Crude palm oil (CRPO) was dry fractionated at 25 °C to get crude palm olein (CRPOL, 77%) and crude palm stearin (CRPS, 23%). Low and high melting crude palm stearin (LMCRPS 14.3% and HMCRPS 8.7%) were separated by further fractionation of CRPS with acetone. The physico-chemical parameters and nutraceutical distribution showed variation in different fractions. The CRPO contained 514.7 mg·Kg−1 of β-carotene and 82.6%, 16.1%, 12.5% and 3.1% of it was distributed in CRPOL, CRPS, LMCRPS and HMCRPS respectively. The distribution of phytosterols in fraction was 1870.2, 1996.8, 1190.9, 1290.4 and 115.4 mg·Kg−1 for CRPO, CRPOL, CRPS, LMCRPS and HMCRPS respectively. Total tocopherol composition was 535.5, 587.1, 308.0, 305.6 and 36.2 mg·Kg−1 for CRPO, CRPOL, CRPS, LMCRPS and HMCRPS respectively. The results show that the fractionation of CRPO may be helpful in the preparation of nutraceutical-rich fractions.
Palm oil is obtained from the fleshy fruit mesocarp of
Palm oil is semi-solid in consistency under ambient conditions (20–30 °C). It consists of an admixture of low melting and high melting glycerides which form a heterogeneous slurry in the liquid oil (Timms,
Usually palm oil undergoes refining, bleaching and deodorization steps. Steam distillation is the commonly engaged purification process and operates at high temperatures (250–265 °C) under vacuum (5 mmHg). Under this condition minor components including carotenoids and tocotrienols, which are potent fat-soluble antioxidants present in crude palm oil, are degraded or stripped off and accumulate in the palm fatty acid distillate (PFAD). This mode of purification and further fractionation leads to a loss in minor components from the starting palm oil and would not be available for consumption. The final nutraceutical quality of the product must be evaluated in depth. The evaluation of nutraceutical retention in palm oil by alternate methods like solvent deacidification, enzymatic deacidification instead of conventional steam distillation is also important. Gee (
Crude red palm oil (CRPO) extracted from the Indian grown
Crude red palm oil (CRPO) fractions were collected by two different fractionation methods including dry fractionation and solvent fractionation. Dry fractionation was carried out for the initial fractionation of CRPO. Initially three different batches of CRPO obtained from the industry (20 kg each) were melted at 65 °C, equal portions of these three batches were mixed well and kept for crystallization at 25 °C for 24 h in a temperature controlled chamber. The same amount was fractionated using vacuum filtration into a liquid fraction and solid fraction. These fractions were considered as 77% of liquid olein (CRPOL) and 23% of solid stearin (CRPS). Dry fractionation cannot be used to separate the liquid fraction entrapped in the stearin fraction because of its higher viscosity, low volatility and the small differences between molecular weight and component volatilities of the stearin fraction. The solid fraction (CRPS) was further fractionated by solvent to separate residual olein at 25 °C using acetone in the ratio of 1:4 to the CRPS. The strength of separation of LMCRPS and HMCRPS depends on achieving high solubility and selectivity for the high melting and low melting triglycerides present. Hence, the solvent fractionation was carried out to achieve higher solubility of low melting glycerides from CRPS. The crystallized material was separated by vacuum filtration and the solvent was evaporated using Rotavapor (Buchi Labortechnik, Swizerland) at 40 °C. The fractions obtained were low melting CRPS (LMCRPS) (14.3%) and high melting CRPS (HMCRPS) (8.7%) and used for further study (
Schematic diagram for the preparation of different fractions from crude palm oil.
The color of CRPO and its fractions was evaluated using a Hunter Lab Labscan XE spectrophotometer (Hunter Associates Laboratory Inc, Restone Virginia, USA). 15 mL of sample were placed in a sample cup and were used for transmittance color measurements in liquid media. Color of samples was obtained by using a 2/°C (2° observer/ illuminant C). The results were expressed as L*, a*, b*, respectively indicating lightness (0–100), green-red components and blue-yellow components.
