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 FormationIf 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 L S S L S L L L O L L L L S O L O S L O O L O O O S O O L S Continued reaction S O O S O O O S S O O L L S S L L L

S S S S

S

SSS

(SUS

SSU)

(SUU

USU)

UUU

Random InteresterificationA. S (Stearic acid 35%) O (Oleic acid 30%) L (Linoleic acid 35%) B. S (50%) O (40%) L (10%)

After random interesterification, the triglyceride compositions are: Sample A Triglyceride SSS OOO LLL SSO SSL OOS OOL LLS LLO SOL* % = 4.3 = 2.1 = 4.3 = 11.0 = 12.8 = 9.5 = 9.5 = 12.8 = 11.0 = 22.0 Sample B Triglyceride SSS OOO LLL SSO SSL OOS OOL LLS LLO SOL* % = 12.5 = 6.4 = 0.1 = 30.0 = 7.5 = 24.0 = 4.8 = 1.5 = 1.2 = 12.0

*Total triglycerides containing 3 different fatty acids.

Catalysts High temperature catalysts: KOH and NaOH Low temperature catalysts: Sodium Methoxide (NaOCH 3)

Reaction Mechanisms1. The formation of enolate ion 2. The formation of Beta-Keto ester 3. Interesterification

Catalyst Function in InteresterificationInitial removal of an E-proton by the base catalyst leads to the charge delocalized enolate anion.O CH3 C CH3 + OH-

H2O +

O CH3 C CH2-

OCH3 C CH2

CH3

O C CH2

Enolate Ion FormationO O O C O C H2R1 C O C H2R2 C O C H2R3 OR1 O O O C C H C O C H 2 R2 C O C H 2 R3 R1 + O C H3

-

CH3OH

+

O O O O C

C

-

H C O C H2R2 C O C H2R3

O O O O C C H C O C H2R2 C O C H2R3 R1

Mechanism for Intramolecular Ester-Ester InterchangeO O C CH R1 O COCH2R2 O COCH2R3 _ O O C _ H C R1 O C CH2R2 O O COCH2R3 O H O O C C C CH2R2 R1 O

-

O COCH2R3

I Enolate ion formation

II

III Beta-Keto ester formation

O O O O C

H O C R1 C CH2 R2

_ O O O C H O C R1 C CH2R2

_

_ Intraesterification O O O COCH2R2 O C C H COCH2R3 V R1

COCH2 R3 III

O

COCH2R3 IV

Mechanism for Intermolecular Ester-Ester InterchangeO O C C H O C O C H 2R 2 R1

_O

O C C H 2R4

+

O

C O C H 2R 5

O

C O C H 2R 3

O

C O C H 2R 6

IO O C H C O C O

VI _

VII

R 1 C H 2R 4 O O C O C H 2R 2 C O C H 2R 3 O O C O C H 2R 5 C O C H 2R 6

Mechanism for Intermolecular Ester-Ester InterchangeInteresterification_

Beta-Keto ester formationO O C H C R1 R2 R3 R 5C O O O O C C H 2R 4 R6_

R4 R 2+ R3

R1 R5 R6

IXR1 R2 + R3 R5 R4 R6

_

VIII

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 L S S L S L L L O L L L L S O L O S L O O L O O O S O O L S Continued reaction S O O S O O O S S O O L L S S L L L

S S S S

S

SSS

(SUS

SSU)

(SUU

USU)

UUU

Direct InteresterificationInteresterification 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 MixtureS O L Catalyst O L S S L S L L L O L L L L S O L O S L O O L O O O S O O L S Continued reaction S O O S O O O S S O O L L S S L L L

S S S S

S

SSS

(SUS

SSU)

(SUU

USU)

UUU

Directed InteresterificationS 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__________________________________________________________________ S3(%) S2U(%) SU2(%) U3(%) __________________________________________________________________ Natural Lard Completely Random 2.0 4.3 27.0 23.8 47.0 44.4 24.0 27.5

Directed Random 8.4 17.4 41.4 32.9 __________________________________________________________________

Intraesterification, Interesterification and Equilibrium Mixture.S O L Catalyst O L S S L S L L L O L L L L S O L O S L O O L O O O S O O L S Continued reaction S O O S O O O S S O O L L S S L L L

S S S S

S

SSS

(SUS

SSU)

(SUU

USU)

UUU

Benefits of InteresterificationLard 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 TemperaturesPound cake volume (ml)Storage temperature (C ) Storage time (weeks) Lard (Natural) PML CML DIL 2 1475 1500 1525 1505 24 16 1435 1445 1565 1455 1 1400 1470 1535 1595 30 9 1190 1335 1550 1305 1 1400 1400 1510 1440 38 4 1100 1295 1555 1355

ApplicationsShortenings: 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 ConsistencyPlasticity is the changes in consistency as a function of temperature. Consistency is the apparent hardness at a temperature

Margarines High Stability Margarine Blends1. 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 eating qualities.

Nutritional Margarine BlendsHigh 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 46rC and produces a waxy feel in the mouth. On randomization, its melting point is reduced to 35rC. 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 OilSCI Fat Hydrogenated palm kernel oil (PKO) Int. hydrogenated PKO 50% hydrogenated 50% int. hydrogenated M.P.(rC) 46.8 10 74.2 20 67.0 35 15.4 38 11.7

35.0

65.0

49.9

1.4

1.1

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

Alpha

Beta Prime

Beta

Double Chain Length Structures of Triglycerides

D D

D

Alpha (Vertical tuning fork)

Beta-Prime (Tilted tuning fork)

Beta (Stacked chair)

Characteristics of Triglygeride Polymorphs________________________________________________________________________ ________________________________________________________________________

Alpha

Beta-Prime

Beta

Platelet 5Q Most loosely packed

Fine needle 1Q More closely packed

Long needle 25-50 Q Most closely packed

________________________________________________________________________