Crystallisation and Physical
Properties of Fats
18-19 June 2008
Ghent University, Belgium
Improving the Physical and Chemical
Properties of Cocoa Butter by Selected Oil
Processing Technologies
Dr. ir. G. Calliauwa,b, ir. J. Vila Ayalaa, ir. B. Scholsa, Dr. V. Gibona,
Dr. ir. W. De Greyta, Prof. Dr. ir. I. Foubertc & Prof. Dr. ir. K. Dewettinckb
aDesmet Ballestra Group
bFTE, Ghent University
cKULeuven-Kortrijk
KULeuven-Kortrijk
De Smet Presentation
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Outline of the Presentation
• Introduction: Cocoa Butter Processing
• Steam Refining
• Chemical impact
• Crystallization “in process”
• Crystallization “of product”
• (Static Fractionation)
• Principle
• Process
• Product
• Conclusions
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Cocoa
Butter
Oil
Processing
Processing
Cleaning
Cleaning // Drying
Drying
Fermentation
Cracking
Flaking
Cracking
Flaking
Roasting
Seed
Bean
Seed
Dehulling
Dehulling
Dutching
Preparation
Speciality
Speciality Fats
Fats
Frying
Frying oil
oil
Mechanical
Mechanical Extraction
Extraction
Meal
Meal
Solvent
Solvent Extraction
Extraction
Extraction
Crude
Crude
Oil
Oil
Hydrogenation
Hydrogenation
Degumming
Degumming
Interesterification
Interesterification
Neutralising
Neutralising
Margarine
Margarine
Fractionation
Fractionation
Modification
Refined
Refined
Oil
Oil
Bleaching
Bleaching
Soap
Soap
Winterising
Winterising
Lubricants
Lubricants
Deodorising
Deodorising
Biodiesel
Biodiesel
Oleochemical
Processes
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Refining
3
Oil Quality
OIL PROCESSING
Organoleptic/stability
Functional Properties
-Desired taste, odour
-Light color (brilliant)
-High thermal stability
-High oxidative stability
-Long shelf life
- Good melting profile
- Desired Plasticity
- Crystallisation kinetics
OIL
QUALITY
Refining
Modification
Nutritional Quality
- Balanced FA composition
- No trans FA
- High tocopherol content,…
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Steam Refining:
Packed Column
Principle
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Steam Refining
Purpose:
1. Removal of unwanted odour and taste
2. Removal of excessive FFA (>1.75% as oleic acid)
while preserving TAG-distribution of oil, colour,
oxidative stability,…
Principle:
Stripping of volatiles with carrier gas (steam) at high
temperature (laws of Raoult & Dalton)
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Steam Refining
Packed Column:
∆
∆
•Continuous countercurrent
•Short residence time
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Steam Refining:
Chemical Impact
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Steam Refining:
Odour & Taste, TAG
• Higher temperature leads to more bland taste
Europe: residual aroma desired (e.g. 180°C)
U.S.: favouring bland taste (e.g. 200°C)
• No observable effect on TAG-distribution
TAG-ratios remain unchanged
No TFA formation
No interesterification effects
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Steam Refining:
FFA-reduction
Residual
ResidualFFA-concentration
FFA-concentration (%)
(%)
1.4
1.4
1.2
1.2
FFA
1.0
1.0
1% steam
2% steam
3% steam
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
0.0
0
20
20
40
40
60
60
8080
Mean
(mbar)
Mean vapor
vapor pressure of FFA (hPa)
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Steam Refining:
FFA-reduction
Dijkstra equation
Steam (%)
Transfer units u
R²
1
1.70 ± 0.18
0.974
2
2.04 ± 0.10
3
1.93 ± 0.09
lower model quality
( PO)u ( Pv S − PO)
V2 = V1
( Pv S )u +1 − ( PO)u +1
0.994
0.995
Bailey equation
S =
Steam (%)
A
B
E (%)
R²
1
1.40 ± 0.06
0.136 ± 0.011
82
0.992
2
1.33 ± 0.03
0.272 ± 0.014
91
0.992
3
1.33 ± 0.02
0.393 ± 0.018
Extended Bailey equation
90
0.999
P .O
V
. ln 1
E . Pv
V2
lower model quality
V 2 = y 0 + a exp( −bPv )
Steam (%)
A
B
y0
E (%)
R²
1
1.40 ± 0.05
0.138 ± 0.012
0.03 ± 0.02
83
0.993
2
1.32 ± 0.04
0.288 ± 0.021
0.04 ± 0.02
96
0.996
3
1.32 ± 0.02
0.390 ± 0.014
0.01 ± 0.03
94
0.999
FFA-removal can be described by various physical/mathematical models
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Steam Refining:
Colour of Cocoa Butter
250
Natural
Alkalized
Bleached Alkalized
Crude Natural
Crude Alkalized
Crude Bleached Alkalized
240
230
Depending on feedstock
pre-treatment and process
conditions:
Total Color (-)
220
210
200
190
Heat bleaching
180
Heat darkening
170
Heat bleaching
110
100
150
160
170
180
190
200
210
220
230
Deodorization Temperature (°C)
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Steam Refining:
Theobromine & Caffeine
Residual concentration in CB (%)
100
At mild temperatures:
Free Fatty Acids
Theobromine
Caffeine
80
Removal of T & C > FFA
60
40
20
Deposit of T & C in vapour
condensation system
0
140
160
180
200
220
240
260
280
Stripping Temperature (°C)
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Steam Refining:
Crystallization
‘in process’
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Steam Refining:
Theobromine & Caffeine
1e+6
Theobromine in FAD
Theobromine in CB
Caffeine in FAD
Caffeine in CB
Solubility (ppm)
1e+5
Adjustment of
scrubber
temperatures to
solve T&C in FAD
1e+4
x3
1e+3
1e+2
+ 40°C
1e+1
40
60
80
100
120
140
160
Temperature (°C)
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Steam Refining:
Crystallization
of Product
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Steam Refined Cocoa Butter:
Non-isothermal crystallization
• DSC
• 3 repetitions
• 3 factors
Temperature
Steam
FFA
• 8 parameters
• FMLR
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Steam Refined Cocoa Butter:
Non-isothermal crystallization
Melting
Crystallization
• Models show…
I.C.
