Palm mid fraction

Md Ali, A.R. and Dimick, P.S. (1994) Thermal analysis of palm mid fraction, cocoa butter and milk fraction blends by differential scanning calorimetry. J. Am. Oil Chem. Soc., 71(3), 299-302. 

Palm oil is fractionated more than any other oil. A single fractionation converts palm oil (IV 51-53) to palm olein (IV 56-59) and to hard stearin (IV 32-36). Each of these can be fractionated a second or a third time to give a range of products, including superolein (IV 64—66), topolein (IV 70-72), soft stearin (IV 40 2), super stearin (IV 17-21), soft palm mid-fraction (IV 42 8), and hard pahn mid-fraction (IV 32-36). These materials have a wide range of food and nonfood uses and extend considerably the use of palm oil. 

Unilever developed a method for upgrading palm mid-fraction (PMF) as a cocoa butter equivalent. The PMF is too rich in palmitic acid and has too little stearic acid, but this deficiency can be repaired by enzyme-catalysed acidolysis with stearic acid. Reaction is confined to the exchange of palmitic acid by stearic acid at the sn-1 and 3 positions with no movement of oleic acid from the sn-2 position. A similar product is produced enzymatically by acidolysis of high-oleic sunflower oil (rich in triolein) and stearic acid. 

In addition to hydrogenated palm olein, hydrogenated palm mid fraction is an excellent ingredient for high-stability plastic fat products. Palm mid fraction is even higher in POP than palm olein. 

Figure 3.11 Solid fat content of palm oil products. PO palm oil POo palm olein POs palm stearin PMF palm mid-fraction. Key —0—, PO — —, POo —A—, POs —X—, PMF —6—, POs (hard).

These are fats rich in symmetrical disaturated TAGs which behave like cocoa butter in all respects, and are able to mix in all proportions with cocoa butter. The desirable characteristics of cocoa butter are due to the SOS TAGs (S = saturated) which provide suitable melting point and solid fat content to give rapid melt in the mouth and cooling sensations. Palm mid-fraction (PMF), which has high contents of POP, is easily formulated with other SOS fats for chocolate products (Berger 1981). About 70%-80% PMF with 20%-30% shea or sal stearin, or 60%-65% PMF with 20%-30% shea or sal stearin and 15%-20% illipe are suitable for plain and for milk chocolate with 15% milkfat. Compatibility of cocoa butter (CB) and CBE is affected by addition of milkfat and its fractions into the product (Sabariah etal. 1998). Eutectic interactions between anhydrous milkfat (AMF), CBE and CB were noticeable due to different polymorphism encountered in these fats. 

HO high-oleic acid soybean oil PMF palm mid-fraction... 

Palm oil contains almost equal proportions of saturated (palmitic 48%, stearic 4%, and myristic 1%) and unsaturated acids (oleic 37% and linoleic 10%). The oil can be fractionated to give palm stearin, palm olein, and palm mid fraction. It is used mainly for food purposes but has some nonfood uses. Valuable by-products obtained from palm oil are carotene, tocopherols and tocotrienols (vitamin E), and palm-fatty acid distillate (PFAD). Palm kernel oil is lauric oil, similar in composition to coconut oil (lauric acid 50% and myristic acid 16%) and contains palmitic acid (8%), capric acid (3%), caprilic acid (3%), stearic acid (2.5%), oleic acid (15%), and linoleic acid (2.5%). ... 

An example of the value of this technique is to be found in the upgrading of palm mid fraction in terms of its potential as a cocoa butter substitute. Before interesterification this contains POP (58%), POS (13%) and SOS (2%). These values are changed to 19, 32 and 13% after interesterification with stearic acid in the presence of A. niger lipase which is 1,3-specific. 

Cocoa butter substitutes are prepared by separating out a middle melting fraction from palm oil and blending the resulting product with other exotic tropical fats. These fats are called palm mid-fractions. The slip melting points and iodine values of a few such fats are also plotted in Fig. 8.2 for added interest. It is unlikely that palm oil will ever be adulterated or contaminated with a palm mid-fraction as these fractions command a high price and are traded separately from the conventional bulk oils. 

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