Sains Malaysiana 39(5)(2010): 795–803

Optimisation of Urea Complexation by Box-Behnken Design

(Pengoptimuman Pengkompleksan Urea Menggunakan Reka Bentuk Box-Behnken)

Chin Yoong Fei, Jumat Salimon* & Mamot Said

School of Chemical Sciences & Food Technology

Faculty of Science & Technology, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor D.E., Malaysia

Diserahkan: 14 April 2009 / Diterima: 10 Disember 2009

ABSTRACT

Urea complexation is a method favoured by researchers to separate fatty acids based on molecular structure. In this study, effects of urea amount, crystallisation temperature and crystallisation time on the final products of urea complexation were examined. Box-Behnken Design (BBD) was employed to study the significance of these factors and the optimum conditions for the technique were predicted and verified. Results showed that urea-to-polyunsaturated fatty acid (PUFA) mole ratio and crystallisation temperature were two significant variables for enrichment of PUFA in non-urea complexing fraction (NUCF). In a 17-point experimental design, percentage of saturated fatty acid (SFA) was reduced almost entirely from initial 4.49%, monounsaturated fatty acid (MUFA) reduced from 57.02% to 41.32%, while PUFA increased from 33.49% to 53.87% in NUCF. Optimum condition for maximum PUFA and minimum SFA and MUFA contents was predicted at urea-to-PUFA mole ratio of 20, crystallisation temperature of –20 ^oC and crystallisation time of 29.67 h.

Keywords: Box-Behnken design (BBD); optimisation; polyunsaturated fatty acid (PUFA); urea complexation

ABSTRAK

Pengkompleksan urea merupakan kaedah yang sering digunakan oleh para penyelidik untuk memisahkan campuran asid lemak berdasarkan struktur molekul. Dalam kajian ini, kesan amaun urea, suhu penghabluran dan tempoh penghabluran terhadap hasil akhir pengkompleksan urea telah dikaji. Reka bentuk Box-Behnken (BBD) telah digunakan untuk mengkaji signifikasi faktor-faktor ini. Keadaan optimum faktor-faktor ini telah diramal dan disahkan. Keputusan menunjukkan nisbah mol urea-kepada-asid lemak poli tak tepu (PUFA) serta suhu penghabluran merupakan dua pembolehubah yang signifikan bagi peningkatan kandungan PUFA di dalam fraksi bukan pengkompleks urea (NUCF). Dalam suatu reka bentuk eksperimen 17 titik, hampir kesemua asid lemak tepu (SFA) telah disingkirkan daripada peratusan asal 4.49%, asid lemak mono tak tepu (MUFA) telah dikurangkan daripada 57.02% kepada 41.32%, manakala PUFA telah ditingkatkan daripada 33.49% kepada 53.87% di dalam NUCF. Keadaan optimum bagi pengasingan PUFA yang maksimum dan kandungan SFA dan MUFA yang minimum telah diramalkan pada nisbah mol urea-kepada-PUFA sebanyak 20 mol, suhu penghabluran –20 ^oC dan tempoh penghabluran selama 29.67 jam.

Kata kunci: Asid lemak poli tak tepu (PUFA); pengkompleksan urea; pengoptimuman; reka bentuk Box-Behnken (BBD)

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*Pengarang untuk surat-menyurat; email: jumat@ukm.my