Category Archives: 2000 Vol 12 No 2

Compositional and differential scanning calorimetry (DSC) studies of crystals of palm olein

The composition and thermal properties of palm olein upon storage have been investigated by numerous techniques such as Differential Scanning Calorimetry (DSC), Gas Chromatography (GC) and High Performance Liquid Chromatography (HPLC). DSC melting and crystallization thermograms of crystals separated from palm olein differed in their characteristics, according to the composition of the olein and the storage conditions. A comparison was made between oleins of iodine value (IV) in the range of 56-61 which were stored at conditions of 20°C and 5°C. The more unsaturated olein was stored at 5ºC. Oleins with higher unsaturations showed crystals with a group of exotherms and endotherms which generally did not differ much with duration of storage. Crystals of the more saturated types of olein still retained the two exothermic and endothermic peaks, as observed in palm oil. The crystals of unsaturated oleins (IV of 60.6) tended to have a higher proportion of POO than POP, in contrast to the crystals of oleins (IV of 57.7) where the POP content is higher. With longer storage period, these exotherms and endotherms were shifted closer together, depicting polymorphism upon melting. With a long duration of storage, as in ambient storage conditions, another set of olein samples resulted in crystals with harder characteristics and a melting point of about 68°C. These crystals contained high diglycerides, confirming earlier works on the strong role of diglycerides in the crystallization stability of palm olein.

Synthesis and characterization of acetylated glucose fatty esters from palm and palm kernel oil fatty methyl esters

Acetylated glucose fatty esters (AGFE) were synthesized from palm and palm kernel fatty acid methyl esters (FAME) through a one-stage solvent-free interesterfication reaction with glucose pentaacetate (GPA). Two main products obtained and identified were mono-and di-substituted AGFEE. The hydrophile-lipophile balance (HLB), ternary phase diagram, cytotoxicity and antimicrobial bioassays were studied.

Physico-chemical properties of binary systems of alpha-sulphonated methyl ester derived from palm stearin and nonionic surfactants

The effects of mixing sodium alpha-sulphonated methyl ester derived from palm stearin salt ( α -SMEPS) with nonylphenol ethoxylate alcohol (NONIPOL) and polyoxyethylene (20) sorbitan monoester (TWEEN) in mixed micelles systems were studied as a function of their weight ratios. Changes in the critical micelle concentration (CMC) and surface tension were observed at different weight ratios of the mixed surfactant. Incorporating the nonionic surfactants into α-SMEPS solution changed the surface properties of the system by lowering the Kraft temperature and decreasing the foaming stability. The effects of these mixed anionic-nonionic surfactant were due to inter-action between the different hydrophobic and hydrophilic portions of the surfactants.

Nutrient cycling in an oil palm plantation: the effects of residue management practices during replanting on dry matter and nutrient uptake of young palms

Oil palm residues during replanting contributed significant amount of nutrients that can be recycled in the plantation. The management of oil palm residues affects the release of nutrients and hence their uptake and the growth of young palms. Dry matter and nutrient uptake of young palms and ground cover were estimated. Planting young palms directly onto the residue pile is the most effective method of biomass management during replanting as it provides better synchronization between nutrient release and plant uptake.

The young palms only utilized about 10% – 20% of the total nutrient uptake that is mostly found in the fronds. The young palms planted onto the residue pile is the most effective method of biomass management during replanting as it provides better synchronization between nutrient release and plant uptake.

The young palms only utilized about 10%-20% of the total nutrient uptake that is mostly found in the fronds. The young palms planted onto the residue pile without inorganic fertilizer inputs immobilized about 30 kg N ha-1, 3 kg P ha-1, 43 kg K ha-‘, 6 Kg Ca ha-1 and 4 kg Mg ha-1, over the 18-month period of assessment. The results obtained showed that the chipped and shredded (C / S) treatment was the most efficient. More than 80% of the nutrients were consumed by the ground cover which comprised legumes and weeds. The ground cover immobilized about 254 kg N ha-1, 19 kg P ha-1, 181 kg K ha-‘, 56 kg Ca ha-1 and 28 kg P ha-1 over 18 months and became a transient pool that would recycle its nutrients at a later stage in the plantation life.

