Osman Hassan

Effects of changes in chemical and structural characteristic of ammonia fibre expansion (AFEX) pretreated oil palm empty fruit bunch fibre on enzymatic saccharification and fermentability for biohydrogen

Oil palm empty fruit bunch (OPEFB) fibre is widely available in Southeast Asian countries and found to have 60% (w/w) sugar components. OPEFB was pretreated using the ammonia fibre expansion (AFEX) method and characterised physically by the Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that there were significant structural changes in OPEFB after the pretreatment step, and the sugar yield after enzymatic hydrolysis using a cocktail of Cellic Ctec2® and Cellic Htec2® increased from 0.15gg(-1) of OPEFB in the raw untreated OPEFB sample to 0.53gg(-1) of OPEFB in AFEX-pretreated OPEFB (i.e. almost a fourfold increase in sugar conversion), which enhances the economic value of OPEFB. A biohydrogen fermentability test of this hydrolysate was carried out using a locally isolated bacterium, Enterobacter sp. KBH6958. The biohydrogen yield after 72h of fermentation was 1.68mol H2 per mol sugar. Butyrate, ethanol, and acetate were the major metabolites.

Application of Box-Behnken Design in Optimization of Glucose Production from Oil Palm Empty Fruit Bunch Cellulose

Oil palm empty fruit bunch fiber (OPEFB) is a lignocellulosic waste from palm oil mills. It contains mainly cellulose from which glucose can be derived to serve as raw materials for valuable chemicals such as succinic acid. A three-level Box-Behnken design combined with the canonical and ridge analysis was employed to optimize the process parameters for glucose production from OPEFB cellulose using enzymatic hydrolysis. Organosolv pretreatment was used to extract cellulose from OPEFB using ethanol and water as the solvents. The extracted cellulose was characterized by thermogravimetric analysis, FTIR spectroscopy, and field emission scanning electron microscopy. Hydrolysis parameters including amount of enzyme, amount of cellulose, and reaction time were investigated. The experimental results were fitted with a second-order polynomial equation by a multiple regression analysis and found that more than 97% of the variations could be predicted by the models. Using the ridge analysis, the optimal conditions reaction time found for the production of glucose was 76 hours and 30 min, whereas the optimum amount of enzyme and cellulose was 0.5 mL and 0.9 g, respectively. Under these optimal conditions, the corresponding response value predicted for glucose concentration was 169.34 g/L, which was confirmed by validation experiments.

Effect of Process Parameters on Quality Properties of Microwave Dried Red Pitaya (Hylocereus costaricensis)

The effect of microwave power density on the microwave drying of red pitaya (Hylocereus costaricensis) was investigated using a small modified commercial microwave. Microwave power density was varied in the range of 5.47 to 19.02 W/g. The ambient, internal sample and sample surface temperatures, and moisture loss were measured during microwave drying at various microwave power densities. The drying rate increased with increasing power density. The temperature profiles rapidly reached their saturation level. The experimental moisture loss data were fitted to the Tang and Cenkowski drying model using a value of residual sum of squares (RSS) to evaluate the goodness of fitting the model. The dried product was analysed to examine the quality such as color, shrinkage, tensile hardness and structure. The results showed that the color change is higher at higher power density and temperature because of the faster browning rate and faster drying rate. The beginning of the color change corresponded closely to the beginning of the falling rate period. The microwave drying also caused the red pitaya to shrink to a greater extent of up to 70% at higher power density because of the faster drying rate. The internal structure also tended to collapse during microwave drying.

Effects of buffer properties on cyclodextrin glucanotransferase reactions and cyclodextrin production from raw sago (Cycas revoluta) starch.

Results from the present study have shown that the ionic species of buffers, pH values and reaction temperature can affect the enzyme unit activities and product specificity of Toruzyme® (Novo Nordisk A/S Bagsvaerd, Denmark) CGTase (cyclodextrin glucanotransferase). Applying a similar reaction environment (acetate buffer, pH 6.0; temperature, 60 °C), the CGTase was found to be capable of producing pre dominantly β‐cyclodextrin from either raw or gelatinized sago (Cycas revoluta) starch. Changing the buffer from acetate to phosphate reduced the yield of β‐cyclodextrin from 2.48 to 1.42 mg/ml and also affected the product specificity, where production of both α‐ and β‐cyclodextrins were more pronounced. The decrease in the production of cyclodextrins in phosphate buffer was significant at both pH 6.0 and 7.0. However, changing the buffer to Tris/HCl (pH 7.0) showed a significant increase in β‐cyclodextrin production. Increasing the ionic strength of sodium acetate and Tris/HCl buffers at pH 6.0 and 7.0 to equivalent ionic strength of phosphate buffers showed no significant effects on cyclodextrin production. Higher yield of cyclodextrins at pH 7.0 when Tris/HCl was used might be due to the binding of chloride ions at the calcium‐binding sites of the CGTase, resulting in the shift of the optimum pH close to physiological environment, leading to an increase in the activities and specificity.

