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.     

Colorimetric determination of total tocopherols in palm oil,olein and stearin

By using a preliminary heat-bleach at 250 C the Emmerie-Engel method has been adapted for the determination of total tocopherols (including tocotrienols) in crude as well as refined palm oil, olein and stearin. Total tocopherol contents found were: Crude palm oil, 794 ppm (n=10); RBD palm oil, 563 ppm (n=13); RBD palm olein, 643 ppm (n=40); RBD palm stearin, 261 ppm (n=19), where n is the number of samples analyzed. During the detergent fractionation no tocopherols were lost, but the tocopherols were concentrated in the olein fraction. The fate of the tocopherols during degumming, bleaching and steam refining/deodorizing of Crude palm olein containing 978 ppm total tocopherol was studied. Over the whole refining process only 8% of the tocopherols were lost, 62% of the original tocopherols were retained in the RBD palm olein, while the remaining 30% were concentrated in the fatty acid distillate which contained 7,040 ppm tocopherol.     

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.     

A lamellar liquid crystal with a vegetable oil

The molecular arrangement was studied in the sodium octanoate and cetyltrimethylammonium bromide (CTAB) system, a lamellar liquid crystal, before and after the addition of a vegetable oil [refined, bleached and deodorized (RBD) palm olein] by means of small-angle x-ray diffraction and optical microscopy. Results from the small-angle x-ray showed the RBD palm olein molecules to be partitioned between the nonpolar methyl group layers for both systems. The water molecules, located between the polar head groups, showed less penetrating tendency into the layered structure of cationic surfactant than into the anionic one, both before and after addition of RBD palm olein.     

Lipase‐catalyzed alcoholysis of vegetable oils

Fatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n‐hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent‐free reaction medium using methanol or 2‐propanol as alcohol substrates. This could be overcome by a three‐step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1‐propanol, 1‐butanol and isobutanol (50‐65% conversion after 24 h) in solvent‐free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.     

Effect of TBHQ on quality characteristics of RBD olein during frying

The changes in quality characteristics of refined, bleached and deodorized palm olein (RBD olein) during heating with intermittent frying for 5 hr/day for weight consecutive days in three systems were compared. The systems were (i) RBD olein without antioxidant (system 1); (ii) RBD olein to which 200 ppm of tertiary butylhydroquinone (TBHQ) had been added prior to frying on the first day (system 2), and (iii) RBD olein which had TBHQ added to a level of 200 ppm at the start of each day. The addition of TBHQ reduced the level of polar components and polymers in the oil, decreased the rates of change in iodine value and dielectric constant and decreased the rate of oxidation of C18:2. The reduction in the rates of these undesirable changes was more pronounced when the TBHQ was added to the system on each day of frying than when there was a single addition of TBHQ prior to frying on the first day. The undesirable effect of adding TBHQ was that it darkened the oil.     

Comparison of visual and automated colorimeters—An international collaborative study

Color as a fundamental quality of edible oils has been determined primarily by visual comparison methods for many decades. The automatic colorimeters introduced recently made it possible to replace the manually operated visual color instrument, which requires experience to master and is often subject to operator variabilities. A previous study with an automatic colorimeter, Colourscan, to measure the colors of refined and refined bleached cottonseed oils showed good agreement (r ²=0.99) with visual color measurements by means of the Lovibond-AOCS Color Scale. The current work is to establish a broad-scale correlation between the automated colorimeter and visual color measurements. In this international effort, factory-processed refined and refined, bleached, deodorized (RBD) canola, corn, cottonseed, peanut, sunflower and soybean oils, as well as refined palm olein, RBD palm oil, and washed, dried, filtered and deodorized tallow were used. A total of 14 laboratories from the United States and Canada, and 16 laboratories from 12 countries outside of North America, participated in this collaborative study. The results of this study, with statistical analyses, are reported.     

Synergistic effects of rosemary, sage, and citric acid on fatty acid retention of palm olein during deep-fat frying

A study to optimize the use of oleoresin rosemary extract, sage extract, and citric acid in refined, bleached, and deodorized (RBD) palm olein during deep-fat frying of potato chips was performed using response surface methodology. Results showed that the natural antioxidants used in this study retarded oil deterioration, as evidenced by retention of fatty acid profiles. The linoleic to palmitic (C18∶2/C16∶0) ratio was chosen as the parameter for optimizing the use of natural antioxidants in RBD palm olein during deep-fat frying. Linoleic (R ²=0.946) and palmitic (R ²=0.825) acids were found to be the most important dependent variables, giving highest R ² values to various antioxidant treatments after 25 h of frying. All three antioxidants had independent significant (P<0.05) effects on the C18∶2/C16∶0 ratio. In fact, significant effects on the C18∶2/C16∶0 ratio of RBD palm olein were also given by a second-order form. A combination of 0.076% oleoresin rosemary extract, 0.066% sage extract, and 0.037% citric acid produced the optimal retention of the essential fatty acid C18∶2. In addition, a synergistic effect among these antioxidants on the fatty acid ratio of RBD palm olein was found.     

