Malaysian Journal of Analytical Sciences Vol 22 No 4 (2018): 715 - 722

ENZYMATIC HYDROLYSIS OF OIL PALM EMPTY FRUIT BUNCH AND ITS KINETICS

(Hidrolisis Enzim Tandan Buah Kelapa Sawit dan Sifat Kinetik)

Nazlee Faisal Ghazali* and Nurul Aqilah Makhtar

Department of Bioprocess Engineering,

Faculty of Chemical and Energy Engineering,

Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru, Johor, Malaysia

*Corresponding author: nazlee@utm.my

Received: 16 April 2017; Accepted: 7 March 2018

Abstract

Oil palm lignocellulosic biomass is a potential substrate for the production of renewable chemicals from agricultural wastes. Empty fruit bunch (EFB) is one of the biomass waste aside from the trunk and frond from oil palm plantation. Bioconversion of oil palm lignocellulose using enzymes to fermentable sugar could be used for the production of bioethanol. However, the bioconversion is challenging due to the complex interactions between substrate and enzymes. In order to utilize EFB as the feedstock, it is important to understand the effect of enzyme concentration and substrate concentration on the bioconversion of EFB. In this study, we investigated the effect of enzyme loading and substrate loading for the maximum conversion of oil palm lignocellulose. The results show that as the enzyme loading increased, the rate of reaction and also the yield of reducing sugar (RS) and glucose initially increased and then plateaued. High enzyme loading might lead to enzyme in excess and enzyme layering around the substrate. Similar pattern was also observed on the reaction rate as the substrate loading increased. However, the yield of RS and glucose decreased as the substrate loading increase. It could be explained by the substrate recalcitrance and product inhibition. The initial product formation rates were used to determine the kinetic parameters such as maximum rate constant V_max and the half saturation constant K_m. From this study, feasible amount of cellulase and EFB substrate could be identified for maximum conversion and facilitate bioethanol production.

Keywords: cellulase, oil palm lignocellulose, biomass, empty fruit bunch

Abstrak

Biojisim kelapa sawit lignoselulosa ialah substrat yang berpotensi untuk pengeluaran bahan kimia boleh diperbaharui daripada sisa pertanian. Tandan buah sawit (EFB) merupakan salah satu daripada sisa biojisim selain daripada batang dan pelepah dari ladang kelapa sawit. Penukaran biologi daripada lignoselulosa kelapa sawit menggunakan enzim untuk menghasilkan gula boleh digunakan untuk pengeluaran bioetanol. Walau bagaimanapun, penukaran biologi adalah mencabar berikutan interaksi kompleks antara substrat dan enzim. Dalam usaha untuk menggunakan EFB sebagai bahan mentah, ia adalah penting untuk memahami kesan kepekatan enzim dan substrat kepekatan pada penukaran EFB. Dalam kajian ini, kami telah menyiasat kesan enzim dan substrat untuk penukaran maksimum lignoselulosa kelapa sawit. Keputusan menunjukkan apabila muatan enzim meningkat, kadar tindak balas dan hasil gula (RS) dan glukosa pada awalnya meningkat tetapi kemudiannya mendatar. Muatan enzim tinggi mungkin membawa kepada enzim yang berlebihan dan enzim lapisan sekitar substrat. Corak yang sama berlaku pada kadar tindak balas apabila muatan substrat meningkat. Walau bagaimanapun, hasil RS dan glukosa menurun apabila muatan substrat meningkat. Ia boleh dijelaskan oleh kesusahan degradasi substrat dan perencatan oleh produk. Kadar pembentukan produk awal digunakan untuk menentukan parameter kinetik seperti kadar maksimum malar V_max dan pemalar separuh tepu K_m. Daripada kajian ini, jumlah celulase dan EFB substrat dapat dikenalpasti untuk penukaran maksimum dan memudahkan pengeluaran bioethanol.

Kata kunci: selulosa, lignoselulosa kelapa sawit, biojisim, tanda buah kelapa sawit

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