Optimization of pretreatments for the hydrolysis of oil palm empty fruit bunch fiber (EFBF) using enzyme mixtures

Published Date
September 2013, Vol.56:137–146, doi:10.1016/j.biombioe.2013.04.021

Author 

Osman Hassan ^a,,,

Tang Pei Ling ^a

Mohammad Yusof Maskat ^a

Rosli Md. Illias ^b

Khairiah Badri ^a

Jamaliah Jahim ^c

Nor Muhammad Mahadi ^d

aSchool of Chemical Sciences and Food Technology, Faculty Science and Technology, The National University of Malaysia, 43600 Bangi, Selangor, Malaysia

bFaculty of Bioengineering and Biotechnology, Universiti Teknologi Malaysia, Malaysia

cFaculty of Chemical Engineering, The National University of Malaysia, Malaysia

dMalaysia Genome Institute, Malaysia

Received 21 March 2012. Revised 28 December 2012. Accepted 26 April 2013. Available online 31 May 2013.

Highlights

• Optimization of pretreatments using steam, acid and alkali, singularly and in combination.
• •
  Pretreatment parameters were optimized using statistical design.
• •
  The pretreated samples were hydrolyzed using optimized combinations of three cellulolytic enzymes.
• •
  Morphological effects of pretreatment were observed using SEM and increased yield of sugar was obtained from the treatments.

Abstract

A study was conducted to optimize sugar production from oil palm empty fruit bunch fiber (EFBF). Three different pretreatments were applied to EFBF, namely steam, steam with 5% sodium hydroxide (steam + 5% NaOH) and steam with 5% acetic acid (steam + 5% acetic acid). The hydrolyzability of the pretreated EFBF was determined using cellulolytic enzyme mixture comprising of Celluclast 1.5L (C), Viscozyme L (V) and Novozyme 188 (N). The different pretreatments showed varying degree of severities to the morphology of the fiber. Steam + 5% acetic acid pretreatment was found to cause the most severe changes to the EFBF surface. The optimum combinations of the enzymes for EFBF degradation, using a fixed parameters, were determined using Simplex Lattice mixture design. For untreated, steam pretreated, steam + 5% NaOH, steam + 5% acetic acid EFBFs, the optimum combinations enzyme were 0.49C: 0.45V: 0.06N, 0.88C: 0.12N, 0.78C: 0.03V: 0.2N and 0.90C: 0.03V: 0.07N respectively. Surface morphology of EFBF appears to be the major contributing factor that affects efficiency of enzymatic hydrolysis. Among these four samples, steam + 5% acetic acid pretreated EFBF gave the highest yield of sugars (44.36% xylose; 52.03% glucose). Applying the best enzymatic combinations, saccharification of pretreated samples was optimized using RSM. saccharification of the steam + 5% acetic acid pretreated EFBF was able to yield 99.90 ± 10.92 mg g⁻¹xylose and 281.77 ± 28.00 mg g⁻¹ glucose at 2.51% enzyme loading (with total protein loading 22.1 mg per gram EFBF) in 4.55% EFBF for 35.08 h of reaction. Overall, through the combination of steam + 5% acetic acid pretreatment, enzyme mixture optimization and optimization of enzymatic saccharification, EFBF has the potential to produce substantial amount of sugars (62.36% xylose; 81.84% glucose).

Keywords

Oil palm empty fruit bunch fiber (EFBF)

Alkaline

Dilute acid

Steam

Pretreatments

Enzymatic hydrolysis

---

 Table 1

Table 1.

Fig. 1.

 Table 2

Table 2.

 Table 3

Table 3.

Fig. 2.

Fig. 3.

 Table 4

Table 4.

 Table 5

Table 5.

Fig. 4.

 Table 6

Table 6.

• ∗ 
  Corresponding author. Tel.: +60 (0)389213805; fax: +60 (0)389213232.

For further details log on website :
http://www.sciencedirect.com/science/article/pii/S0960852412000429