Confectionery and Chocolate Engineering: Principles and Applications

Confectionery and chocolate manufacture has been dominated by large-scale industrial processing for several decades. It is often the case though, that a trial and error approach is applied to the development of new products and processes, rather than verified scientific principles. Confectionery and Chocolate Engineering: Principles and Applications, Second edition, adds to information presented in the first edition on essential topics such as food safety, quality assurance, sweets for special nutritional purposes, artizan chocolate, and confectioneries. In addition, information is provided on the fading memory of viscoelastic fluids, which are briefly discussed in terms of fractional calculus, and gelation as a second order phase transition. Chemical operations such as inversion, caramelization, and the Maillard reaction, as well as the complex operations including  conching, drying, frying, baking, and roasting used in confectionery manufacture are also described. This book provides food engineers, scientists, technologists and students in research, industry, and food and chemical engineering-related courses with a scientific, theoretical description and analysis of confectionery manufacturing, opening up new possibilities for process and product improvement, relating to increased efficiency of operations, the use of new materials, and new applications for traditional raw materials.

Table of Contents:
Preface xxiii Preface to the second edition xxvii Acknowledgements xxix Part I: Theoretical introduction 1 Principles of food engineering 3 1.1 Introduction 3 1.2 The Damköhler equations 6 1.3 Investigation of the Damköhler equations by means of similarity theory 8 1.4 Analogies 14 1.5 Dimensional analysis 16 1.6 System theoretical approaches to food engineering 19 1.7 Food safety and quality assurance 21 Further reading 22 2 Characterization of substances used in the confectionery industry 23 2.1 Qualitative characterization of substances 23 2.2 Quantitative characterization of confectionery products 33 2.3 Preparation of recipes 49 2.4 Composition of chocolate confectioneries biscuits and wafers made for special nutritional purposes 56 Further reading 60 3 Engineering properties of foods 61 3.1 Introduction 61 3.2 Density 61 3.3 Fundamental functions of thermodynamics 65 3.4 Latent heat and heat of reaction 71 3.5 Thermal conductivity 76 3.6 Thermal diffusivity and Prandtl number 78 3.7 Mass diffusivity and Schmidt number 81 3.8 Dielectric properties 85 3.9 Electrical conductivity 91 3.10 Infrared absorption properties 95 3.11 Physical characteristics of food powders 96 Further reading 107 4 The rheology of foods and sweets 109 4.1 Rheology: its importance in the confectionery industry 109 4.2 Stress and strain 109 4.3 Solid behaviour 115 4.4 Fluid behaviour 120 4.5 Viscosity of solutions 159 4.6 Viscosity of emulsions 161 4.7 Viscosity of suspensions 164 4.8 Rheological properties of gels 166 4.9 Rheological properties of sweets 171 4.10 Rheological properties of wheat flour doughs 183 4.11 Relationship between food oral processing and rheology 193 Further reading 194 5 Introduction to food colloids 197 5.1 The colloidal state 197 5.2 Formation of colloids 199 5.3 Properties of macromolecular colloids 202 5.4 Properties of colloids of association 208 5.5 Properties of interfaces 210 5.6 Electrical properties of interfaces 219 5.7 Theory of colloidal stability: the DLVO theory 221 5.8 Stability and changes of colloids and coarse dispersions 224 5.9 Emulsion instability 233 5.10 Phase inversion 243 5.11 Foams 245 5.12 Gelation as a second-order phase transition 256 Further reading 261 Part II: Physical operations 6 