Temperature (°C)
Steam (%)
FFA (%)
R²
Heat (J/g)
74.53
0.0320*
n.s.
n.s.
0.22
Start temperature (°C)
15.05
0.0235*
n.s.
1.163
0.19
Onset temperature (°C)
18.07
n.s.
n.s.
-0.043*
0.43
Peak max 1 (°C)
13.39
n.s.
0.185
0.376*
0.26
Peak max 2 (°C)
2.09
n.s.
n.s.
n.s.
-
Heat (J/g)
86.27
n.s.
n.s.
-3.01*
0.31
Onset temperature (°C)
11.01
0.0097
n.s.
0.982*
0.23
Peak max (°C)
26.23
-0.0129
-0.022
-1.422*
0.53
•I.C.: intercept
•n.s.: not significant
•*most significant variable as indicated by ANOVA
…overall low influence, FFA most significant
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Steam Refined Cocoa Butter:
Isothermal crystallization at 20°C
50
XRD-measurements show:
40
Isotherm al time (min)
•
45
35
30
Inten
si ty
to ’
(a.u.)
1. Two-step crystallization:
25
20
140
120
1 00
80
60
40
2. Earlier formation of
in strongly refined CB
20
17
18
19
21
20
22
23
24
25
2θ (°)
3. Slightly higher angles in SAXS for
in strongly refined CB
4. Slightly sooner occurrence of ’
• Modeling the ’ isothermal crystallization with
Foubert-model:
( (
f ( t ) = a F 1 − 1 + 0 . 99
(1 − n )
)
−1 e
De Smet Presentation
(( n − 1 )K (t − t _ ind ))
)
1
1− n
19
Steam Refined Cocoa Butter:
Isothermal crystallization at 20°C
• When plotted as function of FFA, models show…
86
Up to 12% more heat release by ‘-crystals
Induction
time t_ind a(h)
Heat release
at equilibrium
(J/g)
F
0 .4 0
84
for 1.4% FFA removed
26
08.3
80
0 .3 2
Reduced induction times
78
76
0 .2 8
74
Overall, increasing rate constants
0 .0
0 .0
0 .2
0 .2
0 .4
0 .4
0 .6
0 .6
0 .8
0 .8
1 .0
1 .0
1 .21 .2
1 .41 .4
-connce
cen n
tra
u tte
r (%
FFFFAA-co
tra
tiotio
n ninincoco
coco
a a
b ubtte
r (%
) )
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Steam Refined Cocoa Butter:
At Equilibrium
• ‘Equilibrium’ after tempering (40h at 24-26°C)
•
XRD-measurements show overall presence
•
However, PLM shows:
V
high FFA
low FFA
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Steam Refined Cocoa Butter:
SFC-values at 20, 25 and 30°C
Solid Fat Content at equilibrium (%)
90
80
70
60
S F C a t 2 0 °C
S F C a t 2 5 °C
S F C a t 3 0 °C
50
40
30
1 .4
1 .2
1 .0
0 .8
0 .6
0 .4
0 .2
0 .0
F F A -co n ce n tra tio n in co co a b u tte r (% )
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Steam Refined Cocoa Butter:
Predicting SFC?
Process conditions
FFA
SFC
SFC at equilibrium (%)
80
75
70
40
35
0
20
40
60
Mean vapor pressure of FFA (mbar)
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or
Conclusions
• Final Remarks
• The Wrap-up
• The Endtro
• Take Home Messages
• Food for Thought
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The Endtro
Current situation for CB:
supply
FFA
time
1.75%
demand
• Two-way expanding playing field for steam refining
• Need for efficient FFA-removal in short residence time
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Acknowledgements
Prof. Dr. Johan Wouters & ing. Bernadette Norberg
(CBS, FUNDP, Namur) for the use of their XRD-facilities
Further reading
•Calliauw, G., Vila Ayala, J., Gibon, V., Foubert, I., Dewettinck, K., Wouters, J. & De
Greyt, W. (2008) Models for FFA-removal and phase behaviour changes of cocoa
butter by packed column steam refining. Journal of Food Engineering (available
online)
•Vila Ayala, J., Calliauw, G., Foubert, I., Dewettinck, K., Dyer, B. & De Greyt, W. (2007).
Impacts of bleaching and packed column steam refining on cocoa butter properties.
Journal of American Oil Chemists' Society, 84, 1069-1077.
De Smet Presentation
26
Crystallisation and Physical
Properties of Fats
18-19 June 2008
Ghent University, Belgium
Improving the Physical and Chemical
Properties of Cocoa Butter by Selected Oil
Processing Technologies
Dr. ir. G. Calliauwa,b, ir. J. Vila Ayalaa, ir. B. Scholsa, Dr. V. Gibona,
Dr. ir. W. De Greyta, Prof. Dr. ir. I. Foubertc & Prof. Dr. ir. K. Dewettinckb
aDesmet Ballestra Group
bFTE, Ghent University
cKULeuven-Kortrijk
KULeuven-Kortrijk
De Smet Presentation
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