Minor constituents of palm oil

Crude palm oil contains about 1% of minor components including carotenoids, tocopherols, sterols, triterpene alcohols, phospholipids, glycolipids and terpenic and paraffinic hydrocarbons. The nutritionally important components such as carotenes and tocopherols also improve stability of the oil. Although a highly valued product, carotene unfortunately is bleached or destroyed in refining because suitable recovery technology is not available. Thermal degradation of carotene, previously suspected of giving rise to undesirable chemicals, now is known to furnish mainly harmless hydrocarbons, most of which are removed by the deodorization step in refining. Tocopherols, being natural antioxidants, need to be carefully preserved during milling, refining, fractionation and modification of palm oils. The accumulation of tocopherols in the palm fatty acid distillate promises to provide a new source for the recovery of this valuable substance. The role played by phospholipids is frequently misunderstood because they can act in two ways, i.e. as an antioxidant synergist and a surface active agent to disperse impurities in oil. In crude palm oil the phospholipid content is small, because most of it is removed during milling; the phosphorus content is due mainly to inorganic phosphorus. Among the sterols, cholesterol constitutes too small a percentage to be of much concern. Sterols, triterpenoids and terpenoid hydrocarbons are also potentially useful side products should recovery technology become available. Other newly characterized minor and trace components also are discussed.     

Composition of oil

International trade in palm oil has increased considerably over the last ten years, and so too has the trade in processed palm oil products, especially palm fractions. It is important to establish reliable purity criteria for palm oil, not only because of the commercial need to verify oil authenticity, but also to comply with foodstuff labelling legislation in many countries. Palm kernel and coconut oils both contain about 47% lauric acid. This gives the oils close similarities in physical and chemical properties. The oils do differ, however, and it is important to be able to distinguish between them. Purity problems can arise as a result of commingling of oils with one another, or as a result of fractionation perhaps coupled with subsequent blending. A research program jointly funded by the (U.K.) Ministry of Agriculture, Fisheries and Foods, the Federation of Oils, Fats & Seeds Associations Ltd (FOSFA International), and the Leatherhead Food RA, was established to study purity characteristics of the major edible vegetable oils. Forty-seven samples of crude palm oil were obtained from reliable sources, often plantation managers, together with five samples of palm olein and eight samples of palm stearin. Fifty-four palm kernel and 23 coconut oils were obtained in the laboratory from seed samples of known geographical origins and authenticities. These oil samples were analyzed for fatty acid, triglyceride, sterol and tocopherol compositions; the melting properties were also determined, and in the case of palm oil the compositions of the acids at the triglyceride 2-positions were measured. Compositional ranges will be presented for the different geographical production areas in each case and related to existing data, e.g., of PORIM and Codex. An initial statistical analysis of the results has shown that a combination of values from the carbon number analysis differentiates palm kernel and coconut oils, and can be used to decide on the proportion of each in a blend. In the case of palm oil samples suspected to be contaminated with palm fractions, it was found useful to plot melting point against iodine value, and to compute the product of the C48 triglyceride content and the palmitic acid enrichment factor.     

Separation of palm carotene from crude palm oil by adsorption chromatography with a synthetic polymer adsorbent

Palm carotene was successfully concentrated from crude palm oil by a single-stage chromatographic process on a synthetic porous polymer. Carotene was concentrated to about 10⁵ ppm solution, which is about 160 times the original concentration in crude palm oil. Carotene recovery varied from 40 to 65% depending upon chromatographic conditions. The fatty acid composition of the palm oil did not change during the carotene recovery process, and the carotene composition was also almost the same as that in palm oil. Adsorption isotherms of the adsorbent differed from other adsorbents. This new recovery method for palm carotene may be suitable as an edible palm oil pretreatment process due to its efficient mass recovery of a valuable bioresource.     

Utilization of Malaysian palm oil and palm kernel oil for fatty acids and derivatives

Malaysia produces ca. 65% of the world’s palm oil, or (in 1982) ca. 3,500,000 metric tons. By 1985, this will increase to 80% of world production, or ca. 4,800,000 metric tons. Palm oil products are refined, bleached and deodorized oil for edible purposes, palm olein for edible use, palm stearin for edible or industrial use, and the acid oil or fatty acid distillate for industrial uses. The Malaysian processors naturally want to upgrade the products as much as possible.     