Comminution 265 6.1 Changes during size reduction 265 6.2 Rittinger’s surface theory 266 6.3 Kick’s volume theory 267 6.4 The third or Bond theory 268 6.5 Energy requirement for comminution 268 6.6 Particle size distribution of ground products 269 6.7 Particle size distributions 273 6.8 Kinetics of grinding 275 6.9 Comminution by five-roll refiners 276 6.10 Grinding by a melangeur 280 6.11 Comminution by a stirred ball mill 284 Further reading 289 7 Mixing/kneading 290 7.1 Technical solutions to the problem of mixing 290 7.2 Power characteristics of a stirrer 290 7.3 Mixing time characteristics of a stirrer 292 7.4 Representative shear rate and viscosity for mixing 292 7.5 Calculation of the Reynolds number for mixing 292 7.6 Mixing of powders 294 7.7 Mixing of fluids of high viscosity 300 7.8 Effect of impeller speed on heat and mass transfer 301 7.9 Mixing by blade mixers 302 7.10 Mixing rolls 303 7.11 Mixing of two liquids 304 Further reading 304 8 Solutions 306 8.1 Preparation of aqueous solutions of carbohydrates 306 8.2 Solubility of sucrose in water 308 8.3 Aqueous solutions of sucrose and glucose syrup 309 8.4 Aqueous sucrose solutions containing invert sugar 311 8.5 Solubility of sucrose in the presence of starch syrup and invert sugar 312 8.6 Rate of dissolution 312 8.7 Solubility of bulk sweeteners 315 Further reading 316 9 Evaporation 317 9.1 Theoretical background: Raoult’s law 317 9.2 Boiling point of sucrose/water solutions at atmospheric pressure 318 9.3 Application of a modification of Raoult’s law to calculate the boiling point of carbohydrate/water solutions at decreased pressure 319 9.3.1 Sucrose/water solutions 319 9.3.2 Dextrose/water solutions 319 9.3.3 Starch syrup/water solutions 319 9.3.4 Invert sugar solutions 319 9.3.5 Approximate formulae for the elevation of the boiling point of aqueous sugar solutions 320 9.4 Vapour pressure formulae for carbohydrate/water solutions 323 9.5 Practical tests for controlling the boiling points of sucrose solutions 330 9.6 Modelling of an industrial working process for hard boiled sweets 331 9.7 Boiling points of bulk sweeteners 335 Further reading 335 10 Crystallization 337 10.1 Introduction 337 10.2 Crystallization from solution 337 10.3 Crystallization from melts 355 10.4 Crystal size distributions 371 10.5 Batch crystallization 374 10.6 Isothermal and non-isothermal recrystallization 375 10.7 Methods for studying the supermolecular structure of fat melts 376 10.8 Crystallization of glycerol esters: Polymorphism 381 10.9 Crystallization of cocoa butter 385 10.10 Crystallization of fat masses 398 10.11 Crystallization of confectionery fats with a high trans-fat portion 411 10.12 Modelling of chocolate cooling processes and tempering 414 10.13 EU programme ProPraline 421 Further reading 422 11 Gelling emulsifying stabilizing and foam formation 424 11.1 Hydrocolloids used in confectionery 424 11.2 Agar 424 11.3 Alginates 429 11.4 Carrageenans 432 11.5 Furcellaran 437 11.6 Gum arabic 437 11.7 Gum tragacanth 438 11.8 Guaran gum 439 11.9 Locust bean gum 439 11.10 Pectin 440 11.11 Starch 444 11.12 Xanthan gum 447 11.13 Gelatin 448 11.14 Egg proteins 453 11.15 Foam formation 458 Further reading 466 12 Transport 468 12.1 Types of transport 468 12.2 Calculation of flow rate of non-newtonian fluids 468 12.3 Transporting dessert masses in long pipes 470 12.4 Changes in pipe direction 471 12.5 Laminar unsteady flow 472 12.6 Transport of flour and sugar by airflow 472 Further reading 477 13 Pressing 478 13.1 Applications of pressing in the confectionery industry 478 13.2 Theory of pressing 478 13.3 Cocoa liquor pressing 480 Further reading 482 14 Extrusion 483 14.1 Flow through a converging die 483 14.2 Feeders used for shaping confectionery pastes 