Effectiveness of antioxidants in refined,bleached and deodorized palm olein

The addition of antioxidants butylated hydroxytoluene (BHT), propyl gallate (PG), tertiary butylhydroquinone (TBHQ), dilaurylthiodipropionate (DLTDP), and trihydroxybutyrophenone (THBP) at a level of 200 ppm to refined, bleached and deodorized (RBD) palm olein resulted in the retardation of the oxidative deterioration of the oil when stored at 60 C for a period of 10 weeks. The extent of oxidative deterioration was determined by measuring the peroxide and anisidine values and E _{1 cm} ^1% at 232 nm and 268 nm of the oil. Butylated hydroxyanisole (BHA) proved to be a relatively ineffective antioxidant, whereas TBHQ afforded the most protection for the RBD olein.     

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.     

Lipase-catalyzed hydrolysis of palm oil

The hydrolysis of palm oil, palm olein and palm stearin, soybean oil, corn oil and peanut oil by the commercial lipase fromCandida rugosa (formerly known asC. cylindracea) was studied. The optimal conditions for the hydrolysis of palm oil by the lipase were established. The lipase fromC. rugosa exhibits an optimal activity at 37 C and at pH 7.5. The optimal oil to hexane ratio is 1 g of oil to 0.5 ml hexane. The rate of hydrolysis of palm oil by the lipase is linear on a logarithmic scale. Under the same conditions, palm oil and palm olein were hydrolyzed at the same rate, whereas palm stearin was hydrolyzed much more slowly.     

Chemical and physical analyses and sensory evaluation of six deep-frying oils

The performance of three high-oleic canola oils with different levels of linolenic acid [low-linolenic canola (LLC), medium-linolenic canola (MLC), and high-linolenic canola (HLC)], a medium-high-oleic sunflower oil, a commercial palm olein and a commercial, partially hydrogenated canola oil, was monitored by chemical and physical analyses and sensory evaluation during two 80-h deep-frying trials with potato chips. Linolenic acid content was a critical factor in the deep-frying performance of the high-oleic canola oils and was inversely related to both the sensory ranking of the food fried in the oils and the oxidative stability of the oils (as measured by color index, free fatty acid content, and total polar compounds). LLC and sunflower oil were ranked the best of the six oils in sensory evaluation, although LLC performed significantly better than sunflower oil in color index, free fatty acid content, and total polar compounds. MLC was as good as palm olein in sensory evaluation, but was better than palm olein in oxidative stability. Partially hydrogenated canola oil received the lowest scores in sensory evaluation. High-oleic canola oil (Monola) with 2.5% linolenic acid was found to be very well suited for deep frying.     

Determination of free fatty acids in palm oil by near-infrared reflectance spectroscopy

A near-infrared (NIR) spectroscopy calibration was developed for the determination of free fatty acids (FFA) in crude palm oil and its fractions based on the NIR reflectance approach. A range of FFA concentrations was prepared by hydrolyzing oil with 0.15% (w/w) lipase in an incubator at 60°C (200 rpm). Sample preparation was performed in Dutch cup, and the spectra were measured in duplicate for each sample. The optimized calibration models were constructed with multiple linear regression analysis based on C=O overtone regions from 1850–2050 nm. The best wavelength combinations were 1882, 2010, and 2040 nm. Multiple correlation coefficients squared (R ²) were: 0.994 for crude palm oil, 0.961 for refined-bleached-deodorized (RBD) palm olein, and 0.971 for RBD palm oil. Calibrations were validated with an independent set of 8–10 samples. R ² of validation were 0.997, 0.943, and 0.945, respectively. The developed method was rapid, with a total analysis time of 5 min, and environmentally friendly, and its accuracy was generally good for raw-material quality control.     

The Effect of Type of Oil and Degree of Degradation on Glycidyl Esters Content During the Frying of French Fries

The aim of the study was to determine the effect of oil degradation on the content of glycidyl esters (GEs) in oils used for the frying of French fries. As frying media, refined oils such as rapeseed, palm, palm olein and blend were used. French fries were fried for 40 h in oils heated to 180 °C in 30‐min cycles. After every 8 h of frying, fresh oil and samples were analyzed for acid and anisidine values, color, refractive index, fatty acid composition, and content and composition of the polar fraction. GEs were determined by LC–MS. Hydrolysis and polymerization occurred most intensively in palm olein, while oxidation was reported for rapeseed oil. The degradation of oil caused increased changes in the RI of frying oils. Losses of mono‐ and polyunsaturated fatty acids were observed in all samples, with the largest share in blend. The highest content of GE found in fresh oil was in palm olein (25 mg kg^?1) and the lowest content of GE was found in rapeseed oil (0.8 mg kg^?1). The palm oil, palm olein and blend were dominated by GEs of palmitic and oleic acids, while rapeseed oil was dominated by GE of oleic acid. With increasing frying time, the content of GEs decreased with losses from 47 % in rapeseed oil to 78 % in palm oil after finishing frying.     