The slip melting point (SMP) of the different fractions was analyzed according to AOCS Official Methods (AOCS O.M. No. Cc 3-25, 1997). Samples were taken in an open capillary tube to the height of 1 cm. Samples were tempered at 10 °C for 16 h. The tubes were heated slowly in a temperature controlled water bath until the fat column rose due to hydrostatic pressure. The temperature at the rising of the fat column was expressed as SMP using the average of four replicates.
The free fatty acid value (FFA) was determined by AOCS O.M.No. Ca 5a-40. Oil was titrated against 0.1 N of NaOH solution in a neutralized alcohol medium using phenolphthalein as indicator and expressed as the percentage of palmitic acid. The peroxide value (PV) of the samples was determined by titration against 0.1 N of sodium thiosulphate solution in the presence of a potassium iodide solution using starch as indicator (O.M.No. Ca 8-53). The saponification value was determined by AOCS O.M.No. Cd 3-25. 5 g of samples were saponified using 50 mL of 5% ethanolic KOH solution in a conical flask connected to an air condenser and boiled until the oil was completely saponified, cooled and titrated with 0.5 N HCl using phenolphthalein as indicator. The iodine value (IV) was determined according to AOCS O.M.No. Cd 1d-92 (Wijs Method). The sample taken in carbon tetrachloride was treated with 25 mL of Wijs solution. The excess of iodine monochloride was treated with potassium iodide and liberated iodine was titrated with 0.1 N of sodium thiosulphate solution using starch as indicator. Unsaponifiable matter was determined according to AOCS O.M.No. Ca 6a-40. 5 g of oil samples were refluxed with 5 mL of 50% KOH solution in the presence of 30 mL ethanol until the oil was completely saponified, extracted with petroleum ether, desolventized and its weight was determined. The experiments were carried out in quadruplicate and the arithmetic mean was reported.
The monoacylglyceride (MAG), diacylglyceride (DAG) and Triacylglyceride (TAG) contents of the samples were estimated by using AOCS O.M.No. Cd 11c-93 (2004). A glass column (i.d. 1.8 cm; length, 30 cm) (Borosil Glass Works Ltd., Mumbai, India) was used in which a silica (100–120 mesh size) bed was prepared from the slurry of silica in petroleum ether. MAG, DAG, and TAG were eluted with a standard solvent system and the quantity of each fraction was determined gravimetrically after evaporating the solvent as per AOCS O.M.No. Cd 11c-93.
The fatty acid methyl esters (FAME) of the oil samples were prepared by transesterification using methanolic KOH, according to AOCS O.M.No. Ce 2-66. The analysis was done using a gas chromatograph (model-GC-20A, Shimadzu Corporation, Japan) equipped with an FID detector and a glass capillary column (30 m×0.25 mm), coated with poly (90% biscyanopropyl/10% cyanopropylphenyl) siloxane with a film thickness of 0.2 µm (SP-2380) (Supelco Analytical, Bellefonte, Pennsylvania, USA). The operating conditions were as follows: nitrogen flow 40 mL·min−1, hydrogen flow 40mL·min−1, air flow 300 mL·min−1, column temperature maintained isothermal at 180 °C, injector temperature 220 °C and detector temperature 230 °C. A reference standard FAME mixture (Supelco Inc., Bellefonte, PA, USA) was analyzed under the same operating conditions to determine peak identity. The FAMEs were expressed as relative area% (AOCS O.M.No. Ce 2-66).
