Transcript INTERESTERIFICATION

INTERESTERIFICATION
Interesterification
Interesterification involves an exchange of acyl group
among triglycerides.
Acyl groups may exchange positions within a
triglyceride or among triglyceride molecules.
Interesterification
Probablity of Different Triglycerides Formation
If A, B, and C are the molar percentages of fatty acids A, B, and C
for a commercial oil,
Then, molar percentage of glycerides containing only 1 acid is:
% AAA = A3 : 10,000
Molar percentage of glycerides containing 2 acids is:
% AAB = 3A2B : 10,000
And molar percentage of glycerides containing 3 acids is:
% ABC = 6ABC : 10,000
Intraesterification, Interesterification and Equilibrium Mixture.
S
O
L
Catalyst
O
O
L
S
O
S
S
S
L
S
Continued reaction
O
O
S
L
O
(SUS
L
SSU)
O
O
O
L
L
O
O
O
L
L
S
L
O
(SUU
S
O
S
O
S
L
L
S
S
L
L
SSS
S
S
S
S
S
L
O
O
L
USU)
O
UUU
L
S
L
L
Random Interesterification
A.
S (Stearic acid 35%)
B.
S (50%)
O (Oleic acid 30%)
O (40%)
L (Linoleic acid 35%)
L (10%)
After random interesterification, the triglyceride compositions are:
Sample A
Triglyceride
SSS
OOO
LLL
SSO
SSL
OOS
OOL
LLS
LLO
SOL*
Sample B
%
= 4.3
= 2.1
= 4.3
= 11.0
= 12.8
= 9.5
= 9.5
= 12.8
= 11.0
= 22.0
Triglyceride
SSS
OOO
LLL
SSO
SSL
OOS
OOL
LLS
LLO
SOL*
*Total triglycerides containing 3 different fatty acids.
%
= 12.5
= 6.4
= 0.1
= 30.0
= 7.5
= 24.0
= 4.8
= 1.5
= 1.2
= 12.0
Catalysts
• High temperature catalysts: KOH and NaOH
• Low temperature catalysts: Sodium Methoxide (NaOCH 3)
Reaction Mechanisms
1. The formation of enolate ion
2. The formation of Beta-Keto ester
3. Interesterification
Catalyst Function in Interesterification
Initial removal of an -proton by the base catalyst
leads to the charge delocalized enolate anion.
O
CH3
+
C CH3
OH
O-
O
CH3
C CH2
H2O +
-
-
CH3
CH3
C CH2
O C CH2
Enolate Ion Formation
O
C O C H2R1
O
C O C H2R2
O
C O C H2R3
O
O
C
-
C
+
O C H3
-
CH3OH
OR1
O
C
H
C
R1
H
O
C O C H2R2
O
C O C H 2 R2
O
C O C H2R3
O
C O C H 2 R3
O
O
C
C
R1
H
O
C O C H2R2
O
C O C H2R3
+
Mechanism for Intramolecular Ester-Ester Interchange
O
O C CH R1
_
_
O
O C
O H O
O C C C CH2R2
R1
O
H
C R1
O C CH2R2
O
O COCH2R3
O COCH2R2
O COCH2R3
I
Enolate ion formation
-
O COCH2R3
II
III
Beta-Keto ester formation
O
O
H O
C
C
C
_
CH2 R2
_
O
R1
O
O
_
Intraesterification
O
O
H O
C
C
C
COCH2R2
O
CH2R2
O
C
R1
O
COCH2 R3
III
O
COCH2R3
IV
C
R1
H
O
COCH2R3
V
Mechanism for Intermolecular Ester-Ester Interchange
O
C
O
_
O
C
R1
O
C
C H 2R
O
C O C H 2R 5
O
C O C H 2R 6
H
O
C O C H 2R 2
O
C O C H 2R 3
+
I
VI
_
O
VII
O
H
O
C
C
C
O
R 1 C H 2R 4
O
C O C H 2R 2
O
C O C H 2R 5
O
C O C H 2R 3
O
C O C H 2R 6
4
Mechanism for Intermolecular Ester-Ester Interchange
Interesterification
_
Beta-Keto ester formation
O
O
H
O
C
C
C
_
C H 2R 4
R6
R4
R1
R 2+
R5
R1
IX
R2
R 5C O O
R3
O
VIII
R6
R3
_
R1
R5
R2 +
R4
R3
R6
X
Random Esterification
Interesterification can be carried out to an equilibrium
condition, at which point the fatty acids assume an
almost random distribution among triglycerides.
Intraesterification, Interesterification and Equilibrium Mixture.
S
O
L
Catalyst
O
O
L
S
O
S
S
S
L
S
Continued reaction
O
O
S
L
O
(SUS
L
SSU)
O
O
O
L
L
O
O
O
L
L
S
L
O
(SUU
S
O
S
O
S
L
L
S
S
L
L
SSS
S
S
S
S
S
L
O
O
L
USU)
O
UUU
L
S
L
L
Direct Interesterification
Interesterification can be directed away from
its usually random end-point if the fat is
allowed to crystallize during reactions.
