Chocolate Science and Technology

CHOCOLATE SCIENCE AND TECHNOLOGY This second edition provides information on recent advances in the science and technology of chocolate manufacture and the entire international cocoa industry. It provides detailed reviews of a wide range of topics, including cocoa production, cocoa and chocolate manufacturing operations, sensory perception of chocolate quality, flavour release and perception, sugar replacement and alternative sweetening solutions in chocolate production, industrial manufacture of sugar-free chocolates and the nutrition and health benefits of cocoa and chocolate consumption. The topics cover modern cocoa cultivation and production practices with special attention to cocoa bean composition, genotypic variations in the bean, post-harvest pretreatments, fermentation and drying processes and the biochemical basis of these operations. The scientific principles behind industrial chocolate manufacture are outlined, with detailed explanations of the various stages of chocolate manufacturing, including mixing, refining, conching and tempering. Other topics covered include the chemistry of flavour formation and development during cocoa processing and chocolate manufacture; volatile flavour compounds and their characteristics and identification; sensory descriptions and character; and flavour release and perception in chocolate. The nutritional and health benefits of cocoa and chocolate consumption and the application of HACCP and other food safety management systems such as ISO 22000 in the chocolate processing industry are also addressed. Additionally, detailed research on the influence of different raw materials and processing operations on the flavour and other quality characteristics of chocolates have been provided, with scope for process optimization and improvement. The book is intended to be a desk reference for all those engaged in the business of making and using chocolate worldwide; confectionery and chocolate scientists in industry and academia; students and practising food scientists and technologists; nutritionists and other health professionals; and libraries of institutions where agriculture, food science and nutrition are studied and researched.

Preface xix Acknowledgements xxi About the author xxiii 1 History, origin and taxonomy of cocoa 1 1.1 Introduction 1 1.2 History of cocoa 2 1.3 Taxonomy of cocoa 5 1.4 Morphological and varietal characteristics of cocoa 6 1.4.1 The cocoa plant 6 1.5 Varietal effects on cocoa bean flavour 10 1.6 The concept of this book 15 2 World cocoa production processing and chocolate consumption pattern 17 2.1 Introduction 17 2.2 World production of cocoa 17 2.3 Major changes in world cocoa trade 20 2.4 Cocoa yield in producing countries 22 2.5 World cocoa grindings trends between 2005–2006 and 2014–2015 23 2.6 World stocks of cocoa beans 26 2.7 International cocoa price developments 26 2.8 Cocoa processing trends 31 2.9 Cocoa and chocolate consumption 33 2.9.1 Apparent cocoa consumption 33 2.9.2 World chocolate consumption 34 2.9.3 World consumption of chocolate products 35 2.9.4 World consumption of premium chocolate products 38 2.10 Fairtrade cocoa and chocolate in the modern confectionery industry 39 2.10.1 Sustainable fairtrade cocoa production 39 2.10.2 Future of the fairtrade cocoa and confectionery industry 41 2.11 The organic cocoa in chocolate confectionery industry 42 2.11.1 The global organic food industry 42 2.11.2 The organic cocoa industry 43 2.11.3 Consumption patterns of organic cocoa 44 2.11.4 Certification and market for organic cocoa 45 2.12 The changing chocolate market 48 3 Traditional and modern cocoa cultivation practices 49 3.1 Introduction 49 3.2 Environmental requirements for cocoa cultivation 51 3.2.1 Temperature 51 3.2.2 Rainfall 52 3.2.3 Soils and nutrition 52 3.3 Traditional cocoa cultivation practices 53 3.3.1 Growth and propagation 53 3.4 Modern cocoa cultivation practices using vegetative propagation 54 3.5 Establishment and shade 54 3.6 Flowering and pod development 60 3.7 Harvesting of cocoa pods 64 3.8 Pod breaking 67 3.9 The cocoa pod 68 3.10 Good agricultural practices in cocoa cultivation 69 3.10.1 Quality improvement practices 69 3.10.2 Weed control 71 3.10.3 Pruning 71 4 Cocoa diseases and pests and their effects on chocolate quality 73 4.1 Introduction 73 4.2 Major cocoa diseases 73 4.2.1 Cocoa swollen shoot virus disease (CSSVD) 73 4.2.2 Black pod disease 74 4.2.3 Witches broom disease 76 4.3 Cocoa pests 77 4.3.1 Pod borers (capsids cocoa thrips and mealy bugs) 77 4.4 Cocoa crop protection 79 5 Cocoa bean composition and chocolate flavour development 80 5.1 Introduction 80 5.2 Bean composition and flavour precursor formation 81 5.2.1 Physical structure and chemical composition of the cocoa bean 81 5.2.2 Cocoa pulp: the fermentation substrate 83 5.2.3 Polyphenols and chocolate flavour quality 85 5.2.4 Effects of proteins and sugars on flavour precursor formation 85 5.3 Effects of genotype on cocoa bean flavour 87 5.4 Flavour development during post-harvest treatments of cocoa 87 5.4.1 Changes in biochemistry of the bean during flavour precursor formation in cocoa fermentation 87 5.4.2 Microbial succession and enzymatic activities during flavour precursor generation in cocoa fermentation 90 5.4.3 Drying 94 5.5 Conclusion 98 6 Cocoa processing technology 102 6.1 Introduction 102 6.2 Bean selection and quality criteria 102 6.2.1 Free fatty acid 103 6.3 Cocoa quality grading and storage 106 6.4 Selection of bean blends and chocolate flavour quality 107 6.5 Steps in cocoa processing 108 6.5.1 Cleaning breaking and winnowing 108 6.5.2 Sterilization 109 6.5.3 Alkalization 109 6.5.4 Roasting 110 6.5.5 Nib grinding and liquor treatment 111 6.5.6 Liquor pressing 112 6.5.7 Cake grinding (kibbling) 112 6.5.8 Cocoa powder production 112 6.5.9 Cocoa butter –chemistry, standards and quality characteristics 112 7 Industrial chocolate manufacture – processes and factors influencing quality 117 7.1 Introduction 117 7.2 Chocolate manufacturing processes 120 7.2.1 Mixing 120 7.2.2 Refining 121 7.2.3 Conching 123 7.3 Tempering, lipid crystallization and continuous phase character during chocolate manufacture 126 7.4 Casting and moulding 130 7.5 Cooling 130 7.6 Demoulding 130 7.7 Wrapping/Packaging 132 7.8 Factors influencing rheological and textural qualities in chocolate 132 7.8.1 Particle size distribution 132 7.8.2 The role of fats 142 7.8.3 The role of sugar 143 7.8.4 The role of milk and other dairy components 144 7.8.5 The role of surfactants 145 7.8.6 Moisture and chocolate flow behaviour 146 7.9 Chocolate quality and defects 146 7.9.1 Chocolate quality 146 7.9.2 Chocolate defects 150 7.10 Conclusion and further research 152 8 The chemistry of flavour development during cocoa processing and chocolate manufacture 154 8.1 Introduction 154 8.2 Influence of bean selection on chocolate flavour quality 154 8.3 Effect of roasting 155 8.3.1 Maillard reactions – aldol condensation, polymerization and cyclization 159 8.3.2 Effects of alkalization 161 8.4 Flavour development during chocolate manufacture 162 8.4.1 Conching 162 8.5 Key flavour compounds in milk chocolate 163 8.6 Key flavour compounds in dark chocolate 163 8.7 Conclusion 169 9 Alternative sweetening and bulking solutions in chocolate manufacture 171 9.1 Introduction 171 9.2 Types of sugar substitutes and their characteristics 172 9.3 High-potency sweeteners 173 9.3.1 Stevia rebaudioside A 173 9.3.2 Thaumatin 176 9.4 Bulk sweeteners 178 9.4.1 Polyols (sugar alcohols) 178 9.4.2 Sucralose 181 9.4.3 Tagatose 183 9.4.4 Trehalose 185 9.4.5 Isomultulose 187 9.5 Low-digestible carbohydrate polymers 188 9.5.1 Polydextrose 189 9.5.2 Inulin and oligofructose 191 9.5.3 Maltodextrin 193 9.6 Laxation and low–digestible carbohydrate polymers 193 9.7 Applicability and suitability of different sweeteners and carbohydrate polymers in chocolate processing 194 9.8 Importance of blending different sugar substitutes 200 10 Sensory character and flavour perception of chocolates 202 10.1 Summary and industrial relevance 202 10.2 Introduction 203 10.3 Sensory perception of quality in chocolates 204 10.3.1 Appearance 208 10.3.2 Texture 208 10.3.3 Taste 209 10.3.4 Flavour and aroma 210 10.4 Sensory assessment of chocolates 211 10.5 Factor influencing chocolate flavour 212 10.6 Flavour release and perception of sweetness in chocolate 213 10.7 Dynamism of flavour perception in chocolate 215 10.8 Retronasal flavour release and perception during chocolate consumption 216 10.9 Measurement of flavour release and intensity in chocolates 218 10.10 Electronic noses and tongues as online sensors for sensory assessment of chocolates 221 10.11 Conclusion 222 11 Nutritional and health benefits of cocoa and chocolate consumption 223 11.1 Summary and significance 223 11.2 