The triglyceride composition was analyzed using a Shimadzu HPLC system consisting of an LC-10A pump, fitted with a 20 µL injector pump and an RID-10A detector. Isocratic separation of the triglycerides was achieved by reverse phase HPLC on a C18 column (Discovery C18 column, 15 cm×4 mm id, 5 µm, Sigma-Aldrich, Bellefonte, PA, USA). The mobile phase was acetone: acetonitrile (70:30,v/v). TAG was calculated as a relative area percentage as per AOCS O.M.No. Ce 5b-89. TAG peaks were identified based on the theoretical carbon number described by Bland
The carotene content was determined by diluting 1g of melted palm oil at 65 °C to 10 mL using acetone and from this a 1 mL aliquot was further diluted to 10 mL with acetone and the absorbance was measured at 446 nm using a UV-vis spectrophotometer Shimadzu UV-1601 (Shimadzu Corporation, Kyoto, Japan) followed by calculation using the diffusion coefficient of 383 and expressed as mg·kg−1 oil (Chandrasekaram
The determination of tocopherol composition by HPLC (Shimadzu) consisted of an LC-10A pump, injector fitted with 20 µL loop and Fluorescent detector. The analysis was carried out with normal phase HPLC separation on a silica column (LichroCART 250-4, Lichosorb Si60 (5 µm) 25 cm×4 mm id column, Merck KGaA, Darmstadt, Germany). The mobile phase was hexane: isopropyl alcohol (99.5:0.5,v/v) at a flow rate of 1mL·min−1 and detected by fluorescence at excitation and emission wavelengths of 290 nm and 330 nm respectively. Tocopherols were quantified based on peak areas with an external standard α-tocopherol. Tocotrienols were expressed as α-tocopherol equivalents as suggested by the AOCS Official Method O.M.No. Ce 8-86 (2004).
HPLC equipped with an LC-10A pump (Shimadzu, Tokyo, Japan), a 20 µL injection loop and a photo diode-array detector was used for the estimation of individual phytosterols in the samples. The temperature was controlled at 30±0.1 °C with a column heater. Separation was performed on a Kromasil 100 C18 5µm column (15 cm×0.4 cm i.d.; Teknokroma, Barcelona, Spain), with 30:70 (v/v) methanol: acetonitrile as mobile phase with a flow rate of 1.2 mL·min−1. The detection wavelength was 205 nm (Sánchez-Machado
Phenolics were extracted with methanol/water (80:20v/v) (Brenes
Squalene in the samples was determined by HPLC according to Nenadis and Tsimidou (
The determination of the content of the coenzyme Q10 was carried out by HPLC (Shimadzu) equipped with (10A VP, Shimadzu, Kyoto, Japan) a UV-detector (SPD-10AV VP, Shimadzu) coupled to a 20 µL loop injector. The isocratic separation of samples was achieved on a C-18 column, 10 µm, u-Bondapack, (4.6×300 mm; Millipore, Milford, MA) using methanol/
The stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) was used for the determination of the free radicalscavenging activity of the samples. Sample sizes of 5, 10, 25, 50, and 75 mg were mixed to an equal volume of 10−4 M toluenic solution of DPPH (4mL). The mixtures were incubated at room temperature for 30 min in the dark and absorbance was read at 517nm against a blank. The RSA was calculated using the following formula:
Physico-chemical characteristics of different fractions prepared from crude red palm oil
Parameters | CRPO | CRPOL | CRPS | LMCRPS | HMCRPS |
---|---|---|---|---|---|
Color | |||||
L* | 43.9±0.0a | 49.8±0.1b | 55.9±0.0c | 48.0±0.01d | 86.2±0.01e |
a* | 28.7±0.1a | 36.5±0.1b | 21.2±0.01c | 28.4±0.02d | 0.8±0.1e |
b* | 39.3±0.7a | 49.7±0.1b | 55.4±0.03c | 47.0±0.04d | 10.7±0.02e |
SMP (°C) | 25.5±0.18a | 23.0±0.18b | 52.0±0.35c | 36.0±0.18d | 61.0±0.35e |
FFA (%) | 7.16±0.04a | 7.36±0.16a | 4.98±0.24b | 6.26±0.17c | 0.87±0.00d |
PV (meq O2·Kg−1) | 5.97±0.02a | 6.85±0.04b | 5.97±0.02a | 6.15±0.04c | trace |
SV (mg KOH·g−1) | 198±1.40a | 197±0.57a | 201±1.3b | 198±0.42a | 203±0.42b |
IV (g I2·100g−1) | 50.6±0.38a | 53.4±0.33b | 34.2±0.25c | 45.8±0.38d | 16.0±0.34e |
USM (%) | 0.54±0.04a | 0.63±0.02a | 0.24±0.04b | 0.42±0.04c | 0.18±0.07b |
MAG (%) | 3.87±0.08a | 3.75±0.12ab | 3.73±0.24ab | 4.21±0.21a | 3.00±0.06c |
DAG (%) | 8.83±0.10a | 10.54±0.16b | 8.24±0.01c | 11.25±0.10d | 5.59±0.12e |
TAG (%) | 80.14±0.12a | 78.56±0.08b | 83.40±0.12c | 78.04±0.24d | 90.54±0.14e |
All values are average±standard deviation. N=4. Values in the same row with a different superscript indicate significant difference at p<0.05. CRPO=Crude Red Palm Oil, CRPOL=Crude Red Palm Olein, CRPS=Crude Red Palm Stearin, LMCRPS=Low Melting Crude Red Palm Stearin, HMCRPS=High Melting Crude Red Palm Stearin.
