Chocolate Science and Technology

The Author Emmanuel Ohene Afoakwa, Department of Nutrition and Food Science, University of Ghana, Ghana Formerly of Nestlé Product Technology Centre, York, UK

• Preface xixAcknowledgements xxiAbout the author xxiii1 History, origin and taxonomy of cocoa 11.1 Introduction 11.2 History of cocoa 21.3 Taxonomy of cocoa 51.4 Morphological and varietal characteristics of cocoa 61.4.1 The cocoa plant 61.5 Varietal effects on cocoa bean flavour 101.6 The concept of this book 152 World cocoa production processing and chocolate consumption pattern 172.1 Introduction 172.2 World production of cocoa 172.3 Major changes in world cocoa trade 202.4 Cocoa yield in producing countries 222.5 World cocoa grindings trends between 2005–2006 and 2014–2015 232.6 World stocks of cocoa beans 262.7 International cocoa price developments 262.8 Cocoa processing trends 312.9 Cocoa and chocolate consumption 332.9.1 Apparent cocoa consumption 332.9.2 World chocolate consumption 342.9.3 World consumption of chocolate products 352.9.4 World consumption of premium chocolate products 382.10 Fairtrade cocoa and chocolate in the modern confectionery industry 392.10.1 Sustainable fairtrade cocoa production 392.10.2 Future of the fairtrade cocoa and confectionery industry 412.11 The organic cocoa in chocolate confectionery industry 422.11.1 The global organic food industry 422.11.2 The organic cocoa industry 432.11.3 Consumption patterns of organic cocoa 442.11.4 Certification and market for organic cocoa 452.12 The changing chocolate market 483 Traditional and modern cocoa cultivation practices 493.1 Introduction 493.2 Environmental requirements for cocoa cultivation 513.2.1 Temperature 513.2.2 Rainfall 523.2.3 Soils and nutrition 523.3 Traditional cocoa cultivation practices 533.3.1 Growth and propagation 533.4 Modern cocoa cultivation practices using vegetative propagation 543.5 Establishment and shade 543.6 Flowering and pod development 603.7 Harvesting of cocoa pods 643.8 Pod breaking 673.9 The cocoa pod 683.10 Good agricultural practices in cocoa cultivation 693.10.1 Quality improvement practices 693.10.2 Weed control 713.10.3 Pruning 714 Cocoa diseases and pests and their effects on chocolate quality 734.1 Introduction 734.2 Major cocoa diseases 734.2.1 Cocoa swollen shoot virus disease (CSSVD) 734.2.2 Black pod disease 744.2.3 Witches broom disease 764.3 Cocoa pests 774.3.1 Pod borers (capsids cocoa thrips and mealy bugs) 774.4 Cocoa crop protection 795 Cocoa bean composition and chocolate flavour development 805.1 Introduction 805.2 Bean composition and flavour precursor formation 815.2.1 Physical structure and chemical composition of the cocoa bean 815.2.2 Cocoa pulp: the fermentation substrate 835.2.3 Polyphenols and chocolate flavour quality 855.2.4 Effects of proteins and sugars on flavour precursor formation 855.3 Effects of genotype on cocoa bean flavour 875.4 Flavour development during post-harvest treatments of cocoa 875.4.1 Changes in biochemistry of the bean during flavour precursor formation in cocoa fermentation 875.4.2 Microbial succession and enzymatic activities during flavour precursor generation in cocoa fermentation 905.4.3 Drying 945.5 Conclusion 986 Cocoa processing technology 1026.1 Introduction 1026.2 Bean selection and quality criteria 1026.2.1 Free fatty acid 1036.3 Cocoa quality grading and storage 1066.4 Selection of bean blends and chocolate flavour quality 1076.5 Steps in cocoa processing 1086.5.1 Cleaning breaking and winnowing 1086.5.2 Sterilization 1096.5.3 Alkalization 1096.5.4 Roasting 1106.5.5 Nib grinding and liquor treatment 1116.5.6 Liquor pressing 1126.5.7 Cake grinding (kibbling) 1126.5.8 Cocoa powder production 1126.5.9 Cocoa butter –chemistry, standards and quality characteristics 1127 Industrial chocolate manufacture – processes and factors influencing quality 1177.1 Introduction 1177.2 Chocolate manufacturing processes 1207.2.1 Mixing 1207.2.2 Refining 1217.2.3 Conching 1237.3 Tempering, lipid crystallization and continuous phase character during chocolate manufacture 1267.4 Casting and moulding 1307.5 Cooling 1307.6 Demoulding 1307.7 Wrapping/Packaging 1327.8 Factors influencing rheological and textural qualities in chocolate 1327.8.1 Particle size distribution 1327.8.2 The role of fats 1427.8.3 The role of sugar 1437.8.4 The role of milk and other dairy components 1447.8.5 The role of surfactants 1457.8.6 Moisture and chocolate flow behaviour 1467.9 Chocolate quality and defects 1467.9.1 Chocolate quality 1467.9.2 Chocolate defects 1507.10 Conclusion and further research 1528 The chemistry of flavour development during cocoa processing and chocolate manufacture 1548.1 Introduction 1548.2 Influence of bean selection on chocolate flavour quality 1548.3 Effect of roasting 1558.3.1 Maillard reactions – aldol condensation, polymerization and cyclization 1598.3.2 Effects of alkalization 1618.4 Flavour development during chocolate manufacture 1628.4.1 Conching 1628.5 Key flavour compounds in milk chocolate 1638.6 Key flavour compounds in dark chocolate 1638.7 Conclusion 1699 Alternative sweetening and bulking solutions in chocolate manufacture 1719.1 Introduction 1719.2 Types of sugar substitutes and their characteristics 1729.3 High-potency sweeteners 1739.3.1 Stevia rebaudioside A 1739.3.2 Thaumatin 1769.4 Bulk sweeteners 1789.4.1 Polyols (sugar alcohols) 1789.4.2 Sucralose 1819.4.3 Tagatose 1839.4.4 Trehalose 1859.4.5 Isomultulose 1879.5 Low-digestible carbohydrate polymers 1889.5.1 Polydextrose 1899.5.2 Inulin and oligofructose 1919.5.3 Maltodextrin 1939.6 Laxation and low–digestible carbohydrate polymers 1939.7 Applicability and suitability of different sweeteners and carbohydrate polymers in chocolate processing 1949.8 Importance of blending different sugar substitutes 20010 Sensory character and flavour perception of chocolates 20210.1 Summary and industrial relevance 20210.2 Introduction 20310.3 Sensory perception of quality in chocolates 20410.3.1 Appearance 20810.3.2 Texture 20810.3.3 Taste 20910.3.4 Flavour and aroma 21010.4 Sensory assessment of chocolates 21110.5 Factor influencing chocolate flavour 21210.6 Flavour release and perception of sweetness in chocolate 21310.7 Dynamism of flavour perception in chocolate 21510.8 Retronasal flavour release and perception during chocolate consumption 21610.9 Measurement of flavour release and intensity in chocolates 21810.10 Electronic noses and tongues as online sensors for sensory assessment of chocolates 22110.11 Conclusion 22211 Nutritional and health benefits of cocoa and chocolate consumption 22311.1 Summary and significance 22311.2 Introduction 22311.3 Chemistry and composition of cocoa flavonoids 22511.4 Chocolate types and their major nutritional constituents 22611.5 Antioxidant properties and their mechanism of action 22911.6 Effects on endothelial function, blood pressure and the cardiovascular system 23111.7 Effects on insulin sensitivity and carcinogenic properties 23211.8 Cocoa, chocolate and aphrodisiac properties 23311.9 Conclusion 23412 Processing effects on the rheological textural and melting properties during chocolate manufacture 23612.1 Summary and industrial relevance 23612.2 Introduction 23712.3 Materials and methods 24112.3.1 Materials 24112.3.2 Preparation of chocolate samples 24112.3.3 Determination of particle size distribution 24212.3.4 Rheological measurements 24212.3.5 Tempering procedure 24412.3.6 Texture measurements 24412.3.7 Colour measurements of solid dark chocolate 24612.3.8 Microstructure analysis 24712.3.9 Determination of melting properties of dark chocolates 24812.3.10 Experimental design