in Food Packaging, Packaging Consultancy and Training, 20 Albert Reed Gardens, Tovil, Maid- stone, Kent ME15 6JY, UK Brian P.F. Day Research Section Leader, Food Packaging & Coatings, Food Science Australia, 671 Sneydes Road (Private Bag 16), Werribee, Victoria 3030, Australia Mike Edwards Microscopy Section Manager, Chemistry & Biochem- istry Department, Campden & Chorleywood Food Research Association, Chipping Campden, Glouces- tershire, GL55 6LD, UK Patrick J. Girling Consultant in Glass Packaging, Doncaster, UK (for- merly with Rockware Glass) Bruce Harte Director, Michigan State University, School of Pack- aging, East Lansing, Michigan, 48824-1223, USA Mark J. Kirwan Consultant in Packaging Technology, London, UK (formerly with Iggesund Paperboard) Nick May Senior Research Officer, Process and Product Devel- opment Department, Campden & Chorleywood Food Research Association, Chipping Campden, Glouces- tershire, GL55 6LD, UK Derek McDowell Head of Supply and Packaging Division, Loughry College, The Food Centre, Cookstown, Co. Tyrone, BT80 9AA, Northern Ireland Michael Mullan Head of Food Education and Training Division, Loughry College, The Food Centre, Cookstown, Co. Tyrone, BT80 9AA and Department of Food Science, The Queen’s University of Belfast, Newforge Lane, Belfast, BT9 5PX, Northern Ireland xvi CONTRIBUTORS Bev Page Packaging Consultant, Oak Shade, 121 Nottingham Road, Ravenshead, Nottingham NG15 9HJ, UK John W. Strawbridge Consultant in Plastics Packaging, Welwyn, UK (for- merly with Exxon-Mobil) Gary S. Tucker Process Development Section Leader, Department of Process and Product Development, Campden & Chorleywood Food Research, Association Chipping Campden, Gloucestershire, GL55 6LD, UK Diana Twede Associate Professor, Michigan State University, School of Packaging, East Lansing, Michigan, 48824-1223, USA James Williams Flavour Research and Taint Investigations Manager, Campden & Chorleywood Food Research Associ- ation, Chipping Campden, Gloucestershire, GL55 6LD, UK Preface This volume informs the reader about food preservation processes and techniques, product quality and shelf life, and the logistical packaging, packaging materials, machinery and processes, necessary for a wide range of packaging presentations. It is essential that those involved in food packaging innovation have a thor- ough technical understanding of the requirements of a product for protection and preservation, together with a broad appreciation of the multi-dimensional role of packaging. Business objectives may be: the launch of new products or the re-launch of existing products the provision of added value to existing products or services cost reduction in the supply chain. This book sets out to assist in the attainment of these objectives by informing designers, technologists and others in the packaging chain about key food packaging technologies and processes. To achieve this, the following five principal subject areas are covered: 1. food packaging strategy, design and development (chapter 1) 2. food bio-deterioration and methods of preservation (chapter 2) 3. packaged product quality and shelf life (chapter 3) 4. logistical packaging for food marketing systems (chapter 4) 5. packaging materials and processes (chapters 5–10). Chapter 1 introduces the subject of food packaging and its design and develop- ment. Food packaging is an important source of competitive advantage for retailers and product manufacturers. Chapter 2 discusses bio-deterioration and methods of food preservation that are fundamental to conserving the integrity of a product and protecting the health of the consumer. Chapter 3 discussess packaged product quality and shelf life issues that are the main concerns for product stability and consumer acceptability. Chapter 4 discusses logistical packaging for food marketing systems – it considers supply chain efficiency, distribution hazards, opportunities for cost reduction and added value, com- munication, pack protection and performance evaluation. Chapters 5, 6, 7 and 8 consider metal cans, glass, plastics and paper and paperboard, respectively. Chapters 9 and 10 discuss active packaging and modified atmosphere packaging (MAP) respectively – these techniques are used to extend the shelf life and/or guarantee quality attributes such as nutritional content, taste and the colour of many types of fresh, processed and prepared foods. xviii PREFACE The editors are grateful for the support of authors who are close to the latest developments in their technologies, and for their efforts in making this know- ledge available. We also wish to extend a word of gratitude to others who have contributed to this endeavour: Andy Hartley, Marketing Manager, and Sharon Crayton, Prod- uct Manager of Rockware Glass, UK; Nick Starke, formerly Head of Research & Development, Nampak, South Africa; Frank Paine, Adjunct Professor, School of Packaging, Michigan State University; and Susan Campbell. Richard Coles Derek McDowell Mark Kirwan Contents Contributors xv Preface xvii 1 Introduction 1 RICHARD COLES 1.1 Introduction 1 1.2 Packaging developments – an historical perspective 2 1.3 Food supply and the protective role of packaging 4 1.4 The value of packaging to society 7 1.5 Definitions and basic functions of packaging 8 1.6 Packaging strategy 9 1.7 Packaging design and development 9 1.7.1 The packaging design and development framework 12 1.7.1.1 Product needs 13 1.7.1.2 Distribution needs and wants of packaging 13 1.7.1.3 Packaging materials, machinery and production processes 16 1.7.1.4 Consumer needs and wants of packaging 18 1.7.1.5 Multiple food retail market needs and wants 22 1.7.1.6 Environmental performance of packaging 26 1.7.2 Packaging specifications and standards 28 1.8 Conclusion 29 Literature reviewed and sources of information 29 2 Food biodeterioration and methods of preservation 32 GARY S. TUCKER 2.1 Introduction 32 2.2 Agents of food biodeterioration 33 2.2.1 Enzymes 33 2.2.2 Microorganisms 34 2.2.2.1 Bacteria 35 2.2.2.2 Fungi 38 2.2.3 Non-enzymic biodeterioration 40 2.3 Food preservation methods 41 2.3.1 High temperature 41 2.3.1.1 Blanching 42 2.3.1.2 Thermal processing 42 2.3.1.3 Continuous thermal processing (aseptic) 47 2.3.1.4 Pasteurisation 51 2.3.2 Low temperature 52 2.3.2.1 Freezing 52 2.3.2.2 Chilling and cooling 53 vi CONTENTS 2.3.3 Drying and water activity control 54 2.3.4 Chemical preservation 56 2.3.4.1 Curing 57 2.3.4.2 Pickling 58 2.3.4.3 Smoking 58 2.3.5 Fermentation 59 2.3.6 Modifying the atmosphere 60 2.3.7 Other techniques and developments 61 2.3.7.1 High pressure processing 61 2.3.7.2 Ohmic heating 62 2.3.7.3 Irradiation 62 2.3.7.4 Membrane processing 62 2.3.7.5 Microwave processing 63 References 63 3 Packaged product quality and shelf life 65 HELEN BROWN and JAMES WILLIAMS 3.1 Introduction 65 3.2 Factors affecting product quality and shelf life 68 3.3 Chemical/biochemical processes 69 3.3.1 Oxidation 70 3.3.2 Enzyme activity 73 3.4 Microbiological processes 74 3.4.1 Examples where packaging is key to maintaining microbiological shelf life 75 3.5 Physical and physico-chemical processes 77 3.5.1 Physical damage 77 3.5.2 Insect damage 78 3.5.3 Moisture changes 78 3.5.4 Barrier to odour pick-up 81 3.5.5 Flavour scalping 81 3.6 Migration from packaging to foods 81 3.6.1 Migration from plastic packaging 83 3.6.2 Migration from other packaging materials 86 3.6.3 Factors affecting migration from food contact materials 88 3.6.4 Packaging selection to avoid migration and packaging taints 89 3.6.5 Methods for monitoring migration 89 3.7 Conclusion 91 References 91 4 Logistical packaging for food marketing systems 95 DIANA TWEDE and BRUCE HARTE 4.1 Introduction 95 4.2 Functions of logistical packaging 96 4.2.1 Protection 97 4.2.2 Utility/productivity 98 4.2.3 Communication 99  CONTENTS vii 4.3 Logistics activity-specific and integration issues 100 4.3.1 Packaging issues in food processing and retailing 100 4.3.2 Transport issues 101 4.3.3 Warehousing issues 104 4.3.4 Retail customer service issues 106 4.3.5 Waste issues 107 4.3.6 Supply chain integration issues 108 4.4 Distribution performance testing 109 4.4.1 Shock and vibration testing 110 4.4.2 Compression testing 111 4.5 Packaging materials and systems 112 4.5.1 Corrugated fiberboard boxes 112 4.5.2 Shrink bundles 115 4.5.3 Reusable totes 115 4.5.4 Unitization 116 4.6 Conclusion 119 References 119 5 Metal cans 120 BEV PAGE, MIKE EDWARDS and NICK MAY 5.1 Overview of market for metal cans 120 5.2 Container performance requirements 120 5.3 Container designs 121 5.4 Raw materials for can-making 123 5.4.1 Steel 123 5.4.2 Aluminium 124 5.4.3 Recycling of packaging metal 124 5.5 Can-making processes 124 5.5.1 Three-piece welded