Applications of ultrasound in analysis, processing and quality control of food: A review

We investigated organogel formation in dispersions of CW in safflower oil (SFO) Candelilla wax (CW) has as its main component hentriacontane (789%), a n-alkane with self assembly properties in organic solvents (ie, vegetable oils) Results showed that, independent of the cooling rate (ie, 1 °C/min and 10 °C/min) and gel setting temperature (T
 set), the CW organogels observed a thermoreversible behavior This was evaluated by the behavior of thermal parameters that characterized organogel formation (gelation temperature, T
 g; heat of gelation, ΔHg) and melting (melting temperature, T
 p; heat of melting, ΔHM) after two heating-cooling cycles For a given CW concentration (ie, 05, 10, and 3%), the magnitude of ΔHM and T
 p and the structural organization of the organogel, depended on the cooling rate, the thermodynamic drive force for gelation, and the annealing process occurring at high Tset (ie, 25  °C) At T
 set of 25 °C the microplatelet units that formed the organogel aggregated as a function of storage time, a process that resulted in an increase in organogel hardness In contrast, at T
 set of 5 °C annealing occurred in a limited extent, but gels had higher solid fat content and microplatelet units of a smaller size than the gels obtained at 25 °C The result was a three-dimensional network with greater hardness than the one obtained at 25 °C The 3% CW organogels showed no phase separation up to 3 months at room temperature, with textures of potential use by the food industry

Thermal and Textural Properties of Organogels Developed by Candelilla Wax in Safflower Oil

