Composition and thermal profile of crude palm oil and its products

Gas-liquid chromatography and high-performance liquid chromatography (HPLC) were used to determine fatty acids and triglyceride (TG) compositions of crude palm oil (CPO), refined, bleached, and deodorized (RBD) palm oil, RBD palm olein, and RBD palm stearin, while their thermal profiles were analyzed by differential scanning calorimeter (DSC). The HPLC chromatograms showed that the TG composition of CPO and RBD palm oil were quite similar. The results showed that CPO, RBD palm oil, RBD olein, and superolein consist mainly of monosaturated and disaturated TG while RBD palm stearin consists mainly of disaturated and trisaturated TG. In DSC cooling thermograms the peaks of triunsaturated, monosaturated and disaturated TG were found at the range of −48.62 to −60.36, −25.89 to −29.19, and −11.22 to −1.69°C, respectively, while trisaturated TG were found between 13.72 and 27.64°C. The heating thermograms of CPO indicated the presence of polymorphs β₂′, α, β₂′, and β₁. The peak of CPO was found at 4.78°C. However, after refining, the peak shifted to 6.25°C and became smaller but more apparent as indicated by RBD palm oil thermograms. The heating and cooling thermograms of the RBD palm stearin were characterized by a sharp, high-melting point (high-T) peak temperature and a short and wide low-melting point (low-T) peak temperature, indicating the presence of occluded olein. However, for RBD palm olein, there was only an exothermic low-T peak temperature. The DSC thermograms expressed the thermal behavior of various palm oil and its products quite well, and the profiles can be used as guidelines for fractionation of CPO or RBD palm oil.     

Trans-free vanaspati containing ternary blends of palm oil-palm stearin-palm olein and palm oil-palm stearin-palm kernel olein

Four samples of trans-free vanaspati were made using palm oil-palm stearin-palm olein (PO-POs-POo) blends (set A) and another four samples (set B) using palm oil-palm stearin-palm kernel olein (PO-POs-PKOo). Palm stearin iodine value [iodine value (IV), 30] and soft palm stearin (IV, 44) were used in this study. The products were evaluated for their physical and chemical properties. It was observed that most of the vanaspati were granular (grainy) and had a shiny appearance. Chemical analyses indicated that vanaspati consisting of PO-POs-POo had higher IV (47.7–52.4) than the PO-POs-PKOo vanaspati (37.5–47.3). The higher IV demonstrated by set A samples was due to their higher content of unsaturated fatty acids, 46.0–50.0% compared to 36.6–45.0% in set B. Decreasing the amount of palm oil while increasing palm stearin in the formulations resulted in higher slip melting points and higher yield values. Eutectic interaction was observed in PO-POs-PKOo blends. The β′ crystalline form was predominent in PO-POs-POo samples (set A). One formulation in set B exhibited β crystallinity. From the differential scanning calorimetry thermograms, samples in set B showed a high peak at the low-melting region as well as a high peak at the high-melting region. In set A, the peak at the low-melting region was relatively lower.     

Resistance to crystallization of blends of palm olein with soybean oil stored at various temperatures

The aim of the study was to determine the resistance to crystallization of palm olein (POo) with soybean oil (SBO) at different temperatures. POo of iodine value (IV) 65 gave better resistance to crystallization than POo of IV 60 or IV 63. For applications such as salad oil, the use of POo of IV 65 is limited to 30% when blended with SBO. If POo of either IV 60 or IV 63 is chosen, its use in salad oil is limited to 10% only. However, for applications other than salad oil, such as for cooking or frying, 100% POo of any IV could be used. For cold climates, the amount of POo (IV 60 or 63) recommended to get a clear oil is 10–30%. Alternatively, up to 40% POo of IV 65 can be blended with SBO. For temperate climates, the amount of POo (IV 60 or 63) recommended can be up to 60%. With POo of IV 65, the amount recommended is as high as 80–90% for application as a cooking or frying oil.     