cans 125 5.5.2 Two-piece single drawn and multiple drawn (DRD) cans 126 5.5.3 Two-piece drawn and wall ironed (DWI) cans 127 5.6 End-making processes 129 5.6.1 Plain food can ends and shells for food/drink easy-open ends 130 5.6.2 Conversion of end shells into easy-open ends 130 5.7 Coatings, film laminates and inks 131 5.8 Processing of food and drinks in metal packages 132 5.8.1 Can reception at the packer 132 5.8.2 Filling and exhausting 133 5.8.3 Seaming 135 5.8.4 Heat processing 137 5.8.5 Post-process can cooling, drying and labelling 138 5.8.6 Container handling 139 5.8.7 Storage and distribution 140 5.9 Shelf life of canned foods 141 5.9.1 Interactions between the can and its contents 142 5.9.2 The role of tin 142 5.9.3 The dissolution of tin from the can surface 144 5.9.4 Tin toxicity 145 viii CONTENTS 5.9.5 Iron 146 5.9.6 Lead 147 5.9.7 Aluminium 147 5.9.8 Lacquers 147 5.10 Internal corrosion 148 5.11 Stress corrosion cracking 148 5.12 Environmental stress cracking corrosion of aluminium alloy beverage can ends 149 5.13 Sulphur staining 149 5.14 External corrosion 149 5.15 Conclusion 150 References and further reading 151 6 Packaging of food in glass containers 152 P.J. GIRLING 6.1 Introduction 152 6.1.1 Definition of glass 152 6.1.2 Brief history 152 6.1.3 Glass packaging 152 6.1.4 Glass containers market sectors for foods and drinks 153 6.1.5 Glass composition 153 6.1.5.1 White flint (clear glass) 153 6.1.5.2 Pale green (half white) 154 6.1.5.3 Dark green 154 6.1.5.4 Amber (brown in various colour densities) 154 6.1.5.5 Blue 154 6.2 Attributes of food packaged in glass containers 154 6.2.1 Glass pack integrity and product compatibility 156 6.2.1.1 Safety 156 6.2.1.2 Product compatibility 156 6.2.2 Consumer acceptability 156 6.3 Glass and glass container manufacture 156 6.3.1 Melting 156 6.3.2 Container forming 157 6.3.3 Design parameters 158 6.3.4 Surface treatments 158 6.3.4.1 Hot end treatment 158 6.3.4.2 Cold end treatment 159 6.3.4.3 Low-cost production tooling 160 6.3.4.4 Container inspection and quality 161 6.4 Closure selection 163 6.4.1 Normal seals 164 6.4.2 Vacuum seals 164 6.4.3 Pressure seals 164 6.5 Thermal processing of glass packaged foods 165 6.6 Plastic sleeving and decorating possibilities 165 6.7 Strength in theory and practice 166 6.8 Glass pack design and specification 167 6.8.1 Concept and bottle design 167 6.9 Packing – due diligence in the use of glass containers 169  CONTENTS ix 6.10 Environmental profile 171 6.10.1 Reuse 171 6.10.2 Recycling 171 6.10.3 Reduction – lightweighting 172 6.11 Glass as a marketing tool 172 References 172 Further reading 173 7 Plastics in food packaging 174 MARK J. KIRWAN and JOHN W. STRAWBRIDGE 7.1 Introduction 174 7.1.1 Definition and background 174 7.1.2 Use of plastics in food packaging 175 7.1.3 Types of plastics used in food packaging 177 7.2 Manufacture of plastics packaging 178 7.2.1 Introduction to the manufacture of plastics packaging 178 7.2.2 Plastic film and sheet for packaging 179 7.2.3 Pack types based on use of plastic films, laminates etc. 183 7.2.4 Rigid plastic packaging 186 7.3 Types of plastic used in packaging 189 7.3.1 Polyethylene 189 7.3.2 Polypropylene (PP) 191 7.3.3 Polyethylene terephthalate (PET or PETE) 194 7.3.4 Polyethylene naphthalene dicarboxylate (PEN) 195 7.3.5 Polycarbonate (PC) 196 7.3.6 Ionomers 196 7.3.7 Ethylene vinyl acetate (EVA) 197 7.3.8 Polyamide (PA) 197 7.3.9 Polyvinyl chloride (PVC) 198 7.3.10 Polyvinylidene chloride (PVdC) 199 7.3.11 Polystyrene (PS) 200 7.3.12 Styrene butadiene (SB) 201 7.3.13 Acrylonitrile butadiene styrene (ABS) 201 7.3.14 Ethylene vinyl alcohol (EVOH) 201 7.3.15 Polymethyl pentene (TPX) 202 7.3.16 High nitrile polymers (HNP) 202 7.3.17 Fluoropolymers 203 7.3.18 Cellulose-based materials 203 7.3.19 Polyvinyl acetate (PVA) 204 7.4 Coating of plastic films – types and properties 205 7.4.1 Introduction to coating 205 7.4.2 Acrylic coatings 205 7.4.3 PVdC coatings 206 7.4.4 PVOH coatings 206 7.4.5 Low-temperature sealing coatings (LTSCs) 206 7.4.6 Metallising with aluminium 207 7.4.7 SiOx coatings 207 7.4.8 DLC (Diamond-like coating) 208 7.4.9 Extrusion coating with PE 208 x CONTENTS 7.5 Secondary conversion techniques 208 7.5.1 Film lamination by adhesive 208 7.5.2 Extrusion lamination 210 7.5.3 Thermal lamination 211 7.6 Printing 211 7.6.1 Introduction to the printing of plastic films 211 7.6.2 Gravure printing 211 7.6.3 Flexographic printing 212 7.6.4 Digital printing 212 7.7 Printing and labelling of rigid plastic containers 212 7.7.1 In-mould labelling 212 7.7.2 Labelling 213 7.7.3 Dry offset printing 213 7.7.4 Silk screen printing 213 7.7.5 Heat transfer printing 213 7.8 Food contact and barrier properties 214 7.8.1 The issues 214 7.8.2 Migration 214 7.8.3 Permeation 215 7.8.4 Changes in flavour 216 7.9 Sealability and closure 217 7.9.1 Introduction to sealability and closure 217 7.9.2 Heat sealing 217 7.9.2.1 Flat jaw sealing 218 7.9.2.2 Crimp jaw conditions 219 7.9.2.3 Impulse sealing 220 7.9.2.4 Hot wheel sealing 220 7.9.2.5 Hot air sealers 221 7.9.2.6 Gas flame sealers 221 7.9.2.7 Induction sealing 221 7.9.2.8 Ultrasonic sealing 221 7.9.3 Cold seal 221 7.9.4 Plastic closures for bottles, jars and tubs 221 7.9.5 Adhesive systems used with plastics 222 7.10 How to choose 222 7.11 Retort pouch 224 7.11.1 Packaging innovation 224 7.11.2 Applications 225 7.11.3 Advantages and disadvantages 226 7.11.4 Production of pouches 227 7.11.5 Filling and sealing 228 7.11.6 Processing 229 7.11.7 Process determination 230 7.11.8 Post retort handling 231 7.11.9 Outer packaging 231 7.11.10 Quality assurance 232 7.11.11 Shelf life 232 7.12 Environmental and waste management issues 233 7.12.1 Environmental benefit 233 7.12.2 Sustainable development 233 7.12.3 Resource minimisation – lightweighting 233  CONTENTS xi 7.12.4 Plastics manufacturing and life cycle assessment (LCA) 234 7.12.5 Plastics waste management 235 7.12.5.1 Introduction to plastics waste management 235 7.12.5.2 Energy recovery 236 7.12.5.3 Feedstock recycling 236 7.12.5.4 Biodegradable plastics 237 Appendices 238 References 239 Further reading 240 Websites 240 8 Paper and paperboard packaging 241 M.J. KIRWAN 8.1 Introduction 241 8.2 Paper and paperboard – fibre sources and fibre separation (pulping) 243 8.3 Paper and paperboard manufacture 245 8.3.1 Stock preparation 245 8.3.2 Sheet forming 245 8.3.3 Pressing 246 8.3.4 Drying 247 8.3.5 Coating 248 8.3.6 Reel-up 248 8.3.7 Finishing 248 8.4 Packaging papers and paperboards 248 8.4.1 Wet strength paper 249 8.4.2 Microcreping 249 8.4.3 Greaseproof 249 8.4.4 Glassine 249 8.4.5 Vegetable parchment 249 8.4.6 Tissues 250 8.4.7 Paper labels 250 8.4.8 Bag papers 250 8.4.9 Sack kraft 250 8.4.10 Impregnated papers 250 8.4.11 Laminating papers 251 8.4.12 Solid bleached board (SBB) 251 8.4.13 Solid unbleached board (SUB) 251 8.4.14 Folding boxboard (FBB) 252 8.4.15 White lined chipboard (WLC) 253 8.5 Properties of paper and paperboard 254 8.5.1 Appearance 254 8.5.2 Performance 254 8.6 Additional functional properties of paper and paperboard 255 8.6.1 Treatment during manufacture 255 8.6.1.1 Hard sizing 255 8.6.1.2 Sizing with wax on machine 255 8.6.1.3 Acrylic resin dispersion 255 8.6.1.4 Fluorocarbon dispersion 255 8.6.2 Lamination 255 xii CONTENTS 8.6.3 Plastic extrusion coating and laminating 256 8.6.4 Printing and varnishing 257 8.6.5 Post-printing roller varnishing/coating/laminating 258 8.7 Design for paper and paperboard packaging 258 8.8 Package types 259 8.8.1 Tea and coffee bags 259 8.8.2 Paper bags and wrapping paper 259 8.8.3 Sachets/pouches/overwraps 260 8.8.4 Multiwall paper sacks 262 8.8.5 Folding cartons 263 8.8.6 Liquid packaging cartons 265 8.8.7 Rigid cartons or boxes 267 8.8.8 Paper based tubes, tubs and composite containers 268 8.8.8.1 Tubes 268 8.8.8.2 Tubs 268 8.8.8.3 Composite containers 268 8.8.9 Fibre drums 268 8.8.10 Corrugated fibreboard packaging 269 8.8.11 Moulded pulp containers 272 8.8.12 Labels 273 8.8.13 Sealing tapes 275 8.8.14 Cushioning materials 276 8.8.15 Cap liners (wads) and diaphragms 276 8.9 Systems 277 8.10 Environmental profile 277 Reference 281 Further reading 281 Websites 281 9 Active packaging 282 BRIAN P.F. DAY 9.1 Introduction 282 9.2 Oxygen scavengers 284 9.2.1 ZERO2™ oxygen scavenging materials 288 9.3 Carbon dioxide scavengers/emitters 289 9.4 Ethylene scavengers 290 9.5 Ethanol emitters 292 9.6 Preservative releasers 293 9.7 Moisture absorbers 295 9.8 Flavour/odour adsorbers 296 9.9 Temperature control packaging 297 9.10 Food safety, consumer acceptability and regulatory issues 298 9.11 Conclusions 300 References 300 10 Modified atmosphere packaging 303 MICHAEL MULLAN and DEREK MCDOWELL Section A MAP gases, packaging