38 OFI JANUARY 2010

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There is a worldwide trend towards nat-ural fats and waxes as a renewableresource due to environmental con-cerns and the availability and cost ofparaffin wax.

Natural waxes have a wide range of applica-tions and the magnitude of annual worldwidewax consumption is reflected in these statistics:

� Paraffin waxes: (including microcrystallinewaxes) 3M tonnes/year

� Polyolefin waxes: 200,000 tonnes/year� Fischer-Tropsch (FT) wax: 100,000 tonnes/ year� Montan wax: 50,000 tonnes/year� Carnauba wax: 15,000 tonnes/year� Beeswax: 10,000 tonnes/year� Candelilla: 1,000 tonnes/year� Other vegetable waxes: 2,000 tonnes/year

Carnauba and Candelilla wax are the mostimportant and most widely used vegetable waxes.Beeswax is the most important animal wax.

Composition of wax

The chemical composition of most natural waxconsists of, among others, triglycerides and car-bon acids, such as stearic acid, oleic acid andpalmitic acid. The functional acid groups oftriglycerides are blocked and they are thereforeless reactive than free fatty acids.Some waxes can be made simply by hydro-

genating appropriate oils and fats. Hydrogenationreduces the degree of unsaturation in the fattyacid groups and is a catalytic process wherebythe number of double bonds are reduced and iso-merisation of the residual fatty acids is pro-

moted. Liquid oils with unsaturated glyceridesare transformed into fats containing a higher per-centage of saturated triglycerides.Hydrogenation is often called hardening of oilsand soft fats. Hardened fats contain smallamounts of free fatty acids and therefore colourpigments and additives are more stable in hard-ened fats. Non-hardened fats contain largeramounts of free fatty acids that are more reactivethan glycerin esters (fats).

Palm wax

Palm oil is one of the most widely consumed edi-ble oils in the world today. The oil palm producesfruit which consist of a hard kernel inside a shell,which is surrounded by a fleshy mesocarp.Palm kernel oil is yellowish in colour and has

a fatty acid composition different from that ofpalm oil. Palm kernel oil contains mainly lauricacid and more than 80% saturated fatty acids.Palm kernel oil closely resembles coconut oil inits fatty acid formulation and characteristics andtherefore is a cost effective substitute for coconutoil in the production of quality soap.Due to its environmentally friendly attributes,

palm oil wax offers marketability as a sustainableor renewable resource. Palm oil is semi-solid atroom temperature; a characteristic broughtabout by its 50% saturation level. The palm fruitsare harvested and sent to palm oil mills toundergo sterilisation, bunch stripping, oil extrac-tion, oil clarification and purification.This crude palm oil then becomes the raw

material for palm oil refineries where it is furtherprocessed by neutralisation, bleaching anddeodorisation. The refined, bleached anddeodorised (RBD) palm oil then undergoes frac-tionation by which RBD palm olein and RDBpalm stearin are produced and these, in turn, canbe further fractionated to obtain specialisedproducts such as cooking oil, cooking fats, mar-garines (domestic and commercial), cocoa buttersubstitutes and creamers.

NATURAL WAXES

With a global trend towardsnatural fats and waxes,Dr Madelyn Bekker explains theeconomic significance, generalchemical composition, productionprocesses, applications andtypical properties of the mostimportant natural waxes

The world of wax

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(prime yellow) and the outer palm leaves wax isyellow, grey-green or grey-brown depending onthe climatic condition during vegetation.Carnauba is one of the hardest and highestmelting natural waxes. It has a fine crystallinestructure and a weakly aromatic odour andcharacteristic hay-like smell in the moltenstate.

Carnauba is used in cosmetics, pharmaceuti-cals, candles, polishes, the food sector, polymerprocessing, inks, paper coatings and fruit coat-ings.

Candelilla wax

The Candelilla plant (EuphorbiaAntisyphillitica and Pedilanthus Pavonis)grows in Northeastern Mexico in the wilds of thenorth central plains and foothills of theChihuahua Desert, a semi-arid area of morethan 100,000km2.

Candelilla wax is fundamentally differentfrom Carnauba wax in its high hydrocarboncontent of 45% and resin content of 20%. Thetypical chemical composition of Candelilla is42% hydrocarbons (90% paraffins and 2%alkenes), 39% wax, resin and sitosteroyl esters,6% lactones, 8% free wax and resin acids, and 5%free wax and resin alcohols.

As in all natural waxes, in Candelilla wax, thewax acids or alcohols with even-numbered car-bon chains have typical and distinctive chainlength distributions.

