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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
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.
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Veröffentlichungsjahr: 2016
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Table of Contents
Cover
Title Page
Copyright
Dedication
Preface
Preface to the second edition
Acknowledgements
Part I: Theoretical introduction
Chapter 1: Principles of food engineering
1.1 Introduction
1.2 The Damköhler equations
1.3 Investigation of the Damköhler equations by means of similarity theory
1.4 Analogies
1.5 Dimensional analysis
1.6 System theoretical approaches to food engineering
1.7 Food safety and quality assurance
Further reading
Chapter 2: Characterization of substances used in the confectionery industry
2.1 Qualitative characterization of substances
2.2 Quantitative characterization of confectionery products
2.3 Preparation of recipes
2.4 Composition of chocolate, confectioneries, biscuits and wafers made for special nutritional purposes
Further reading
Chapter 3: Engineering properties of foods
3.1 Introduction
3.2 Density
3.3 Fundamental functions of thermodynamics
3.4 Latent heat and heat of reaction
3.5 Thermal conductivity
3.6 Thermal diffusivity and Prandtl number
3.7 Mass diffusivity and Schmidt number
3.8 Dielectric properties
3.9 Electrical conductivity
3.10 Infrared absorption properties
3.11 Physical characteristics of food powders
Further reading
Chapter 4: The rheology of foods and sweets
4.1 Rheology: its importance in the confectionery industry
4.2 Stress and strain
4.3 Solid behaviour
4.4 Fluid behaviour
4.5 Viscosity of solutions
4.6 Viscosity of emulsions
4.7 Viscosity of suspensions
4.8 Rheological properties of gels
4.9 Rheological properties of sweets
4.10 Rheological properties of wheat flour doughs
4.11 Relationship between food oral processing and rheology
Further reading
Chapter 5: Introduction to food colloids
5.1 The colloidal state
5.2 Formation of colloids
5.3 Properties of macromolecular colloids
5.4 Properties of colloids of association
5.5 Properties of interfaces
5.6 Electrical properties of interfaces
5.7 Theory of colloidal stability: the DLVO theory
5.8 Stability and changes of colloids and coarse dispersions
5.9 Emulsion instability
5.10 Phase inversion
5.11 Foams
5.12 Gelation as a second-order phase transition
Further reading
Part II: Physical operations
Chapter 6: Comminution
6.1 Changes during size reduction
6.2 Rittinger's surface theory
6.3 Kick's volume theory
6.4 The third or Bond theory
6.5 Energy requirement for comminution
6.6 Particle size distribution of ground products
6.7 Particle size distributions
6.8 Kinetics of grinding
6.9 Comminution by five-roll refiners
6.10 Grinding by a melangeur
6.11 Comminution by a stirred ball mill
Further reading
Chapter 7: Mixing/kneading
7.1 Technical solutions to the problem of mixing
7.2 Power characteristics of a stirrer
7.3 Mixing time characteristics of a stirrer
7.4 Representative shear rate and viscosity for mixing
7.5 Calculation of the Reynolds number for mixing
7.6 Mixing of powders
7.7 Mixing of fluids of high viscosity
7.8 Effect of impeller speed on heat and mass transfer
7.9 Mixing by blade mixers
7.10 Mixing rolls
7.11 Mixing of two liquids
Further reading
Chapter 8: Solutions
8.1 Preparation of aqueous solutions of carbohydrates
8.2 Solubility of sucrose in water
8.3 Aqueous solutions of sucrose and glucose syrup
8.4 Aqueous sucrose solutions containing invert sugar
8.5 Solubility of sucrose in the presence of starch syrup and invert sugar
8.6 Rate of dissolution
8.7 Solubility of bulk sweeteners
Further reading
Chapter 9: Evaporation
9.1 Theoretical background: Raoult's law
9.2 Boiling point of sucrose/water solutions at atmospheric pressure
9.3 Application of a modification of Raoult's law to calculate the boiling point of carbohydrate/water solutions at decreased pressure
9.4 Vapour pressure formulae for carbohydrate/water solutions
9.5 Practical tests for controlling the boiling points of sucrose solutions
9.6 Modelling of an industrial working process for hard boiled sweets
9.7 Boiling points of bulk sweeteners
Further reading
Chapter 10: Crystallization
10.1 Introduction
10.2 Crystallization from solution
10.3 Crystallization from melts
10.4 Crystal size distributions
10.5 Batch crystallization
10.6 Isothermal and non-isothermal recrystallization
10.7 Methods for studying the supermolecular structure of fat melts
10.8 Crystallization of glycerol esters: Polymorphism
10.9 Crystallization of cocoa butter
10.10 Crystallization of fat masses
10.11 Crystallization of confectionery fats with a high
trans
-fat portion
10.12 Modelling of chocolate cooling processes and tempering
10.13 EU programme ProPraline
Further reading
Chapter 11: Gelling, emulsifying, stabilizing and foam formation
11.1 Hydrocolloids used in confectionery
11.2 Agar
11.3 Alginates
11.4 Carrageenans
11.5 Furcellaran
11.6 Gum arabic
11.7 Gum tragacanth
11.8 Guaran gum
11.9 Locust bean gum
11.10 Pectin
11.11 Starch
11.12 Xanthan gum
11.13 Gelatin
11.14 Egg proteins
11.15 Foam formation
Further reading
Chapter 12: Transport
12.1 Types of transport
12.2 Calculation of flow rate of non-newtonian fluids
12.3 Transporting dessert masses in long pipes
12.4 Changes in pipe direction
12.5 Laminar unsteady flow
12.6 Transport of flour and sugar by airflow
Further reading
Chapter 13: Pressing
13.1 Applications of pressing in the confectionery industry
13.2 Theory of pressing
13.3 Cocoa liquor pressing
Further reading
Chapter 14: Extrusion
14.1 Flow through a converging die
14.2 Feeders used for shaping confectionery pastes
14.3 Extrusion cooking
14.4 Roller extrusion
Further reading
Chapter 15: Particle agglomeration: instantization and tabletting