Preface Acknowledgements About the author 1 Chocolate production and consumption patterns 1.1 History of cocoa and chocolate 1.2 World production and consumption of cocoa and chocolate products 1.2.1 World production and consumption of cocoa 1.2.2 World cocoa prices 1.2.3 World consumption of chocolate products 1.2.4 World consumption of premium chocolate products 1.3 Fairtrade cocoa and chocolate in modern confectionery industry 1.3.1 Future of Fairtrade cocoa and confectionery industry 1.4 The concept of this book 2 Cocoa cultivation, bean composition and chocolate flavour precursor formation and character 2.1 Introduction 2.2 Cocoa cultivation and practices 2.2.1 Cultivation of cocoa 2.2.2 Flowering and pod development 2.2.3 Harvesting and pod opening 2.2.4 Cocoa diseases and pests and their influence on chocolate quality 2.3 Bean composition and flavour precursor formation 2.3.1 Chemical composition of the bean 2.3.2 Polyphenols and chocolate flavour quality 2.3.3 Effects of proteins and sugars on flavour precursor formation 2.3.4 Microbial succession and enzymatic activities during flavour precursor generation in cocoa fermentation 2.4 Effect of genotype on cocoa bean flavours 2.5 Flavour development during post-harvest treatments of cocoa 2.5.1 Fermentation processes 2.5.2 Drying 2.6 Conclusion 3 Industrial chocolate manufacture processes and factors influencing quality 3.1 Introduction 3.2 Cocoa processing and technology 3.2.1 Bean selection and quality criteria 3.2.2 Cleaning, breaking and winnowing 3.2.3 Sterilisation 3.2.4 Alkalisation 3.2.5 Roasting 3.2.6 Nib grinding and liquor treatment 3.2.7 Liquor pressing 3.2.8 Cake grinding (kibbling) 3.2.9 Cocoa powder production 3.3 Chocolate manufacturing processes 3.3.1 Mixing 3.3.2 Refining 3.3.3 Conching 3.4 Tempering, lipid crystallisation and continuous phase character during chocolate manufacture 3.5 Particle size distribution in chocolate 3.6 Compositional effects on rheological and textural qualities in chocolate 3.6.1 The role of fats 3.6.2 The role of sugar 3.6.3 The role of milk and other dairy components 3.6.4 The role of surfactants in modern chocolate confectionery 3.7 Moisture and chocolate flow 3.8 Chocolate quality and defects 3.8.1 Chocolate quality 3.8.2 Chocolate defects 3.9 Conclusion and further research 4 The chemistry of flavour development during cocoa processing and chocolate manufacture 4.1 Introduction 4.2 Influence of bean selection on chocolate flavour quality 4.3 Effect of roasting 4.3.1 Maillard reactions aldol condensation, polymerisation and cyclisation 4.3.2 Effects of alkalisation 4.4 Flavour development during chocolate manufacture 4.4.1 Conching 4.5 Key flavour compounds in milk chocolate 4.6 Key flavour compounds in dark chocolate 4.7 Conclusion 5 Sensory character and flavour perception of chocolates 5.1 Summary and industrial relevance 5.2 Introduction 5.3 Sensory perception of quality in chocolates 5.3.1 Appearance 5.3.2 Texture 5.3.3 Taste 5.3.4 Flavour and aroma 5.4 Sensory assessment of chocolates 5.5 Factor influencing chocolate flavour 5.6 Flavour release and perception of sweetness in chocolate 5.7 Dynamism of flavour perception in chocolate 5.8 Retronasal flavour release and perception during chocolate consumption 5.9 Measurement of flavour release and intensity in chocolates 5.10 Electronic noses and tongues as online sensors for sensory assessment of chocolates 5.11 Conclusion 6 Nutritional and health benefits of cocoa and chocolate consumption 6.1 Summary and significance 6.2 Introduction 6.3 Chemistry and composition of cocoa flavonoids 6.4 Chocolate types and their major nutritional constituents 6.5 Antioxidant properties and their mechanism of action 6.6 Effects on endothelial function, blood pressure and cardiovascular system 6.7 Effects on insulin sensitivity and carcinogenic properties 6.8 Cocoa, chocolate and aphrodisiac properties 6.9 Conclusion 7 Structure properties (rheology, texture and melting) relationships in chocolate manufacture 7.1 Summary and industrial relevance 7.2 Introduction 7.3 Materials and methods 7.3.1 Materials 7.3.2 Preparation of chocolate samples 7.3.3 Determination of particle size distribution 7.3.4 Rheological measurements 7.3.5 Tempering procedure 7.3.6 Texture measurements 7.3.7 Colour measurements of solid dark chocolate 7.3.8 Microstructure analysis 7.3.9 Determination