The production of Candelilla wax is confinedto areas where rugged climatic and topographi-cal conditions combine to produce the highestwax-yielding varieties. Plants growing in thehottest and driest areas produce a scale-likecovering on the plant which, after processing athundreds of rural sites, yields a hard, brittlewax. Plant material is boiled with 0.2% sul-phuric acid in open vessels. The wax isskimmed off into barrels. Yields based on plantmaterial are 3-4%. Candellila wax is thereforenon-hardened (non-hydrogenated) wax andwould contain more free fatty acids.

Candelilla is used in cosmetics, polishes, phar-maceuticals, precision casting, lubricants, adhe-sives, paper coatings and sizing, chewing gumbase, electric insulators and candle compositions.

Palm olein is the liquid fraction obtained byfractionation of palm oil. The physical character-istics of palm olein is different from those of palmoil as it is fully liquid in warm climate and has anarrow range of glycerides. Palm olein is widelyused as cooking oil due to its good resistance tooxidation and formation of breakdown productsat frying temperatures and longer shelf life of fin-ished products. Palm stearin is the pasteobtained by the fractionation of palm oil. Palmstearin is cheaper than palm olein and the phys-ical characteristics of palm stearin differ signifi-cantly from those of palm oil and it is available ina wider range of melting points and iodine values.

Palm kernel oil is obtained from the kernel ofthe oil palm fruit. Palm kernel olein is the liquidcomponent of palm kernel oil obtained from frac-tionation. Palm kernel stearin is the solid frac-tion of palm kernel oil obtained fromfractionation. Palm kernel oil, palm kernel oleinand palm kernel stearin find uses in margarine,confectioneries, coffee whitener, filled milk, bis-cuit cream and coating fats; with little or no fur-ther processing. There is a growing trend to usepalm kernel oil products as an ingredient in theproduction of non-hydrogenated trans-fat freemargarine.

Depending on the price, palm wax can beobtained from the hydrogenation of palm oil,palm stearin, palm kernel oil or palm kernelolein. The degree of unsaturation in the fattyacid groups of the oil is reduced. Liquid palm oilwith unsaturated fatty acids are thus trans-formed into palm fat containing a higher per-centage of saturated triglycerides.

About 25% of the palm fat available is used fornon-edible products which include agriculturalemulsifiers, stabilisers in PVC and paper manu-facturing, a range of soaps, detergents and toi-letries, pharmaceuticals, rubber, solvents,leather and candle making wax. Palm wax isvery suitable to candle applications as it resistsmelting in hot summer months, has high con-traction (making de-molding easier), takescolours easily and holds fragrance well. Thepalm wax candle also releases the scentthroughout the entire candle and the scent of apalm wax candle does not fade away. Pure palmwax burns at a cooler temperature (about 2oCless) and at a slower rate than paraffin waxes.Palm wax candles have approximately 45%longer burn time as compared to the usual sizedparaffin wax candle and the paraffin candleflame size is approximately 10mm higher than apure palm wax candle. Pure palm candles alsodo not deform after three hours of burning;compared to a paraffin candle that shows signsof deformation at the top. Palm wax can be eas-ily manipulated to produce an infinite array ofsurface patterns ranging from complex crys-talline designs to smooth solid colours.

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NATURAL WAXES

Paraffin waxes contain macro- and micro-crystalline components. The crystal structure ofpalm wax is different from paraffin wax as itforms a pure micro-crystalline structure that isso fine that light does not penetrate the purepalm candle.

The more palm wax a candle contains, themore dye is required to give colour strength.Palm wax influences dye colour stability (freefatty acids change colour in sunlight). The reac-tive functional acid groups accelerate thedecaying of dyes.

Carnauba wax

Carnauba wax is by far the most important veg-etable wax. Carnauba wax is obtained from theleaves of a palm tree known as CopernicaCerifera, which is also referred to as the “Treeof Life”. This slow-growing Carnauba palmflourishes in the north-eastern regions of Brazil.The majority of tree harvesting takes place inthe Brazilian states of Ceara and Piaui. The fan-shaped leaves are covered with wax to preventdehydration in the equatorial climate.

The production process of cutting of theleaves and sprouts takes place during the drymonths of September to February, with workersusing knives on long poles to trim the leavesfrom mature trees. The cut leaves are sun-driedand mechanically thrashed to remove the crudewax. The wax is then melted over water.Carnauba wax is therefore non-hardened (non-hydrogenated) wax. The dried leaves are alsochopped and chips removed to give a mixture of60% wax and 40% leaves. The annual yield ofwax is 150g/palm. The colour and quality of thewax are governed by the age of the leaves. Theunopened heart leaves have light coloured wax

FIGURE 1: PROPERTIES OF DIFFERENT TYPES OF WAX

PALM OIL WAX OFFERS MARKETABILITY AS A SUSTAINABLE OR RENEWABLE RESOURCE

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