15.1 Theoretical background
15.2 Processes of agglomeration
15.3 Granulation by fluidization
15.4 Tabletting
Further reading
Part III: Chemical and complex operations: stability of sweets: artisan chocolate and confectioneries
Chapter 16: Chemical operations (inversion and caramelization), ripening and complex operations
16.1 Inversion and caramelization
16.2 Acrylamide formation
16.3 Alkalization of cocoa material
16.4 Ripening
16.5 Complex operations
16.6 Drying/frying, baking and roasting
Further reading
Chapter 17: Water activity, shelf life and storage
17.1 Water activity
17.2 Shelf life and storage
17.3 Storage scheduling
Further reading
Chapter 18: Stability of food systems
18.1 Common use of the concept of food stability
18.2 Stability theories: types of stability
18.3 Shelf life as a case of marginal stability
18.4 Stability matrix of a food system
Further reading
Chapter 19: Artisan chocolate and confectioneries
19.1 Actuality of artisanship in the confectionery practice
19.2 The characteristics of the artisan products
19.3 Raw materials and machinery
19.4 The characteristics of the artisan confectionery technologies
19.5 Managing an artisan workshop
19.6 An easy and effective shaping technology for producing praline bars
Further reading
Part IV: Appendices
Appendix 1: Data on engineering properties of materials used and made by the confectionery industry
A1.1 Carbohydrates
A1.2 Oils and fats
A1.3 Raw materials, semi-finished products and finished products
Appendix 2: Comparison of Brix and Baumé concentrations of aqueous sucrose solutions at 20 °C (68 °F)
Appendix 3: Survey of fluid models: some trends in rheology
A3.1 Decomposition method for calculation of flow rate of rheological models
A3.2 Calculation of the friction coefficient (
ξ
) of non-newtonian fluids in the laminar region
A3.3 Tensorial representation of constitutive equations: The fading memory of viscoelastic fluids
A3.4 Computer simulations in food rheology and science
A3.5 Ultrasonic and photoacoustic testing
Further reading
Appendix 4: Fractals
A4.1 Irregular forms: fractal geometry
A4.2 Box-counting dimension
A4.3 Particle-counting method
A4.4 Fractal backbone dimension
Further reading
Appendix 5: Introduction to structure theory
A5.1 The principles of the structure theory of blickle and seitz
A5.2 Modelling a part of fudge processing plant by structure theory
Further reading
Appendix 6: Technological layouts
Further reading
References
Index
End User License Agreement
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Guide
cover
Table of Contents
Preface
Part I: Theoretical introduction
Begin Reading
List of Illustrations
Chapter 1: Principles of food engineering
Figure 1.1 Hierarchical structure of materials.
Chapter 2: Characterization of substances used in the confectionery industry
Figure 2.1 Hierarchical structure of foods. Example: an aqueous solution contains solid particles and oil droplets coupled by an emulsifier to the aqueous phase.
Figure 2.2 Structural formula of chocolate. d = dispersion; e = emulsion.
Figure 2.3 Structural formula of hard-boiled candy. s = solution.
Figure 2.4 Structural formula of crystallized hard-boiled candy. s = solution.
Figure 2.5 Structural formula of toffee/fudge. s = solution; e = emulsion; cry = crystallization.
Figure 2.6 Structural formula of fondant. s = solution; cry = crystallization.
Figure 2.7 Structural formula of jelly. s = solution; sw = swelling.
Figure 2.8 Structural formula of nut brittle (croquante). d = dispersion.
Figure 2.9 Structural formula of marzipan (or of persipan, with apricot stones). d = dispersion.
Figure 2.10 Structural formula of confectionery foams. s = solution; sw = swelling; f = foaming.
Figure 2.11 Structural formula of granules, tablets and lozenges. s = solution; d = dispersion; sw = swelling.
Figure 2.12 Structural formula of dragées.
Figure 2.13 Structural formula of dough. s = solution; e = emulsion; g = gelling; sw = swelling.
Figure 2.14 Structural formula of biscuits and crackers. d = dispersion.
Figure 2.15 Structural formula of wafers. s = solution; d = dispersion; e = emulsion; g = gelling; sw = swelling.
Figure 2.16 Structural formula of ice cream. s = solution; e = emulsion; sw = swelling; f = foaming; cry = crystallization
Figure 2.17 Reducing sugar versus water content in sugar confectionery.
Figure 2.18 Pulling of sugar mass.
Chapter 3: Engineering properties of foods
Figure 3.1 Angle of repose
α.
Source: Peleg (1983). Reproduced with permission from Springer.
Figure 3.2 Flow rate of powders and of liquids.
D
= aperture diameter;
h
= head height above aperture;
D
p
= typical size of granules;
Q
= volume flux of stored material. Source: Peleg (1983). Reproduced with permission from Springer.
Figure 3.3 Schematic representation of the most common caking mechanisms in food powders. Source: Peleg (1983). Reproduced with permission from Springer.
Chapter 4: The rheology of foods and sweets
Figure 4.1 Typical stresses on a cube.
Figure 4.2 Interpretation of the strain tensor.
Figure 4.3 Uniaxial compression of a cylindrical sample.
Figure 4.4 Deformation curves for linear elastic (Hookean), elastoplastic and nonlinear elastic materials.
Figure 4.5 Velocity profile of fluid between parallel plates.
Figure 4.6 Types of elastic deformation.
Figure 4.8 Types of viscous deformation.
Figure 4.7 Types of plastic deformation.
Figure 4.9 Flow curves for typical time-independent fluids. The flow curves of Newtonian and Bingham fluids are straight only in the ideal case; otherwise, they are convex or concave.
Figure 4.10 Shear-thinning behaviour of an Ostwald–de Waele fluid represented by a plot of the consistency variables.
Figure 4.11 Static and dynamic yield stresses.
Figure 4.12 Representation of Tresca's criterion by means of Mohr circles.