Effect of chemical interesterification on triacylglycerol and solid fat contents of palm stearin,sunflower oil and palm kernel olein blends

Palm stearin (POs) with an iodine value of 41.4, sunflower oil (SFO) and palm kernel olein (PKOo) were blended in various ratios according to a three‐component mixture design and subjected to chemical interesterification (CIE). Triacylglycerol (TAG) and solid fat content (SFC) profiles of the chemically interesterified (CIEed) blends were analyzed and compared with those of the corresponding non‐CIEed blends. Upon CIE, extensive rearrangement of fatty acids (FA) among TAG was evident. The concentrations of several TAG were increased, some decreased and several new TAG might also have been formed. The changes in the TAG profiles were reflected in the SFC profiles of the blends. The SFC of the CIEed blends, except the binary blends of POs/PKOo which experienced an increase in SFC following CIE, revealed that they were softer than their respective starting blends. Randomization of FA distribution within and among TAG molecules of POs and PKOo led to a modification in TAG composition of the POs/PKOo blends and improved miscibility between the two fats, and consequently diminished the eutectic interaction that occurred between POs and PKOo.     

Effect of enzymatic transesterification with flaxseed oil on the high-melting glycerides of palm stearin and palm olein

The effects of enzymatic transesterification on the melting behavior of palm stearin and palm olein, each blended separately with flaxseed oil in the ratio of 90∶10 and catalyzed by various types of lipases, were studied. The commercial lipases used were Lipozyme IM, Novozyme 435, and myceliumbound lipases of Aspergillus flavus and A. oryzae. The slip melting point (SMP) of the palm stearin/flaxseed oil (PS/FS) mixture transesterified with lipases decreased, with the highest drop noted for the mixture transesterified with Lipozyme IM. However, when palm stearin was replaced with palm olein, the SMP of the palm olein/flaxseed oil (PO/FS) mixture increased, with the commercial lipases causing an increase of 41 to 48% compared to the nontransesterified material. As expected, the solid fat content (SFC) of the transesterified PS/FS was lower at all temperatures than that of the nontransesterified PS/FS sample. In contrast, all transesterified PO/FS increased in SFC, particularly at 10°C. Results from DSc and HPLC analyses showed that the high-melting glycerides, especially the tripalmitin of palm stearin, were hydrolyzed. Consequently, 1,3-dipalmitoylglycerol was found to accumulate in the mixture. There was no difference in the FA compositions between the transesterified and nontransesterified mixtures.     

Crystallization kinetics of palm stearin in blends with sesame seed oil

This study investigates the crystallization kinetics of palm stearin (PS), a palm oil fraction, in blends with sesame seed oil. The results indicate that the crystallization behavior of PS in sesame oil is mainly associated with the crystallization of tripalmitin. Therefore, crystallization of blends of 26, 42, 60, and 80% (wt/vol) PS in sesame oil was described by equations developed for simpler systems (e.g., Fisher and Turnbull equation). The isothermal crystallization, melting profile, and fitting of the kinetics of nucleation to the Fisher and Turnbull equation showed that the 26, 42, and 60% PS/sesame oil blends crystallized mainly in the β₁′ polymorph state. In contrast, the 80% blend crystallized in two different polymorph states (i.e., β₁′ at T⪯307.6 K and β₁ at T≽308.2 K). The data indicated that, in spite of the higher concentration of PS in the 80% PS/sesame oil system, crystallization in the β₁ state required more free energy for nucleation (δG _c ) than β₁′ crystallization in the 26, 42, and 60% PS/sesame oil. At the low cooling rate used (1 K/min) it was observed that, for a particular PS blend, the higher the effective supercooling the higher the viscosity of the oil phase and the smaller the induction time of crystallization (T_i). Additionally, the β₁′ crystals from PS, developed at the highest effective supercooling investigated, were smaller than the β₁ crystals obtained at lower effective supercooling.     

Steam deacidification of palm oil

This work presents the application of response surface methodology (RSM) to the study of the effects of three factors (temperature, percent stripping steam and the stearin/olein ratio) on the losses/transfer of fatty compounds during the steam deacidification of blends of palm oil fractions (stearin and olein) as model systems. The responses of interest were the final oil acidity and the loss of neutral oil (NOL). These experiments were unprecedented in terms of the monitoring and controlling of the process variables during the heating and stripping periods in a laboratory scale batch deodorizer. The results revealed that the oil composition was an important and statistically significant factor in the selection of more suitable processing variables, besides temperature and steam.     