materials and equipment 303 10.A1 Introduction 303 10.A1.1 Historical development 304  CONTENTS xiii 10.A2 Gaseous environment 304 10.A2.1 Gases used in MAP 304 10.A2.1.1 Carbon dioxide 304 10.A2.1.2 Oxygen 305 10.A2.1.3 Nitrogen 305 10.A2.1.4 Carbon monoxide 305 10.A2.1.5 Noble gases 306 10.A2.2 Effect of the gaseous environment on the activity of bacteria, yeasts and moulds 306 10.A2.2.1 Effect of oxygen 306 10.A2.2.2 Effect of carbon dioxide 307 10.A2.2.3 Effect of nitrogen 308 10.A2.3 Effect of the gaseous environment on the chemical, biochemical and physical properties of foods 308 10.A2.3.1 Effect of oxygen 309 10.A2.3.2 Effects of other MAP gases 310 10.A2.4 Physical spoilage 311 10.A3 Packaging materials 311 10.A3.1 Main plastics used in MAP 312 10.A3.1.1 Ethylene vinyl alcohol (EVOH) 312 10.A3.1.2 Polyethylenes (PE) 312 10.A3.1.3 Polyamides (PA) 313 10.A3.1.4 Polyethylene terephthalate (PET) 313 10.A3.1.5 Polypropylene (PP) 313 10.A3.1.6 Polystyrene (PS) 314 10.A3.1.7 Polyvinyl chloride (PVC) 314 10.A3.1.8 Polyvinylidene chloride (PVdC) 314 10.A3.2 Selection of plastic packaging materials 315 10.A3.2.1 Food contact approval 315 10.A3.2.2 Gas and vapour barrier properties 315 10.A3.2.3 Optical properties 318 10.A3.2.4 Antifogging properties 318 10.A3.2.5 Mechanical properties 318 10.A3.2.6 Heat sealing properties 319 10.A4 Modified atmosphere packaging machines 319 10.A4.1 Chamber machines 319 10.A4.2 Snorkel machines 319 10.A4.3 Form-fill-seal tray machines 320 10.A4.3.1 Negative forming 320 10.A4.3.2 Negative forming with plug assistance 321 10.A4.3.3 Positive forming with plug assistance 321 10.A4.4 Pre-formed trays 323 10.A4.4.1 Pre-formed trays versus thermoformed trays 323 10.A4.5 Modification of the pack atmosphere 324 10.A4.5.1 Gas flushing 324 10.A4.5.2 Compensated vacuum gas flushing 324 10.A4.6 Sealing 325 10.A4.7 Cutting 325 10.A4.8 Additional operations 325 10.A5 Quality assurance of MAP 326 10.A5.1 Heat seal integrity 326 10.A5.1.1 Nondestructive pack testing equipment 328 xiv CONTENTS 10.A5.1.2 Destructive pack testing equipment 328 10.A5.2 Measurement of transmission rate and permeability in packaging films 329 10.A5.2.1 Water vapour transmission rate and measurement 329 10.A5.2.2 Measurement of oxygen transmission rate 331 10.A5.2.3 Measurement of carbon dioxide transmission rate 331 10.A5.3 Determination of headspace gas composition 331 10.A5.3.1 Oxygen determination 331 10.A5.3.2 Carbon dioxide determination 331 Section B Main food types 331 10.B1 Raw red meat 331 10.B2 Raw poultry 332 10.B3 Cooked, cured and processed meat products 333 10.B4 Fish and fish products 334 10.B5 Fruits and vegetables 335 10.B6 Dairy products 338 References 338 Index 340 1 Introduction Richard Coles 1.1 Introduction This chapter provides a context for considering the many types of packaging technology available. It includes an historical perspective of some packaging developments over the past 200 years and outlines the value of food packaging to society. It highlights the protective and logistical roles of packaging and introduces packaging strategy, design and development. Packaging technology can be of strategic importance to a company, as it can be a key to competitive advantage in the food industry. This may be achieved by catering to the needs and wants of the end user, opening up new distribution channels, providing a better quality of presentation, enabling lower costs, increasing margins, enhancing product/brand differentiation, and improving the logistics service to customers. The business drive to reduce costs in the supply chain must be carefully balanced against the fundamental technical requirements for food safety and product integrity, as well as the need to ensure an efficient logistics service. In addition, there is a requirement to meet the aims of marketing to protect and project brand image through value-added pack design. The latter may involve design inputs that communicate distinctive, aesthetically pleasing, ergonomic, functional and/or environmentally aware attributes. Thus, there is a continual challenge to provide cost effective pack performance that satisfies the needs and wants of the user, with health and safety being of paramount importance. At the same time, it is important to minimise the envir- onmental impact of products and the services required to deliver them. This chal- lenge is continually stimulated by a number of key drivers – most notably, legislation and political pressure. In particular, there is a drive to reduce the amount of packaging used and packaging waste to be disposed of. The growing importance of logistics in food supply means that manufacturing and distribution systems and, by implication, packaging systems, have become key interfaces of supplier–distributor relationships. Thus, the role of the market and the supply chain has increasing significance in the area of packaging innovation and design. Arising from the above discussion is the need for those involved in packaging design and development to take account of technological, marketing, legal, logistical and environmental requirements that are continually changing. Con- sequently, it is asserted that those involved in packaging need to develop an 2 FOOD PACKAGING TECHNOLOGY integrated view of the effect on packaging of a wide range of influences, including quality, production, engineering, marketing, food technology R&D, purchasing, legal issues, finance, the supply chain and environmental management. 1.2 Packaging developments – an historical perspective The last 200 years have seen the pack evolve from being a container for the product to becoming an important element of total product design – for example, the extension from packing tomato ketchup in glass bottles to squeezable co-extruded multi-layer plastic bottles with oxygen barrier material for long shelf life. Military requirements have helped to accelerate or precipitate some key packaging developments. These include the invention of food canning in Napoleonic France and the increased use of paper-based containers in marketing various products, including soft cheeses and malted milk, due to the shortage of tinplate for steel cans during the First World War. The quantum growth in demand for pre-packaged foods and food service packaging since the Second World War has dramatically diversified the range of materials and packs used. These have all been made possible by developments in food science and techno- logy, packaging materials and machine technology. An overview of some developments in packaging during the past 200 years is given below. 1800–1850s. In 1809 in France, Nicolas Appert produced the means of thermally preserving food in hermetically sealed glass jars. In 1810, Peter Durand designed the soldered tinplate canister and commercialised the use of heat preserved food containers. In England, handmade cans of ‘patent preserved meats’ were produced for the Admiralty (Davis, 1967). In 1852, Francis Wolle of Pennsylvania, USA, developed the paper bag-making machine (Davis, 1967). 1870s. In 1871, Albert L. Jones in the USA patented (no. 122,023) the use of corrugated materials for packaging. In 1874, Oliver Long patented (no. 9,948) the use of lined corrugated materials (Maltenfort, 1988). In 1879, Robert Gair of New York produced the first machine-made folding carton (Davis, 1967). 1880s. In 1884, Quaker Oats packaged the first cereal in a folding box (Hine, 1995). 1890s. In 1892, William Painter in Baltimore, USA, patented the Crown cap for glass bottles (Opie, 1989). In 1899, Michael J. Owens of Ohio conceived the idea of fully automatic bottle making. By 1903, Owens had commercialised the industrial process for the Owens Bottle Machine Company (Davis, 1967). 1900s. In 1906, paraffin wax coated paper milk containers were being sold by G.W. Maxwell in San Francisco and Los Angeles (Robertson, 2002).  INTRODUCTION 3 1910s. Waxed paperboard cartons were used as containers for cream. In 1912, regenerated cellulose film (RCF) was developed. In 1915, John Van Wormer of Toledo, Ohio, commercialised the paper bottle, a folded blank box called Pure-Pak, which was delivered flat for subsequent folding, gluing, paraffin wax coating, filling with milk and sealing at the dairy (Robertson, 2002). 1920s. In 1923, Clarence Birdseye founded Birdseye Seafoods in New York and commercialised the use of frozen foods in retail packs using cartons with waxed paper wrappers. In 1927, Du Pont perfected the cellulose casting process and introduced their product, Cellophane. 