Figure 4.13 Sketch of a log(viscosity) versus log(shear stress) plot according to Barnes (1999), which shows the steep increase of viscosity by decreasing the shear stress.
Figure 4.14 Various ways of shaping dough using extensional flow.
Figure 4.15 The basic types of extensional flow.
Figure 4.16 The Weissenberg effect: a viscoelastic fluid may climb an impeller shaft. (a) Newtonian fluid and (b) viscoelastic fluid.
Figure 4.19 Recoil phenomenon of a viscoelastic fluid. (a) Newtonian fluid and (b) viscoelastic fluid.
Figure 4.20 Maxwell model (series connection).
Figure 4.21 Kelvin model (parallel connection).
Figure 4.22 Response of a Kelvin fluid to a constant stress
τ
0
.
Figure 4.23 The Burgers model: a Kelvin and a Maxwell model coupled in series.
Figure 4.24 Oscillatory strain between rectangular plates.
Figure 4.25 Phase inversion of an emulsion (relative viscosity vs. volume concentration of solid).
Figure 4.26 Fluid model given by Kot and Gligalo (1969) for extrusion of dessert fillings.
Figure 4.27 Model for the soft part of bread (1). Consecutive phases of the deformation process are indicated by a–e. (a) Initial phase at
t
=
t
(0); (b) elastic deformation; (c) retarded elastic deformation; (d) after
t
=
t
(1) (the stress has ceased), recovery of the first phase of elastic deformation (phase
b
); (e) recovery of phase
c
.
Figure 4.28 Soft part of bread (2). Consecutive phases of the deformation process are indicated by a–f. (a–c) As in Figure 4.27; (d) plastic deformation (represented by a St Venant model); (e) recovery of phase ‘b’ (elastic deformation); (f) recovery of phase ‘c’ (retarded elastic deformation).
Figure 4.29 Glücklich/Shelef model for wheat dough.
Figure 4.30 Shvedov model.
Chapter 5: Introduction to food colloids
Figure 5.1 In the colloidal region, the material parameters do not change discontinuously (dotted line), but continuously (continuous line).
Figure 5.2 The colloidal region: generation of colloids by deformation and dispersion.
Figure 5.3 The various types of colloidal systems, considered as combinations of states.
Figure 5.4 The effect of strain on an amorphous polymer as the temperature is increased.
Figure 5.5 Illustration of Young's equation.
γ
SV
= solid–vapour interfacial energy,
γ
SL
= solid–liquid interfacial energy and
γ
LV
= liquid–vapour interfacial energy.
Figure 5.6 Electric double layer: (a) in concentrated electrolyte; (b) in dilute electrolyte; (c) when one ion adsorbs strongly.
Figure 5.7 Attractive (
V
A
), repulsive (
V
R
) and resultant (
V
R+A
) potentials according to the DLVO theory.
Figure 5.8 Potential conditions for flocculation according to the DLVO theory.
Figure 5.9 Stability of colloids and coarse dispersions, and transformations between them.
Figure 5.10 Water droplet on an interface between a solid particle and an oil phase.
γ
= contact angle.
Figure 5.11 A Plateau border.
Figure 5.12 Shrinkage of bubbles.
Chapter 6: Comminution
Figure 6.1 Particle size distribution of chocolate (differential curve):
D
′(
x
) versus log
x
; evaluation due to log-normal distribution (see Section 6.7.3.).
Figure 6.2 Particle size distribution of chocolate (cumulative curve).
Figure 6.3 Five-roll refiner. R = roller.
Figure 6.4 Angle of pulling in and distance of rubbing in a roll refiner.
Figure 6.5 Particle size and yield as functions of the velocity increase of roller 1.
Figure 6.6 Particle size versus productivity for a five-roll refiner with and without pre-refining.
Figure 6.7 Forces on a particle in a melangeur.
Chapter 7: Mixing/kneading
Figure 7.1 Definition of representative viscosity.
Chapter 9: Evaporation
Figure 9.1 Schematic diagram of an industrial candy-cooking machine: 1, feed pump; 2, vapour chamber; 3, stainless steel coil; 4, vapour input valve; 5, vapour purge; 6, expansion chamber; 7, tempering piston; 8, outlet; 9, vacuum chamber; 10, air inlet valve; 11, paste reservoir; 12, PT100 sensor; 13, temperature controller.
Figure 9.2 Boiling point of candy solution as a function of the total solids concentration at 100 kPa (=1 bar). BPR = boiling-point rise.
Chapter 10: Crystallization
Figure 10.1 Metastable zone.
Figure 10.2 The work curve of fondant crystallization.
Figure 10.3 Fat crystal network.
Figure 10.4 Homogeneous nucleation: increasing overcooling (with decreasing temperatures) first the term
G
°/
kT
becomes dominant which increases the nucleation rate, later the term
E
d
/
kT
becomes dominant, and as a result, the nucleation rate will be decreased.
Figure 10.5 Shape of the Kolmogorov–Avrami equation.
Figure 10.6 (a) Visual comparison of fit between the Avrami, Gompertz and Foubert models (isothermal crystallization of cocoa butter as measured by means of DSC). (b) Isothermal crystallization of cocoa butter at 20 °C: SAXS diffraction patterns as a function of time. Time span 2, from 0.56 h onwards;
s
(horizontal axis) is the wavenumber of the X-rays. In time span 1 (0–10.56 h), the formation of the α modification is practically entirely completed, but the formation of β′ is still at an early stage. In time span 2, the formation of the β′ modification takes place. (c) Example of a two-step process and a fit obtained by combining two Foubert equations. (d) Example of crystallization curves obtained with a fractional model using the following parameter values:
K
α
= 6/h,
K
β′
= 3/h,
n
α
= 100,
n
β′
= 4,
τ
α
= 0.01 h and
τ
β′
= 0.5 h.
Figure 10.7 Plots of log
n
versus
L
for (a) a continuous and (b) a batch crystallizer.