491 14.3 Extrusion cooking 495 14.4 Roller extrusion 497 Further reading 500 15 Particle agglomeration: instantization and tabletting 501 15.1 Theoretical background 501 15.2 Processes of agglomeration 512 15.3 Granulation by fluidization 514 15.4 Tabletting 516 Further reading 524 Part III: Chemical and complex operations: stability of sweets: artisan chocolate and confectioneries 16 Chemical operations (inversion and caramelization) ripening and complex operations 527 16.1 Inversion and caramelization 527 16.2 Acrylamide formation 538 16.3 Alkalization of cocoa material 540 16.4 Ripening 542 16.5 Complex operations 545 16.6 Drying/frying baking and roasting 562 Further reading 577 17 Water activity shelf life and storage 579 17.1 Water activity 579 17.2 Shelf life and storage 594 17.3 Storage scheduling 601 Further reading 602 18 Stability of food systems 604 18.1 Common use of the concept of food stability 604 18.2 Stability theories: types of stability 604 18.3 Shelf life as a case of marginal stability 606 18.4 Stability matrix of a food system 607 Further reading 608 19 Artisan chocolate and confectioneries 609 19.1 Actuality of artisanship in the confectionery practice 609 19.2 The characteristics of the artisan products 609 19.3 Raw materials and machinery 610 19.4 The characteristics of the artisan confectionery technologies 611 19.5 Managing an artisan workshop 611 19.6 An easy and effective shaping technology for producing praline bars 612 Further reading 614 Part IV: Appendices 1 Data on engineering properties of materials used and made by the confectionery industry 617 A1.1 Carbohydrates 617 A1.2 Oils and fats 626 A1.3 Raw materials semi-finished products and finished products 626 2 Comparison of Brix and Baumé concentrations of aqueous sucrose solutions at 20 ∘C(68 ∘F) 643 3 Survey of fluid models: some trends in rheology 645 A3.1 Decomposition method for calculation of flow rate of rheological models 645 A3.1.1 The principle of the decomposition method 645 A3.1.2 Bingham model 646 A3.1.3 Casson models 647 A3.1.4 Herschel–Bulkley–Porst–Markowitsch–Houwink (HBPMH) (or generalized Ostwald–de Waele) model 651 A3.1.5 Ostwald–de Waele model (The power law) 653 A3.2 Calculation of the friction coefficient (ξ) of non-newtonian fluids in the laminar region 653 A3.3 Tensorial representation of constitutive equations: The fading memory of viscoelastic fluids 654 A3.3.1 Objective derivatives and tensorial representation of constitutive equations 654 A3.3.2 Boltzmann’s equation for the stress in viscoelastic solids: The fading memory of viscoelastic fluids 656 A3.3.3 Constitutive equations of viscoelastic fluids 657 A3.3.4 Application of the constitutive equations to dough rheology 658 A3.3.5 Rheological properties at the cellular and macroscopic scale 659 A3.4 Computer simulations in food rheology and science 660 A3.5 Ultrasonic and photoacoustic testing 660 A3.5.1 Ultrasonic testing 660 A3.5.2 Photoacoustic testing 661 Further reading 661 4 Fractals 663 A4.1 Irregular forms: fractal geometry 663 A4.2 Box-counting dimension 664 A4.3 Particle-counting method 665 A4.4 Fractal backbone dimension 666 Further reading 666 5 Introduction to structure theory 668 A5.1 The principles of the structure theory of blickle and seitz 668 A5.1.1 Attributes and their relations: structure 668 A5.1.2 Structure of attributes: a qualitative description 669 A5.1.3 Hierarchic structures 670 A5.1.4 Structure of measure: a quantitative description 670 A5.1.5 Conservative elements: conservative substantial fragments 670 A5.1.6 New way of looking 672 A5.2 Modelling a part of fudge processing plant by structure theory 673 Further reading 674 6 Technological layouts 675 Further reading 686 References 687 Index 737