1930s. In 1935, a number of American brewers began selling canned beer. In 1939, ethylene was first polymerised commercially by Imperial Chemical Industries (ICI) Ltd.. Later, polyethylene (PE) was produced by ICI in associ- ation with Du Pont. PE has been extensively used in packaging since the 1960s. 1940s. During the Second World War, aerosol containers were used by the US military to dispense pesticides. Later, the aerosol can was developed and it became an immediate postwar success for dispensing food products such as pasteurised processed cheese and spray dessert toppings. In 1946, polyvinylidene chloride (PVdC) – often referred to as Saran – was used as a moisture barrier resin. 1950s. The retort pouch for heat-processed foods was developed origin- ally for the US military. Commercially, the pouch has been most used in Japan. Aluminium trays for frozen foods, aluminium cans and squeezable plastic bottles were introduced e.g. in 1956, the Jif squeezable lemon- shaped plastic pack of lemon juice was launched by Colman’s of Norwich, England. In 1956, Tetra Pak launched its tetrahedral milk carton that was constructed from low-density polyethylene extrusion coated paperboard. 1960s. The two-piece drawn and wall-ironed (DWI) can was developed in the USA for carbonated drinks and beers; the Soudronic welded side- seam was developed for the tinplate food can; tamper evident bottle neck shrink-sleeve was developed by Fuji Seal, Japan – this was the precursor to the shrink-sleeve label; aluminium roll-on pilfer-proof (ROPP) cap was used in the spirits market; tin-free steel can was developed. In 1967, the ring- pull opener was developed for canned drinks by the Metal Box Company; Tetra Pak launched its rectangular Tetra Brik Aseptic (TBA) carton system for long-life ultra-heat treated (UHT) milk. The TBA carton has become one of the world’s major pack forms for a wide range of liquid foods and beverages. 1970s. The bar code system for retail packaging was introduced in the USA; methods were introduced to make food packaging tamper evident; boil-in-the-bag frozen meals were introduced in the UK; MAP retail packs were introduced to the US, Scandinavia and Europe; PVC was used for beverage bottles; frozen foods in microwaveable plastic con- tainers, bag-in-box systems and a range of aseptic form, fill and seal (FFS) flexible packaging systems were developed. In 1973, Du Pont developed the injection stretch blow-moulded PET bottle which was used for colas and other carbonated drinks. 4 FOOD PACKAGING TECHNOLOGY 1980s. Co-extruded plastics incorporating oxygen barrier plastic materials for squeezable sauce bottles, and retortable plastic containers for ambient foods that could be microwave heated. PET-coated dual-ovenable paper- board for ready meals. The widget for canned draught beers was commercialised – there are now many types of widget available to form a foamy head in canned and glass bottled beers. In 1988, Japan’s longest surviving brand of beer, Sapporo, launched the contoured can for its lager beer with a ring-pull that removed the entire lid to transform the pack into a handy drinking vessel. 1990s. Digital printing of graphics on carton sleeves and labels for food packaging was introduced in the UK; shrink-sleeve plastic labels for glass bottles were rapidly adopted by the drinks industry; shaped can technology became more widely adopted in the USA and Europe as drinks companies sought ways of better differentiating their brands. Since the advent of the food can in the 19th century, protection, hygiene, product quality and convenience have been major drivers of food technology and packaging innovation. In recent years, there has been a rising demand for packaging that offers both ease of use and high quality food to consumers with busy lifestyles. The 1980s, in particular, saw the widespread adoption by the grocery trade of innovations such as gas barrier plastic materials utilised in aseptic FFS plastic containers for desserts, soups and sauces; plastic retail tray packs of premium meat cuts in a modified atmosphere; and retortable plastic containers for ambient storage ready meals that can be microwave heated. Technological developments often need to converge in order for a packaging innovation to be adopted. These have included developments in transportation, transport infrastructures, post-harvest technology, new retail formats and domestic appliances such as refrigerators, freezers and microwave ovens. For example, the development of the microwave oven precipitated the development of con- venience packaging for a wide range of foods. In addition, the socio-cultural and demographic trends, consumer lifestyles and economic climate must gen- erate sufficient market demand for an innovation to succeed. 1.3 Food supply and the protective role of packaging Packaging for consumer products is an area where supply and demand is con- tinuously changing due to the development of an international food market and adaptation to consumer, distribution, legal and technological requirements. Broad external influences on packaging for fast-moving consumer products may be summarised as follows: technological political/legal  INTRODUCTION 5 socio-cultural demographic ecological raw material availability economic. The world’s total food production has more than doubled over the past fifty years due to improved methods in animal husbandry, the use of advanced seed varieties and crop protection products that boost crop yields and quality. Mass production of packaged food has been enabled by technological innovations in food production, processing and logistics with packaging playing a key role. The economies of scale involved and the intense industrial competition have made many products more affordable. Consumer demand for pre-packaged food continues to increase in advanced economies and a growing global population is also fuelling the demand. This is increasingly the case in newly industrialised countries experiencing rapid urbanisation. In response to changing consumer lifestyles, large retail groups and food service industries have evolved. Their success has involved a highly competi- tive mix of logistical, trading, marketing and customer service expertise, all of which is dependent on quality packaging. They have partly driven the dramatic expansion in the range of products available, enabled by technological innov- ations, including those in packaging. The retailing, food manufacturing and packaging supply industries are continu- ing to expand their operations internationally. The sourcing of products from around the world is increasingly assisted by a reduction in trade barriers. The effect has been an increase in competition and a downward pressure on prices. Increased competition has led to a rationalisation in industry structure, often in the form of mergers and takeovers. For packaging, it has meant the adoption of new materials and shapes, increased automation, extension of pack size ranges and a reduction in unit cost. Another effect of mergers among manufacturers and retailing groups on packaging is the reappraisal of brands and their pack designs. Increasing market segmentation and the development of global food supply chains have spurred the adoption of sophisticated logistical packaging systems. Packaging is an integral part of the logistical system and plays an important role in preventing or reducing the generation of waste in the supply of food. Figure 1.1 illustrates the distribution flows of food from the farm to the consumer. It should be noted, however, that some parts of the chain permit the use of returnable packages. Packaging assists the preservation of the world’s resources through the prevention of product spoilage and wastage, and by protecting products until they have performed their function. The principal roles of packaging are to contain, protect/preserve food and inform the user. Thereby, food waste may be minimised and the health of the consumer safeguarded. 6 FOOD PACKAGING TECHNOLOGY Packer Farms co-ops Primary processors Secondary processors Regional distribution centres, wholesalers, cash and carry Retail outlets Consumer Figure 1.1 Food distribution systems (adapted from Paine & Paine, 1983). Packaging combined with developments in food science, processing and preservation techniques, has been applied in a variety of ways to ensure the safety of the consumer and integrity of the product. The success of both pack- aging and food technology in this regard is reflected by the fact that the contents of billions of packs are being safely consumed every day. In order to help minimise food waste throughout the supply chain and save cost, an optimum level of packaging is required. Significant food wastage occurs in many less developed countries – between 30% and 50% of food produced is wasted due to inadequate means of preservation, protection, storage and trans- portation (World Health Organisation). In developed countries, where modern processing, packaging and distribution systems are commonplace, food wastage before it reaches the consumer is only 2–3%. Less than 1% of packaged food goes to waste, compared with between 10% and 20% of unpackaged food. – Industry Council for Packaging and the Environment (INCPEN) Food wastage can represent a much greater financial loss than just the cost of spoilt product. For example, there may be costs associated with salvage, dis- posal, administration, replacement, insurance and litigation. There is the potential  INTRODUCTION 7 loss of customer goodwill, which is an important consideration in today’s highly competitive marketplace. A Tetra Pak motto is that a package should save more than it costs. 