Interesterification
In certain lipids the distribution of fatty acids at various
positions of the triglyceride are not random.
In some cases this is desirable, in other cases, randomness is
desired.
Exchange of fatty acids may occur at 250 ° C with no catalyst or
at 0° C with the proper catalyst.
Interesterification and melting point
Melting Point ° F
| Fat | Before | After |
|---|---|---|
| Soybean oil | 19.4 | 41.9 |
| Cottonseed | 50.9 | 93.2 |
| Lard | 109.4 | 109.4 |
| Coconut Oil | 78.8 | 82.8 |
25% Tristearin + |
|
|
Lard Performance and Interesterification
| Penetration at | Before | After |
|---|---|---|
| 70° F | 62 | 65 |
| 80° F | 80 | 130 |
| 90° F | 140 | 225 |
| Air Incorporation (%) | ||
| Pound Cake | 62 | 225 |
| Loaf Volume | 850 | 1495 |
Catalyst is usually sodium methoxide
Interesterification within a triglyceride
Or between triglycerides. Start with
and end with:
Initial Reaction
Exist in Two Isomeric Forms
Can be represented as
Enolate Ion
Enolate Ion
True catalyst in interesterification
Sodium methoxide is used up early in the reaction.
Carbonyl is very electrophilic and may accept an electron from a nucleophilic group, such as the resonance bond in the ion.
Directed Interesterification
Native lard is too uniform and tends to from b crystals which do not incorporate air well
Randomized lard has the proper crystal structure, but is too soft. Best performance when lard contains about 10% trisaturated glycerides.
It is possible to have the reaction occur at a temperature that is below the melting point of GS3. This will cause these molecules to solidify and they are not able to participate in further reactions.
Results in a lard with b' crystals and
the proper consistency.