Figure 10.8 Cooling curves of fats, determined with a Shukoff flask. The crystallization is characterized by [
T
(max) −
T
(min)]/[
t
(max) −
t
(min)].
Figure 10.9 Solid-fat-content curve of cocoa butter.
Figure 10.10 Interpretation of solid-fat-index curve (dilatation curve).
Figure 10.11 The melting peak – the change of enthalpy during the melting of fats.
Figure 10.12 Principle of solid-fat-content determination by NMR.
Figure 10.13 Average composition of cocoa butter and the
chair
shape of triacylglycerols (TAGs).
Figure 10.14 Oleic and elaidic acids –
cis–trans
isomers.
Figure 10.15 Double- and triple-chain-length arrangements and short and long spacings of tilted dimers of triglycerides.
Figure 10.16 Change of free enthalpy of fat crystal modifications as a function of temperature.
Figure 10.17 Polymorphic transformation of cocoa butter modifications β′(IV) → β(V) on shearing.
Figure 10.18 Monotropic (one-way) changes of cocoa butter modifications during tempering and cooling.
Figure 10.19 Temperature profile in the chocolate tempering process.
Figure 10.20 Typical temperimeter curves.
Figure 10.21 Moulding of chocolate.
Figure 10.22 Temperature profile of cooling process. CBE = cocoa butter equivalent, CBR = cocoa butter replacer, CBS cocoa butter substitute.
Figure 10.23 Solid-fat-content curves for filling fats and fats for coating of ice cream.
Figure 10.24 Modelling of heat flux as a function of released crystallization heat
Q
m
.
Figure 10.26 Specific crystallization rate as a function of cooling time. Calculated temperature plot in different layers of the chocolate coating during cooling by forced convection.
Figure 10.25 Cooling curve
T
(
t
) for chocolate crystallization obtained from measured and calculated values.
Figure 10.27 Vertical cross section of a mould with thermocouple positions.
Figure 10.28 Cooling curves for (a) untempered and (b) tempered chocolate with a nominal air-cooling rate of 2 °C/min.
Figure 10.29 Plot of effective heat capacity as a function of temperature and cooling rate.
Figure 10.30 Convective heat flux divided by radiative heat flux as a function of temperature; = 0.93, ambient air temperature = 20 °C.
Chapter 11: Gelling, emulsifying, stabilizing and foam formation
Figure 11.1 Schematic layout of agar jelly production.
Figure 11.2 Schematic layout of pectin jelly technology.
Figure 11.3 Schematic layout of a starch jelly technology (liquorice).
Figure 11.4 Electric charge of a type A and type B gelatin molecule as a function of pH of solution. p
I
= iso-ionic point.
Figure 11.5 Schematic layout of technology for gelatin jellies.
Figure 11.6 Bubble rise ratio
U
/
u
as a function of volume fraction
ϕ
in various regions of Reynolds number.
Figure 11.7 Density of foam as a function of time of whipping (values for information only).
Figure 11.9 Density of foam as a function of time of whipping with various concentrations of whipping agent (values for information only).
Figure 11.10 Foaming by (a) one-step method and (b) two-step method.
Chapter 12: Transport
Figure 12.1 Air friction coefficient as a function of Reynolds number for smooth and rough tube surfaces.
Figure 12.2 Hydrodynamic friction coefficient
C
E
of globular particles as a function of Reynolds number.
Figure 12.3 Choice of ventilator.
Chapter 14: Extrusion
Figure 14.1 Plot of adaptor zone profile and flow velocity.
Chapter 15: Particle agglomeration: instantization and tabletting
Figure 15.1 Effect of distance between particles. The curves are labelled with values of
V
liq
/
V
sol
; see text for details.
Figure 15.2 van der Waals forces.
d
= particle diameter.
Figure 15.3 Theoretical solidity of a granule.
Figure 15.4 Comparison of forces acting between particles.
Figure 15.5 Aggregation in a fluidized bed.
Figure 15.6 Plot of pressure versus volume in tabletting.
Figure 15.7 Compression profile: plot of displacement versus time and force versus time.
Figure 15.8 Plots of crushing strength versus pressure for single and double compression.
Figure 15.9 Lubricant selection: plots of ejection force versus compression pressure for three different lubricants.
Chapter 16: Chemical operations (inversion and caramelization), ripening and complex operations
Figure 16.1 Effect of invertase on the reducing sugar content of fondant products during storage at 20 °C and 50% relative humidity.
Figure 16.2 Change of penetration under the effect of invertase during storage at 20 °C and 50% relative humidity.
Figure 16.3 Melting of sugar: variation of hydroxymethylfurfurol (HMF) content of molten sugar with temperature (a) under laboratory conditions and (b) Sucromelt 3400 machine (O. Hänsel), by Mohos (1982).
Figure 16.4 Structural formula of acrylamide.
Figure 16.5 Changes during alkalization (German process).
Figure 16.6 Triangle model of conching.
Figure 16.7 Quantitative conching model based on conserved substantial fragments. For example, means a material flux consisting of oxygen and water.
Figure 16.8 Triangle model of the structure of dough: model of processes in aqueous medium.
Figure 16.9 The ERH as the function of the moisture of cocoa beans.
Figure 16.10 Principles of various machinery solutions of roasting by Probat.
Chapter 17: Water activity, shelf life and storage
Figure 17.1 Typical water sorption isotherms.
Figure 17.2 Adsorption/desorption of water on the surface of foods – data for information only. The middle region
Less strongly bound water layer and capillary absorbed water
has boundaries at about
A
= 0.33 and
B
= 0.75.
Figure 17.3 Isotherm of sucrose.
Figure 17.4 Moisture content of sucrose as a function of size of sucrose crystals.
Figure 17.5 Isotherm of cocoa powder at room temperature. ERH = equilibrium relative humidity. Note that this Figure is for information only.
Figure 17.6 Determination of shelf life of foods.
Figure 17.7 Model for storage scheduling by fuzzy logic.
Chapter 18: Stability of food systems
Figure 18.1 Shelf life defined as a kind of marginal (Lyapunov) stability.