1.4 The value of packaging to society The value of food packaging to society has never been greater nor, paradoxically, has packaging attracted so much adverse media publicity and political attention. In response, stakeholders in the food industries need to fully appreciate and actively promote the positive contributions that their packaging makes to the quality of life. Food packaging is governed by a mass of laws, regulations, codes of practice and guidelines. The societal benefits of packaging may include the following: prevents or reduces product damage and food spoilage, thereby saving energy and vital nutrients, and protecting the health of the consumer requires less municipal solid waste disposal since it promotes processed food residue recycling for use as animal feed or compost. For example, from 454 g (1 lb) of fresh corn-on-the-cob purchased at the supermarket, the customer eats approximately only 170 g (six ounces), and the rest ends up in the trash can and, ultimately, in the local landfill (Institute of Pack- aging Professionals, IOPP, USA). This same amount of edible frozen corn can be packed in a polyethylene bag weighing less than 5 g (less than 0.18 ounce) lowers the cost of many foods through economies of scale in mass pro- duction and efficiency in bulk distribution. Savings are also derived from reduced product damage reduces or eliminates the risk of tampering and adulteration presents food in an hygienic and often aesthetically attractive way communicates important information about the food and helps consumers make informed purchases provides functional convenience in use or preparation, freeing up more time promotes goods in a competitive marketplace and increases consumer choice facilitates the development of modern retail formats that offer consumers the convenience of the one-stop shop and the availability of food from around the world throughout the year extends the shelf life with the benefit of prolonged product use, thereby reducing wastage saves energy through the use of ambient packs that do not require refriger- ation or frozen distribution and storage. 8 FOOD PACKAGING TECHNOLOGY The food industry is aware of current public concerns related to packaging which include: packaging litter and the volume of packaging waste in municipal waste cost of disposal and recovery of discarded packaging in municipal waste pollution associated with methods of disposal, i.e. landfill and incineration ease of opening perception of over-packaging due to apparently excessive ullage (free space) resulting from product settlement legibility of labels integrity of information on labels contamination of food due to the packaging itself accidents involving packaging. 1.5 Definitions and basic functions of packaging There are many ways of defining packaging reflecting different emphases. For example: A means of ensuring safe delivery to the ultimate consumer in sound condition at optimum cost. A coordinated system of preparing goods for transport, distribution, storage, retailing and end-use. A techno-commercial function aimed at optimising the costs of delivery while maximising sales (and hence profits). However, the basic functions of packaging are more specifically stated: Containment: depends on the product’s physical form and nature. For example, a hygroscopic free-flowing powder or a viscous and acidic tomato concentrate Protection: prevention of mechanical damage due to the hazards of distribution Preservation: prevention or inhibition of chemical changes, biochemical changes and microbiological spoilage Information about the product: legal requirements, product ingredients, use etc. Convenience: for the pack handlers and user(s) throughout the packaging chain Presentation: material type, shape, size, colour, merchandising display units etc. Brand communication: e.g. pack persona by the use of typography, symbols, illustrations, advertising and colour, thereby creating visual impact Promotion (Selling): free extra product, new product, money off etc.  INTRODUCTION 9 Economy: for example, efficiency in distribution, production and storage Environmental responsibility: in manufacture, use, reuse, or recycling and final disposal. 1.6 Packaging strategy Packaging may also be defined as: a means of safely and cost effectively delivering products to the consumer in accordance with the marketing strategy of the organisation. A packaging strategy is a plan that addresses all aspects and all activities involved in delivering the packaged product to the consumer. Packaging strategy should be allied to clearly defined marketing and manufac- turing strategies that are consistent with the corporate strategy or mission of the business. Key stakeholders in the strategic development process include management from technical/quality, manufacturing, procurement, marketing, supply chain, legal and finance functions. Packaging is both strategically and tactically important in the exercise of the marketing function. Where brands compete, distinctive or innovative packaging is often a key to the competitive edge companies seek. In the UK, for example, the development of the famous widget for canned draught beers opened up marketing opportunities and new distribution channels for large breweries. The packaging strategy of a food manufacturer should take into consideration the factors listed in Table 1.1. 1.7 Packaging design and development Marketing pull is a pre-requisite to successful innovation in packaging mater- ials, forms, designs or processes. The most ingenious technological innovation has little chance of success unless there is a market demand. Sometimes, an Table 1.1 Framework for a packaging strategy Technical requirements of the product and its packaging to ensure pack functionality and product protection/preservation throughout the pack’s shelf life during distribution and storage until its consumption Customer’s valued packaging and product characteristics, for example, aesthetic, flavour, convenience, functional and environmental performance Marketing requirements for packaging and product innovation to establish a distinct (product/service) brand proposition; protect brand integrity and satisfy anticipated demand at an acceptable profit in accordance with marketing strategy Supply chain considerations such as compatibility with existing pack range and/or manufacturing system Legislation and its operational/financial impacts, for example, regulations regarding food hygiene, labelling, weights and measures, food contact materials, due diligence etc. Environmental requirements or pressures and their impacts, for example, light-weighting to reduce impact of taxes or levies on amount of packaging used 10 FOOD PACKAGING TECHNOLOGY innovation is ahead of its time but may be later adopted when favoured by a change in market conditions. Specialist technical research, marketing research and consumer research agencies are employed to identify opportunities and minimise the financial costs and risks involved in the development, manufacture and marketing of a new product. For example, the radical redesign of tea bag packs in the UK was based on focus group consumer research. The result was a rigid upright carton with an integral easy tear-off board strip but without the traditional film over-wrap that was difficult to open. Nitrogen gas-flushed metallised polyester pouches are used to contain 40 tea bags for convenient tea caddy or cupboard storage. Carton designs may contain either a single pouch or multiple pouches. The pouch prevents spillage of tea dust, provides freshness and conveys a fresh image. The carton shape, label and colour combinations were also redesigned for extra on shelf impact. This packaging innovation has been widely adopted by retailers and other manufacturers for their branded teas. Generally, more successful new product developments are those that