A fourier transform infrared spectroscopic method for determining butylated hydroxytoluene in palm olein and palm oil

A simple, rapid, and direct FTIR spectroscopic method was developed for the determination of BHT content in refined, bleached, and deodorized (RBD) palm olein and RBD palm oil. The method used sodium chloride windows with a 50-mm transmission path. Fifty stripped oil samples of both RBD palm olein and RBD palm oil were spiked with known amounts of BHT concentrations up to 300 mg/kg (ppm). The data were separated into two sets for calibration and validation using partial least squares models. FTIR results for both oils correlated well with results obtained by the IUPAC HPLC-based method. For RBD palm olein, the coefficient of determination (R ²) was 0.9907 and the SE of calibration (SEC) was 8.47 ppm. For RBD palm oil, an R ² of 0.9848 and an SEC of 10.73 ppm were achieved. Because of the significant decrease in analysis time and reduction in solvent usage, this FTIR method for BHT is especially well suited for routine quality control applications in the palm oil industry.     

Polymorphic stability of hydrogenated palm oleins in dilutions with unhydrogenated liquid oils

Palm oil was hydrogenated under selective and nonselective conditions. Some of the hydrogenated samples were chosen for their physical characteristics and were diluted with 70% sunflower oil. A commercial hydrogenated palm olein (H-olein) was diluted up to 80% with canola oil. The diluted mixtures were evaluated for their polymorphic β' stability by a temperature-cycling procedure between 4 and 20°C. All of the mixtures were stable in the β' form. The dropping point and solid fat content of the mixtures were compared with those of commercial soft and stick margarines. Soft margarines can be prepared from mixtures of 20% H-olein and 80% unhydrogenated oil, and stick margarines from 40% H-olein and 60% liquid oil. If canola oil is the liquid oil, the saturated content in the soft formulation is 13% and that of a stick formulation 17%.     

Clarity of blends of double-fractionated palm olein with low-erucic acid rapeseed oil

Double-fractionated palm olein (DfPOo) fractions with iodine values (IV) of 60 and 65 were each blended with low-erucic acid rapeseed (LEAR) oil in various proportions. Clarities of the blends at different temperatures were determined. Maximum levels of DfPOo-IV60 and DfPOo-IV65 in blends that remained clear at 20°C for at least 120 d were 40 and 80%, respectively. At 15°C, the maximum levels were 10 and 40%, and at 10°C, 10 and 20%, respectively. At 5°C, only a blend of 10% DfPOo-IV65 in LEAR remained clear for 120 d. Maximum levels of DfPOo-IV60 and DfPOo-IV65 in blends that passed the cold test were 30% for both palm oleins. Maximum levels of the palm oleins in blends with LEAR were higher than those of blends with soybean oil. Cloud points were lower in palm olein/LEAR blends than those of palm olein/soybean oil blends, probably because LEAR contains less saturated fatty acids than soybean oil.     

DSC study on the melting properties of palm oil, sunflower oil, and palm kernel olein blends before and after chemical interesterification

Changes in DSC melting properties of palm oil (PO), sunflower oil (SFO), palm kernel olein (PKOo), and their belends in various ratios were studied by using a combination of blending, and chemical interesterification (CIE) techniques and determining total melting (ΔH _f ) and partial melting (ΔH _i°C ) enthalpies. Blending and CIE significantly modified the DSC melting properties of the PO/SFO/PKOo blends. PO and blends containing substantial amounts of PO and PKOo experienced an increase in their DSC ΔH _f and ΔH _i°C following CIE. The DSC ΔH _f and ΔH _i°C of PKOo, blends of PO/SFO at 1∶1 and 1∶3 ratios, and all blends of PKOo/SFO significantly decreased after CIE. The DSC ΔH _f and ΔH _i°C of SFO changed little following CIE. Randomization of FA distribution within and among TAG molecules of PO and PKOo led to modification in TAG composition of the PO/PKOo blends and improved miscibility between the two fats and consequently diminished the eutectic interaction that occurred between PO and PKOo.     

Determination of free fatty acids in crude palm oil and refined-bleached-deodorized palm olein using fourier transform infrared spectroscopy

A rapid direct Fourier transform infrared (FTIR) spectroscopic method using a 100 μ BaF₂ transmission cell was developed for the determination of free fatty acid (FFA) in crude palm oil (CPO) and refined-bleached-deodorized (RBD) palm olein, covering an analytical range of 3.0–6.5% and 0.07–0.6% FFA, respectively. The samples were prepared by hydrolyzing oil with enzyme in an incubator. The optimal calibration models were constructed based on partial least squares (PLS) analysis using the FTIR carboxyl region (C=O) from 1722 to 1690 cm⁻¹. The resulting PLS calibrations were linear over the range tested. The standard errors of calibration (SEC) obtained were 0.08% FFA for CPO with correlation coefficient (R ²) of 0.992 and 0.01% FFA for RBD palm olein with R ² of 0.994. The standard errors of performance (SEP) were 0.04% FFA for CPO with R ² of 0.998 and 0.006% FFA for RBD palm olein with R ² of 0.998, respectively. In terms of reproducibility (r) and accuracy (a), both FTIR and chemical methods showed comparable results. Because of its simpler and more rapid analysis, which is less than 2 min per sample, as well as the minimum use of solvents and labor, FTIR has an advantage over the wet chemical method.     