Where, Acontrol is the absorbance of the control without extract, and Asample is the absorbance of the reaction mixture. The RSA was expressed as IC50 and was calculated using a plot of percent radical-scavenging activity against concentration (mg·mL−1) to determine the concentration of extract necessary to reduce DPPH by 50% (Shimada
All data were expressed as the mean±standard deviation of the quadruplicate analysis. The Tukeys-Kramer Multiple Comparison Test was used to calculate significance differences using the statistical package, GraphPad Instat Demo [DATA-SET.ISD]. Statistical significance was declared at p<0.05.
Palm oil is light yellow to orange-red in color, depending on its carotenoid content. Rossi
The maximum limit of slip melting point (SMP) of palm olein is 24 °C and a further decrease in SMP makes the oil more clear, but this will increase the processing cost (Miskandar
Choon-Hui
The amount of hydroperoxides in oil can be indexed by the peroxide value (PV). The oil with a large amount of unsaturated fatty acids is more prone to oxidation than oil with high levels of saturated fatty acids. The initial CRPO showed 5.97 meqO2·Kg−1 of PV. Primary fractionation products showed a PV of 6.85 and 5.97 meqO2·Kg−1 respectively for CRPOL and CRPS. Secondary fractionation products showed 6.15 meqO2·Kg−1 for LMCRPS and below detection limit (<0.5 meqO2·Kg−1) for HMCRPS. The high levels of PV in CRPOL (6.85 meqO2·Kg−1) and LMCRPS (6.15 meqO2·Kg−1) was mostly due to a higher level of distribution of hydroperoxides in these fractions than in the other fractions and may be due to the formation of new hydroperoxides during the primary and secondary fractionation processes. The PV of HMCRPS indicated that the fractionation process can be used for the preparation of fractions with low or no hydro peroxide.
The saponification value determines the physico-chemical properties of an oil and indicates the average molecular weight of the fatty acids present in the oil. The analysis of SV shows that HMCRPS (203 mg KOH·g−1) had the highest value while CRPOL (197 mg KOH·g−1) had lowest among all the samples. The SV showed an increase from liquid CRPOL (197 mg KOH·g−1) to solid HMCRPS (203 mg KOH· g−1) indicating that changes in the glyceride composition of each sample had occurred. Here the values showed an increase of SV from olein to stearin, indicating a variation in average molecular weight.
The fractionation of CRPO modifies the physico-chemical characteristics of fractions by changing the iodine value (IV) and saturated/unsaturated fatty acid ratio. IV is an indicator for measuring the unsaturation of oils and it can be used to define the quality and functionality of the fractions. The results showed that the most unsaturated fraction was CRPOL (53.4). The least unsaturation was shown by HMCRPS (16.0). The CRPO showed an IV of 50.6 and the fractionation of CRPO provided two fractions with IV of 53.4 and 34.2. The variation in the IV of the two fractions indicates significant levels of separation of saturated fatty acids from the starting material. Similarly, the fractionation of CRPS IV of 34.2 provided two different fractions having IV of 45.84 and 16.02 which indicates the separation of highly saturated glycerides from the CRPS.