Biological modification of oil composition

Prospects for modification of palm oil composition through oil palm breeding, tissue culture and enzyme-catalyzed transesterification are reviewed. Present emphasis in oil modification is toward greater unsaturation. The greatest prospect for this area lies in the interspecific hybridization ofE. oleifera andE. guineensis. The target recommended is for a hybrid oil of iodine value above 72 having a palmitic acid content below 25% and an oleic acid content above 60%. It is noted that the variability of linoleic acid in the oil palm is limited regardless of species. The greatest contribution towards unsaturation, therefore, lies mainly in oleic acid. Tissue culture is seen as a potential propagating tool for selecting progenies of important crosses from the hybridization ofE. oleifera andE. guineensis, while enzyme-catalyzed transesterification using a 1,3 specific lipase offers the possibility of enhancing the level of linoleic acid in palm oil. Besides breeding for unsaturation, production of palms giving oils of specific fatty acid or triglyceride types also may be possible ultimately.     

Dehulling of palm kernel of oil palm (Elaeis guineensis) to obtain superior-grade palm kernel flour and oil

A novel method has been developed for the removal of the thin, dark-brown skin, called testa, from the palm kernel of the oil palm (Elaeis guineensis) by chemical treatment. Studies carried out for this purpose included physical or mechanical means, dry or wet heat, solvents and other chemicals. Of the procedures tried, treatment with hydrochloric acid (HCl) resulted in complete removal of the testa, producing a pearl-white palm kernel. All other treatments were found to be ineffective. Based on our laboratory studies, semi-large-scale trials were made with 4N HCl for continuous dehulling of palm kernel in an abrasive peeling machine for the preparation of superiorgrade kernel flour and oil.     

Soap and related products: Palm and lauric oil

There are three main methods for producing soap: direct saponification of fats and oils, neutralization of fatty acids and saponification of fatty acid methyl esters. Our unique process of soapmaking, based on the methyl ester saponification method, is described here. By this process, high-quality toilet soaps can be produced from palm stearin and palm kernel oil as well as tallow and coconut oil. A new sulfonation process was developed to produce high-quality α-SFMe (α-sulfo fatty acid methyl ester) from palm stearin as the starting material. Quality and performance of α-SFMe bear comparison with those of LAS, AES, AS or AOS. Thus α-SFMe is a promising surfactant for detergents and will contribute to expanding the use of palm oil in the near future.     

Determination of mono- and diglycerides in palm oil,olein and stearin

Partial glycerides are important constituents of palm oil and can have significant effects on the physical properties of products containing palm oil or on the fractionation of palm oil. A method is described for their routine determination in palm oil. By analysis of 28 weekly composite samples of crude palm oil the following results were obtained: free fatty acids, mean=3.76%, range 2.4 to 4.5%; monoglycerides, mean=0.28%, range 0.21 to 0.34%; diglycerides, mean=6.30%, range 5.3 to 7.7%. During detergent fractionation of palm oil, diglycerides concentrate in the palm olein, but monoglycerides concentrate in the palm stearin. Palm fatty acid distillate was found to contain approximately 3% each of mono- and diglycerides. Because the refining and fractionation processes are continuous in the refinery, it is not possible to follow a single identifiable batch of crude palm oil through the refinery. To circumvent this problem, crude palm oil, stearin and olein from the refinery were bleached and steam refined in the laboratory and the partial glyceride contents determined at each stage of processing. Except for fractionation, the content of glycerides did not change during processing. For oil, olein and stearin, monoglycerides were reduced significantly both after bleaching and after steam refining.     

棕榈油在全球的贸易

深入阐述了棕榈油、月桂酸和工业油脂化学在马来西亚和印度尼西亚等生产大国的市场概况,进而看到棕榈油在全球的贸易。同时,也分析了棕榈油和月桂油在中国的市场状况和市场潜力,不管是对马来西亚还是整个世界来说,中国是非常重要的市场。     

Detection of palm oil in vanaspati by thin layer chromatography

Palm oil (raw or refined), as such, or the unsaponifiable matter of palm oil and vanaspati (mostly hydrogenated soybean oil containing 5% sesame oil), when separated on a silver nitrate impregnated Silica Gel G plate or a Silica Gel G plate using (a) hexane/ether/acetic acid (80:20:1.5) or (b) chloroform, respectively, for development showed distinct differences. On the basis of this, two systems have been suggested for the detection of palm oil in vanaspati. About 5% adulteration can be detected by the first method and 10% by the second.     