Introduction 223 11.3 Chemistry and composition of cocoa flavonoids 225 11.4 Chocolate types and their major nutritional constituents 226 11.5 Antioxidant properties and their mechanism of action 229 11.6 Effects on endothelial function, blood pressure and the cardiovascular system 231 11.7 Effects on insulin sensitivity and carcinogenic properties 232 11.8 Cocoa, chocolate and aphrodisiac properties 233 11.9 Conclusion 234 12 Processing effects on the rheological textural and melting properties during chocolate manufacture 236 12.1 Summary and industrial relevance 236 12.2 Introduction 237 12.3 Materials and methods 241 12.3.1 Materials 241 12.3.2 Preparation of chocolate samples 241 12.3.3 Determination of particle size distribution 242 12.3.4 Rheological measurements 242 12.3.5 Tempering procedure 244 12.3.6 Texture measurements 244 12.3.7 Colour measurements of solid dark chocolate 246 12.3.8 Microstructure analysis 247 12.3.9 Determination of melting properties of dark chocolates 248 12.3.10 Experimental design and statistical analysis 248 12.4 Results and discussion 249 12.4.1 Particle size distribution of molten dark chocolate 249 12.4.2 Rheological properties of molten dark chocolate 249 12.5 Relationships between Casson model and ICA recommendations 258 12.6 Textural properties 262 12.6.1 Molten dark chocolate 262 12.6.2 Hardness of tempered dark chocolate 266 12.6.3 Colour measurements 267 12.6.4 Relationships between textural properties and appearance of dark chocolate 268 12.7 Microstructural properties of molten dark chocolate 270 12.8 Melting properties of dark chocolate 274 12.8.1 Effects of particle size distribution 276 12.8.2 Effects of fat content 281 12.8.3 Effects of lecithin 282 12.9 Relationships between rheological, textural and melting properties of dark chocolate 284 12.10 Conclusion 294 13 Tempering behaviour during chocolate manufacture: Effects of varying product matrices 297 13.1 Summary and industrial relevance 297 13.2 Introduction 298 13.3 Materials and methods 300 13.3.1 Materials 300 13.3.2 Tempering procedure 300 13.3.3 Determination of particle size distribution 301 13.3.4 Experimental design and statistical analysis 301 13.4 Results and discussion 304 13.4.1 Particle size distribution of dark chocolates 304 13.4.2 Effect of particle size distribution on tempering behaviour 308 13.4.3 Effect of fat content on tempering behaviour 312 13.5 Conclusion 316 14 Tempering and fat crystallization effects on chocolate quality 317 14.1 Summary and industrial relevance 317 14.2 Introduction 318 14.3 Materials and methods 319 14.3.1 Materials 319 14.3.2 Determination of particle size distribution 320 14.3.3 Tempering experiment 320 14.3.4 Texture measurements 320 14.3.5 Colour and gloss measurements 321 14.3.6 Image acquisition and capture 321 14.3.7 Determination of melting properties 322 14.3.8 Microstructural determinations 322 14.3.9 Scanning electron microscopy 322 14.3.10 Experimental design and statistical analysis 323 14.4 Results and discussion 323 14.4.1 Particle size distribution of dark chocolates 323 14.4.2 Fat crystallization behaviours during tempering of dark chocolate 324 14.4.3 Effect of temper regime and PSD on mechanical properties 325 14.4.4 Effect of temper regime and PSD on colour and gloss 328 14.4.5 Effect of temper regime and PSD on melting properties 330 14.4.6 Effect of temper regime on microstructure 339 14.4.7 Effect of temper regime on scanning electron microstructure 339 14.5 Conclusion 343 15 Fat bloom formation and development in chocolates 345 15.1 Summary and industrial relevance 345 15.2 Introduction 346 15.3 Materials and methods 347 15.3.1 Materials 347 15.3.2 Determination of particle size distribution 348 15.3.3 Tempering experiment 348 15.3.4 Texture measurements 349 15.3.5 Surface colour and gloss measurements 349 15.3.6 Determination of melting properties 349 15.3.7 Microstructural determinations 350 15.3.8 Experimental design and statistical analysis 350 15.4 Results and discussion 350 15.4.1 Particle size distribution of dark chocolates 350 15.4.2 Changes in textural properties during blooming 351 15.4.3 Changes in appearance (Surface Whiteness and Gloss) during blooming 353 15.4.4 Changes in melting behaviour during blooming 357 15.4.5 Changes in microstructure during blooming 359 15.5 Conclusion 364 16 Matrix effects on flavour volatiles character and release in chocolates 365 16.1 Summary