Effect of enzymatic transesterification on the melting points of palm stearin-sunflower oil mixtures

Transesterification with lipases may be used to convert mixtures of fats to plastic fats, making them more suitable for use in edible products. In our study, 1,3-specific (Aspergillus niger, Mucor javanicus, Rhizomucor miehei, Rhizopus javanicus, and Rhizopus niveus) and nonspecific (Pseudomonas sp. and Candida rugosa) lipases were used to transesterify mixtures of palm stearin and sunflower oil (PS-SO) at a 40:60 ratio in a solvent-free medium. The transesterified mixtures of PS-SO were analyzed for their percentage free fatty acids (FFA), degree and rate of transesterification, solid fat content, slip melting point (SMP), and melting characteristics by differential scanning calorimetry. Results indicated that Pseudomonas sp. lipase produced the highest degree (77.3%) and rate (50.0 h⁻¹) of transesterification, followed by R. miehei lipase at 32.7% and 27.1 h⁻¹, respectively. The highest percentage FFA liberated was also in the reaction mixtures catalyzed by Pseudomonas sp. (2.5%) lipase and R. miehei (2.4%). Pseudomonas-catalyzed mixtures produced the biggest drop in SMP (13.5°C) and showed complete melting at below body temperature. All results indicated conversion of the PS-SO mixtures to a more fluid product. The findings also suggest that the specificity of lipases may not play a significant role in lowering the melting point of the PS-SO mixtures.     

Enzymatic incorporation of stearic acid into a blend of palm olein and palm kernel oil: Optimization by response surface methodology

Response surface methodology was used to model the incorporation of stearic acid into a blend of palm olein and palm kernel oil in hexane using the sn-1,3-regiospecific lipase Lipozyme RM IM. The factors investigated were incubation time, temperature, and substrate molar ratio. A second-order model with interaction was used to fit the experimental data. The coefficients of determination, R ² and Q ², were 0.96 and 0.90, respectively. The adjusted R ² was 0.95. The regression probability was less than 0.001, and the model showed no lack of fit. Also, a linear relationship was observed between the predicted and observed values. All parameters studied had positive effects on incorporation of stearic acid, with substrate molar ratio having the greatest effect. The interaction terms of substrate molar ratio with temperature and time also had positive effects on incorporation, whereas the effect of the squared term of substrate molar ratio was negative. The quadratic terms of temperature and time, as well as their interaction term, had no significant effect on incorporation at α_0.05. Model verification was done by performing a chi-square test, which showed that there was no significant difference between predicted values and a new set of observed responses.     

Utilization of high-melting palm stearin in lipase-catalyzed interesterification with liquid oils

Palm stearin with a melting point (m.p.) of 49.8°C was fractionated from acetone to produce a low-melting palm stearin (m.p.=35°C) and a higher-melting palm stearin (HMPS, m.p.=58°C) fraction. HMPS was modified by interesterification with 60% (by weight) of individual liquid oils from sunflower, soybean, and rice bran by means of Mucor miehei lipase. The interesterified products were evaluated for m.p., solid fat content, and carbon number glyceride composition. When HMPS was interesterified individually with sunflower, soybean or rice bran at the 60% level, the m.p. of the interesterified products were 37.5, 38.9, and 39.6°C, respectively. The solid fat content of the interesterified products were 30–35 at 10°C, 17–19 at 20°C, and 6–10 at 30°C, respectively. The carbon number glyceride compositions also changed significantly. C₄₈ and C₅₄ glycerides decreased remarkably with a corresponding increase of the C₅₀ and C₅₂ glycerides. All these interesterified products were suitable for use as trans acid-free and polyunsaturated fatty acid-rich shortening and margarine fat bases.     

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.     