are implemented as a total concept with packaging forming an integral part of the whole. An example of the application of the total product concept is the distinctive white bottle for the rum-based spirit drink Malibu which reflects the coconut ingredient. There are many examples such as cartons with susceptors for microwave heating of frozen chips, pizzas and popcorn, and dispensing packs for mints. Ideally, package design and distribution should be considered at the product concept stage. Insufficient communication may exist between marketing and distribution functions; a new product is manufactured and pack materials, shape and design are formulated to fulfil the market requirements. It is only then that handling and distribution are considered. Product failure in the marketplace due to inadequate protective packaging can be very costly to rectify. Marketing departments should be aware of distribution constraints when designing a total product concept. With high distribution costs, increased profitability from product and pack innovation can be wiped out if new packaging units do not fit in easily with existing distribution systems. It is necessary to consider whether packs are produced for their marketability or, for their physical distribution practicability. This would not necessarily be important if it were not for the significance of distribution costs, in particular those for refrigerated products. The development of packs is frequently a time-consuming and creative endeavour. There may be communication difficulties between business func- tions and resource issues that impede pack development. The use of multi- disciplinary teams may expedite the packaging development process. This has the effect of improving the quality of the final product by minimising problems caused by design consequences that can result from sequential development. Computer assisted design (CAD) and rapid prototyping facilities for design  INTRODUCTION 11 and physical modelling of packs give packaging development teams the ability to accelerate the initial design process. In packaging development, thorough project planning is essential. In partic- ular, order lead times for packaging components need to be carefully planned with suppliers at an early stage in order to ensure a realistic time plan. For example, the development of a plastic bottle pack for a juice drink may involve typical stages listed in Table 1.2. There may be issues such as a supplier’s availability of injection stretch blow-moulding machines due to seasonal demand for drinks containers and consequent lack of spare production capacity. With reference to the definition: Packaging in product distribution is aimed at maximising sales (and repeat sales, and so profits), while minimising the total overall cost of distribution from the point of pack filling onwards. Pack- aging is regarded as a benefit to be optimised rather than merely a cost to be minimised (Paine & Paine, 1983). Packaging optimisation is a main concern of the packaging development function. The aim is to achieve an optimal balance between performance, qual- ity and cost, i.e. value for money. It involves a detailed examination of each cost element in the packaging system and an evaluation of the contribution of each item to the functionality of the system (Melis, 1989). Packaging should be considered as part of the process of product manufac- turing and distribution, and the economics of the supply chain should take into account all those operations – including packaging – involved in the delivery of the product to the final user. In certain cases, this may be extended to take account of the costs involved in reuse or waste collection, sorting, recovery Table 1.2 Typical stages in the design and development of a new plastic bottle pack Define packaging strategy Prepare packaging brief and search for pack design concepts: functional and graphical Concept costing, screening and approval by cross-functional packaging team Pack component supplier selection through liaison with purchasing Cost tooling; design and engineer new moulds for bottles and caps with suppliers Test pack prototype: dimensional, drop impact, leak, compression, cap fit etc. Commission artwork for labels Shelf life testing; barrier performance evaluation Model and sample production: filling system; labelling; casing etc. Market test prototype Design, cost and evaluate transit pack performance for prototype: drop, compression etc. Determine case arrangement on pallets and assess influence of factors affecting stacking performance: brick or column stacking, relative humidity, moisture, pallet design etc. Define quality standards and packaging specifications Conduct production and machine trials: efficiency and productivity performance Plan line change-overs Develop inspection methods and introduce a quality assurance service Commission production line for new or changed packaging systems Fine-tune packaging operations and specifications 12 FOOD PACKAGING TECHNOLOGY Table 1.3 Typical handling operations for an ambient storage retail pack Production line container forming, de-palletising or de-nesting Container transfer on conveyor system and container inspection (cleaning) Filling, sealing (processing) and labelling Casing, case sealing and coding Palletising and stretch-wrapping Plant storage Transport to warehouse Lorry transport to retail regional distribution centre (RDC) RDC storage Pallet break-bulk and product order pick for stores at RDC Mixed product load on pallets or roll cages to RDC dispatch Loaded pallets or roll cages delivered by lorry to retail stores Loads moved to back of store storage area for a short period Load retail cabinet or fill shelf merchandising display and disposal. The overall or total packaging system cost stems from a number of different components including materials utilisation, machinery and produc- tion line efficiency, movement in distribution, management and manpower. They may include some of the operations listed in Table 1.3. Adopting a systems approach to packaging can yield significant benefits other than just cost. Savings can be functionally derived by, perhaps, even increasing packaging costs for better pack performance and recouping savings in other areas such as more productive plant operations or cheaper handling, storage/transportation. This is known as a total systems approach to packaging optimisation (Melis, 1989). 1.7.1 The packaging design and development framework The framework presented in Table 1.4 ideally models the information require- ments for packaging design and development. It considers all the tasks a pack has to perform during production and in distribution from the producer to the consumer, taking into account the effect on the environment. Each of the aspects listed in Table 1.4 is discussed and a checklist of fac- tors for each aspect presented. The market selected for discussion here is the Table 1.4 The packaging design and development framework (developed from Paine, 1981) Product needs Distribution needs and wants Packaging materials, machinery and production processes Consumer needs and wants Market needs and wants Environmental performance  INTRODUCTION 13 multiple retail market that dominates the food supply system in the UK grocery trade. 1.7.1.1 Product needs The product and its package should be considered together i.e. the total product concept. A thorough understanding of a product’s characteristics, the intrinsic mechanism(s) by which it can deteriorate, its fragility in distribution and possible interactions with packaging materials – i.e. compatibility – is essential to the design and development of appropriate packaging. These characteristics concern the physical, chemical, biochemical and microbiological nature of the product (see Table 1.5). The greater the value of the product, the higher is the likely investment in packaging to limit product damage or spoilage i.e. there is an optimum level of packaging. 