Frying performance of a sunflower/palm oil blend in comparison with pure palm oil

The aim of this study was to test the performance of a vegetable oil blend formulated as alternative to pure palm oil as frying medium. For this purpose, the evolution of many analytical parameters (free acidity, spectrophotometric indices, total polar components, fatty acid composition, short‐chain fatty acids, tocopherol and tocotrienol content and composition, color, flavor evaluated by means of an electronic nose) of the selected blend (sunflower/palm oil 65 : 35 vol/vol) has been monitored during a prolonged frying process (8 h discontinuous frying without oil replenishment) in comparison to pure palm oil. Sensory attributes of the fried food were also evaluated. The blend proved to keep qualitative parameters comparable to those shown by palm oil during the prolonged frying process. Even if some oxidation indices, such as spectrophotometric indices, short‐chain fatty acids and total polar components, increased faster in the blend, it showed a higher tocopherol content and a lower increment in free fatty acids as compared to pure palm oil. Chips fried in the two oils did not show significantly different sensory profiles.     

The nutritional reputation of palm oil

The high saturated fatty acid content of palm oil and hence its potential to raise circulating levels of cholesterol has given this tropical oil a bad nutritional reputation. Three considerations suggest that this reputation may soon need to be re‐evaluated. First, the need of the edible oil industry to find alternatives to partially hydrogenated oils has led to the reintroduction of palm oil. What evidence there is suggests that replacement of partially hydrogenated oils with palm oil leads to a rise in HDL‐cholesterol levels an effect which would be expected to lead to a fall in the risk of developing heart disease. Second, palm oil is a very rich source of tocotrienols the neglected part of the vitamin E complex. If beneficial effects of tocotrienols on health were to be demonstrated then this would inevitably improve the nutritional reputation of palm oil. Third, red palm oil is the richest and most available vegetable source of provitamin A carotenoids known and it has been shown that this oil can improve vitamin A status in populations which are deficient in this vitamin.     

Manufacture of palm kernel oil using the traditional coconut oil processing system

The traditional processing system of coconut oil, comprising grating of coconut meats, extraction with boiling water, cooling, followed by skimming off the cream, and heating it to dryness to give coconut oil, has been adapted for the manufacture of palm kernel oil. Palm kernels were crushed in a laboratory hammer mill, extracted with several lots of boiling water, cooled, the resulting cream skimmed off, and heated to dryness to yield palm kernel oil. A comparison of existing traditional and new adapted processing systems showed that the yield palm kernel oil obtained in both cases was about the same. Furthermore, the specific gravity, melting point, refractive index, and saponification number were similar, but the moisture content, acid value, color, and odor were dissimilar.     

Quality of byproducts from chemical and physical refining of palm oil and other oils

Being byproducts, palm soapstock, palm acid oil and palm fatty acid distillates (PFAD) have a wide range of quality and composition. They also consist of many impurities and minor components. Due to development of refining techniques. PFAD have largely replaced palm acid oil, especially in the producing countries. Although both palm acid oil and PFAD can be used for making low-quality laundry soap directly, they are often subjected to further treatment. They have found many industrial applications, especially in the feed and fatty acid industries. Quality of recovered oil from spent earth can be as good as bulk of the bleached stock if proper solvent such as hexane is used for extraction. Spent earth can also be used for incineration to produce energy, cattlefeed and landfill.     

Bernam bleachability test method for palm oil

A bleachability test method called the Bernam method is proposed for crude palm oil, based upon the percentage of color removed on the original color, as measured on a Lovibond 1 in. cell. The test uses absorption bleaching by 3% activated fuller’s earth (Fulmont 237) at 150 C under inert gas blanket. It shows improved sensitivity over two existing bleach-ability methods and to both primary and secondary oxidation of palm oil, as measured by the peroxide, anisidine, and total oxidation values. It has been applied successfully to detect changes in the quality of palm oil during production, storage, and shipment to the consumer. In view of its encouraging response to oxidation, it should be possible for the consumer to relate the method to process conditions in the refining of palm oil.     