of melting properties of dark chocolates 7.3.10 Experimental design and statistical analysis 7.4 Results and discussion 7.4.1 Particle size distribution of molten dark chocolate 7.4.2 Rheological properties of molten dark chocolate 7.5 Relationships between casson model and ICA recommendations 7.6 Textural properties 7.6.1 Molten dark chocolate 7.6.2 Hardness of tempered dark chocolate 7.6.3 Colour measurements 7.6.4 Relationships between textural properties and appearance of dark chocolate 7.7 Microstructural properties of molten dark chocolate 7.8 Melting properties of dark chocolate 7.8.1 Effects of particle size distribution 7.8.2 Effects of fat content 7.8.3 Effects of lecithin 7.9 Relationships between rheological, textural and melting properties of dark chocolate 7.10 Conclusion 8 Tempering behaviour during chocolate manufacture: effects of varying product matrices 8.1 Summary and industrial relevance 8.2 Introduction 8.3 Materials and methods 8.3.1 Materials 8.3.2 Tempering procedure 8.3.3 Determination of particle size distribution 8.3.4 Experimental design and statistical analysis 8.4 Results and discussion 8.4.1 Particle size distribution of dark chocolates 8.4.2 Effect of particle size distribution on tempering behaviour 8.4.3 Effect of fat content on tempering behaviour 8.5 Conclusion 9 Tempering and fat crystallisation effects on chocolate quality 9.1 Summary and industrial relevance 9.2 Introduction 9.3 Materials and methods 9.3.1 Materials 9.3.2 Determination of particle size distribution 9.3.3 Tempering experiment 9.3.4 Texture measurements 9.3.5 Colour and gloss measurements 9.3.6 Image acquisition and capture 9.3.7 Determination of melting properties 9.3.8 Microstructural determinations 9.3.9 Scanning electron microscopy 9.3.10 Experimental design and statistical analysis 9.4 Results and discussion 9.4.1 Particle size distribution of dark chocolates 9.4.2 Fat crystallisation behaviours during tempering of dark chocolate 9.4.3 Effect of temper regime and PSD on mechanical properties 9.4.4 Effect of temper regime and PSD on colour and gloss 9.4.5 Effect of temper regime and PSD on melting properties 9.4.6 Effect of temper regime on microstructure 9.4.7 Effect of temper regime on scanning electron microstructure 9.5 Conclusion 10 Fat bloom formation and development in chocolates 10.1 Summary and industrial relevance 10.2 Introduction 10.3 Materials and methods 10.3.1 Materials 10.3.2 Determination of particle size distribution 10.3.3 Tempering experiment 10.3.4 Texture measurements 10.3.5 Surface colour and gloss measurements 10.3.6 Determination of melting properties 10.3.7 Microstructural determinations 10.3.8 Experimental design and statistical analysis 10.4 Results and discussion 10.5 Conclusion 11 Matrix effects on flavour volatiles character and release in chocolates 11.1 Summary and industrial relevance 11.2 Introduction 11.3 Materials and methods 11.3.1 Materials 11.3.2 Tempering procedure 11.3.3 Determination of particle size distribution 11.3.4 Quantification of flavour volatiles by gas chromatography 11.3.5 Gas chromatography olfactometry analytical conditions 11.3.6 Experimental design and statistical analysis 11.4 Results and discussion 11.4.1 Particle size distribution of dark chocolates 11.4.2 Characterisation of flavour compounds in dark chocolates 11.4.3 Effects of particle size distribution on flavour volatile release 11.4.4 Effects of fat content on flavour volatile release 11.4.5 Relating flavour volatiles release to PSD and fat content: product spaces 11.5 Conclusion 12 Conclusions and industrial applications 12.1 Conclusions: Structure properties relationships in chocolate manufacture 12.2 Conclusions: Tempering behaviour from response surface methodology 12.3 Conclusions: Effects of tempering and fat crystallisation on microstructure and physical properties 12.4 Conclusions: FAT bloom formation and development with undertempering 12.5 Conclusions: Flavour volatiles and matrix effects related to variations in PSD and FAT content 12.6 Industrial relevance and applications of research findings in this book 12.7 Recommendations for further research studies References Appendix 1: Abbreviations used and their meanings Appendix 2: Abbreviations, acronyms and websites of organizations related to cocoa and chocolate industry Appendix 3: Glossary of chocolate terminologies Index

