Category Archives: 1999 Vol 11 No 1

Physical and chemical properties of shortenings from palm oil : tallow and palm olein : tallow blends with and without interesterification

Palm oil and palm olein were blended with tallow at level of 80%, 70% and 60%. Part of the blends was interesterified. Blends and interesterified blends were processed into shortenings. These shortenings and a commercial shortening as control were evaluated for their solid fat content (SFC) and slip melting points (SMP), fatty acid (FA) and triglycerides (TG) composition, and creaming and baking properties. The slip melting points of the interesterified shortenings for palm oil:tallow and palm olein:tallow blends were higher than those of non-interesterified, but lower than the commercial shortening. The two most abundant fatty acids present in both blends were palmitic and stearic. The shortenings were rich in C52 and C50 glycerides. Interesterification process increased the solid fat content of the blends, except in 60:40 palm olein:tallow. Creaming power after 12 minutes of beating improved in the interesterified palm olein:tallow blends. However, creaming properties of the interesterified palm oil:tallow blends were poorest among the shortenings. Baking performance of non-interesterified palm oil:tallow blends was better than interesterified group.

An accurate and precise method of determining oil to bunch in oil palm

This paper describes a simple oil balance method for the determination of oil to bunch (O/B) and kernel to bunch (K/B) whereby the tedious manual process of removing the mesocarp eliminated by cutting the fruit longitudinally into two halves. After drying and removing the dried kernels, the dry mesocarp and shell are reduced into fine particles using an electric grinder which also homogenize the sample leading to greater accuracy in oil determination. Comparison of this method with the routine Blaak’s bunch analysis method showed that Blaak’s method gave O/B results which were higher than those of the oil balance method by an average of 15% of the mean O/B. On the other hand, the O/B and K/B figures obtained by the oil balance method agreed closely with the mill oil and kernel extraction rates after taking into account harvesting and processing losses.

Linear regression analysis showed that O/B decreased as bunch weight increased mainly due to a decreasing oil content of the fruits.

The results of a sampling exercise verified that the oil balance method was accurate with the estimates differing from the true values by about 1% unit for O/B and 2% units for K/B. Greater precision was obtained with fruit samples taken from all the fruits which  had been stripped from the spikelets after three days compared to fruits from intact spikelet samples taken on the first day. After quantification of the coefficients of variation (CV) of the bunch component ratios, the  CVs or precisions of estimating O/B and K/B using different sampling systems were computed.

Quantification of oil palm biomass and nutrient value in a mature plantation. I. Above-ground biomass

Oil palm biomass in a mature plantation was quantified and the availability of its nutrient contents and values was estimated. In the present study, the nutrient stocks of above-ground standing oil palm biomass and the contribution of each palm component were quantified and measured directly in order to obtain more precise values. The total above-ground biomass amounted to about 85t ha-1 and the trunk contributed the major portion to about 48% of oil palm standing biomass. The  total nutrient stocks of above ground biomass produced at felling of old stands based on per hectare basis are 577kg N, 50kg P, 1255kg K, 141kg Mg and 285kg Ca which could be recycled in the plantation both as organic matter and savings in monetary value worth about RM 2550 ha-1. Removal of this biomass for other value-added products has implications for plantation management in terms of losses of nutrients and organic matter to maintain soil fertility. Appropriate management of this biomass could enable its carry-over of nutrients necessary to support the growth of the following rotation of crop.

Notes on oil palm productivity. IV. Carbon dioxide gradients and fluxes and evapotranspiration, above and below the canopy

Continuous measurements of atmospheric COconcentrations made at various heights within and above a mature oil palm canopy showed that concentrations varied widely during the course of a 24-hour period – building up to high levels overnight within the canopy and falling rapidly with the onset of photosynthesis in the morning. Measurement of CO2 fluxes, both within the atmospheric boundary layer above the canopy and within the trunk space, allowed the relative contribution of CO2 supplied from the above and below-canopy atmosphere to the total canopy CO2 assimilation to be assessed. Similar assessment of water vapour fluxes provided a measure of the percentage of water lost as evapotranspiration (ET) which was channelled through the palms. Below-canopy CO2 uptake averaged 18.5% of the above-canopy flux and 15.6% to total flux. Evapotranspiration from the ground (from soil and ground flora) was almost 13% of total evapotranspiration, so that over 87% of ET took place directly from the palm canopy.

Notes on oil palm productivity. V. Evaluation of alternative mechanisms for supporting seasonal variation in dry matter production

Three alternative mechanisms leading to seasonal variations in bunch and total dry matter production commonly found in stands of oil palm, were examined using a simulation model. The alternatives were: (i) the use of a store of reserve assimilate to accommodate both shortfalls and excesses in current assimilate production, (ii) variation in response to sink demand in the light-saturated rate of gross photosynthesis (AMAX), and (iii) variation in the proportion of gross assimilates consumed in dark respiration (%R). The alternatives were tested using data from three palm populations for one of which, trunk carbohydrate concentrations had also been measured.

The results show that with certain assumptions, any of these processes could account for the seasonal variations in productivity recorded. However, certain periods of relatively high or low productivity required extreme variations in AMAX, which were considered unlikely. The variations in %R which were needed were also thought unlikely as periods of high productivity required %R to decrease, whereas the opposite trend was more probable. Thus, of the three processes, the utilization of storage reserves appeared the most likely means of accommodating variations in sink demand. However, a model based solely on use of assimilate storage was not entirely consistent with measured changes in trunk reserves and changes in AMAX and / or use of reserves, located in other parts of the palm may be involved.

Further research needed to resolve this issue is suggested.

Mono- and dibasic acids from liquid phase oxidation of palm oil products

The main objective of the research was to convert palm oil products into basic intermediates for use in the chemical industry. In this paper, oxidative cleavage of palm oil products into dibasic acids and low molecular weight monobasic acids by liquid phase oxidation of palm oil products in discussed. Identification of reaction products was done with gas chromatography and gas chromatography/mass spectroscopic techniques and it was found that the major dibasic acids formed in the reaction were suberic and azelaic acids. The dibasic acids produced were concentrated by water washing followed by crystallization. The maximum purity of azelaic acid achieved was 78% .The dibasic acids are useful materials for the syntheses of lubricants, plasticizers, polyamides and polyesters.

Oxidation and thermal degradation of carotenoids

Carotenoids are widely used in food applications. Their highly unsaturated nature makes them susceptible to degradation by oxidation and thermal processes, especially under severe processing and storage conditions. The mechanisms during auto-, photo-catalyzed and photosensitized-oxidations of trans β-carotene are discussed. The oxidation products formed are mixture of epoxides, apocarotenal and hydroxy compounds. Isomerization, oxidation and breakdown of the carotenoid molecule occur as a result of thermal degradation. Two types of thermal degradation products are formed: volatile and non-volatile. The volatile fraction consists of low molecular weight molecules which vapourizes. The non-volatile fraction is the residual fraction after vapourization of the volatile fraction. The mechanisms for formation of the two fractions are discussed.

 

Effects of weather on yield components of the oil palm in a forest location in Nigeria

Simple linear correlations, stepwise multiple regressions and path coefficient analysis were used to determine the relationship between climatic variables and yield components in the oil palm; i.e. number of bunches (NB), fresh fruit bunch yield (FFB) and mean bunch weight (MBW) over a  13-and 20-year period. Yield could be reliably predicted from minimum relative humidity and sunshine hours 18-24 months prior to harvest.