Chapter 19: Artisan chocolate and confectioneries
Figure 19.1 Handwork shaping of praline by frames of various size.
Figure 19.2 The steps of the handwork shaping.
List of Tables
Chapter 1: Principles of food engineering
Table 1.1 Derivation of dimensionless numbers
Table 1.2 Another way of deriving dimensionless numbers
Chapter 2: Characterization of substances used in the confectionery industry
Table 2.1 Calculation of a milk chocolate recipe (all values in m/m%)
Table 2.2 Cartesian product of phases.
a
Table 2.3 Manufacture of crystal chocolate: experimental results
Table 2.4 Recipes for dark chocolate
Table 2.5 Composition of various confectionery products containing flour
Table 2.6 Hydrophilic character and presence of gluten skeleton for products containing flour.
a
Table 2.7 Material matrix for 100 kg of end product
Table 2.8 Production matrix showing the amounts (in tonnes and in units of 100 kg) to be produced for each product
Table 2.9
G
-matrix, showing the total raw material demand of the production process, for each raw material
Table 2.10 Calculation of efficiency
Table 2.11 Values of the matrix
V
T
and the product
V
1 ×
n
*
D
n
× 1
Table 2.12 Glycaemic index, insulinaemic index, relative sweet and energy values of sucrose, glucose and various polyols
Chapter 3: Engineering properties of foods
Table 3.1 Densities of some ingredients
Table 3.2 Approximate bulk density and moisture content of various food powders
Table 3.3 Some fundamental functions of thermodynamics
Table 3.4 Thermal properties of food constituents
Table 3.5 Calculation of specific heat capacity of milk chocolate and dark chocolate.
a
Table 3.6 Calculation of specific heat capacity of orange marmalade and almond paste.
a
Table 3.7 Calculation of specific heat capacity of cocoa nibs and sweets.
a
Table 3.8 Thermal property equations for food components (−40 °C ≤
t
≤ 150 °C)
Table 3.9 Thermal property equations for water and ice (−40 °C ≤
t
≤ 150 °C)
Table 3.10 Specific heat capacity of milk chocolate no. 8.301 calculated according to the thermal property model of Choi and Okos (1986)
Table 3.11 Specific heat capacity (J/kg K) of several materials used or produced by the confectionery industry
Table 3.12 Latent heat and relative cooling effect of sucrose, fructose and some polyols used in confectionery practice
Table 3.13 Temperatures and enthalpies (
H
) of exothermic reactions of carbohydrates during pyrolysis
Table 3.14 Dielectric properties of water
Table 3.16 Relative dielectric constants of some vegeTable oils at 20 °C and their dependence on temperature
Table 3.17 Temperature and frequency dependence of tan
δ
of water
Table 3.18 Some typical electrical conductivities of materials
Table 3.19 Effect of moisture content on the mechanical characteristics of selected food powders
Table 3.20 Effect of anticaking agents on the bulk density and compressibility of selected food powders
Chapter 4: The rheology of foods and sweets
Table 4.1 Values of steady shear and normal-stress differences.
a
Table 4.2 Shear rates typical of familiar materials and processes
Table 4.3 Terminology used for fluids with time-dependent behaviour
Table 4.4 Viscosity data
Table 4.5 Flow curve of a plain chocolate evaluated as a Bingham fluid and as a Casson (
n
= ½) fluid
Table 4.7 The values of the constants
n
,
A
,
B
,
a
and
b
in Eqn (4.216)
Table 4.8 The
n
and
K
values at various temperatures for Maksimov
et al.
's model
Table 4.9 Viscosity of whipped masses as a function of whipping time
Chapter 5: Introduction to food colloids
Table 5.1 Calculation of rate constant for the swelling of stringy agar according to Eqn (5.16).
a
Chapter 6: Comminution
Table 6.1 Material behaviour with respect to hardness
Table 6.2 Testing sieve data
Table 6.3 Particle size distribution of a chocolate mass measured by the Coulter counter method
Table 6.4 Relationship between length of rollers and productivity for Carle & Montanari machines
Chapter 8: Solutions
Table 8.1 Constants in Eqn (8.22) according to type of impeller
Table 8.2 Melting point and water solubility of some polyols
Chapter 9: Evaporation
Table 9.1 Elevation of boiling point (°C) of aqueous sucrose solutions as a function of concentration at various pressures
Table 9.2 Boiling points of aqueous sucrose solutions of various concentrations (m/m%), measured by Bukharov (1935) and calculated according to Eqn (9.6)
Table 9.3 Elevation of boiling point (°C) of dextrose solutions as a function of concentration at various pressures
Table 9.4 Elevation of boiling point (°C) of aqueous starch syrup solutions as a function of concentration at various pressures
Table 9.5 Elevation of boiling point (°C) of aqueous invert sugar solutions as a function of concentration at various pressures
Table 9.6 Constants in Eqns (9.22) and (9.23)
Table 9.7 Elevation of boiling point for aqueous carbohydrate solutions, for
S
= 1.
a
Table 9.8 Sugar-boiling tests used in practice.