Optical properties for mechanical harvesting of oil palm FFB

The engineering properties of agricultural materials constitute important engineering data in the design of machines to be used in harvesting. A colour camera vision system was developed to distinguish between different categories of oil palm fruit bunches. The maturity or colour ripening index was based on different colour intensity. Machine vision employs a computer and camera to analyse and interpret images equivalent to the human eye and brain. The colours namely red, green and blue (RGB) of the palm oil fruit bunch were investigated using camera vision. The specimens were captured using a CCD camera, Matrox Meteor card, and Matrox Intellicam software. The laboratory results showed that the ripe fruit bunch could be differentiated from other categories of fruit bunches based on RGB intensity. A computer program written was able to differentiate the ripe fruit bunch and send a signal to the controller to activate the machine or robot arm to carry out harvesting.

Identification of flower specific proteins in the oil palm (Elaeis guineensis) by two-dimensional gel electrophoresis

Total RNA was isolated from young etiolated oil palm seedlings, leaves and inflorescences at different stages of development. The mRNA was subsequently extracted by oligo-dT cellulose chromatography and in vitro translated using a rabbit reticulocyte system. The translated products were examined by SDS-PAGE gel electrophoresis as well as a combination of SDS-PAGE and isoelectric focusing (two-dimensional polyacrylamide gel electrophoresis). Both methods revealed differences in banding pattern between the inflorescence (flower) and vegetative (leaf and young etiolated seedlings) tissues, indicating differential gene expression. Some changes were also observed in the pattern of in vitro translation products for mRNA extracted from the different stages of flowering.

Decomposition and N & K release by oil palm empty fruit bunches applied under mature palms

The oil palm empty fruit bunch (EFB) is one of the major waste products of the oil palm industry and is currently used as an organic mulch in young and mature oil palm plantations. A field experiment was set up to monitor EFB decomposition and N and K release for a period of 10 months with the EFB placed in single or double layers stacked along mature oil palm interrows with and without inorganic N and K fertilizers. The quantity of EFB applied was 37.5 t ha-1 applied in a single layer and 75 t ha-1 applied in a double layer. N was applied as ammonium sulphate and K as muriate of potash at three rates of 0, 3.5 and 7.0 kg fertilizers palm-1 yr-1. The frequency of fertilizer application was once and three times per year. Random samplings of EFB were taken from the single layer, and from the top and bottom layer of the double layer treatment and dry weights, N and K concentrations determined.

The EFB dry matter loss followed an exponential model. There was a 50% loss in dry matter in the initial three months and 70% dry matter loss after eight months. The single layer EFB decomposed faster than the double layer top or bottom. Addition of inorganic N fertilizer enhanced significantly dry matter loss in the single layer EFB. Inorganic K fertilizer application did not significantly affect EFB decomposition for all treatments. Release of EFB-N was not detected during the 10-month period of the study. Release of EFB-K was very rapid during the initial stages of decomposition, with 90% of it released after six months of decomposition. At 10 months, more than 99% of EFB-K and been released.

Studies on factors affecting the colour stability of some commercial palm fatty acids

The colour stability of some commercial palm fatty acids at 90°C, 110 ° C and 130ºC was investigated. The degree of whiteness of palm fatty acid started to decrease at 110ºC and rate in percentage of whiteness decreasing was faster at higher temperatures. The general order of colour stability of palm fatty acids to heat at 130ºC and 110ºC are respectively as below:

98% palmitic acid > double pressed > triple
pressed > single pressed > 70% strearic > 70% oleic acid.
98% palmitic acid > 70% stearic acid > triple pressed > double pressed > single pressed > 70% oleic acid.

The likely factors, viz. minor constituents and trace unsaturated acids, affecting the colour development were studied. Minor constituents were isolated from the various types of palm fatty acids and were found to consist mainly of straight chain hydrocarbons. The major hydrocarbons present in 70% oleic acid were tentatively identified as hydrocarbons C26H50 and C26H52. The exact structures are yet to be identified. The minor components which affect the colour stability of palm fatty acid could be removed by silicic acid or citric acid treatments. Dimers of oleic acid-oleic acid and oleic acid linoleic acid were among the components identified in the yellow components fraction isolated from heated palm fatty acids which could be causing the yellow colour. The results indicated that the problem of colour stability of the palm fatty acids is rather complex and is mostly likely due to the presence of traces of unsaturated fatty acids and some unknown minor components in fatty acids.