Characterisation of fucoidan extracted from Malaysian Sargassum binderi

Fucoidan is a sulphated polysaccharide that consists mainly of fucose, normally found in brown seaweeds. In this study, fucoidan was extracted from Sargassum binderi (Fsar) from Malaysia and subsequently characterised. The chemical characteristics of Fsar were found to be different than those of commercial food grade fucoidan (Fysk) and those of previously studied fucoidans. NMR analysis proposed that the main structure of Fsar is →3)fuc-2-OSO3(-)(1→3)fuc(1→. The molecular weight (47.87kDa) and degree of sulphation (0.20) of Fsar were higher than those of Fysk, at 27.98kDa and 0.15, respectively. However, Fsars polydispersity index (1.12) and fucose content (34.50%) were lower than those of Fysk, at 1.88 and 43.30%, respectively. Both Fsar and Fysk showed similar thermo-gravimetric properties with four mass losses, amorphous in nature and negative optical rotations. Results show that Fsar has fundamental characteristics of fucoidan with different structural conformation i.e. variation in glycosidic linkages and sulphate group orientation.

Chemical Profiling and Quantification of Tannins in Phyllanthus niruri Linn. Fractionated by SFE Method

Chemical profiles or fingerprints of polyphenolic compounds (condensed and hydrolyzable tannins) in various fractions of Phyllanthus niruri Linn extracted using supercritical carbon dioxide and various polar cosolvents, namely water, methanol, and ethanol are presented. Chemical analysis of the extracted fractions was undertaken using High Performance Liquid Chromatography (HPLC) with the in-house method. Good peak reproducibility of intra-day (R.S.D range 0.01–0.21 min) and inter-day (R.S.D range 0.5–0.8 min) was obtained for the detection of ellagitannins (hydrolyzable tannins) and flavonoids (condensed tannins). Fractions extracted using ethanol-water mixtures as cosolvent at 200 bar and 60°C exhibited an appealing behavior whereby non-polar compounds and flavonoids were able to be fractionated before the extraction of ellagitannins. Contents of three major ellagitannins, namely gallic acid (0.39–0.48% g/g), corilagin (2.42–3.00% g/g), and ellagic acid (5.94–6.48% g/g), were relatively higher compared to the commercial HEPAR-P™ standardized extract (0.21, 2.64, and 4.17% g/g, respectively). The study shows that the supercritical fluid extraction (SFE) method with the use of appropriate cosolvents is able to produce P. niruri fractions with improved yields and different chemical characteristic, which thus can be used as a rapid preparative tool for further downstream processing of plant samples.

Fibrous Agricultural Biomass as a Potential Source for Bioconversion to Vanillic Acid

This study was conducted to assess the potential of six fibrous agricultural residues, namely, oil palm empty fruit bunch fiber (OPEFBF), coconut coir fiber (CCF), pineapple peel (PP), pineapple crown leaves (PCL), kenaf bast fiber (KBF), and kenaf core fiber (KCF), as a source of ferulic acid and phenolic compounds for bioconversion into vanillic acid. The raw samples were pretreated with organosolv (NaOH-glycerol) and alkaline treatment (NaOH), to produce phenol-rich black liquor. The finding showed that the highest amount of phenolic compounds and ferulic acid was produced from CCF and PP, respectively. This study also found that organosolv treatment was the superior method for phenolic compound extraction, whereas alkaline treatment was the selective method for lignin extraction. Vanillic acid production by Aspergillus niger I-1472 was only observed when the fermentation broth was fed with liquors from PP and PCL, possibly due to the higher levels of ferulic acid in those samples.