1.7.1.2 Distribution needs and wants of packaging A thorough understanding of the distribution system is fundamental for designing cost-effective packaging that provides the appropriate degree of protection to the product and is acceptable to the user(s). Distribution may be defined as the journey of the pack from the point of filling to the point of end use. In some instances, this definition may be extended to include packaging reuse, waste recovery and dis- posal. The three distribution environments are climatic, physical and biological (Robertson, 1990). Failure to properly consider these distribution environments Table 1.5 Product needs Nature of the product Physical nature Gas, viscous liquid, solid blocks, granules, free-flowing powders, emulsions, pastes etc. Chemical or biochemical nature Ingredients, chemical composition, nutritional value, corrosive, sticky, volatile, perishable, odorous etc. Dimensions Size and shape Volume, weight & density Method of fill, dispense, accuracy, legal obligation etc. Damage sensitivity Mechanical strength properties or fragility/weaknesses Product deterioration: Intrinsic mechanism(s) including changes in Organoleptic qualities Taste, smell, colour, sound and texture Chemical breakdown For example, vitamin C breakdown in canned guavas Chemical changes For example, staling of bread Biochemical changes For example, enzymatic, respiration Microbiological status For example, bacterial count Product shelf life requirement Average shelf life needed Use-life needed Technical shelf life For example, is migration within legal limits? 14 FOOD PACKAGING TECHNOLOGY will result in poorly designed packages, increased costs, consumer complaints and even avoidance by the customer. Climatic environment is the environment that can cause damage to the product as a result of gases, water and water vapour, light (particularly UV), dust, pres- sure and the effects of heat or cold. The appropriate application of technology will help prevent or delay such deleterious effects during processing, distribution and storage (see Table 1.6). Physical environment is the environment in which physical damage can be caused to the product during warehouse storage and distribution that may involve one or more modes of transportation (road, rail, sea or air) and a variety of handling operations (pallet movement, case opening, order picking etc.). These movements subject packs to a range of mechanical hazards such as impacts, vibrations, compression, piercing, puncturing etc. (see Table 1.7). In general, the more break-bulk stages there are, the greater is the opportunity for manual handling and the greater is the risk of product damage due to drops. In the retail environment, the ideal is a through-distribution merchandising unit – for example, the roll cage for cartons of fresh pasteurised milk. Biological environment is the environment in which the package interacts with pests – such as rodents, birds, mites and insects – and microbes. For pests, Table 1.6 The climatic environment Protection requirement against the climatic environment includes: High/low temperature Small or extreme variations Moisture Ingress or egress Relative humidity Condensation, moisture loss or gain Light Visible, infra-red and UV Gases and vapour Ingress/egress: oxygen, moisture etc. Volatiles and odours Ingress or egress – aromas, taints Liquid moisture For example, corrosion due to salt laden sea spray Low pressure External pressure/internal pack pressure variation due to change in altitude or aircraft pressurisation failure Dust Exposure to wind driven particles of sand, grit etc. Table 1.7 The physical environment Protection against mechanical hazards of storage and transportation by Shocks Vertical and horizontal impacts, e.g. from drops, falls, throwing Vibration Low frequency vibrations from interactions of road or rail surfaces with vehicle suspension and engines; handling equipment; machinery vibration on ships High frequency aerodynamic vibration on aircraft Compression/crushing Dynamic or static loading; duration of stacking; restraint etc. Abrasion Contact with rough surfaces Puncture Contact with sharp objects, e.g. hooks Racking or deformation Uneven support due to poor floors, pallet design, pallet support Tearing Wrong method of handling  INTRODUCTION 15 an understanding of their survival needs, sensory perceptions, strength, capabilities and limitations is required. For microbes, an understanding of microbiology and methods of preservation is necessary (see Table 1.8). Other factors that need to be considered when designing packaging for dis- tribution purposes include, convenience in storage and display, ease of handling, clearly identifiable and secure. There are trade-offs among these factors. These trade-offs concern the product and distribution system itself. For distributors, the package is the product and they need characteristics that help the distribu- tion process (see Table 1.9). Any change in distribution requirements for certain products affects the total performance of the pack. Identifying the optimum design of a packaging system requires a cost–benefit trade-off analysis of the performance of the three levels of packaging: primary pack: in direct contact with the food or beverage, e.g. bottle and cap, carton secondary or transit package: contains and collates primary packs – for example, a shrink-wrapped corrugated fibreboard tray or case tertiary package, e.g. pallet, roll cage, stretch-wrap. An example is the multi-pack made from solid unbleached board (unbleached sulphate or Kraft board) used to collate 12 cans of beer. It can offer benefits such as enhanced promotional capability, more effective use of graphics, better shelf display appearance (no discarded trays), significant saving in board usage, increased primary package protection, better print flexibility during production, improved handling efficiency in retail operations (for example, faster shelf fill), tamper evidence, stackability, ease of handling by the consumer, faster product scanning at the store retail checkout, thereby improving store efficiency and/or customer service. In terms of the physical nature of a product, it is generally not presented to the distribution function in its primary form, but in the form of a package or unit load. These two elements are relevant to any discussion concerned with the relationship of the product and its package. The physical characteristics of a product, any specific packaging requirements and the type of unit load are Table 1.8 The biological environment Microbes Bacteria, fungi, moulds, yeasts and viruses Pests Rodents, insects, mites and birds Table 1.9 Special packaging features for distribution to enable: Ease of distribution: handling, stocking and shipment Protection against soiling, stains, leaks, paint flakes, grease or oil and polluted water Security in distribution for protection against pilferage, tampering and counterfeiting Protection from contamination or leakage of material from adjacent packs 16 FOOD PACKAGING TECHNOLOGY all-important factors in the trade-off with other elements of distribution when trying to seek least cost systems at given service levels (Rushton & Oxley, 1989). For example, individual two-pint cartons of milk may be assembled in shrink- wrapped collations of eight cartons, which in turn are loaded onto pallets, stretch-wrapped and trans-shipped on lorries capable of carrying a given number of pallet loads. At the dairy depot, the shrink-wrapped multi-packs may be order picked for onward delivery to small shops. In the case of large retail stores, the individual cartons of milk may be automatically loaded at the dairy into roll cages that are delivered to the retailer’s merchandising cabinet display area without an intermediate break-bulk stage. 1.7.1.3 Packaging materials, machinery and production processes Packaging is constantly changing with the introduction of new materials, technology and processes. These may be due to the need for improved product quality, productivity, logistics service, environmental performance and profit- ability. A change in packaging materials, however, may have implications for consumer acceptance. The aim is a fitness for purpose approach to packaging design and development that involves selection of the most appropriate mater- ials, machinery and production processes for safe, environmentally sound and cost effective performance of the packaging system. For example, there is the case of a packaging innovation for a well-known brand of a milk chocolate covered wafer biscuit. The aluminium foil wrap and printed-paper label band were replaced by a printed and coated oriented polypropylene (OPP) film flow-wrap with good gas and moisture barrier properties. Significant cost savings in pack materials and production oper- ations were achieved. For example, only one wrapping operation is now required instead of the two previously used, and production speeds are much higher on account of the high tensile properties of OPP. There is also a lower risk of damage to the plastic wrapper in distribution and a net environmental benefit from using minimal material and energy resource. However, initial consumer research revealed a degree of resistance to this packaging change by those consumers who enjoyed the traditional ceremony of carefully unwrapping the foil pack and their ability to snap-off bars through the foil. The company