a
Table 9.9 Elevation of boiling point (°C) of aqueous isomalt solutions
Chapter 10: Crystallization
Table 10.1 Data for demonstration of the
L
law in Example 10.3
Table 10.2 Avrami exponent
n
for different growth and nucleation mechanisms
Table 10.3 Distinction between various confectionery vegeTable fats using the Kolmogorov–Avrami equation (rounded values)
Table 10.4 Crystal polymorphs
Table 10.5 Dew point of air of 16 °C as a function of the relative humidity of air (RH) calculated according to Barenbrug (1974) by using the Magnus–Tetens formula
Table 10.6 Typical triglyceride compositions (average in m/m%) of components used in CBEs
Table 10.7 VegeTable fats that may be used in chocolate to a maximum of 5% according to the European Union Directive 2000/36/EC
Chapter 11: Gelling, emulsifying, stabilizing and foam formation
Table 11.1 Grades specified by Japanese agricultural standard for powdered agar
Table 11.2 Main areas of application of gelatin in confectionery
Table 11.3 Foamed confectionery products
Chapter 12: Transport
Table 12.1 Evaluation of the flow curve of a milk chocolate according to the Bingham (
τ
;
D
) and Casson (
τ
0.5
;
D
0.5
) models
Table 12.2 Evaluation of the flow curve of a truffle mass according to the Ostwald–de Waele model
Table 12.3 Physical parameters of air at normal atmospheric pressure
Chapter 15: Particle agglomeration: instantization and tabletting
Table 15.1 Binding mechanisms and technical operations of dry and wet agglomeration
Table 15.2 Values of constants for instant green tea and instant coffee
Chapter 16: Chemical operations (inversion and caramelization), ripening and complex operations
Table 16.1 Catalytic ability of various acids in inversion, according to Ostwald
Table 16.2 Relationship between the inversion ability and the dissociation of inorganic and organic acids.
a
Table 16.3 Penetration versus consistency relationship for stored fondant products that contain invertase
Table 16.4 Variation of liquid-phase content during storage as a function of invertase content
Table 16.5 Relationships between raw materials and unit operations carried out in chocolate manufacture
Table 16.6 Duration of sugar crystal coating (candying) depending on the concentration of the candying solution and the temperature
Chapter 17: Water activity, shelf life and storage
Table 17.1 Evaluation of relative humidity of air at various temperatures by measuring the dew point
Table 17.2 Water activity of sucrose solutions
Table 17.3 Equilibrium relative humidity (ERH) of salts used in chamber system
Table 17.4 Calculated water activity data for three saturated salt solutions
Table 17.5 Approximate equilibrium relative humidity (ERH) for confectionery products
Table 17.6 Calculation of equilibrium relative humidity (ERH) for hard-boiled drops according to several models
Table 17.7 Calculated values of mould-free shelf life (MFSL)
Table 17.8 Water vapour permeability (WVP) of some packaging materials.
a
Confectionery and Chocolate Engineering
Principles and Applications
Ferenc Á. Mohos
University of Szeged and Corvinus University of Budapest, Hungary
Second Edition
This edition first published 2017 © 2017 by John Wiley & Sons Ltd
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Names: Mohos, Ferenc Á., author.
Title: Confectionery and chocolate engineering: principles and applications / Ferenc Á. Mohos.
Description: Chichester, West Sussex, United Kingdom ; Hoboken, New Jersey :
John Wiley & Sons Inc., 2017. | Includes bibliographical references and index.
Identifiers: LCCN 2016035917 | ISBN 9781118939772 (cloth) | ISBN 9781118939765 (Adobe PDF) | ISBN 9781118939758 (ePub)
Subjects: LCSH: Confectionery. | Chocolate. | Chemistry, Technical. | Food-Analysis.
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Cover image: SerAlexVi/Gettyimages
To the memory of my parents
Ferenc Mohos and Viktória Tevesz
Preface
The purpose of this book is to describe the features of the unit operations in confectionery manufacturing. The approach adopted here might be considered as a novelty in the confectionery literature. The choice of the subject might perhaps seem surprising, owing to the fact that the word confectionery is usually associated with handicraft instead of engineering. It must be acknowledged that the attractiveness of confectionery can be partly attributed to the coexistence of handicraft and engineering in this field. Nevertheless, large-scale industry has also had a dominant presence in this field for about a century.
The traditional confectionery literature focuses on technology. The present work is based on a different approach, where, by building on the scientific background of chemical engineering, it is intended to offer a theoretical approach to practical aspects of the confectionery and chocolate industry. However, one of the main aims is to demonstrate that the structural description of materials used in chemical engineering must be complemented by taking account of the hierarchical structure of the cellular materials that are the typical objects of food engineering. By characterizing the unit operations of confectionery manufacture, without daring to overestimate the eventual future exploitation of the possibilities offered by this book, I intend to inspire the development of new solutions in both technology and machinery, including the intensification of operations, the application of new materials and new and modern applications of traditional raw materials.
I have studied unit operations in the confectionery industry since the 1960s. During my university years, I began dealing with the rheological properties of molten chocolate (the Casson equation, rheopexy, etc.). This was an attractive and fruitful experience for me. Later on, I worked for the Research Laboratory of the Confectionery Industry for 3 years. Altogether I spent – on and off – half a century in this field, working on product development, production, quality control/assurance, purchasing and trading. These tasks, related mainly to sugar confectionery and chocolate, convinced me that a uniform attitude is essential for understanding the wide-ranging topics of confectionery and chocolate manufacture. As a young chemical engineer, I also started lecturing undergraduate and graduate students. Having gathered experience in education (compiling lectures, etc.), I found that this conviction was further confirmed.
In the late 1960s, my attention was firmly focused on the unit operations in this industry, and I tried to utilize and build on the results produced by the Hungarian school of chemical engineering (M. Korach (Maurizio Cora), P. Benedek, A. László and T. Blickle). Benedek and László discussed the topics of chemical engineering, placing the Damköhler equations in the centre of the theory, similarly to the way in which electricity is based on the Maxwell equations. Blickle and the mathematician Seitz developed structure theory and applied it to chemical engineering. Structure theory exploits the tools of abstract algebra to analyse the structures of system properties, materials, machinery, technological changes, etc. It is a useful method for defining concepts and studying their relations. The outcome of these studies is well reflected in several books and university lectures published by me and serves as the theoretical background for the present book as well.
Chapter 1 introduces the Damköhler equations as a framework for chemical engineering. This chapter outlines the reasons why this framework is suitable for studying the unit operations of the confectionery industry in spite of the cellular structure of the materials. In Chapter 2, the structural characterization of raw materials and products is discussed by means of structure theory. This chapter also demonstrates in detail the methods for preparing confectionery recipes taking compositional requirements into account.