The unsaponifiable matter of crude palm oil comprises mainly carotenoids, tocopherols, tocotrienols, phytosterols, squalene and the coenzyme Q. The results showed 0.54% of unsaponifiable matter in the starting palm oil. CRPOL showed enrichment in unsaponifiable matter (0.63%). CRPS showed 0.24% of unsaponifiable matter and the further fractionation showed an enrichment of unsaponifiable matter in LMRPS (0.42%). HMCRPS showed the least amount (0.18%) of unsaponifiable matter as compared to other fractions. The unsaponifiable matter in the samples showed that the level of incorporation of unsaponifiable matter depends on the fluidity.
The content of acylglycerols is an important determinant of oil quality. They will affect the physical properties of oil and can cause cloudiness in oil even at less than 10% of total concentration. DAG, MAG and FFA are the metabolites in the biosynthesis of TAG and the products of lipolytic activity. MAG and DAG are present in significant amounts in palm oil. CRPO consists of 0.21–0.34% MAG. In the present study CRPO showed MAG of 3.78%. The MAG level was higher in LMCRPS (4.21%) as compared to other fractions. A total DAG concentration in CRPO ranging from 5.3 to 7.7% has been reported in the literature (Jacobsberg and Oh,
The fatty acid composition of the CRPO showed that palmitic acid (41.8%), oleic acid (37.4%) and linoleic acid (14.1%) were the major fatty acids in CRPO. The minor fatty acids found were stearic acid (3.5%), myristic acid (1.6%), lauric acid (1.2%), caprylic acid (0.3%) and caproic acid (0.2%) (
Fatty acid composition (%) of crude palm oil and its fractions
Fatty acids | CRPO | CRPOL | CRPS | LMCRPS | HMCRPS |
---|---|---|---|---|---|
Caprylic (C8:0) | 0.3±0.04a | 0.1±0.00a | nd | nd | nd |
Caproic (C10:0) | 0.2±0.01a | 0.1±0.00a | nd | nd | nd |
Lauric (C12:0) | 1.2±0.04a | 0.5±0.02b | 0.2±0.01c | 0.3±0.01d | nd |
Myristic (C14:0) | 1.6±0.02a | 1.2±0.02b | 1.4±0.02c | 1.4±0.02c | 1.5±0.04d |
Palmitic (C16:0) | 41.8±0.35a | 40.9±0.73a | 55.7±0.35b | 43.7±0.73c | 79.7±1.20d |
Stearic (C18:0) | 3.5±0.08a | 3.3±0.14a | 3.9±0.28b | 3.7±0.03ab | 5.7±0.02c |
Oleic (C18:1) | 37.4±0.40a | 42.3±0.21b | 30.6±0.73c | 40.2±0.35d | 10.1±0.06e |
Linoleic (C18:2) | 14.1±0.06a | 11.6±0.03b | 8.2±0.03c | 10.8±0.04d | 3.0±0.04e |
SAFA | 48.6 | 46.1 | 61.2 | 49.1 | 86.9 |
MUFA | 37.4 | 42.3 | 30.6 | 40.2 | 10.1 |
PUFA | 14.1 | 11.6 | 8.2 | 10.8 | 3.0 |
All values are average±standard deviation. N=4. Values in the same row with different superscript indicate significant difference at p<0.05. CRPO=Crude Red Palm Oil, CRPOL=Crude Red Palm Olein, CRPS=Crude Red Palm Stearin, LMCRPS=Low Melting Crude Red Palm Stearin, HMCRPS=High Melting Crude Red Palm Stearin.
