Category Archives: 2002 Vol 14 No 1

Chemical composition of oil droplets from palm oil mill sludge

Oil droplets from the centrifuge sludge of a palm oil mill were separated by high speed centrifugation, dried and extracted with organic solvents, methanol and chloroform. The oil droplets (73 wt %) was solvent extractable. The extract was determined to consist of 84 wt % neutral lipids and 14 wt % of complex lipids (6 wt% glycolipids and 10 wt% phospholipids). The neutral lipids consisted of 83% triglycerides, 8% diglycerides, 0.5% monoglycerides and 8.0% free fatty acids.

Five types of glycolipids were determined and identified as digalactosyl diglycerides (22%), steryl glycosides (17%), cerebroside (9%), monogalactosyl diglycerides (20%) and esterified steryl glycoside (26%). Five types of phospholipids were determined and identified. They were phosphatidylethanolamine (21%), phosphatidylglycerol (37%), phosphatidylcholine (17%) and phosphatidylserine together with phosphatidylinositol at 11%. Palmitic acid (C16:0) and oleic acid (C18:1) were the major fatty acids found in the lipids.

The oil droplets found in the sludge were not unruptured oil droplets inherent in ripe mesocarp or young palm fruits. From the chemical analysis of the lipids associated with the oil droplets, it was deduced that oil droplets from the sludge are indeed formed in the milling process and possibly stabilized by the surface active agents of mainly phospholipids and glycolipids. The relatively high concentration of such biosurfactant in the oil droplets may have commercial potential as a value-added resource from the palm oil milling process.

Fatty acid composition of edible oils in the Malaysian markets, with special reference to the trans-fatty acids

A total of 113 samples of various types of palm and palm kernel oil products, their fractions, palm-based and non-palm-based cooking oils obtained from local manufacturers and the retail market were analysed for their trans-fatty acid compositions and contents by capillary gas chromatography. Trans-fatty acids were generally absent in crude palm and palm kernel oils. However, they were present at 0.01%-0.06% in refined palm kernel products and 0%-0.61% in refined palm products, all well below the 1.0% level stipulated by some importers. These trans-fatty acids were formed from their natural cis -isomers as a result of the high temperature used during deodorization.
In cooking oil, the trans-fatty acid contents of palm-based products were 0.25%-0.67%, again well below 1%. However, in the non-palm-based cooking oils, the contents of the 14 samples ranged from 0.43%-3.83%. The higher contents in the non-palm-based oils were expected as they had high contents of unsaturated fatty acids, which are more prone to isomerization at elevated temperatures

Preparation of cellulose from oil palm empty fruit bunches via ethanol digestion: effect of acid and alkali catalysts

Ethanol digestion of oil palm empty fruit bunches (OPEFB) fibres at a temperature between 165ºC – 180ºC for 2 hr and at a solid-to-liquid ratio of 10:1, ethanol-to-water ratio of 1:1, and with or without 10% 1N HCl and 1.25 M NaOH as catalysts was studied in order to prepare cellulose via ethanol pulping. The pulp produced was studied for yield, moisture content, solubility in cold/hot water and 1% NaOH, lignin, holocellulose and α-cellulose content.
The highest yield of pulp (57%, oven dried weight basis) was from OPEFB fibres digested at 170ºC for 2 hr without addition of catalyst, whereas OPEFB fibres digested at 175ºC for 2 hr with acid catalyst gave the lowest yield of 45% (oven dried weight basis) pulp. Higher cooking temperature gave lower yield of pulp since the reaction hydrolyzed out the hemicellulose, lignin and part of the cellulose. The reactions at 165ºC, 170ºC and 175ºC with acid catalyst produced 56%, 50% and 45% of pulp yield, respectively. It was found that a temperature of 180ºC with or without catalyst was too high for pulping because it totally digested the fibre into a viscous soluble pulp.
On the effect of catalysts, acid catalyst was found to enhance the pulping of OPEFB fibres. Without the acid catalyst, at temperature of 165ºC, the fibres could not be fully cooked and would still be in the fibrous form. Reactions at 170ºC and 175ºC without catalyst gave 57% and 55% yield of pulp, respectively whereas with acid catalyst gave 50% and 45% yield of pulp respectively. The base catalyst could only fully pulp the OPEFB fibres at a temperature of 175ºC, but the fibres dissolved at temperature 180ºC.
Pulp produced at 175ºC for 2 hr with 10% 1.25 M NaOH gave the best quality pulp, which contained lowest lignin and highest holocellulose at 8.2% and 91.8% (based on the dry weight of pulp), resp ectively. The maximum yield of α-cellulose (isolated from the pulp) also was obtained from OPEFB digested with alkali catalyst at 175 ºC for 2 hr (64.3% based from dry weight of pulp; 34.1% based on dry weight of OPEFB).

Performance and heritability estimations on oil palm progenies tested in different environments

Forty oil palm (Elaeis guineensis Jacq.) dura x pisifera (DxP) crosses derived from the North Carolina Mating Design 1 (NCM 1) were evaluated in six locations (Kudat, Sabah; Beaufort, Sabah; Teluk Intan, Perak; Carey Island, Selangor; Kepong, Selangor and Kluang, Johor). Fifteen pisifera palms were chosen as male parents and each was crossed to two to four dura female parents.

Environmental factors contributed to the phenotypic variability in all the agronomic characters. Hence, the variation in performance of the genotypes in the different locations was partly a reflection of the differences in soil type, soil fertility and rainfall. Generally, Carey Island and Teluk Intan were the more favourable environments for yield than the marginal environments, such as Kudat and Kluang.

The results showed that the environment had a great influence on the genetic variance components. In general, the heritability estimates for yield and its components and bunch quality characters fluctuated from location to location. However, the estimates for vegetative characters were fairly consistent and higher than those for yield and its components, and bunch quality characters.

Microstructure of medium density fibreboard from oil palm empty fruit bunch fibre

Using sequentially acquired 2-D images of microtome sections via a light microscope, 3-D models of the microstructure of commercial and laboratory produced medium density fibreboards (MDF) were constructed. To assess the accuracy of the 3-D models, they were analysed for their ratios of inter-fibre void using an image analysis technique. The study indicated that it was feasible to use this technique to determine the variation in inter-fibre void ratio at different depths in the MDF. The ratio of void area varied significantly in a gradient from the top/bottom of the boards to the core (middle). However, in the other directions (along the length and breadth), there were no significant differences in the void ratio. The ratio of void area within each panel was negatively related to the density

The effect of disalt on the biodegradability of methyl ester sulphonates (MES)

The biodegradability of methyl ester sulphonates (MES) was found to be affected by the disodium salt (disalt) content. The higher the disalt content, the lower is the biodegradability of MES. Disalt has a lower surface activity and is sparingly soluble in water when compared to the monosodium salt MES. These characteristics lower the biodegradability of disalt when compared to the monosodium salt. The biodegradability of a commercial MES sample was found to be better than linear alkylbenzene sulphonates (LAS), thus offering an additional advantage for the commercialization of oleochemical-based surfactant