Chapter 3 and Appendices 1 and 2 all deal with the engineering properties of the materials used in confectionery. Heat transfer and mass transfer are not discussed individually but are included in other chapters.
Rheology is essential to confectionery engineering. Therefore, a relatively large part of the book (Chapter 4) discusses the rheological properties of both Newtonian and non-Newtonian fluids, along with elasticity, plasticity, extensional viscosity, etc. Non-Newtonian flow, especially that of Casson fluids, is discussed in Chapter 12 and Appendix 3.
Some relevant topics in colloid chemistry are discussed in Chapters 5 and 11. In this context, the basics of fractal geometry cannot be ignored; thus, Appendix 4 offers an outline thereof. Comminution plays an important role in this field, as new procedures and machines related to comminution enable new chocolate technologies to be developed.
Chapters 7–9 discuss the operations of mixing, as well as the topics of solutions of carbohydrates in water and the evaporation of these solutions. These chapters provide confirmation that the Dühring rule, the Ramsay–Young rule, etc. are also valid for these operations.
Crystallization (Chapter 10) from aqueous solutions (candies) and fat melts (chocolate and compounds) is a typical operation in confectionery practice, and thus I highlight its dominant characteristics. In Chapter 13, pressing is briefly discussed. Extrusion (Chapter 14) and agglomeration (Chapter 15) are typical operations that manifest the wide-ranging nature of the confectionery industry.
Chapter 16 deals with inversion, the Maillard reaction and such complex operations as conching and also new trends in chocolate manufacture and (tangentially) baking.
Chapter 17 deals with the issues of water activity and shelf life. A separate chapter (Chapter 18) is devoted to food stability. The real meaning of such an approach is that from the start of production to the consumer's table, the kinetics of the changes in the raw materials and products must be taken into consideration. Furthermore, in the light of this attitude, the concept of food stability must be defined more exactly by using the concepts of stability theory.
For the sake of completeness, Appendix 6 contains some technological outlines.
I intended to avoid the mistake of he who grasps much holds little (successfully? who knows?); therefore, I have not been so bold as to discuss such operations – however essential – as fermentation, baking and panning, about which I have very little or no practical knowledge. Similarly, I did not want to provide a review of the entire circle of relevant references.
Thus the substance that I grasped turned out to be great but rather difficult, and I wish I could say that I have coped with it. Here the gentle reader is requested to send me their remarks and comments for a new edition hopefully to be published in the future.
My most pleasant obligation is to express my warmest thanks to all the colleagues who helped my work. First of all, I have to mention the names of my professors, R. Lásztity (Technical University of Budapest) and T. Blickle (University of Chemical Engineering, Veszprém), who were my mentors in my PhD work, and Professor J. Varga (Technical University of Budapest), my first instructor in chocolate science. I am grateful to Professor S. Szántó and Professor L. Maczelka (Research Laboratory of the Confectionery Industry), who consulted me very much as a young colleague on the topics of this field. I highly appreciate the encouragement obtained from Mr M. Halbritter, the former president of the Association of Hungarian Confectionery Manufacturers; Professor Gy. Karlovics (Corvinus University of Budapest and Bunge Laboratories, Poland); Professor A. Fekete (Corvinus University of Budapest); Professor A. Salgó (Technical University of Budapest); Professor G. Szabo (Rector, Szeged University of Sciences); Professor A. Véha (Dean, Szeged University of Sciences); and Professor E. Gyimes (Szeged University of Sciences).
I am also indebted to Professor C. Alamprese (Università degli Studi di Milano, Italy); Ms P. Alexandre, a senior expert at CAOBISCO, Brussels, Belgium; Professor R. Scherer (Fachhochschule Fulda, Germany); and Professor H.-D. Tscheuschner and Professor K. Franke (Dresden University of Technology, Germany), as well as to D. Meekison for his valuable help provided in copyediting.
Last but not least, I wish to express my deep and cordial thanks to my family: to my daughter Viktória for correcting my poor English and to my wife Irén, who with infinite patience has tolerated my whimsicality and the permanent and sometimes shocking disorder around me and (despite all this) assured me a normal way of life.
Ferenc Á. Mohos Budapest, Hungary
Preface to the second edition
Since the appearance of the first edition in 2010, important developments have emerged in the food engineering that called for a certain revision of the original version of the work completed 5 years ago. Therefore, the objectives of the current edition are twofold: on the one hand, it seeks to reflect main relevant research results, and on the other hand, it also intends to incorporate the discussion of such operations as drying, baking and roasting which are important topics in the confectionary practice. My hope is that new additions will not only enrich the content of the first edition but also shed light on fresh trends in the industry.
Individual chapters have been completed by the following themes: In Chapter 1 (and Appendix 5), the Blickle–Seitz system theory and SAFES methodology are presented in connection with the principles of food engineering. An easy matrix method of dimensional analysis is outlined. Relevant new issues in relation to food safety and quality assurance are also discussed in this chapter. Chapter 2 now also includes recipes of chocolate of high cocoa content and confectioneries for special dietetic purpose. Further in Chapter 4, new results concerning yield stress, microrheology and food oral processing are discussed. Chapter 10 highlights an important new initiative of the European Union, the so-called the ProPraline project. As a result of the new edition, Chapter 16 includes the topic of acrylamide formation in confectioneries of high current relevance. Also the operations of drying, baking and roasting are discussed here. A completely new chapter was added (Chapter 19) in order to reflect on the topics of manufacturing artisan chocolate and confectioneries. Important modifications also concern Appendix 3 in relation to linear flow models, whereby the Bingham, the Casson and the Ostwald–de Waele flow curves and the corresponding volume rates are presented. Furthermore, the constitutive equations of rheology in tensorial and in fractional calculus are briefly presented. Finally, topics of ultrasonic and photoacoustic testing are also highlighted as new emerging topics.