The TAG composition of CRPO and its primary and secondary fractions were analyzed. The main TAG of CRPO was POP (25.5%), PPP (20.8%), POO (14.0%), PLP/MOP (7.8%) and POL (6.7%, where P is palmitic acid, O is oleic acid, L is linoleic acid and M is myristic acid. The minor TAGs in CRPO include: PPS (4.8%), SOP (4.7%), OOO (2.3%), SOO (2.0%), MOL (2.0%), OOL (1.2%) and other TAGs with 0.6% (
Triglyceride profile of a) crude red palm oil (CRPO), b) red palm olein (CRPOL), c) red palm stearin (CRPS), d) low melting red palm stearin (LMCRPS) and e) high melting red palm stearin (HMCRPS).
Triglyceride profile of crude palm oil and its fractions
TAG | TCN | CRPO (%) | CRPOL (%) | CRPS (%) | LMCRPS (%) | HMCRPS (%) |
---|---|---|---|---|---|---|
MOL | 42.7 | 2.0 | 2.7 | 1.2 | 2.9 | nd |
MLP/MOM | 43.3/43.4 | 0.4 | 0.6 | 2.2 | 0.7 | 0.2 |
OOL | 44.1 | 1.2 | 2.2 | 0.4 | 1.9 | 0.2 |
POL | 44.7 | 6.7 | 9.9 | 1.6 | 10.6 | 1.0 |
PLP/MOP | 45.3/45.4 | 7.8 | 8.5 | 6.9 | 9.9 | 1.5 |
MPP | 46.0 | 1.3 | 0.1 | 7.3 | 0.2 | 2.7 |
OOO | 46.2 | 2.3 | 3.6 | 3.4 | 3.8 | 1.5 |
POO | 46.8 | 14.0 | 20.6 | 14.4 | 23.7 | 2.2 |
POP | 47.4 | 25.5 | 25.4 | 23.7 | 28.2 | 6.3 |
PPP | 48.0 | 20.8 | 1.6 | 15.2 | 1.5 | 67.3 |
StOO | 48.8 | 2.0 | 3.2 | 2.6 | 2.8 | 0.5 |
StOP | 49.4 | 4.7 | 6.2 | 5.7 | 5.5 | 0.8 |
PPSt | 50.0 | 4.8 | 0.3 | 3.3 | 0.3 | 13.8 |
StOSt | 51.4 | 0.8 | 8.3 | 7.0 | 0.2 | 0.5 |
PStSt | 52.0 | 0.6 | 0.0 | 0.4 | 2.2 | 1.4 |
Others | – | 0.5 | 2.3 | 0.6 | nd | nd |
Σ UUU | – | 3.5 | 5.8 | 3.8 | 5.7 | 1.7 |
Σ SUU | – | 24.7 | 36.3 | 19.8 | 40.1 | 3.6 |
Σ SSU | – | 39.2 | 49.0 | 45.5 | 44.4 | 9.3 |
Σ SSS | – | 27.5 | 2.1 | 26.3 | 4.2 | 85.1 |
Nd=not detected. M=Myristic, O=oleic, L=linoleic, P=palmitic, St=stearic, S=saturated, U=unsaturated. TCN=Theoretical Carbon Number [(ECN-(0.7×L)-(0.6×O], ECN=Equivalent Carbon number [CN-(2×ND), L=linoleic acid, O=Oleic, CN=Carbon Number, ND=Number of Double bond, CRPO=Crude Red Palm Oil, CRPOL=Crude Red Palm Olein, CRPS=Crude Red Palm Stearin, LMCRPS=Low Melting Crude Red Palm Stearin, HMCRPS=High Melting Crude Red Palm Stearin.