and statistical analysis 24812.4 Results and discussion 24912.4.1 Particle size distribution of molten dark chocolate 24912.4.2 Rheological properties of molten dark chocolate 24912.5 Relationships between Casson model and ICA recommendations 25812.6 Textural properties 26212.6.1 Molten dark chocolate 26212.6.2 Hardness of tempered dark chocolate 26612.6.3 Colour measurements 26712.6.4 Relationships between textural properties and appearance of dark chocolate 26812.7 Microstructural properties of molten dark chocolate 27012.8 Melting properties of dark chocolate 27412.8.1 Effects of particle size distribution 27612.8.2 Effects of fat content 28112.8.3 Effects of lecithin 28212.9 Relationships between rheological, textural and melting properties of dark chocolate 28412.10 Conclusion 29413 Tempering behaviour during chocolate manufacture: Effects of varying product matrices 29713.1 Summary and industrial relevance 29713.2 Introduction 29813.3 Materials and methods 30013.3.1 Materials 30013.3.2 Tempering procedure 30013.3.3 Determination of particle size distribution 30113.3.4 Experimental design and statistical analysis 30113.4 Results and discussion 30413.4.1 Particle size distribution of dark chocolates 30413.4.2 Effect of particle size distribution on tempering behaviour 30813.4.3 Effect of fat content on tempering behaviour 31213.5 Conclusion 31614 Tempering and fat crystallization effects on chocolate quality 31714.1 Summary and industrial relevance 31714.2 Introduction 31814.3 Materials and methods 31914.3.1 Materials 31914.3.2 Determination of particle size distribution 32014.3.3 Tempering experiment 32014.3.4 Texture measurements 32014.3.5 Colour and gloss measurements 32114.3.6 Image acquisition and capture 32114.3.7 Determination of melting properties 32214.3.8 Microstructural determinations 32214.3.9 Scanning electron microscopy 32214.3.10 Experimental design and statistical analysis 32314.4 Results and discussion 32314.4.1 Particle size distribution of dark chocolates 32314.4.2 Fat crystallization behaviours during tempering of dark chocolate 32414.4.3 Effect of temper regime and PSD on mechanical properties 32514.4.4 Effect of temper regime and PSD on colour and gloss 32814.4.5 Effect of temper regime and PSD on melting properties 33014.4.6 Effect of temper regime on microstructure 33914.4.7 Effect of temper regime on scanning electron microstructure 33914.5 Conclusion 34315 Fat bloom formation and development in chocolates 34515.1 Summary and industrial relevance 34515.2 Introduction 34615.3 Materials and methods 34715.3.1 Materials 34715.3.2 Determination of particle size distribution 34815.3.3 Tempering experiment 34815.3.4 Texture measurements 34915.3.5 Surface colour and gloss measurements 34915.3.6 Determination of melting properties 34915.3.7 Microstructural determinations 35015.3.8 Experimental design and statistical analysis 35015.4 Results and discussion 35015.4.1 Particle size distribution of dark chocolates 35015.4.2 Changes in textural properties during blooming 35115.4.3 Changes in appearance (Surface Whiteness and Gloss) during blooming 35315.4.4 Changes in melting behaviour during blooming 35715.4.5 Changes in microstructure during blooming 35915.5 Conclusion 36416 Matrix effects on flavour volatiles character and release in chocolates 36516.1 Summary and industrial relevance 36516.2 Introduction 36516.3 Materials and methods 36716.3.1 Materials 36716.3.2 Tempering procedure 36816.3.3 Determination of particle size distribution 36816.3.4 Quantification of flavour volatiles by gas chromatography 36816.3.5 Gas chromatography–olfactometry analytical conditions 36916.3.6 Experimental design and statistical analysis 36916.4 Results and discussion 36916.4.1 Particle size distribution of dark chocolates 36916.4.2 Characterization of flavour