Steam (physical) refining deodorizer for malaysian palm oil

The production of Malaysian palm oil is expected to increase 20% per year for the next 5 yr. Already planted are more than a million acres which will start to produce in the next few years. Recent plantings of new strains will produce 2400 to 3000 lb of palm oil per acre. Palmex Industries, Penang, Malaysia started in operation in August, 1975, a physical refining system to produce a deodorized palm oil with 0.03% free fatty acid (FFA) from crude palm oil containing 5.0% FFA. Production records confirm the feasibility of physical refining crude palm oil in Malaysia, ex-porting the oil to the United States, and producing a quality product with a minimum of additional pro-cessing.     

Nature of palm oil in centrifuge sludge waste water

In attempting to improve oil recovery, palm oil retained in the centrifuge sludge waste has been categorized and quantified. It is composed of (i) 30% free oil droplets; (ii) 56% oil released after cellulase treatment followed by detergent washing, and (iii) 14% residual oil which remains diffused and bound to the cell debris. The fatty acid composition indicates that all three oils are palm oil. The separated oil is highly contaminated.     

Quality of nigerian palm oil after bleaching with local treated clays

Laboratory investigations into the possibility of using local Nigerian clays in refining the Nigerian crude palm oil revealed that the Okija clay may possess some potential as an adsorptive cleanser in the refining process. Activated bentonite was used as the standard clay of comparison, and the performance of two local natural clays, leached with various concentrations of sulfuric acid, was evaluated for their use as alternative adsorptive cleansers in refining Nigerian crude palm oil. Measurements of peroxide values, para-anisidine values, carotene content and stabilities of the oils using the active oxygen method were used in assessing the relative performance of the clays. The clays exhibited similar trend of effects on identical batches of alkali-neutralized palm oil. In one set of experiments poor results were obtained when the degummed and alkali-neutralized palm oil was treated with clays leached with sulfuric acid at concentrations of 1M and 4M. Better results were obtained at acid concentrations of 2M and 3M. Bentonite proved better than Okija clay when the leaching was performed with 2M H₂SO₄, but both clays had comparable effectiveness when 3M H₂SO₄ was used for leaching. The Nsu clay gave the least encouraging results. In another series of experiments the results showed that for various dosages of clay, up to 3% by weight of the oil to be refined, the oxidative stability of the processed oil was reasonably good for an oil which was neither deodorized nor treated with antioxidants.     

Comparative evaluation of palm oil color measurement using a prototype palm oil colorimeter

The color of refined palm oil and palm oil products is conventionally measured using the manually operated Lovibond^® Tintometer. In the present study, one manual/visual and three automatic colorimeters for the measurement of vegetable oil color were used for color measurements of refined palm oil. All colorimeters used were commercially available instruments except for an automatic palm oil colorimeter developed specifically for the measurement of palm oil color. The color values obtained from all four instruments were compared using the visually obtained readings as reference values. Results showed that all three automatic instruments gave correlation coefficients of greater than 0.9300 for red color measurements. In addition, the Student t-test showed no difference between the analysis of red color using the visual method and the palm oil colorimeter. This investigation concludes that, although it is extremely difficult to reduce the lack of precision in color measurement of palm oil, a properly designed and calibrated automatic instrument may still be the better choice because reproducibility and repeatability are required in all standard test methods. The palm oil colorimeter offers a ready and relatively inexpensive solution to the problem of color matches based on visual observations.     

Evaluation of physicochemical changes in cooking oil during heating

Rice bran oil and double fractionated palm olein (DF palm olein) were heated at 180 C for 50 hr to measure lipid deterioration in the oils. Free fatty acid content of both oils increased during heating; however, iodine value and smoke point decreased. Solid fat contents of both oils were unaffected by heating time. Cloud point of rice bran oil was much lower than that of palm olein. Color of oils changed gradually to dark brown from light yellow with increased heating time. Absolute content of polyunsaturated fatty acid, such as linoleic acid, reduced more than that of monounsaturated fatty acid, such as oleic acid, in both oils. In both oils, iodine value correlated very well with linoleic acid content, with correlation coefficient higher than 0.96.