The results showed that the carotenoid content of crude palm oil was 514.7 mg·Kg−1 and comparatively higher than the carotene content of Indonesian crude palm oil (456 mg·Kg−1) (Rossi
Nutraceutical composition of crude palm oil and its fractions
Minor components (mg·Kg−1) | CRPO | CRPOL | CRPS | LMCRPS | HMCRPS |
---|---|---|---|---|---|
β-Carotene | 514.7±7.34a | 569.4±9.16b | 338.0±0.93c | 431.5±9.79d | 8.6±0.05e |
Cholesterol | 19.9±0.05a | 21.2±0.07a | 16.1±0.04a | 17.0±0.45ab | 5.1±0.22b |
Stigmasterol | 69.0±0.24a | 72.4±0.28a | 44.2±0.14b | 47.1±1.26b | 4.0±0.17c |
Betasitosterol | 128.1±0.62a | 131.0±0.49a | 80.3±0.15b | 98.0±0.75c | 5.1±0.10d |
Stigmastanol | 1643.2±2.62a | 1772.2±2.02b | 1050.3±0.60c | 1128.3±1.2d | 101.2±0.1e |
Σ Phytosterols | 1870.2 | 1996.8 | 1190.9 | 1290.4 | 115.4 |
α-Tocopherol | 50.0±0.71a | 63.1±0.14b | 38.3±0.35c | 37.1±0.35d | 3.0±0.21e |
α-Tocotrienol | 94.2±0.14a | 107.3±0.35b | 69.0±0.35c | 59.2±0.35d | 5.1±10e |
β+γ-Tocopherol | 3.0±0.07a | 5.1±014b | 2.0±0.03c | 1.00±0.02d | nd |
β+γ-Tocotrienol | 168.3±1.41a | 175.4±1.41b | 55.1±0.35c | 56.2±0.35c | 7.0±0.05d |
δ-Tocotrienols | 220.4±1.41a | 236.2±1.41b | 143.6±0.70c | 152.3±0.70d | 21.1±0.10e |
Σ Tocopherol | 53.0 | 68.2 | 40.3 | 38.1 | 3.0 |
Σ Tocotrienols | 482.5 | 518.9 | 267.7 | 267.5 | 33.2 |
Tocols | 535.5 | 587.1 | 308.0 | 305.6 | 36.2 |
Phenolics | 84.3±0.9a | 87.2±2.1ab | 74.6±9.3a | 78.2±4.1ab | nd |
Squalene | 299.4±24.3a | 360.5±25.4b | 16.4±0.5c | 19.2±4.3c | nd |
Coenzyme Q10 | 40.2±0.11a | 80.4±0.99b | 10.1±0.25c | 16.1±0.28d | nd |
All values are average±standard deviation. N=4. Values in the same row with different superscript indicate significant difference at p<0.05. nd=not detected. CRPO=Crude Red Palm Oil, CRPOL=Crude Red Palm Olein, CRPS=Crude Red Palm Stearin, LMCRPS=Low Melting Crude Red Palm Stearin, HMCRPS=High Melting Crude Red Palm Stearin.
Tocotrienols are the main features of palm oil as compared to other vegetable oils, no other vegetable oil except rice bran oil contains tocotrienols in significant amounts. It is reported that the 70–80% of total vitamin E is constituted by tocotrienols (Chiew
Sterols make up a considerable portion of the unsaponifiable matter in oil. The total sterol content in CRPO is around 500 mg·kg−1. β-Sitosterol is the most abundant sterol (up to 60%). Campesterol, stigmasterol and cholesterol were observed in lower quantities. The following phytosterols were analyzed: cholesterol, stigmasterol, β-sitosterol and stigmastanol. The results showed that cholesterol was present in the smallest amount (19.9 mg·Kg−1) in CRPO. Its distribution in the different fractions of CRPO was 21.2, 16.1, 17.0 and 5.1 mg·Kg−1, respectively for CRPOL, CRPS, LMCRPS and HMCRPS. The Stigmasterol level of the samples showed that there was no significant (p≥0.05) difference in CRPO (69.0 mg·Kg−1) or in CRPOL (72.4 mg·Kg−1). Similarly CRPS (44.2 mg·Kg−1) and LMCRPS (47.1 mg·Kg−1) showed no significant difference in their stigmasterol content. The β-sitosterol level showed 128.1 mg·Kg−1 in CRPO and 131.0 mg·Kg−1 for CRPOL and there was no significant difference (P≥0.05) between CRPO and CRPOL. The fraction CRPS showed 80.3 mg·Kg−1 and the further fractionation distributed β-sitosterol at 9.8 mg·Kg−1 to LMCRPS and 5.1 mg·Kg−1 to HMCRPS. Stigmastanol showed its highest level (1643.2 mg·Kg−1) in CRPO and its fractions as compared to other phytosterols. CRPOL showed enrichment in stigmasterol (1772.2 mg·Kg−1) as compared to CRPS (1050.3 mg·Kg−1). Further fractionation showed an enrichment of stigmasterol in LMCRPS (1128.3 mg·Kg−1) as compared to HMCRPS (101.2 mg·Kg−1).
