Properties of residual palm pressed fibre oil

Residual fibre oil was recovered from palm pressed fibre by using a solvent (hexane). The oil was analysed for its physical and chemical properties. The macro-nutrient and element contents of the pressed fibre were also analysed. The residual fibre oil contained high amounts of phosphorus (144 ppm), vitamin E (1153 ppm) and carotenes (1877 ppm). The compositional content of vitamin E present was 54.0% α-tocopherol, 19.2% α-tocotrienol, 16.7% γ-tocotrienol and 10.1% δ-tocotrienol. The major fatty acids of the residual fibre oil were palmitic and oleic acid at 31.9% and 24.8%, respectively. The oil also contained a high amount of lauric acid (22.0%) which is the major fatty acid in palm kernel oil. Density of the residual fibre oil as a function of temperature was measured at temperatures ranging from 40°C to 75°C. Density exhibited a linear relationship with temperature. Viscosity of the residual fibre oil was shown to decrease with an increase in temperature. The formation of needle-shaped crystals was observed when the residual oil was cooled down from 36°C to 34°C. There were no significant changes in the macro-nutrient and element contents of the palm pressed fibre before and after oil extraction with hexane. * Malaysian Palm Oil Board, P. O. Box 10620, 50720 Kuala Lumpur, Malaysia. E-mail: rusnani@mpob.gov. my ** Department of Process and Chemical Engineering, Faculty of Engineering & Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. operation, the palm pressed fibre also contributes towards better soil and water conservation when used as a mulch for small and large seedlings in polybags in the nurseries (Chan et al., 1981). Oil losses occur at various stages of processing in a palm oil mill. In the pressing stage, oil is ‘lost’ in the pressed fibre. The amount of oil entrapped in these fibre depends very much on the effect of sterilisation on the fruit, the conditioning of the sterilised fruits in the digester, and also the pressure exerted on the press cake during pressing. Oil losses in the pressed fibre range from 5%-8% on a dry weight basis. The utilisation of palm pressed fibre as well as the residual fibre oil recovered from the fibre will be able to change the by-products into valuable products. As palm oil is well-known for its versatility in both edible and non-edible applications, great efforts are currently undertaken to study the application of the by-products generated from the palm oil milling process. These by-product applications require extensive studies on the physico-chemical properties of the by-products in order to ensure their suitability as raw materials for various final INTRODUCTION Fresh fruit bunches (FFB) are processed in the palm oil mill to produce two types of products: crude palm oil (CPO) and palm kernels. Palm oil milling processes consist of various stages which include sterilisation of the FFB, stripping, pressing, clarification and purification of the crude oil, nut cracking and kernel recovery. Besides the two main products, the mill also generates about 1.5 t of empty fruit bunches, 1.6 t of palm pressed fibre, 0.9 t of palm shells, 2.4 t of steriliser condensate, 10.0 t of centrifugal sludge and 0.7 t of dry mill effluent per hectare of oil palm annually as illustrated in Figure 1. Besides being used as a solid fuel for boiler