The trisaturated glycerides crystallize first.
Intraesterification, Interesterification and Equilibrium Mixture
S
O
L
Catalyst
O
O
L
S
O
S
S
S
L
S
Continued reaction
O
O
S
L
O
(SUS
L
SSU)
O
O
O
L
L
O
O
O
L
L
S
L
O
(SUU
S
O
S
O
S
L
L
S
S
L
L
SSS
S
S
S
S
S
L
O
O
L
USU)
O
UUU
L
S
L
L
Directed Interesterification
S
O
L
1.
2.
3.
4.
5.
Stearic-Stearic-Stearic
Oleic-Oleic-Oleic
Linoleic-Linoleic-Linoleic
Oleic-Oleic-Linoleic
Oleic-Linoleic-Linoleic
33.3 mole % solid
8.3 mole % liquid
8.3 mole % liquid
24.9 mole % liquid
24.9 mole % liquid
Effects of Different Interesterification of
Lard on Triglycerides
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S3(%)
S2U(%)
SU2(%)
U3(%)
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Natural Lard
2.0
27.0
47.0
24.0
Completely Random
4.3
23.8
44.4
27.5
Directed Random
8.4
17.4
41.4
32.9
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Intraesterification, Interesterification and Equilibrium Mixture.
S
O
L
Catalyst
O
O
L
S
O
S
S
S
L
S
Continued reaction
O
O
S
L
O
(SUS
L
SSU)
O
O
O
L
L
O
O
O
L
L
S
L
O
(SUU
S
O
S
O
S
L
L
S
S
L
L
SSS
S
S
S
S
S
L
O
O
L
USU)
O
UUU
L
S
L
L
Benefits of Interesterification
Lard may be given different properties by varying the method of
interesterification.
One set of conditions favors intramolecular interchange and
results in a crystal-modified lard (CML).
Conditions favoring random distribution can be controlled to
yield a partially modified lard (PML).
Conditions favoring directed interesterification can be used to
control the GS3 content of direct interesterified lard (DIL).
Baking Evaluation of Modified Lards Stored
at Different Temperatures
Pound cake volume (ml)
Storage temperature (ºC )
Storage time (weeks)
24
30
38
2
16
1
9
1
4
1475
1435
1400
1190
1400
1100
PML
1500
1445
1470
1335
1400
1295
CML
1525
1565
1535
1550
1510
1555
DIL
1505
1455
1595
1305
1440
1355
Lard (Natural)
Applications
Shortenings: The proportion of palmitic acid in the
2-position is reduced from about 64% to 24% on
random interesterification.
Natural lard
Randomized lard
beta
beta’
Randomization of lard improves its plastic range and
thus makes it a better shortening than natural lard.
Plasticity and Consistency
Plasticity is the changes in consistency as a function of
temperature.
Consistency is the apparent hardness at a temperature
Margarines – High Stability Margarine Blends
1. 75 % (co-randomized 40 % coconut oil / 60 % palm oil),
2. 10 % (co-randomized 50% coconut oil / 50 %
hydrogenated canola oil) and
3. 15 % hydrogenated soybean oil
Good spreadability, high temperature stability, and good eatin
qualities.
Nutritional Margarine Blends
High polyunsaturated content and low-to-zero
trans-acid containing margarines are produced by
interesterifying a blend of liquid oil and a fully
hydrogenated oil.
Confectionary Fats
Hydrogenated palm kernel oil is a hard butter melting
at 46C and produces a waxy feel in the mouth.
On randomization, its melting point is reduced to
35C. By blending hydrogenated palm kernel oil and
its randomized product, a whole series of hard butters
with highly desirable melting qualities (rapid melt in
mouth) are obtained
Confectionary Fats from Blend of Hydrogenated and
Interesterified Hydrogenated Palm Kernel Oil
SCI
Fat
M.P.(C)
10
20
35
38
Hydrogenated palm
kernel oil (PKO)
46.8
74.2
67.0
15.4
11.7
Int. hydrogenated
PKO
35.0
65.0
49.9
1.4
1.1
50% hydrogenated
50% int. hydrogenated
41.7
70.0
57.4
8.7
5.2
Effect of Randomization on SCI of an 80:20 Mixture of
Lightly Hydrogenated Soybean Oil and Palm Stearine
Solid Content Index of Cocoa Butter before
and after Interesterification
Changes in SCI of Lard by Interesterification
Cross-Sectional Structures of Triglycerides
Freedom of molecular motion
Beta Prime
Alpha
Beta
Double Chain Length Structures of Triglycerides
D
D
Alpha
(Vertical tuning fork)
Beta-Prime
(Tilted tuning fork)
D
Beta
(Stacked chair)
Characteristics of Triglygeride Polymorphs
________________________________________________________________________
Alpha
Beta-Prime
Beta
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Platelet
Fine needle
Long needle
5m
1m
25-50 m
Most loosely packed
More closely packed
Most closely packed
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