Squalene is a minor constituent of palm oil. It has been reported that the squalene content of CRPO ranges from 200–500 mg·Kg−1 (Kellens
Ubiquinone, a fat soluble nutrient commonly known as coenzyme, is present in CRPO in the range of 10–80 mg·Kg−1. The level of the coenzyme Q10 in CRPO was 40 mg·Kg−1 and it was enriched in CRPOL (80 mg·Kg−1) after dry fractionation. CRPS contains 10 mg·Kg−1 and further fractionation showed enrichment up to 16.1 mg·Kg−1 in LMCRPS. This result is indicative of the fact that the distribution of the coenzyme Q10 increases with fluidity of the fractions.
The palm fruit is a rich source of water soluble phenolics. Most of these phenolics are removed along with the waste stream during the milling process to extract the oil from the palm fruit. It has been reported that the total phenolic content of CRPO was 91.0 mg·Kg−1 of oil (Szydlowska-Czerniak,
The DPPH radical was used to evaluate the free radical scavenging properties of different fractions of CRPO. The samples with lower IC50 indicate stronger RSA. CRPOL, after 30 min of reaction with DPPH, exhibited greater RSA (IC50=19.2 mg·mL−1) than CRPO (IC50=20.9 mg·mL−1) and other fractions. CRPS showed an IC50 value of 30.7 mg·mL−1, which indicates that the presence of antioxidants is in smaller amounts as compared to CRPOL (19 mg·mL−1). LMCRPS and HMCRPS showed an IC50 value of 26 mg·mL−1 and 83 mg·mL−1 respectively. This indicates the enrichment of antioxidants in LMCRPS during the solvent fractionation of CRPS. The variation in RSA among the samples indicates a distribution of nutraceuticals to a varying extent in the different fractions. With regard to the IC50 value, the effectiveness of RSA in descending order was CRPOL>CRPO>LMCRPS>CRPS>HMCRPS (
Radical scavenging activity of different fractions of crude red palm oil.
Commercial purification steps operate with crude semisolid palm oil at high temperatures. Purified palm oil undergoes fractionation to provide different functional properties to foods. This way of processing leads to a nutraceutical loss especially in carotenoids, to a greater extent. This nutraceutical loss can be controlled by modifying de-acidification methods. The fractionation of crude palm oil based on the melting characteristics of triglycerides provides fractions with different properties. The present study reveals the effect of fractionation on the nutraceutical distribution in different fractions of crude palm oil. The fractions ranged from liquid to solid in their physical state. The information on the physico-chemical characteristics and nutraceutical distribution of different fractions helps in designing suitable de-acidification methods including enzymatic de-acidification and low temperature (room temperature) extraction of FFA using a solvent to retain the maximum of these heat-sensitive nutraceuticals in fractions. The de-acidification limitations associated with CRPOL, CRPS and LMCRPS to meet the standard quality and the quality parameters indicates that HMCRPS is not necessary for purification. The retention of nutraceuticals in the crude palm oil fractions make them useful as a functional food to provide nutraceuticals to consumers.
The authors are grateful to Prof. Ram Rajasekharan, Director, CSIR-CFTRI, Mysore for the infrastructural facilities and keen interest. The first author is grateful to CSIR, New Delhi for the award of a Senior Research Fellowship.