promoted the new pack to the consumer on the basis of product freshness and the offer of a free extra bar. Some key properties of the main packaging media are listed in Tables 1.10, 1.11, 1.12 and 1.13, though it should be remembered that, in the majority of primary packaging applications, they are used in combination with each other in order to best exploit their functional and/or aesthetic properties. Most packaging operations in food manufacturing businesses are auto- matic or semi-automatic operations. Such operations require packaging materials that can run effectively and efficiently on machinery. Packaging  INTRODUCTION 17 Table 1.10 Key properties of glass Inert with respect to foods Transparent to light and may be coloured Impermeable to gases and vapours Rigid Can be easily returned and reused Brittle and breakable Needs a separate closure Widely in use for both single and multi-trip packaging Table 1.11 Key properties of tinplate and aluminium Rigid material with a high density for steel and a low density for aluminium Good tensile strength An excellent barrier to light, liquids and foods Needs closures, seams and crimps to form packs Used in many packaging applications: food and beverage cans, aerosols, tubes, trays and drums Can react with product causing dissolution of the metal Table 1.12 Key properties of paper and paperboard Low-density materials Poor barriers to light without coatings or laminations Poor barriers to liquids, gases and vapours unless they are coated, laminated or wrapped Good stiffness Can be grease resistant Absorbent to liquids and moisture vapour Can be creased, folded and glued Tear easily Not brittle, but not so high in tensile as metal Excellent substrates for inexpensive printing Table 1.13 Key properties of plastics Wide range of barrier properties Permeable to gases and vapours to varying degrees Low density materials with a wide range of physical and optical properties Usually have low stiffness Tensile and tear strengths are variable Can be transparent Functional over a wide range of temperatures depending on the type of plastic Flexible and, in certain cases, can be creased needs to be of the specified dimensions, type and format within specified toler- ances. The properties of the material will need to take account of the require- ments of the packing and food processing operations. They will, therefore, need to have the required properties such as tensile strength and stiffness, appropriate for each container and type of material. For example, a horizontal 18 FOOD PACKAGING TECHNOLOGY form/fill/seal machine producing flow wrapped product will require roll stock film of a particular width and core diameter, with a heat- or cold-sealing layer of a particular plastic material of a defined gauge, and film surfaces possessing appropriate frictional, anti-static and anti-blocking properties to provide optimum machine performance. Packaging machinery is set up to run with a particular type of packaging material and even minor changes in the material can lead to problems with machine performance. The introduction of new packaging materials and new designs must be managed with care. Materials should be selected after machine trials have shown that the required machine efficiency and pro- ductivity can be realised. New designs may require minor or major machine modification that will add direct costs in retooled parts. Indirect costs may result from machine downtime, prolonged changeover times and additional training costs for operators. Design changes in primary packs can have a knock-on effect on secondary packs and volume (cube) efficiencies during distribution and storage that results in height and diameter modifications. For example, a minor change in container profile can impact on machine operations from depalletising through conveying, rinsing, filling, sealing, labelling, casing and palletising. Depalletisers will need adjustment to cope with the new profile of containers. Conveyor guide rails may require resetting. Filler and labeller in-feed and out-feed star-wheels spacing screws may need replacing or modification. Fill head height may require adjustment and new filler tubes and cups may be required. Closure diameter may be affected hav- ing an effect on sealer heads that might necessitate adjustment or modification. New labels may be needed which will require modifications and possibly new components such as label pads and pickers. Casing machines may need read- justment to match the new position of containers. A redesigned case may be required and a new pallet stacking plan needed to optimise pallet stability. The direct costs of new package design and machine modification and the indirect costs of reduced productivity prior to packaging lines settling down can be significant. It is important to bring machine and material suppliers into the design project and keep line operations informed at all stages of implemen- tation. Packaging machinery has developed into a wide range of equipment and integrated systems, to achieve a complete range of operational, filling and sealing techniques steered by computerised micro-electronic systems. Tech- nical considerations in packaging materials, machinery and production processes are listed in Table 1.14. 1.7.1.4 Consumer needs and wants of packaging The overall implications of social and economic trends relating to nutrition, diet and health can be summarised concisely as quality, information, convenience, variety,  INTRODUCTION 19 Table 1.14 Packaging materials, machinery and production processes Product/packaging compatibility Identify any packaging material incompatibilities, e.g. migration and environmental stress cracking of plastics Is there a need to be compatible during all conditions of distribution and use? Must the package allow gaseous exchange? For example, to allow respiration of fruits and vegetables Method of processing the product either in the package or independent of it Elevated thermal treatment E.g. Retort sterilisation and pasteurisation, cooking, hot filling, drying, blanching, UHT aseptic, ohmic heating, microwave processing Low temperature treatments Freezing, chilling and cooling Gas change or flush Modified atmosphere gassing Removal of air Vacuumising Chemical Smoking, sugaring, salting, curing, pickling etc. Fermentation E.g. Bacterial fermentation of carbohydrates for yoghurt production Irradiation E.g. Gamma rays to kill pathogens in poultry, herbs and spices Others: Electron beam pasteurisation and sterilisation, gas sterilisation, high pressure processing and membrane processing Closure performance Does the seal need to provide the same degree of integrity as the packaging materials? Re-closure requirement to protect or contain unused portion? Degree of protection required against leakage or sifting? Degree of seal strength and type of seal testing method employed? Application torque and opening torque requirement of caps and closures Performance requirements of packaging in production may concern Machinery for container forming Materials handling Filling, check-weighing and metal detection Sealing, capping or seaming Food processing treatments Labelling/coding Casing Shrink-wrapping; stretch-wrapping Palletisation Labour requirements product availability, health, safety and the environment. Consequently, the food processing and packaging systems employed need to be continuously fine-tuned to meet the balance of consumer needs in particular product areas (see Table 1.15). A branded product is a product sold carrying the product manufacturer’s or retailer’s label and generally used by purchasers as a guide in assessing quality. Sometimes, the qualities of competing branded products are almost indistinguish- able and it is packaging which makes the sale. An interesting or visually attractive pack can give the crucial marketing edge and persuade the impulsive consumer. Packaging should, however, accurately reflect product quality/brand values in order to avoid consumer disappointment, encourage repeat purchase and build brand loyalty. Ideally, the product should exceed customer expectations. 20 FOOD PACKAGING TECHNOLOGY Table 1.15 Consumer needs and wants of packaging Quality Processing and packaging for flavour, nutrition, texture, colour, freshness, acceptability etc. Information Product information, legibility, brand, use etc. Convenience Ease of access, opening and disposal; shelf life, microwaveable etc. Product availability Product available at all times Variety A wide range of products in variety of pack sizes, designs and pack types Health E.g. Enables the provision of extended or long shelf life foods, without the use of preservatives Safety The prevention of