Malaysian Journal of Analytical Sciences Vol 19 No 1 (2015): 222 – 229

 

 

 

SYNTHESIS OF PALM OIL HIGH IN DIACYLGLYCEROL THROUGH DIRECT ESTERIFICATION

 

(Penghasilan Minyak Sawit yang Kaya dengan Diasilgliserol Melalui Kaedah Pengesteran Terus)

 

Anita Sasue, Mamot Said, Zalifah Mohd Kasim*

 

Food Science Programme,

School of Chemical Sciences and Food Technology, Faculty of Science and Technology,

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia.

 

*Corresponding author: zalifah.kasim@ukm.edu.my

 

 

Abstract

Palm oil (PO) mainly constitutes of 90-98% of triacylglycerol, 2-6% of diacylglycerol (DAG) and 2-5% of monoacylglycerol. This study was carried out to produce PO that is high in DAG through direct esterification using 1,3 positional specific lipase from Rhizomucor miehei (RM IM) and Thermomyces lanuginose (TL IM) as catalysts. Palm olein oil has been hydrolysed by water and 4% enzyme in a controlled water bath at 300 rpm for 48 hours at a temperature of 60±2^oC while the esterification process was carried out in a same condition except it was run for 24 hours only. Samples DAG A1 and DAG B1 were synthesized products of the first replication using 10% enzyme TL IM and 10% enzyme RM IM respectively while samples DAG A2 and DAG B2 were synthesized products of second replication. DAG spots found on the thin layer chromatography (TLC) plates of samples DAG A1, A2, B1 and B2 bigger than the spot of the control sample. Based on high performance liquid chromatography chromatogram peak area, the total DAG accumulation showed significant differences (p<0.05) between the usage of enzymes TL IM and RM IM which were 34.28% and 45.67% respectively. The esterification method has clearly increased the DAG content of the control sample which was only 3.17%. Significant differences (p<0.05) also existed in the iodine value (IV), melting and crystallization temperature of all the samples. IV of control sample, DAG A and B were respectively 56.00, 35.00 and 30.50. Differential scanning calorimetry curves showed the melting and crystallization temperature were respectively -3.73^oC and -5.72^oC for samples using TL IM while -4.92 and -6.56 respectively for RM IM. The results concluded that the usage of enzyme RM IM is more effective in the production of PO high in DAG and efficiency of direct esterification process has been proved.

 

Keywords: palm oil, diacylglycerol, triacylglycerol, Rhizomucor miehei, Thermomyces lanuginose

 

Abstrak

Minyak kelapa sawit secara amnya terdiri daripada 90-98% triasilgliserol, 2-6% diasilgliserol (DAG) dan 2-5% monoasilgliserol. Kajian ini telah dijalankan untuk menghasilkan minyak sawit yang kaya DAG melalui tindak balas pengesteran terus bermangkin lipase spesifik 1,3 daripada Rhizomucor miehei (RM IM) dan Thermomyces lanuginose (TL IM). Minyak sawit dihidrolisis menggunakan 4% enzim dalam kukus air pada kelajuan 300 rpm pada suhu 60±2^oC selama 48 jam. Pengesteran terus pula dilakukan dalam kukus air selama 24 jam pada kelajuan 300 rpm pada suhu 60±2^oC. Sampel DAG A1 dan DAG B1 adalah hasil sintesis daripada  tindakan 10% enzim TL IM dan 10% enzim RM 1M masing-masing pada replikasi pertama manakala sampel DAG A2 dan DAG B2 pula ialah hasil sintesis dari replikasi kedua. Analisis kromatografi lapisan nipis  menunjukkan tompokan DAG yang lebih besar dalam keempat-empat sampel DAG A1, A2, B1 dan B2 berbanding sampel asal. Anggaran purata keseluruhan DAG yang terhasil dalam sampel dengan tindakan enzim TL IM dan enzim RM IM berdasarkan luas puncak daripada kromatogram kromatografi cecair berprestasi tinggi (HPLC) adalah masing-masing sebanyak 34.28% dan 45.67%. Keputusannya juga menunjukkan wujudnya perbezaan bererti (P< 0.05) antara kedua-dua sampel DAG A dan B. Nilai iodine dalam minyak sawit, sampel DAG A dan B masing-masing adalah 56.00, 35.00 dan 30.50. Daripada lengkuk kalorimetri pengimbas pembezaan (DSC), suhu purata puncak peleburan dan puncak pengkristalan minyak yang terhasil daripada tindak balas pengesteran terus masing-masing sebanyak -3.73^oCdan -5.72^oC untuk sampel A dengan tindakan enzim TL IM. Manakala untuk sampel B dengan tindakan enzim RM IM purata suhu puncak peleburan dan puncak pengkristalan masing-masing sebanyak -4.92^oC dan -6.56^oC. Suhu peleburan dan pengkristalan dalam sampel kawalan adalah sebanyak 5.06^oC dan -1.75^oC masing-masing. Kesimpulannya, enzim RM IM lebih berupaya menghasilkan minyak kelapa sawit yang kaya DAG dan keberkesanan tindak balas pengesteran terus dalam menghasilkan minyak yang kaya DAG juga telah dibuktikan.

 

Kata kunci: minyak kelapa sawit, diasilgliserol, triasilgliserol, Rhizomucor miehei, Thermomyces lanuginose

 

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