compounds in dark chocolates 37016.4.3 Effects of particle size distribution on flavour volatile release 37416.4.4 Effects of fat content on flavour volatile release 37416.4.5 Relating flavour volatiles release to particle size distribution and fat content: product spaces 37916.5 Conclusion 38117 Process optimization and product quality characteristics during sugar-free chocolate manufacture 38217.1 Summary and industrial relevance 38217.2 Introduction 38217.3 Materials and methods 38417.3.1 Raw materials 38417.3.2 Experimental design and sample preparation 38417.3.3 Analytical methods 38517.4 Results and discussion 38717.4.1 Rheological properties 39017.4.2 Casson plastic viscosity 39017.4.3 Casson yield stress 39217.4.4 Microscopy 39317.4.5 Colour 39517.4.6 Hardness 39517.4.7 Moisture 39617.5 Optimization of chocolate formulation 39617.6 Conclusion 39718 Food safety management systems in chocolate processing 39918.1 Introduction 39918.2 The HACCP system 40018.2.1 HACCP principles 40118.2.2 HACCP plan 40218.2.3 Application of the HACCP system 40518.2.4 Advantages of HACCP 40518.2.5 Shortfalls of HACCP 40618.3 ISO 22000 approach 40618.3.1 Advantages of ISO 22000 40718.3.2 Comparison of ISO 22000 with HACCP 40818.4 Hazards associated with chocolate processing 40818.4.1 Physical hazards 40818.4.2 Chemical hazards 40918.4.3 Microbiological hazards 41118.5 Critical operations in cocoa processing and chocolate manufacture 41318.5.1 Cleaning 41318.5.2 Roasting 41318.5.3 Breaking and winnowing 41418.5.4 Refining 41418.5.5 Conching 41418.5.6 Tempering 41518.6 Conclusion 41519 Application of ISO 22000 and hazard analysis and critical control points (HACCP) in chocolate processing 41619.1 Summary and industrial relevance 41619.2 Introduction 41619.2.1 Hazard analysis and critical control points (HACCP) 41719.2.2 HACCP principles 41819.2.3 ISO 22000 41919.3 Hazards associated with chocolate processing 41919.3.1 Physical hazards 42019.3.2 Chemical hazards 42119.3.3 Microbiological hazards 42119.4 Preprocessing operations 42119.5 Cocoa processing into semi-finished products 42219.5.1 Bean receipt and cleaning – CCP1 42219.5.2 Silos (Storage) – CCP2 42219.5.3 De-bacterizer – CCP3 42219.5.4 The roasting process – CCP4 42219.5.5 Breaking and winnowing 42419.5.6 Milling 42419.5.7 Storage and conditioning – CCP5 42419.5.8 Pressing – CCP6 42519.5.9 Centrifugation and filtration – CCP7 42519.5.10 Kibbling and pulverization 42519.6 Milk chocolate manufacturing operations 42519.6.1 Raw materials reception – CCP1 42519.6.2 Mixing – CCP2 42519.6.3 Refining 42619.6.4 Conching 42719.6.5 Tempering 42719.6.6 Casting and moulding – CCP3 42819.6.7 Cooling 42819.6.8 Demoulding 42819.6.9 Wrapping/Packaging – CCP4 42919.7 Hazard analysis 42919.7.1 Determination of critical control points 43519.7.2 Determination of prerequisite programmes 43519.8 Conclusion 43520 Conclusions and industrial applications 44120.1 Introduction 44120.2 Conclusions: Structure–properties relationships in chocolate manufacture 44120.3 Conclusions: Tempering behaviour from response surface methodology 44320.4 Conclusions: Effects of tempering and fat crystallization on microstructure and physical properties 44420.5 Conclusions: Fat bloom formation and development with under-tempering 44520.6 Conclusions: Flavour volatiles and matrix effects related to variations in PSD and fat content 44520.7 Conclusions: Process optimization and product quality characteristics of sugar-free chocolates 44620.8 Industrial relevance and applications of research findings in this book 44720.9 Recommendations for further research studies 448References 450Appendix 1 Abbreviations 487Appendix 2 Acronyms and websites of organizations related to the cocoa and chocolate industry 490Appendix 3 Glossary of cocoa and chocolate terminologies 492Index 497