Chemical Interesterification of Refined Bleached and Deodorised Palm Olein With Palm Methyl Ester

Chemical interesterification using refined, bleached, and deodorised palm olein (POo) as feedstock with fractionated high iodine value palm methyl ester (ME) to produce liquid oil with high iodine value (IV) as well as high monounsaturation was studied. The interesterification has been conducted under different reaction conditions, including ratio of POo to ME, type of catalyst (Na versus NaOMe), catalyst dosage, reaction temperature, and quality of ME (high peroxide value versus low peroxide value) to develop optimum reaction conditions for maximum conversion to increase the unsaturation of the interesterified oil. The reaction is allowed to proceed for two hours before termination. Samples were taken frequently during the course of reaction and subjected to measurement of triacylglycerol (TAG) and diacylglycerol (DAG) distribution. The catalytic performance of interesterification was evaluated by determining changes in the TAG and DAG compositions by reverse-phase high performance liquid chromatography (HPLC), and fatty acid composition by gas chromatography (GC). After interesterification, the compositions of TAGs in the interesterified oil, such as dilinoleoyl oleoyl glycerol (OLL), dioleoyl linoleoyl glycerol (OLO), and tryoleoyl glycerol (OOO) increased from initial value of 0.4 mole % to 0.6-4.4 mole%, 1.7 mole % to 2.5-16.3 mole %, and 3.7 mole % to 5.2-21.0 mole%, respectively. While the dipalmitoyl linoleoyl glycerol (PLP) and dipalmitoyl oleoyl glycerol (POP) decreased after 2 hours reaction. Interesterified oils obtained contained about 2.0-9.7 mole % of PLP compared to 10.0 mole % in POo and about 6.7-28.2 mole % of POP compared to 30.3 mole % in POo. Meanwhile, the relative concentration of DAG was also changed after the reaction. The relative concentration of DAG of interesterified oils was in the range of 0.6 mole % to 16.6 mole % compared to 7.6 mole % in starting POo (P, O, and L represented palmitic, oleic, and linoleic acid, repectively) An interesterified oil which simulates olive oil has been made from POo. The product obtained from interesterification of POo with low peroxide value methyl ester (LPVME) at optimum condition (POo/LPVME ratio of 1:1.4, using 0.1 % w/w NaOMe catalyst at 100oC) has been subjected to dry fractionation and compositions of the fractionated products have been determined by using HPLC and GC. The physical properties of the fractionated products have also been investigated using various standard techniques. Solid fat content (SFC) and thermal behaviour of fractionated products have been investigated using nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). Other methods, such as slip melting point (SMP), cloud point, crystallisation temperature, cold test, cold stability, and oxidative stability test have also been conducted. The physical properties of fractionated products have been compared with those of olive oil. After fractionated, oleic acid content of the liquid fractions, interesterified oleins increased from 55.9 % before fractionation to 58.8-62.6 % and iodine value of 81.2-88.3. Generally, the products obtained from interesterification followed by fractionation contained higher oleic acid compared to that of starting POo (42.0 %). Therefore, interesterification process followed by fractionation has improved the unsaturation of a palm oil product as well as monounsaturation content, which is comparable to olive oil. Moreover, this product contained lesser DAG content compared to normal POo.

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