Kesan kaedah prarawatan berbeza terhadap tandan kosong kelapa sawit bagi penghasilan glukosa ringkas

In this study, a pretreatment of empty fruit bunch (EFB) using supercritical carbon dioxide (SC-CO2), acid and alkaline were investigated for glucose yield from enzymatic hydrolysis. The chemical composition, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis of EFB before and after pretreatment were determined. From this study, the chemical composition of EFB (% g/g dry biomass) before pretreatment for cellulose, hemicellulose and Klason lignin were recorded as 36.7%, 22.8%, and 24.2%, respectively. After pretreatment, the highest cellulose composition was obtained from EFB treated with alkaline followed by acid and SC-CO2 which gave the results of 48.5%, 47.7% and 38% respectively. The glucose yield after enzymatic hydrolysis for untreated EFB was 17% (w/w). After pretreatment, the glucose yield increased to 84.4%, 34% and 24% for alkaline, acid and SC-CO2 of the treated EFB, respectively. Other than that, XRD analysis showed increase in the crystallinity index after each pretreatment. Morphology analysis showed the surface of the treated EFB looked swollen and ruptured as compared with the surface of the untreated EFB. Between the three pretreatments, alkaline pretreatment gives the highest cellulose composition and glucose yield. Thus, it shows that alkaline pretreatment was the best pretreatment method on EFB compared to acid and SC-CO2 pretreatments.

Deep eutectic solvent (DES) as a pretreatment for oil palm empty fruit bunch (OPEFB) in production of sugar

Oil Palm Empty Fruit Bunch (OPEFB) was pretreated using Deep Eutectic Solvent (DES) at different parameters to enable a highest yield of sugar. DES is a combination of two or more cheap and safe components to form a eutectic mixture through hydrogen bond interaction, which has a melting point lower than that of each component. DES can be used to replace ionic liquids (ILs), which are more expensive and toxic. In this study, OPEFB was pretreated with DES mixture of choline chloride: urea in 1:2 molar ratio. The pretreatment was performed at temperature 110°C and 80°C for 4 hours and 1 hour. Pretreatment A (110°C, 4 hours), B (110°C, 1 hour), C (80°C, 4 hours) and D (80°C, 1 hour). Enzymatic hydrolysis was done by using the combination of two enzymes, namely, Cellic Ctec2 and Cellic Htec2. The treated fiber is tested for crystallinity using XRD and functional group analysis using FTIR, to check the effect of the pretreatment on the fiber and compared it with the untreated fiber. From XRD analysis, DES successfully gave an effect towards degree of crystallinity of cellulose. Pretreatment A (110°C, 4 hours) and B (110°C, 1 hour) successfully reduce the percentage of crystallinity while pretreatment C (80°C, 4 hours) and D (80°C, 1 hour) increased the percentage of crystallinity. From FTIR analysis, DES cannot remove the functional group of lignin and hemicellulose but it is believed that DES can expose the structure of cellulose. Upon enzymatic hydrolysis, DES-treated fiber successfully produced sugar but not significantly when compared with raw. Pretreatment A (110°C, 4 hours), B (110°C, 1 hour), C (80°C, 4 hours) and D (80°C, 1 hour) produced glucose at the amount of 60.47 mg/ml, 66.33 mg/ml, 61.96 mg/ml and 59.12 mg/ml respectively. However, pretreatment C gave the highest xylose (70.01 mg/ml) production compared to other DES pretreatments.

Bacterial microbiome of Coptotermes curvignathus (Isoptera: Rhinotermitidae) reflects the coevolution of species and dietary pattern

Coptotermes curvignathus Holmgren is capable of feeding on living trees. This ability is attributed to their effective digestive system that is furnished by the termites own cellulolytic enzymes and cooperative enzymes produced by their gut microbes. In this study, the identity of an array of diverse microbes residing in the gut of C. curvignathus was revealed by sequencing the near‐full‐length 16S rRNA genes. A total of 154 bacterial phylotypes were found. The Bacteroidetes was the most abundant phylum and accounted for about 65% of the gut microbial profile. This is followed by Firmicutes, Actinobacteria, Spirochetes, Proteobacteria, TM7, Deferribacteres, Planctomycetes, Verrucomicrobia, and Termite Group 1. Based on the phylogenetic study, this symbiosis can be a result of long coevolution of gut enterotypes with the phylogenic distribution, strong selection pressure in the gut, and other speculative pressures that determine bacterial biome to follow. The phylogenetic distribution of cloned rRNA genes in the bacterial domain that was considerably different from other termite reflects the strong selection pressures in the gut where a proportional composition of gut microbiome of C. curvignathus has established. The selection pressures could be linked to the unique diet preference of C. curvignathus that profoundly feeds on living trees. The delicate gut microbiome composition may provide available nutrients to the host as well as potential protection against opportunistic pathogen.