1
Q
Unsweetened Chocolate
A
- Made only with solid chocolate liquor and
the taste is too bitter to eat. - It is use as chocolate flavor for brownies
and cakes.
2
Q
Semi-Sweet Chocolate
A
- Made of solid chocolate liquor and a small
amount of sugar and cocoa butter. - It is use for garnishes and fondues.
3
Q
Sweetened Chocolate
A
- Made from chocolate liquor (cocoa mass) (>15%), cocoa butter and sugar.
- It is use in commercial candies or bars.
4
Q
Bittersweet Chocolate (dark
chocolate)
A
- It is made of chocolate liquor (>35%) with small amount of cocoa butter and sugar,
- It is use in baking.
5
Q
Milk Chocolate
A
- Made from chocolate liquor (>10%), milk solids (>12%), cocoa butter and sugar.
- Often eaten as a candy bar.
6
Q
White Chocolate
A
- Made with cocoa butter (>20%), milk (>14%) and sugar.
- Often used as a coating or decorative garnish.
7
Q
Chocolate ingredients are mixes to a paste and
A
crush into flakes which
are significantly reduced in size.
8
Q
Grinding or Refining
A
step is important in producing smooth chocolate texture.
9
Q
Most chocolate manufacturers use a
A
roll refiner or ball mill for the
refining process.
10
Q
Two functions of refining:
A
- To reduce the particle size of the cocoa mass and other ingredients, such as sugar or milk powder.
- To distribute the cocoa butter evenly throughout the mass and coating all the particles.
11
Q
Conching
A
Improves the flavor of
chocolate by
12
Q
Conching process Improves the flavor of
chocolate by
A
evaporating various volatile
flavor components including organic acids.
13
Q
The chocolate flavor produce depends on
the
A
temperature and processing time
used.
14
Q
Cook flavor start to occur
A
occur at temperature
above 70oC.
15
Q
For milky flavor chocolate, conching
temperature must be kept
A
< 50oC to avoid
Maillard flavor.
16
Q
To ensure the uniform coating of
solid particles,
A
the fat andemulsifier present in the chocolate must coat the sugar and other solid particle uniformly depending on the mixing action of the conche.
17
Q
Conching facilitate
A
particle coating,
promoting a smooth texture in the
final product.
18
Q
Two different types of mixing
A
Shear mixing-Elongational mixing
19
Q
Shear mixing-
A
chocolate is between two
surfaces moving relatively to one another
20
Q
Elongational mixing
A
the material is
squeezed through or spread over a surface
21
Q
Effect of shear rate on the chocolate mixing: Slow shear rate
A
the viscosity will come to an equilibrium level.
22
Q
Higher shear rate
A
produce lower viscosity and thinner chocolate.
23
Q
Medium shear rate
A
The viscosity is at a lower value and tends to
be reached more quickly.
24
Q
Three phases of conching:
A
Dry phase: Pasty phase: Liquid phase:
25
Dry phase:
chocolate mass is crumbly, moisture is
removed
26
Pasty phase:
chocolate is a thick paste, high work input
required by the conche
27
Liquid phase:
high-speed stirring to mix in the final fat
and emulsifier additions
28
1. Dry phase conching
The feed materials normally enters the conche as a powdery
material.
29
The initial moisture content of many milk chocolates
is about
1.6%.
30
The mixing leads to coating of the particles with
cacao butter
or fat.
31
Air movement in this process removes the
volatile substances (organic acids), excess moisture from the chocolate mass which enhancing flavour.
32
Pasty phase conching ~ The viscosity start to fall,
due to continued moisture removal and more solid particles are coated with fat.
33
The solid particles such as sugar, nonfat cocoa and milk
powder are
coated with fat, dissociated by friction and
become rounded.
34
The coating of particles by fat promotes
the smooth texture of
chocolate.
35
Flavor development
by means of shearing and heating
36
Chocolate must be cool before the lecithin is added because
lecithin is less efficient when added at temperature higher
than 60oC.
37
Addition of fat and emulsifier produce chocolate with very
thin texture and homogenization of the chocolate.