Oxidative stability of blends and interesterified blends of soybean oil and palm olein

Improvement of oxidative stability of soybean oil by blending with a more stable oil was investigated. Autoxidation of blends and interesterified blends (9∶1, 8∶2, 7∶3 and 1∶1, w/w) of soybean oil and palm olein was studied with respect to fatty acid composition, fatty acid location and triacylglycerol composition. Rates of formation of triacylglycerol hydroproxides, peroxide value and volatiles were evaluated. The fatty acid composition of soybean oil was changed by blending. Linolenic and linoleic acids decreased and oleic acid increased. The triacylglycerol composition of blends and interesterified blends was different from that of soybean oil. Relative to soybean oil, LnLL, LLL, LLO, LLP, LOO and LLS triacylglycerols were lowered and POO, POP and PLP were higher in blends and interesterified blends (where Ln, L, O, P and S represent linolenic, linoleic, oleic, palmitic and stearic acids, respectively). Interesterification of the blends leads to a decrease in POO and POP and an increase in LOP. Linoleic acid concentration at triacylglycerol carbon-2 was decreased by blending and interesterification. Rates of change for peroxide value and oxidation product formation confirmed the improvement of soybean oil stability by blending and interesterification. But, blends were more stable than interesterified blends. Also, the formation of hexanal, the major volatile of linoleate hydroperoxides of soybean oil, was decreased by blending and interesterification.     

Formulation of zero-<Emphasis Type="Italic">trans</Emphasis> acid shortenings and margarines and other food fats with products of the oil palm

The fruit of the oil palm yields two types of oil. The flesh yields 20–22% of palm oil (C16∶0 44%, C18∶1 39%, C18∶2 10%). This represents about 90% of the total oil yield. The other 10%, obtained from the kernel, is a lauric acid oil similar to coconut oil. Palm oil is semisolid, and a large part of the annual Malaysian production of about 14 million tonnes is fractionated to give palm olein, which is widely used for industrial frying, and palm stearin, a valuable hard stock. Various grades of the latter are available. Formulae have been developed by straight blending and by interesterification of palm oil and palm kernel oil to produce shortenings and margarines using hydrogenated fats to give the consistency required. Products that include these formulations are cake shortenings, vanaspati (for the Indian subcontinent), soft and brick margarines, pastry margarines, and reduced fat spreads. Other food uses of palm products in vegetable-fat ice cream and cheese, salad oils, as a peanut butter stabilizer, and in confectioners fats are discussed briefly here.     

Development of dual stage solvent fractionation as an approach to concentrate carotenoids from crude palm oil with high recovery: The potential use of molecular simulation as a pre-screening tool

Crude palm oil (CPO) is highly abundant in carotenoids. Previous findings found that dry fractionation can concentrate carotenoids from CPO but resulted in a significant loss of carotenoids. Therefore, the present study aimed to utilize solvent fractionation, which offers a better separation efficiency, to concentrate carotenoids from CPO with improved recovery. Computational study revealed a high binding affinity of phytonutrient towards unsaturated triacylglycerols (TAGs) species in olein fraction due to similar polarity. This prediction was further verified with evidence showing strong, positive correlation between the iodine value and carotenoids concentrations of fractionated oil. The difference in binding affinity of saturated and unsaturated TAG towards different solvents can be used as a guide for screening and selection of solvent suitable for recovery of phytonutrient during solvent fractionation. Subsequently, a lab-scale single- stage fractionation study disclosed that crystallization temperature of 15°C, oil to acetone ratio of 1:5 (w/v) for 4 h under agitation at 100 rpm produced olein with the highest carotenoid concentration (637 ppm) and recovery (94%). Subsequent double-stage fractionation successfully concentrated the carotenoids up to 125% with a recovery of >93%. Conclusively, solvent fractionation provides an effective way to concentrate valuable carotenoids from CPO while minimizing the lost.     

Determination of cypermethrin in palm oil matrices

In this study, a new method was developed for the determination of cypermethrin residue in both crude palm oil (CPO) and crude palm kernel oil (CPKO) using GC with electron capture detector. In this method, the oil was extracted with acetonitrile. Aliquots were cleaned‐up using combined solid phase extraction (SPE), and a primary‐secondary amine in combination with graphitized carbon black. The SPE cartridges were first conditioned and then eluted with acetonitrile. Cypermethrin recoveries from the fortified CPO samples were 87–98% with relative standard deviation (RSD) values of 4–8%, while those for the fortified CPKO samples were 83–100% with RSD values of 3–10%. Since good recoveries were obtained with RSD values below 10% in most cases, the proposed methodology will be useful for the analyses of palm oil samples. The method was successfully applied to the analysis of cypermethrin in real palm oil samples from various parts of Malaysia. No cypermethrin residue was found among 30 samples analyzed.