Acknowledgements
The author gratefully acknowledges the permission granted to reproduce the copyright material in this book: AarhusKarlshamn, Denmark (Figs 10.8–10.10 and 10.21); Akadémiai Kiadó, Budapest (Fig. 14.1); AVI Publishing Co. Inc., Westport, USA (Figs 3.1–3.3; Tables 3.1, 3.2, 3.19 and 3.20); Archer Daniels Midland Co. (ADM), IL, USA (Fig. 17.5); Carle & Montanari SpA, Milan (Figs 6.3, 6.5 and 6.6; Table 6.4); Elsevier Science Ltd, The Netherlands (Figs 5.10, 9.1, 9.2, 10.5(a)–(d), 10.6, 10.24–10.30 and 11.6; Tables 3.8 and 3.9); Professor K. Kerti, Budapest (Table 10.3); Professor R. Lásztity, Budapest (Figs 4.26 and 4.27); Professor J. Nyvlt, Prague, Czech Republic (Figs 10.1 and 10.7); Springer Science and Business Media, The Netherlands (Tables 17.2, 17.3 and 17.8; Section 17.1.6); Professor J.F. Steffe, Michigan, USA (Figs 4.5, 4.11, 4.13, 4.15–4.18 and 4.23; Table 4.1); P. Székely, Budapest (Figs 16.1 and 16.2; Tables 16.3 and 16.4); Wiley-VCH Verlag GmbH & Co KGaA, Germany; and Mrs Liselotte Rumpf, Karlsruhe, Germany (Figs 15.1–15.4; Table 15.1).
Every effort has been made to trace copyright holders and to obtain their permission for the use of copyright material. The author apologizes for any errors or omissions in the above list and would be grateful if notified of any corrections that should be incorporated in future reprints or editions of this book.
Part ITheoretical introduction
Chapter 1Principles of food engineering
1.1 Introduction
1.1.1 The Peculiarities of food engineering
Food engineering is based to a great extent on the results of chemical engineering. However, the differences in overall structure between chemicals and foods, that is, the fact that the majority of foods are of cellular structure, result in at least three important differences in the operations of food engineering – the same is valid for biochemical engineering.
1.
Chemical engineering applies the Gibbs theory of multicomponent chemical systems, the principal relationships of which are based on chemical equilibrium, for example, the Gibbs phase rule. Although the supposition of equilibrium is only an approximation, it frequently works and provides good results. In the case of cellular substances, however, the
conditions of equilibrium do not apply in general
, because the cell walls function as semipermeable membranes, which make equilibrium practically possible only in aqueous media and for long-lasting processes. Consequently, the Gibbs phase rule cannot be a basis for determining the degrees of freedom of food engineering systems in general. For further details, see
Section 1.3.2
.
2.
Another problem is that cellular substances prove to be chemically very complex after their cellular structure has been destroyed. In the Gibbs theory, the number of components in a multicomponent system is limited and well defined, not infinite.
The number of components in a food system can be practically infinite or hard to define; in addition, this number depends on the operational conditions
. Certainly, we can choose a limited set of components for the purpose of a study – and this is the usual way – but this choice will not guarantee that exclusively those components will participate in the operation considered.
Therefore, interpretation of the degrees of freedom in food engineering systems causes difficulties and is often impossible, because the number and types of participants (chemical compounds, cell fragments, crystalline substances, etc.) in food operations are hard to estimate: many chemical and physical changes may take place simultaneously, and a small change in the conditions (temperature, pH, etc.) may generate other types of chemical or physical changes. If we compare this situation with a complicated heterogeneous catalytic chemical process with many components, it is evident that in food engineering we struggle with complex tasks that are not easier, only different.
Evidently, comminution plays a decisive role in connection with these peculiarities. However, in the absence of comminution, these two peculiarities – the existence of intact cell wall as barriers to equilibrium and the very high number of operational participants – may appear together as well; for example, in the roasting of cocoa beans, the development of flavours takes place inside unbroken cells. In such cases, cytological aspects (depot fat, mitochondria, etc.) become dominant because the cell itself works as a small chemical plant, the heat and mass transfer of which cannot be influenced by traditional (e.g. fluid-mechanical) means. This problem is characteristic of biochemical engineering.
3.
The third peculiarity, which is a consequence of the cellular structure, is that the operational
participants
in food engineering may be not only chemical compounds, chemical radicals and other molecular groups but also
fragments of comminuted cells
.
In the case of chemical compounds/radicals, although the set of these participants can be infinitely diverse, the blocks from which they are built are well defined (atoms), the set of atoms is limited and the rules according to the participants are built are clear and well defined.
In the case of cellular fragments, none of this can be said. They can, admittedly, be classified; however, any such classification must be fitted to a given task without any possibility of application to a broader range of technological problems. This is a natural consequence of the fact that the fragments generated by comminution, in their infinite diversity, do not manifest such conspicuous qualitative characteristics as chemicals; nevertheless, they can be distinguished because slight differences in their properties, which occur by accident because of their microstructure, may become important.
This situation may be understood as the difference between discrete and continuous properties of substances: while chemical systems consist of atoms and combinations of them, to which stoichiometry can be applied, the systems of food engineering cannot be built up from such well-defined elements. This stoichiometry means that well-defined amounts by mass (atomic masses or molecular masses) may be multiplied by integers in order to get the mass fluxes in a reaction. However, in the recipes that are used for describing the compositions of foods, the mass fluxes are treated as continuous variables, contrary to the idea of stoichiometry.
1.1.2 The hierarchical and semi-hierarchical structure of materials
Although foods also consist of atoms in the final analysis, it is characteristic of food engineering that it does not go to an elementary decomposition of the entire raw material; however, a certain part of the raw material will be chemically modified, and another part will be modified at the level of cells (by comminution). The structures of materials are hierarchical, where the levels of the hierarchy are joined by the containing relation, which is reflexive, associative and transitive (but not commutative): A → B means that B contains A, that is, → is the symbol for the containing relation. The meaning of the reflexive, associative and transitive properties is:
Reflexive: A contains itself.
Associative: if A → (B → C), then (A → B) → C.
Transitive: if A → B → C, then A → C (the property is inheritable).