38
The high quality and expensive chocolates are
conched for
more than 72 hours.
39
After the conching process is completed,
the chocolate mass
is transferred to a tank where it is stored and heated to a
temperature of 45–50 °C until the final processing.
40
Conching Machines
Batch conches* Continuous conches
s
41
Batch conches
- Horizontally stirred rotary conches
- Vertically stirred rotary conches
42
* Continuous conches
- Larger volume continuous conches
- Tourell conche
- Thouet continuous process
- Frisse continuous process
- Short dwell time continuous conches
43
Goal of conching:
* Moisture content is reduced
* Volatile organic acids are reduced
* Surface gloss is improved
* The chocolate mass is converted from a powder to a flow able suspension
* Viscosity is reduced
* Texture and melt characteristics are improved
* Full chocolate flavor is developed
44
Viscosity depends
on the rate at which it is
flowing.
45
Fast moving chocolate being much thinner
than it is
runny slowly down (moulding and
enrobing process)
46
A chocolate may be too thick due to:
* The moisture has not been removed
* The chocolate has been milled too finely
* The chocolate has not been conched
correctly.
47
Factors properties affecting chocolate flow properties
Fat Content/ Particle Size
Distribution/ Emulsifier/ Conching/Vibration/Moisture
48
Liquid fat (cocoa butter and milk fat) enables
the chocolate to flow.
49
As the fat content increases
the distance between the solid particles increases so the
viscosity drops –good flow properties.
50
If a chocolate is too thick,
the further grinding of the cocoa liquor or adding the cocoa butter
or emulsifier should be considered.
51
The chocolate viscosity can be
reduced by
adding fat.
52
However, the price of fat is
expensive and will
increased the
cost of the product.
53
Thus, must ensure that the fats
and emulsifier that are used have
their
maximum effect on the flow
properties.
54
Fat and emulsifier added towards
the end of the conching have a
much bigger effect
on the final
viscosity than added at the
beginning.
55
The smaller particles are important with respect to chocolate
flow properties due to
large amount of fat is required to coat the particles - they can move past one another in the liquid chocolate.
56
Reduce particles diameter will create
more surface area to be coated with fat and increase the chocolate flow properties.
57
Grinding all solid particles below 30μm will reduce
the grittiness of the chocolate.
58
The yield value increases dramatically
as the chocolate becomes finer, but
the plastic viscosity stays almost unchanged.
59
High yield is due to the half
the volume of the chocolate is taken up by solid
particles.
60
Emulsifier use in chocolate -
Lecithin, polyglyceryl
polyricinoleate (PGPR)
61
In the chocolate matrix, lecithin coat the sugar particles to
facilitate flow in the continuous fat phase and
prevent agglomeration.
62
Lecithin are surface-active- hydrophilic (water-loving)
and hydrophobic (water-repelling)
properties enable
lecithin to make stable blends of materials that do not
mix easily and tend to separate.
63
The efficiency of coating sugar by the lecithin is dependent on the
concentrations, approximately 50, 67, and 85% sugar coated for lecithin
concentrations of 0.2, 0.3, and 0.5%, respectively.
64
Increasing concentrations of lecithin,
the interface between the particles and the fat reduces friction and facilitates “lubrication”.
65
The addition of emulsifiers is extremely effective in
reducing chocolate
viscosity, approximately 10 times greater than natural cocoa butter.
66
Vibration
To remove of air bubbles.
67
Viscosity increased with increasing
amplitude of vibration.
68
Principle of tempering:
- To develop a population of seed crystals that are sufficient to avoid heterogeneous crystallization during cooling.
- Provide a seed concentration between 0.1 to 1.15% of cocoa butter mass.
69
The smaller and more regular the size of seed crystals,
the glossier the
chocolate and the greater its bloom resistance.
70
If the crystals size is too large,
large, the crystals tend to re-crystallize during the storage
71
Cooling too fast may induce
crystallization of unstable crystal
polymorphs as well as formation of hair cracks and pores on the
surface
72
Tempering involves the following steps:
1. Complete melting
2. Cooling to the point of crystallization
3. Crystallization
4. Melting out of unstable crystals
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