Palm oil mid fraction

Triglyceride Palm oil mid-fraction (% dry weight) Cocoa butter (% dry weight)... 

The uses cited by Coleman and Macrae (1980) for the lipase catalysed reaction are examples of acidolysis and transesterification. Acidolysis is illustrated by the increase in l(3)-palmitoyl-3(l)-stearoyl-2-olein (POSt) resulting from the reaction of palm oil mid-fraction with stearic acid in the presence of a 1,3-specific enzyme, and by the increase in the content of linoleic acid in olive oil when that oil is reacted with linoleic acid in the presence of an enzyme with fatty acid specificity. An example of transesterification is shown by the increase in POSt triglycerides when a 1,3-specific enzyme is used to catalyse the interesterification of shea butter and palm oil mid-fraction. 

In one example of the Unilever process described by Moore et al. (1991), lipase from Mucor miehei immobilized on celite was used in a packed-bed reactor. The feedstock consisting of equal parts of dry fractionated palm oil mid-fraction with an IV value of 55 and stearic acid was dissolved in hexane. The feedstock was percolated down a column... 

Table 12.7 Comparison of solids content of isolated fractions from products of enzymatic interesteriiication of a mixture of fractionated palm oil mid fraction (1 part) and stearic add (1 part) with cocoa butters...

Fuji Oil (Matsuo et al, 1981) filed the first patents for the lipase-catalysed synthesis of a cocoa butter equivalent from palm oil and stearic acid. Both companies currently manufacture it using 1,3-selective lipases to replace palmitic acid with stearic acid at the 5n-l and sn-2> positions. The reactions usually performed are transesterification or acidolysis of cheap oils using tristearin or stearic acid as the acyl donors and a 1,3-specific lipase (Figure 3). Suitable starting oils besides palm oil mid-fractions are sunflower, rapeseed (Adlercreutz, 1994) and olive (Chang et al, 1990) oils. 

Figure 3. Possible approaches to the synthesis of cocoa butter equivalents (A), addolysis of palm oil mid-fractions with stearic add (B), interesterification between palm oil mid-fractions and stearic acid esters (C), addolysis of palm oil mid-fractions with mixtures of stearic and palmitic acid (D), interesterification between palm oil mid-fractions and stearic and palmitic acid esters. Ol, oleic add. Pa, palmitic acid. St, stearic acid. X, alcohol.

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. 

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. 

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. 

Crude palm oil used to be the main form of export in the past. With the establishment of refineries especially in Malaysia during the mid-1970s and 1980s, refined palm oil products have replaced the crude as the main form of palm oil export. A wide range of processed or semiprocessed products are exported, and these include the different fractions of processed pahn oil known as palm olein (liquid) and palm stearin (solid). The availability of refineries also led to the production of specialty fats products aimed at the confectionery markets. A similar trend has been seen in the export of pahn kernel oil. Palm kernel oil is a coproduct to palm oil produced at a ratio of 10-13 tons of palm kernel oil for every 100 tons of palm oil. Even the export of refined palm kernel oil has begun to decline as more is being used locally by the oleochemical industry that has been estabhshed in recent years. 

The author is developing (mid-2004) zero trans-, no hydrogenation, no interesterification, no modification of any kind, tub and stick margarines. The formula will include specially processed soybean oil, corn oil, cottonseed oil, or mid-oleic sunflower seed oil, and double-fractionated palm oil, or double-fractionated cottonseed oil. The products are proprietary for now. 

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).

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%). ... 

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. 

Cocoa butter has enjoyed a price as high as US 8600/ton in the mid-1980s (Moreton, 1988b Smit et al., 1992) which made it an attractive proposition for several SCO groups to consider as a target. Cocoa butter, however, now (1993) sells at approx. US 3000/tonne which has made it difficult, if not impossible, for these alternative processes to be run economically. Nevertheless, considerable attempts were made in the 1980s to attain a satisfactory cocoa butter equivalent (CBE) yeast oil. The price of a CBE from palm oil fractionation is usually fixed at about 80% of the price of cocoa butter itself and thus a yeast CBE will have to be priced even lower (see section 9.7). 

As an alternative to direct production using yeast technology, there are prospects of producing the correct fatty acyl formulation by transesterify-ing a cheap oil such as mid-palm oil fraction with oleic acid or its various esters including trioleoylglycerol derived from high-oleate sunflower seed oil and an appropriate microbial Upase (see chapter 12 for further details). 

Native or hydrogenated palm, palm kernel, rapeseed, soya, pemiut, coconut, castor, cotton oils, cocoa butter and their derivatives (obtained by fractionation, esterification, concentration mid/or reconstitution fatty acids mid cohols, mono-, di- and triglycerides, cocoa butter substitutes, mmgmine, shortenings, acetylated glycerides, lecithins, etc)... 

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