Frying Quality Characteristics of French Fries Prepared in Refined Olive Oil and Palm Olein

The objective of this study was to compare two oils with different polyunsaturated/saturated (P/S) fatty acid ratios, refined olive oil (P/S 0.75) and palm olein (P/S 0.25), in frying French fries. The chemical qualities of the oil residues extracted from the French fries were assayed for five consecutive batches fried at 1-h intervals. The levels of total polar compounds, free fatty acids, p-anisidine value and phytosterol oxidation products (POPs) were elevated in French fries fried in both oils. The level of total polar compounds increased from 4.6 in fresh refined olive oil to 7.3% in final batches of French fries. The corresponding figures for palm olein were 9.8–13.8%. The level of free fatty acid in fresh refined olive oil increased from 0.06 to 0.11% in final products. These figures for palm olein were 0.04–0.13%. The p-anisidine value increased from 3.7 to 32.8 and 2.5 to 53.4 in fresh oils and in final batches of French fries in refined olive oil and palm olein, respectively. The total amount of POPs in fresh refined olive oil increased from 5.1 to 9.6 μg/g oil in final products. These figures were 1.9 to 5.3 μg/g oil for palm olein.     

Triacylglycerols responsible for the onset of nucleation during clouding of palm olein

This paper discusses the results of an investigation to identify triacylglycerols that induce clouding of refined bleached deodorized (RBD) palm olein, which occurred within 24 h after fractionation. The experiments were conducted in a jacketed glass vessel in which the liquid sample was cooled from 70 to 23°C at a predetermined rate. Clouding began at around 28.5°C. The presence of three different types of saturated triglycerides, namely tripalmitin, dipalmitoyl-myristoylglycerol and dipalmitoyl-stearoyl-rac-glycerol, is critical in the formation of nuclei and thus clouding of the RBD palm olein. This conclusion is based on the significant increase in the relative concentration of these components in the nuclei as compared to the mother oil.     

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.     

Principles of palm olein fractionation: a bit of science behind the technology

Dry fractionation is a well‐established and versatile fat modification technology that can produce a broad spectrum of edible oils and fats. Due to its specific chemical composition, especially palm oil can be processed by this technology into fractions that serve as salad oils, frying oils, margarine fats. Whereas the first step of this multi‐stage production process is well understood, the edible oil industry all over the world is much more often confronted with problems in the second stage of the process, when the liquid palm olein is further fractionated. The process of palm olein crystallization is indeed a lot more difficult to control. This article therefore elaborately explains the main, fundamental causes for this sensitivity of palm olein during the fractional crystallization. It further discusses which and how components present in refined palm olein can be responsible for process instability and how they affect the quality of the end products on an industrial scale. The article also highlights which novelties and innovation in dry fractionation technology are currently under investigation.     

Comparative study of physical methods for lipid oxidation measurement in oils

For the determination of lipid oxidation in oils, electrical, optical, spectroscopic and extraction methods were investigated using rice bran oil and doubly-fractionated palm olein as model systems. The oxidized polar components and dielectric constant of rice bran oil increased very similarly with those of double-fractionated palm olein. In the case of rice bran oil, all of the test methods were shown to possess good statistical correlations. Polar components, dielectric constant, refractive index and polymer content showed relatively better correlations. It was shown that diene and triene content determined by spectroscopic methods was not suitable for more saturated oils such as palm olein.     

Process Technology for the Production of Micronutrient Rich Red Palm Olein

Crude palm oil (CPO) is the richest natural source of carotenes that are destroyed in the conventional processing. There is a growing demand for nutritional products containing bioactive constituents externally fortified or preserved through modified process. A commercially viable process for the production of red palm olein (RPOn) rich in carotenes, tocols and sterols has been developed at pilot scale. The process developed involved neutralization of CPO followed by crystallization at controlled rate of cooling and deodorization of the resultant neutralized and winterized palm olein (WPOn) under controlled conditions of temperature and high vacuum. Analytical data related to micronutrients at each process step was monitored. The RPOn thus produced had not more than 0.25% of free fatty acids (FFA) and it retained more than 80% of the carotenes, about 85% of tocols and 65% of sterols originally present in the CPO. The physico-chemical characteristics of RPOn revealed that it is nutritionally of superior quality compared to that of the commercial refined bleached deodorized (RBD) palm olein currently available in the market. The carotenes, tocols and sterols profile of RPOn by HPLC showed that they were retained in their natural forms.