and industrial relevance 365 16.2 Introduction 365 16.3 Materials and methods 367 16.3.1 Materials 367 16.3.2 Tempering procedure 368 16.3.3 Determination of particle size distribution 368 16.3.4 Quantification of flavour volatiles by gas chromatography 368 16.3.5 Gas chromatography–olfactometry analytical conditions 369 16.3.6 Experimental design and statistical analysis 369 16.4 Results and discussion 369 16.4.1 Particle size distribution of dark chocolates 369 16.4.2 Characterization of flavour compounds in dark chocolates 370 16.4.3 Effects of particle size distribution on flavour volatile release 374 16.4.4 Effects of fat content on flavour volatile release 374 16.4.5 Relating flavour volatiles release to particle size distribution and fat content: product spaces 379 16.5 Conclusion 381 17 Process optimization and product quality characteristics during sugar-free chocolate manufacture 382 17.1 Summary and industrial relevance 382 17.2 Introduction 382 17.3 Materials and methods 384 17.3.1 Raw materials 384 17.3.2 Experimental design and sample preparation 384 17.3.3 Analytical methods 385 17.4 Results and discussion 387 17.4.1 Rheological properties 390 17.4.2 Casson plastic viscosity 390 17.4.3 Casson yield stress 392 17.4.4 Microscopy 393 17.4.5 Colour 395 17.4.6 Hardness 395 17.4.7 Moisture 396 17.5 Optimization of chocolate formulation 396 17.6 Conclusion 397 18 Food safety management systems in chocolate processing 399 18.1 Introduction 399 18.2 The HACCP system 400 18.2.1 HACCP principles 401 18.2.2 HACCP plan 402 18.2.3 Application of the HACCP system 405 18.2.4 Advantages of HACCP 405 18.2.5 Shortfalls of HACCP 406 18.3 ISO 22000 approach 406 18.3.1 Advantages of ISO 22000 407 18.3.2 Comparison of ISO 22000 with HACCP 408 18.4 Hazards associated with chocolate processing 408 18.4.1 Physical hazards 408 18.4.2 Chemical hazards 409 18.4.3 Microbiological hazards 411 18.5 Critical operations in cocoa processing and chocolate manufacture 413 18.5.1 Cleaning 413 18.5.2 Roasting 413 18.5.3 Breaking and winnowing 414 18.5.4 Refining 414 18.5.5 Conching 414 18.5.6 Tempering 415 18.6 Conclusion 415 19 Application of ISO 22000 and hazard analysis and critical control points (HACCP) in chocolate processing 416 19.1 Summary and industrial relevance 416 19.2 Introduction 416 19.2.1 Hazard analysis and critical control points (HACCP) 417 19.2.2 HACCP principles 418 19.2.3 ISO 22000 419 19.3 Hazards associated with chocolate processing 419 19.3.1 Physical hazards 420 19.3.2 Chemical hazards 421 19.3.3 Microbiological hazards 421 19.4 Preprocessing operations 421 19.5 Cocoa processing into semi-finished products 422 19.5.1 Bean receipt and cleaning – CCP1 422 19.5.2 Silos (Storage) – CCP2 422 19.5.3 De-bacterizer – CCP3 422 19.5.4 The roasting process – CCP4 422 19.5.5 Breaking and winnowing 424 19.5.6 Milling 424 19.5.7 Storage and conditioning – CCP5 424 19.5.8 Pressing – CCP6 425 19.5.9 Centrifugation and filtration – CCP7 425 19.5.10 Kibbling and pulverization 425 19.6 Milk chocolate manufacturing operations 425 19.6.1 Raw materials reception – CCP1 425 19.6.2 Mixing – CCP2 425 19.6.3 Refining 426 19.6.4 Conching 427 19.6.5 Tempering 427 19.6.6 Casting and moulding – CCP3 428 19.6.7 Cooling 428 19.6.8 Demoulding 428 19.6.9 Wrapping/Packaging – CCP4 429 19.7 Hazard analysis 429 19.7.1 Determination of critical control points 435 19.7.2 Determination of prerequisite programmes 435 19.8 Conclusion 435 20 Conclusions and industrial applications 441 20.1 Introduction 441 20.2 Conclusions: Structure–properties relationships in chocolate manufacture 441 20.3 Conclusions: Tempering behaviour from response surface methodology 443 20.4 Conclusions: Effects of tempering and fat crystallization on microstructure and physical properties 444 20.5 Conclusions: Fat bloom formation and development with under-tempering 445 20.6 Conclusions: Flavour volatiles and matrix effects related to variations in PSD and fat content 445 20.7 Conclusions: Process optimization and product quality characteristics of sugar-free chocolates 446 20.8 Industrial relevance and applications of research findings in this book 447 20.9 Recommendations for further research studies 448 References 450 Appendix 1 Abbreviations 487 Appendix 2 Acronyms and websites of organizations related to the cocoa and chocolate industry 490 Appendix 3 Glossary of cocoa and chocolate terminologies 492 Index 497