Chocolate Science and Technology

Diverse food-based applications of nuclear magnetic resonance (NMR) technology

Fat-structured food materials are an important component of our diet. The role that fat plays in material functionality, flavor perception, texture and health characteristics is due in large part to its physical properties. An understanding of these physical properties is relevant from scientific, technological and medical perspectives. The physical properties of fat materials, are, in turn, governed by a complex confluence of the various structural levels in a fat material beginning with triglyceride molecules. The formation of nanoscale structural elements by these molecules is the first step in the formation of a fat material as we know it. This review shows how these microstructural elements can be imaged and characterized. It is also shown that the formation of these nanocrystals is affected by the attendant crystallization parameters. Through simulation and a discussion of van der Waals forces, it is shown that these nanoscale elements assemble into colloidal aggregates with fractal character. The influence of microstructure on the mechanical properties of a fat material is explained using a variety of mechanical models. Lastly, this review examines methods by which the properties and characteristics of the various structural levels can be engineered. Shear has been shown to affect the polymorphism and phase transition kinetics of triglyceride crystals. As well, shear has been shown to modify the aggregation of nanocrystals, with consequences for the porosity and diffusivity of oil through the fat crystal network.

Structure and functionality of edible fats

Effect of cooling rate on the structure and mechanical properties of milk fat and lard

The present study endeavors to understand how small changes in the composition of cocoa butter affect its crystal habit, crystallization behavior, microstructure, and mechanical properties. Such compositional variations were attained by blending cocoa butter with 1 and 5% 1,2,3-tristearoyl-glycerol (SSS) or 1,2,3-trilinoleoyl-glycerol (LLL). Structural parameters such as crystallization kinetics, crystal structure, microstructure, and mechanical strength were obtained via differential scanning calorimetry (DSC), pulsed nuclear magnetic resonance (pNMR), X-ray diffraction (XRD), polarized light microscopy (PLM), and texture analysis. Changes in the triacylglycerol (TAG) profile of cocoa butter affected its crystal structure and therefore its functionality. The high melting saturated SSS becomes rapidly undercooled, reducing cocoa butter’s onset crystallization times and temperatures. SSS molecules are spatially bigger (i.e., straighter) relative to cocoa butter’s symmetric monounsaturated TAG (the unsatura...

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Molecular Composition Dynamics and Structure of Cocoa Butter

The present study endeavors to understand how small changes in the composition ofcocoa butter affect its crystal habit, crystallization behavior, microstructure, and mechanical properties. Such compositional variations were attained by blendingcocoa butter with I and 5% 1,2,3-tristearoyl-glycerol (SSS) or 1,2,3-trilinoleoyl-glycerol (LLL). Structural parameters such as crystallization kinetics, crystal structure, microstructure, and mechanical strength were obtained via differential scanning calorimetry (DSC), pulsed nuclear magnetic resonance (pNMR), X-ray diffraction (XRD), polarized light microscopy (PLM), and texture analysis. Changes in the triacylglycerol (TAG) profile of cocoa butter affected its crystal structure and therefore its functionality. The high melting saturated SSS becomes rapidly undercooted, reducing cocoa butter's onset crystallization times and temperatures. SSS molecules are spatially bigger (i.e., straighter) relative to cocoa butter's symmetric monounsaturated TAG (the unsaturated oleic acid in the sn-2 position introduces a kink into the TAG structure), and hence infringe upon the order of the crystal domain, reducing the crystal―melt interfacial tension, and delaying polymorphic transformations. On the other hand, the limited molecular compatibility between cocoa butter's TAGs and the fully unsaturated low melting LLL prevents it from co-crystallizing with the bulk of cocoa butter's TAGs, only slightly affecting the crystallization behavior, increasing the liquid fraction, having no impact on crystal structure yet accelerating polymorphic transformations into the stable β form.

Control of heat and mass transfer conditions during chocolate manufacture is a critical factor influencing product quality and performance. The molecular basis for specific tempering protocols deve...

Crystallization Dynamics of Shear Worked Cocoa Butter

Since the velocity of an ultrasonic wave through a material depends on its density, bulk modulus (K), and shear modulus (G), a new approach to determine the shear elastic modulus and the mass fractal dimension (D) in a fat crystal network was developed. An ultrasonic chirp wave containing a range of frequencies and amplitudes, was used to estimate the structural and mechanical properties of palm oil based fats, crystallized under shear at three different temperatures (20, 25, and 30 °C). Considering the fat crystal network as a two-phase system (i.e. liquid and solid fat) the velocity of sound in both phases was obtained separately, assuming that the speed of sound in the oil phase was inversely dependent on the temperature. A constant shear modulus for the solid fraction was obtained experimentally by rheology, which was independent of the sample’s nature. These parameters were used for the determination of sample compressibility and its corresponding shear modulus by ultrasonic velocimetry. In addition fractal dimensions (D) were determined by using the relationship of the shear elastic modulus (G) to the mass fraction of the solid fat (φ) in a weak-link regime. The obtained results are comparable and consistent with previously reported fractal dimension values. This method allows online determination of the shear modulus of fats and could be potentially applied for quality control purposes in manufacturing.

Rodrigo Campos

Papers

Effect of cooling rate on the structure and mechanical properties of milk fat and lard

Molecular Composition Dynamics and Structure of Cocoa Butter

Molecular Composition Dynamics and Structure of Cocoa Butter

Crystallization Dynamics of Shear Worked Cocoa Butter

Structural and Mechanical Properties of Fats Quantified by Ultrasonics